Directory UMM :Data Elmu:jurnal:S:Small Ruminant Research:Vol36.Issue1.Apr2000:
Small Ruminant Research 36 (2000) 33±42
Effect of complex catalytic supplementation with non-protein
nitrogen on the ruminal ecosystem of growing goats
pasturing on shrub land in Mexico
M.A. Galinaa,b,c,*, M. Guerreroa,b, G. Serranob, R. Moralesb,c, G.F.W. Haenleind
a
Facultad de Estudios Superiores Cuautitlan, UNAM, 54000 Cuautitlan, Mexico
Posgrado Interinstitucional en Ciencias Pecuarias, Universidad de Colima, 28000 Colima, Mexico
c
Granja Puma, Municipio del Marques, QuereÂtaro, Mexico
d
Department of Animal and Food Sciences, University of Delaware, Newark, DE 19717-1303, USA
b
Accepted 20 August 1999
Abstract
Thirty-eight young Alpine goats, 16.1 (0.370) kg body weight (BW), were reared at QuereÂtaro, Mexico, grazing on a
semi-arid woody brush (Caducifolio espinoso) range land. The experimental goats (n 20) were pastured daily and
supplemented with 200 g/day of a complex catalytic feed (CCF). It consisted of molasses (14±18%), urea (8±10%), salt (3±
4%), limestone (3±4%), cottonseed meal (13±18%), rice polishing (10±13%), corn (11±12%), poultry litter (9±10%),
commercial mineral salt (1.3%), ammonium sulfate (0.3±0.5%), cement kiln dust (1.5%), and animal lard (10±15%). The
control goats (n 18) were supplemented daily with 300 g of a balanced concentrate (BC), containing 1.5% commercial
mineral salt, 60% corn, 32.5% wheat bran, and 4% soybean oil meal. Stocking rates varied from 1.45 to 1.85 AU/ha and daily
stocking rate from 36.4 to 58.6 AU/ha. At all times, ®brous forages were available exceeding the voluntary dry matter intake.
One ®stulated goat was kept in each group. Growth of the experimental goats averaged 95 g/day (3) compared to 76 g/day
(5) of the controls (P < 0.005) in 150 days from June to November. Supplementation per kg BW was from 17.5 to 10.4 g BC/
day for the control goats; the experimental goats received 12.2±6.5 g CCF/day. Weight gain in response to fermentable
carbohydrates (FC) averaged 8.95 g BW gain/g FC/day for the control BC goats, compared to 28.2 g BW gain/g FC/day for
the experimental CCF goats. Daily supplies of FC to goats on CCF supplementation were always below the limits for
celullolysis at 6 g/day, while FC supplies of BC rations to the control goats always exceeded them. After 2 h of shrub land
pasture, the ruminal pH rose when CCF was offered and stayed above 6.6 during 12 h, while the ruminal acidity in BC goats
went down to pH 5.57 at 6 h and rose to 6.5 by 12 h. Ammonia (NH3 mg/l) in ruminal liquid of CCF goats was higher
(P < 0.01) in average and all but one sample. Total cost per animal per day including shrub land pasture, management,
medicine and salaries was US $0.06 for experimental goats and US $0.09 for controls (market price for goat meat was US
$1.15/kg; US $1.00 10 Mexican Pesos, November 1998). Daily gain varied during the study period from 77 to 85 g/day in
BC control goats compared to 92±97 g/day in experimental CCF goats. CCF supplementation to shrub land pasturing resulted
in signi®cantly greater weight gains apparently due to elevated ruminal pH, higher availability of fermentable carbohydrates
and ruminal ammonia, augmenting ruminal ecosystem, digestibility and voluntary feed intake. The use of local shrub land
*
Corresponding author. Tel.: 0052-331-411-33; fax: 0052-331-275-81.
E-mail address: galina@cgic.ucol.mx (M.A. Galina).
0921-4488/00/$ ± see front matter # 2000 Published by Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 1 1 5 - 7
34
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
resources and complex catalytic supplementation with non-protein nitrogen provided greater pro®tability from this feeding
system for growing goats than the traditional balanced concentrate feed supplementation. # 2000 Published by Elsevier
Science B.V. All rights reserved.
Keywords: Nutrition; Goats; Growth; Ruminal ecosystem; Supplementation; Shrub land; Urea
1. Introduction
Goats raised on shrub range land, which is rich on
®brous forages, have low performance in body weight
(BW) gain of no more than 50 g/day (Galina et al.,
1993). Forages and crop residues, rich in ®ber and low
in protein are the most abundant feeds for ruminants in
third world nations (Preston, 1995). Recent studies in
Mexico with large ruminants aimed at achieving better
performance from local forages by using complex
catalytic feed (CCF) supplementation (Galina et al.,
1997). Strategies to improve utilization with CCF
feeds in dairy goats have been reported (Morales
et al., 2000).
Utilization of high ®ber diets with CCF needs to
develop new feeding standards, because ruminal protein and energy will add to the nutritional offer in the
feed to the animal (Jackson, 1980; Galina, 1994;
Graham, 1983; Preston, 1995). Goat requirements
have been reviewed (AFRC, 1998), after the work
of Morand-Fehr and Sauvant (1988) and NRC (1981).
Energy requirements for goats are 104.7 kcal/kg
BW0.75 for maintenance plus 25±50% increase to
cover cost of walking, grazing and other activities,
and 13.8 Mcal/kg BW gain (AFRC, 1998). Present
information on energy and protein contents of a feed
has little bearing on how animals utilize their feed,
when digestibility is improved due to bacterial augmentation from favorable energy contents in ration,
resulting in more intestinal true protein. It have even
been suggested that traditional nutritional approaches
should be abandoned for forage-based diets under
®brous forage management (Leng, 1990).
Nutritional utilization of ®brous forages requires
that the imbalance of nutrients for both rumen microorganisms and the host animal must be corrected for
better nutrition of rumen bacteria by providing energy
and nitrogen, which then results in improved bypass
nutrients to reach the intestines for higher production
by the host animal with lowered cost (érskov, 1994;
Wells and Russell, 1996; Russell and Wilson, 1996;
Weimer, 1996).
Better understanding of rumen function and the role
of CCF supplementation has been tested in Mexico
(Galina et al., 1997). Recent studies lead to the concept of ``balancing nutrients'' by providing high protein to energy ratios in absorbed nutrients, and
improving productive ef®ciency (Leng, 1990). Goats
can be considered as animals with a two-compartment
system (Morales et al., 2000). Ef®cient microbial
fermentation relies on the products of the rumen
and those digestible feed components that escape
fermentation (Preston, 1995). Under laboratory conditions, many factors can be isolated and studied in
detail, but few studies have attempted to elucidate
simultaneously the interaction of many factors that
result in the ef®ciency of end-product utilization by
the animal in production trials (Leng, 1990). The
importance of the type of supplement used when
evaluating forages has been emphasized by many
studies (Sanson, 1993). The addition of soluble carbohydrates to diets can have a negative effect on
forage intake and ®ber digestibility (Purroy et al.,
1993). The hypotheses for this decrease in intake
include decreased ruminal pH, a substitution effect,
competition for essential nutrients among cellulolytic
and non-cellulolytic bacteria, and the possible use of
alternative energy sources by cellulolytic bacteria
(Mould, 1989). Many workers found that supplementing basic forage diets of low digestibility with small
quantities of feed that are rich in digestible cellulose or
hemicellulose will increase forage digestibility (JuulNielsen, 1981).
The effect of supplementation with feeds balanced
in easily digestible carbohydrates in complex catalytic
feeds while pasturing on shrub land is unknown. The
objective of the present study was to examine the
effect of a complex catalytic supplementation with
non-protein nitrogen as urea on the utilization of shrub
land by growing goats. The study was to be performed
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
in QuereÂtaro, Mexico, with 38 goats pasturing brush
land and supplemented with complex catalytic feeds.
The study should allow balancing the nutrients needed
by the rumen bacteria and measure the effects of
modifying the ecosystem with suf®cient bypass nutrients on goat growth and economic feasibility. Traditionally balanced supplementation (Morand-Fehr and
Sauvant, 1988) was to be employed for control goats.
2. Material and methods
The study was conducted on the ``Puma'' farm in
the Cerro Prieto region, QuereÂtaro, Mexico, at 208350
latitude North and 1008180 longitude West. The altitude was 1950 m above sea level. Climate is classi®ed
as Bs 1 kw (w) (e), described as dry semiarid with
isolated rains in the winter and a total of 460 mm of
average precipitation per year (GarcõÂa, 1973). The
research was performed on 40 ha of shrub range land
with grasses: Bouteloua curtipendula, Chloris virgata,
Bothriochloa saccharoides, Leptochloa saccharoides,
Leptochloa dubia, Rhyncheltythurum roseum, Panicum obtusum, Bouteloua repens, Aristida adscensionis, Setaria parvi¯ora, Urochloa fasciulata;
leguminous trees: Prosopis laevigata, Acacia farnesiana, Acacia schaffneri, Mimosa biuncifera; and
shrubs: Celtis pallida, Jatropha dioica, Zalazania
augusta, Verbasina serrata, Opuntia spp.
A production of 800 kg DM/ha/year was calculated
(Galina et al., 1998). Grazing management and techniques for shrub land evaluation was published by
Puga (1998). Stocking rates varied from 1.45 to
1.85 AU/ha and daily stocking rate from 36.4 to
58.6 AU/ha. At all times, ®brous forages were available exceeding the voluntary dry matter intake.
Thirty-eight young Alpine goats, 16.1 (0.37) kg
BW, were allocated into two treatment groups in a
production function design. Animals were weighed
every 15 days. On experimental group of 20 goats
were pastured daily and supplemented with 200 g/day
of a complex catalytic feed mixture (CCF) consisting
of molasses (14±18%), urea (8±10%), salt (3±4%),
limestone (3±4%), cottonseed meal (13±18%), rice
polishing (10±13%), corn (11±12%), poultry litter (9±
10%), commercial mineral salt (1.3%), ammonium
sulfate (0.3±0.5%), cement kiln dust (1.5%), and
animal lard (10±15%). The control group of 17 goats
35
was kept on similar management but fed 300 g/day of
a traditional balanced concentrate (BC) composed of
1.5% commercial mineral salts, 60% corn, 32.5%
cottonseed meal, and 4% soybean oil meal. Chemical
feed analyses were performed according to AOAC
(1995); determination of ®ber contents according to
Van Soest and Wine (1967) and Goering and Van Soest
(1975) methods; total energy with a calorimetric bomb
after Hill et al. (1958) and Robinson (1984); shrub
land forages were combined for chemical analyses
with the method of Puga (1998).
Cellulolysis and rumen eco-environment was determined by using one ®stulated goat in each treatment
group to measure pH and ruminal ammonia (N±NH3)
levels. Each goat was sampled every 2 h after supplementation every 15 days, as described by Beatman
(1970), with a portable recorder (Orion 250-A)
equipped with an ion selective electrode for ammonia
(Orion 95-12). From the chemical analyses of the two
supplements the contents and supplies of fermentable
carbohydrates were calculated in g/day. Supplementation in g/day was also recorded monthly in g/kg BW.
Daily voluntary intake was determined for both supplements and for the forages in pasture according to
INRA (1988).
Statistical analyses for pH and ammonia were
performed comparing means with SAS (1996)
procedures (P < 0.05). The statistical model was:
Yij m ti Eij, where Yij is pH or NH3 jth observation of the ith treatment; m the overall mean; t the
treatment effect; i the ith treatment (i 1, 2 supplement type); j is the jth observation (j 1, 2, . . ., 4
(pH); 1, 2, . . ., 4 (NH3) observation); and Eij is the
error.
Statistical analyses of the 4 4 Latin square design
were performed with ANOVA (SAS, 1996), and
differences between means were analyzed according
to Tukey (P < 0.05). The model was: Yijkl m Ai
Bj Tt Eijkl; where Yijkl are variables such as goat
growth, supplementation g/kg BW, fermentable carbohydrates in g/kg BW, and supplementation g/day/g
BW gain; m is the overall mean; Ai the effect from the
ith line (goat); Bj the effect from the jth column (time);
Tt the effect of treatment shown in the jth line/column;
and Eijkl is the error associated with the experimental
unit line/column (ij).
Statistical analyses were also performed by multiple regression comparing variables (SAS, 1996).
36
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Monthly consumption and nutrient requirements as
suggested by Morand-Fehr and Sauvant (1988) were
dependent variables. By regression equation, the nutrient density of the feeding treatments and the total
requirements of the grazing goats were the determinants of probable consumption.
3. Results
Table 1 shows monthly BW of the control and
experimental groups. The amounts of voluntary intake
of BC supplementation went from 17.5 g/day/kg BW
at the beginning of the trial in control goats to 10.4 g/
day/kg BW at the end, when the 300 g/day were
offered. The intake of CCF supplementation went
from 12.2 to 6.5 g/day/kg BW, when 200 g/day were
offered. At the end of the trial, BC supplementation
was 59% lower from initial consumption, CCF supplementation 53% lower. While the amounts offered
remained constant throughout the trial, the BW
increased almost two-fold. Total dry matter intake
(DMI) by the CCF group increased from 3.1% to
3.8% of BW, while the DMI of the BC group
decreased from 3.3% to 2.9% of BW. Forage intake
increased from 265 to 536 g/day in BC, while in CCF
goats it changed from 311 to 973 g/day. Goats in the
CCF group consumed signi®cantly more forage than
the BC controls.
Experimental CCF goats showed an average growth
of 95 g/day (3) compared to 76 g/day (5) (Table 1)
for BC controls during 150 days from June to November (P < 0.005). The rotationally grazed shrub land
pasture consistently had more total forage available
during midsummer and late summer. However, once
the period of plant regrowth ®nished in early autumn,
the rotational pasture had similar or less total forage
standing, while grass was available at all times
exceeding the voluntary dry matter intake. Experimental CCF feeds were consumed for 6±8 h after
offering, in comparison with BC rations, which were
eaten in 15±30 min after supply.
Fig. 1 shows the amounts of fermentable carbohydrates consumed daily/kg BW calculated from the
chemical analyses of the feeds. Response to fermentable carbohydrates in terms of grams BW gain/day/g
FC averaged 8.95 for BC, compared to 28.27 for CCF
goats (P < 0.05) (Table 1). Daily supplies of FC to
goats on CCF supplementation were always below the
limits of 6 g/day for cellulolysis (Mould, 1989), while
FC supplies of BC rations to the control goats always
exceeded them.
Table 1
Monthly BW, supplement fed/kg BW/day, fermentable carbohydrates supplied/kg BW/day and gain/day in each period for CCF and BC
supplement treatments (BW: body weight; FI: forage intake; BC: balanced concentrate; CCF: complex catalytic feed; DMI: dry matter intake;
d: day; FC: fermentable carbohydrates; ab: statistical difference (P < 0.05) among pairs with same shading)
Days
0
30
60
90
120
150
Mean
BW (kg), BC goats
BW (kg), CCF goats
BC total (g/day)
CCF total (g/day)
FI±BC group (g)
FI±CCF group (g)
Total DMI BC (g)
Total DMI CCF (g)
DMI (%) BW±BC
DMI (%) BW±CCF
BC (g/kg) BW
CCF (g/kg) BW
FC (g/day) BC
FC (g/day) CCF
FC (g/g) BW BC gain
FC (g/g) BW CCF gain
BC gain (g/day)
CCF gain (g/day)
17.14
16.41
300
200
265
311
565
511
3.3
3.1
17.50
12.18
11.02a
4.62b
19.45
19.29
300
200
387a
536ab
687
736
3.5
3.8
15.42
10.36
9.71a
3.93b
7.92a
24.42b
77a
96b
21.55
22.19
300
200
400a
617ab
700a
817b
3.2
3.7
13.92
9.01
8.76a
3.42b
7.99a
28.36b
70a
97b
21.40
25.06
300
200
346a
752ab
646a
952b
3.0a
3.8b
12.44a
7.98b
7.83a
3.03b
10.85a
31.68b
85a
96a
26.60
27.93
300
200
478a
832ab
778a
1032b
2.9a
3.8b
11.27ab
7.16ab
7.10a
2.72b
11.69a
35.29b
83a
96a
28.84
30.68
300
200
536a
973ab
836a
1173b
2.9a
3.8b
10.40ab
6.51ab
6.55a
2.47a
11.45a
37.24b
75a
92b
22.44 4.4
25.59 5.35
300
200
402 95.7a
670 234b
702 95.7a
870 234b
3.1 0.24a
3.7 0.28b
13.39 2.66
8.97 2.31
8.49 1.67a
3.36 0.80b
8.95a
28.27b
76a
95b
37
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Fig. 1. Total supplementation g per day, total fermentable carbohydrates g/day and limit of carbohydrate supplementation g/day for
Cellulolysis according to Elias (1983).
Table 2 shows the chemical composition of forages,
CCF and BC supplements. Crude protein contents for
both forages were 7.68% and 8.10%, respectively;
metabolizable energy was 2.12 and 2.49 Mcal for
BC and CCF forages, respectively. Supplements contained 19.8% crude protein for BC and 26.13% for
CCF, due in part to the amount of urea. The table also
shows crude ®ber, NDF, ADF, cellulose, hemicellulose and lignin contents, the later above 8% in both
forages.
Table 3 summarizes the ruminal kinetics of pH
over time in goats fed CCF or BC while pasturing
shrub land. After 2 h on CCF the pH rose and stayed
above 6.6 for 12 h, while the ruminal acidity in
Table 2
Chemical composition of forages, BC and CCF supplements (CCF: complex catalytic feed; BC: balanced concentrate; CCF forage: mixture of
forages consumed by CCF goats; BC forage: mixture of forages consumed by BC goats)
Dry matter (%)
Ash (%)
Ether extract (%)
Crude protein (N 6.25) (%)
Crude fiber (%)
Neutral detergent fiber (%)
Acid detergent fiber (%)
Cellular content (%)
Cellulose (%)
Hemicellulose (%)
Lignin (%)
Nitrogen free extract (%)
Total digestible nutrients (%)
Metabolizable energy (Mcal)a
Digestible energy (Mcal)a
Total energy (Mcal)a
a
Mcal/kg dry matter.
BC forage
CCF forage
BC
CCF
93.69
5.08
2.70
7.68
36.04
75.17
39.73
34.83
32.90
67.27
8.54
61.50
95.49
2.12
3.59
4.37
99.65
9.21
1.08
8.10
35.81
68.82
45.75
31.17
31.67
65.37
9.48
60.80
92.91
2.49
3.35
4.08
90.53
5.60
4.07
19.83
12.56
68.40
13.16
31.59
7.84
55.23
4.86
57.94
99.89
2.83
3.61
4.39
93.12
18.89
9.88
26.13
5.00
37.84
16.66
62.15
8.01.
21.18
4.90
40.10
99.99
3.05
3.71
4.53
38
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Table 3
Ruminal kinetics of pH over time in goats fed CCF or BC on shrub
land pasture (CCF: complex catalytic feed; BC: balanced
concentrate; *A,B: means with different letters indicate statistical
signi®cance (P < 0.01); a,b: means with different letters indicate
statistical signi®cance (P < 0.01))
Hours
0
2
4
6
8
10
12
Average pH
CCF
BC
ab
6.75 0.50
6.98ab 0.09
6.80ab 0.16
6.60b 0.26
6.61b 0.29
6.66ab 0.16
6.69ab 0.29
6.72*A 0.10
6.58a 0.30
5.93ab 0.36
5.59b 0.06
5.57b 0.24
6.00b 0.22
6.12ab 0.28
6.50b 0.23
6.04*B 0.39
BC goats went down to pH 5.57 at 6 h and rose to 6.5
by 12 h.
Table 4 shows the ruminal kinetics of ammonia
(NH3 mg/l) over time in goats fed CCF or BC while on
shrub land pasture. Ammonia was higher (P < 0.01) in
the CCF group on an average and in all but one
sample.
Total cost per animal per day including grass,
management, medicine and salaries was US $0.06
for the experimental CCF goats but US $0.09 for
control BC goats. Market price per kg meat was US
$1.15 calculated in Mexican Pesos per dollar
exchange rate of November 1998 (1 US $ 10 Pesos).
Daily gain varied during the trial from 70 to 85 g/day
in control BC goats to 92 to 97 g/day in experimental
CCF goats (Table 1).
Table 4
Rumen kinetics of ammonia over time (NH3 mg/l); ruminal liquid
from goats pastured on shrub land supplemented with CCF or BC
(CCF: complex catalytic feed; BC: balanced concentrate; a,b:
means with different letters have statistical signi®cance (P < 0.01)
Hours
0
2
4
6
8
10
12
Average NH3
CCF
BC
a
11.04 15.0
27.49a 25.0
24.40a 24.1
13.24a 15.7
13.99a 14.2
16.74a 15.6
14.73a 12.7
17.37a 16.3
7.98a 4.8
16.50b 8.9
14.02ab 9.1
14.10ab 8.5
9.95a 2.67
5.89a 0.91
4.07a 0.99
10.30b 4.0
4. Discussion
Results showed differences in growth rate
(P < 0.05) for experimental over control goats, suggesting that daily gains of 100 g (AFRC, 1998) can be
obtained with good nutritional management. The protein needs of the experimental goats for growth were
met by correcting the nutrient imbalance of the grasses
and providing a continuous non-protein nitrogen
source of urea (Hennessay and Williamson, 1990)
or ammonium sulfate to the rumen bacteria (Leng,
1990; Silva et al., 1989). Ruminal bypass protein, e.g.
®shmeal, and bypass carbohydrates in corn and rice
polishings have proven important in cattle performance when fed ®brous forages (Elliot et al., 1978;
Leng et al., 1977; Naidoo et al., 1977; Galyean, 1996;
Poppi and McLennan, 1995). Bypass protein in our
experiment was supplied by the legume tree leaves
(Puga, 1998). Growth in the control goats was supported mainly by the high protein content in the BC
ration, which hand a substitution effect for the poor
forages (Tables 1 and 2). Low rumen pH and less
ammonia contents in the control goats explained the
effects of concentrate intake in pastured goats. The
high amounts of fermentable carbohydrates also
affected cellulolysis (Elias, 1983; Madrid et al.,
1998). When microbial protein is the main source
of nitrogen for growth, there must be considerable
concern covering the requirements by rumen microbes
for ef®cient growth. Meang et al. (1989) suggested
that microbial growth ef®ciency was improved in
washed rumen microbes by including amino acids
as well as urea in the incubation medium. Amino
acids such as leucine, lysine, threonine and tryptophan
were supplemented in the CCF experimental diet by
the addition of poultry litter as also demonstrated by
Zinn et al. (1996).
Previously, Elias (1983) has shown that small
amounts of easily available energy from fermentable
carbohydrates like in molasses, sugar cane or starch
could increase cellulose digestibility because ruminal
microorganisms are not capable to obtain energy from
cellulose for their cellular functions until the molecule
is digested. Therefore, goats, sheep and cattle supplemented with low levels of sugars between 2 and 6 g/kg
BW/day could improve cellulose digestibility because
rumen microorganisms now have energy for their
cellular functions. Similar ®ndings have been reported
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
when low amounts of citrus by-products were supplemented at 100 g/day and improved digestibility and
intake of DM of urea±NaOH treated straw based diets
(Madrid et al., 1998). The explanation was that at low
levels the supplementation with degradable carbohydrates such as from citrus by-products supplied energy
for ruminal microorganism and improved the ruminal
ecosystem for cellulolysis and straw digestion
(Madrid et al., 1998). However, at more than 6 g of
fermentable carbohydrates (FC) per kg of BW, cellulose digestibility diminished because concentrate supplementation substituted for forage. It has been shown
that moderate amounts of cellobiose added to pure
cultures of cellulolytic bacteria inhibit cellulose
hydrolysis, which suggests an enzyme depressing
system based on less speci®c activity for cellulose
from microorganisms growing in a cellobiose-rich
environment (Elias, 1983). Similar results have been
published by Madrid et al. (1998), when higher levels
of digestible carbohydrates in supplements depressed
the digestion of straw. This is also explained by the
negative effects on cellulolytic activities of the rumen
micro¯ora, when high levels of energy supplements
decrease ruminal pH (Rihani et al., 1993). In our study,
CCF fermentable carbohydrates were always below
the above limits (4.62±2.47 g FC/day) (Table 1) favoring the ruminal ecosystem to stimulate feed intake and
BW gain, while FC from the BC ration was always
above the limits (11.02±6.55 g/day) apparently affecting cellulolysis.
Daily weight gain in the present work apparently
did not equal the levels of metabolizable energy in the
forages (Table 2). Increased voluntary dry matter
intake supplied more energy, because of improved
digestibility from the improved action of cellulolytic
bacteria (Fibrobacter succinogenes, Ruminococcus
albus, R. Flavefaciens) favored by the continuous
presence of non-protein nitrogen (Leng, 1990; Fondevila and Dehority, 1995; Preston, 1995; Brown et
al., 1988). This is indicated by the higher levels of
ruminal ammonia (17.37 mg/l; P < 0.01) (Table 4) in
CCF supplemented goats compared to the BC goats
(10.30 mg/l), creating a favorable protein/energy ratio
for bacterial protein formation (Leng, 1991). The
experimental CCF supplement was consumed over
a period of 6±8 h, while the commercial BC supplement was ingested in less than 30 min after offering
(15±30). This mixture could have insured suf®cient
39
ammonia for microbial growth (50±80 mg NH3±N/l
rumen ¯uid) (Leng, 1991), but the level of ammonia
needed is dependent on the pH of the rumen (Smith,
1984).
Forage offer was kept high all time through the
rational technological mobile grazing (RTMG) system
developed by Puga (1998), boosting digestibility of
the basal diet (Juul-Nielsen, 1981; N'dlovu and
Buchannan-Smith, 1985). Grass was allowed to regrow before returning to be pastured (Puga, 1998).
Sudana and Leng (1986). Showed that supplements
must provide continuous adequate levels of ammonia
for persistent growth of both ®brolytic and saccharolytic microorganisms, by providing in the supplement high concentrations of salt±urea and molasses±
urea to aviod fast intake. Supplementation with
branched-chain VFA has been reported to increase
the apparent ¯ow of microbial-N to the duodenum
(Silva and érskov, 1988). Ruminal pH supported by
calcitic limestone and cement kiln dust could have
played a key role of maintaining cellulolytic bacteria
in our experimental animals (Wheeler, 1979; Wheeler
et al., 1981a, b; Noller et al., 1980).
Rumen acidity is produced by high intake of
starches. Amylose and amylopectin are broken down
early under the in¯uence of amylases. Ruminal pH
environment for microbial activity was lower in the
BC supplemented goats (Table 3). CCF supplementation kept pH above 6.6 all the time, while BC
decreased pH to 5.57 inhibiting celullolysis (Leng,
1991). This may explain the lesser growth of the BC
control goats, depending on energy and protein from
their supplementation, because of less bacterial protein formation. As rumen pH is depressed below 6.2
(Istasse et al., 1986), cellulolysis progressively
decreased and ceased altogether at rumen pH of
around 5.9 (érskov, 1994; Russell and Wilson,
1996; Russell et al., 1979; Weimer, 1996).
Sulfur and phosphorus have been proven to be
essential for bacterial growth (Leng, 1990) as was
assured in our experimental diets. In general practice
there is either no mineral supplement provided or a
``shot gun'' mixture is given as salt licks (McDowell
et al., 1984). In this study, molasses, which is already
rich in minerals was suitably forti®ed with minerals
(Kunju, 1986). Acetic acid does not seem to be a major
constrain to oxidation, because the ruminant reacts to
excess supplies by excreting acetate in the urine
40
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
(érskov, 1991). Long-chain fatty acids in animal lard,
as provided in the CCF supplement, potentially generate reduced nicotinamide adenine dinucleotide
(NADPH) and electron acceptors (NAD) for
increased use of acetate. This and the high energy
density of the animal lard may explain the better
growth performance of the CFF goats on less supplement (200 vs 300 g/day) than the BC controls
(Houtert, 1993).
Molasses as a cheap source of FC, and the buffer
effects of limestone and cement kiln may explain the
complex relationships established by this feed in
manipulating ®ber digestion in the rumen (érskov,
1991). High levels of molasses±urea have been successfully used for fattening of cattle on pasture in
Australia (Anon, 1984), Colombia (Huerta and GonzaÂlez, 1987) and Cuba (ValdeÂs and Delgado, 1990).
It could be suggested from the present results that
goat kids adequately supplemented with small quantities of essential nutrients performed equally well on a
lower digestibility feed, as animals on higher digestibility forage. Pasture management was the other key
to obtain gains from grass offered throughout the study
(Puga, 1998). Heat increment of added acetogenic
substrates will depend on the pattern of fermentation
in the rumen, VFA and the balance of protein available
from the intestine. Goats need to oxidize acetate, the
major thermogenic substrate. Ruminants con®ned to
calorimeters are usually maintained at what is supposed to be thermoneutrality, however, in our study,
animals were exposed to heat and cold (rain) stress and
they responded metabolically according to the insulative properties of their skin. Variances in weekly
gains were related to environmental effects. Acetogenic substrate is the major source of ATP for muscle
metabolism (Pethick, 1984), therefore acetate formation in this study could explain the growth of the
supplemented goats (Leng, 1990).
5. Conclusion
Utilization of ®brous diets by ruminants can be
manipulated in various ways. Digestibility and intake
was improved as evidenced by superior weight gain of
95 g/day for CCF goat kids compared to 76 g/day by
BC goats. This was apparently due to elevated rumen
pH and ammonia levels augmenting the bacterial
ecosystem by offering essential amino acids, longchain fatty acids, non-protein nitrogen, calcium, sulfur
and phosphorus, which in turn improved cellulose
digestion. Direct bypass protein and glycogenic carbohydrates from the rumen are other key ingredients
to the present results. Use of the local resources of
shrub land pasture provided the economical feasibility
and pro®tability of the diet.
Acknowledgements
This research was supported by projects SIMORELOS CONACYT 9501075, 970301029 and PAPIIT
217798 UNAM.
References
AFRC, 1998. The nutrition of goats. AFRC Technical Committee
on Responses to Nutrients, Report 10. CAB International, UK
and New York, 118 pp.
Anon, 1984. Molasses 8% urea. The supplement that saved
North Queensland cattle in the big drought of 1982 and 1983.
Beef cattlemen's Union. Mackay region. Australia 35 pp.
AOAC, 1995. Of®cial Methods of Analysis. Association of Of®cial
Agricultural Chemist, 16th ed. Washington, DC, USA, 600 pp.
Beatman, J.V., 1970. In: Herrero-Hernandez (Ed.), NutricioÂn
Animal. Manual de MeÂtodos AnalõÂticos (Animal Nutrition.
Manual for Analytic Methods). Mexico, 60 pp.
Brown, W.F., Pitman, W.D., Mislevy, P., 1988. Intake and
digestibility and performance by cattle grazing Cynodon
varieties. Nutr. Rep. Int. 38(6), 1201 ±1209.
Elias, A., 1983. DigestioÂn de pastos y forrajes tropicales (Digestion
of tropical pastures and forages). In: Los Pastos en Cuba.
Instituto de Ciencia Animal, Cuba, pp. 187±247.
Elliot, R., Ferreriro, H.M., Priego, A., Preston, T.R., 1978. Rice
polishing as a supplement in sugar cane diets: the quantities of
starch (glucose polymers) entering the proximal duodenum.
Trop. Anim. Prod. 3, 30±35.
Fondevila, M., Dehority, B.A., 1995. Interaction between Fibrobacter succinogenes, Prevotella ruminicola, and Ruminococcus
¯avefaciens in the digestion of cellulose from forages. J. Anim.
Sci. 74, 678±684.
Galina, M.A., 1994. Sistemas Pecuarios biosostenibles y biodiversos. Una alternativa de produccioÂn animal ante el deterioro
ambiental y la contaminacioÂn. (Biodiverse and biosustainable
livestock production systems. An alternative to animal production and deterioration of the environment and pollution). Av. en
InvestigacioÂn Agropecuaria, Mexico 3, 48±75.
Galina, M.A., Morales, R., Hummel, J., 1993. ComparacioÂn de dos
modelos de manejo alimenticio para la produccioÂn de leche de
caprinos. (Comparison of two models for nutritional management of dairy goat production). Pastos y Forrajes, Cuba 16,
263±270.
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Galina, M.A., Pineda, J., Rosado, J., Aguilar, A., Puga, D.C.,
Rubio, C., Murillo, J.C., 1997. Fattening of steers Zebu F1
cross fed high fermentable carbohydrate diet of a continuous
non-protein nitrogen and bypass protein supplement. Adv.
Agric. Res. MeÂxico. 6, 22±32.
Galina, M.A., Puga, D.C., HernaÂndez, A., Haenlein, G., 1998.
Biodiverse and biosustainable system with goats in
Mexico: importance of the forage bank. Small Rumin. Res.
27, 19±23.
Galyean, M.L., 1996. Protein level in beef cattle ®nishing diets:
industry application, University research and systems results. J.
Anim. Sci. 74, 2860±2870.
GarcõÂa, E., 1973. Modi®caciones al sistema de clasi®cacioÂn
climaÂtica de KoÈppen (Modi®cations of KoÈppen climatic
classi®cation system). Instituto de Geogra®a, Universidad
Nacional AutoÂnoma de MeÂxico, MeÂxico, DF, 33 pp.
Goering, H.K., Van Soest, P.J., 1975. Forage Fiber Analyses
(Apparatus, Reagents, Procedures, and Some Applications).
Agriculture Handbook No. 379. United States Department of
Agriculture, Agricultural Research Service, Washington, DC.
Graham, N.Mc., 1983. Feeding standards: an outmoded concept in
ruminant nutrition. In: Farrel, Pran Vohora (Eds.), Recent
Advances in Animal Nutrition in Australia. University of New
England, Armidale, Australia, pp. 184±191.
Hennessay, D.W., Williamson, P.J., 1990. Feed intake and
liveweight of cattle on subtropical native pasture hays. I. The
effect of urea. Aust. Journal Agric. Res. 41, 1169±1177.
Hill, W.H., Seals, J., Montiegel, E., 1958. Destruction of animal
and vegetable tissue by combustion in the Parr oxygen bomb.
Am. Ind. Hyg. Assoc. J. 19, 378.
Houtert, M.F.J., 1993. The production and metabolism of volatile
fatty acids by ruminants fed roughages. A review. Anim. Feed
Sci. Technol. 43, 189±225.
Huerta, H., GonzaÂlez, H., 1987. Ceba de bovinos en pastoreo
suplementados con urea (Fattening of cattle on pasture
supplemented with urea). Bol. Sugerencias de investigacioÂn y
transferencia. SeccioÂn ganado de carne. CRI. La Libertad.
Instituto Colombiano Agropecuario ICA, Colombia.
INRA, 1988. Alimentation de bovines, ovins and caprins (Nutrition
of cattle, sheep and goats), INRA Paris France, 880 pp.
Istasse, L., Reid, G.W., Tait, C.A.G., érskov, E.R., 1986.
Concentrates for dairy cows: effects of feeding method
proportion in diet and type. Anim. Feed. Sci. Technol. 15,
167±182.
Jackson, M.G., Who needs feeding standards? Anim. Feed Sci.
Technol. 6, 101±104.
Juul-Nielsen, J., 1981. Nutritional principles and productive
capacity of the Danish straw-mix system for ruminants. In:
Maximum Livestock Production From Minimum Land in
Bangladesh. Bangladesh Agricultural University, pp. 287±299.
Kunju, P.J.G., 1986. Urea molasses block lick: a feed supplement
for ruminants. In: Ibrahim, Schiere (Eds.), Rice and Related
Feeds in Ruminant Rations. Wageningen, Pudoc, Netherlands,
pp. 261±274.
Leng, R.A., 1990. Factors affecting the utilization of ``poor
quality'' forages by ruminant animals particularly under
tropical conditions. Nutr. Res. Rev. 3, 277±303.
41
Leng, R.A., 1991. Application of Biotechnology to Nutrition of
Animals in Developing Countries. FAO, UN, Rome, No. 90,
146 pp.
Leng, R.A., Kempton, T.J., Nolan, J.V., 1977. Non-protein
nitrogen and bypass proteins in ruminant diets. AMRC Rev.
33, 1±21.
Madrid, J., HernaÂndez, F., Pulgar, M.A., Cid, J.M., 1998. Effect of
citrus by-product supplementation on the intake and digestibility of urea sodium hydroxide-treated barley straw in
goats. Small Rumin. Res. 28, 241±248.
McDowell, L., Conrad, J.H., Ellis, G.L., 1984. Mineral de®ciencies
and imbalances and their diagnosis. In: Gilchrist, Mackie
(Eds.), Herbivore Nutrition in the Subtropics and Tropics. The
Science Press, Craighall, South Africa, pp. 67±88.
Meang, W.J., Chang, M.B., Yun, H.S., Choi, I., 1989. Dilution rates
on the ef®ciency of rumen microbial growth in continuous
culture. Asian±Australian J. Anim. Sci. 2, 477±480.
Morales, A.R., Galina, M.A., JimeÂnez, S., Haenlein, G., 2000.
Improvement of biosustainability of a goat feeding system with
key supplementation. Small Rumin. Res., in press.
Morand-Fehr, P., Sauvant, D., 1988. Alimentation des caprins
(Goat feeding). In: R. Jerrige (Ed.), Alimentation des bovins,
ovins et caprins. Institut National de la Recherche Agronomique, Paris, France, pp. 282±304.
Mould, F.L., 1989. Associative effects of feeds. In: E.R. érskov
(Ed.), Feed Science. Elsevier, The Netherlands, pp. 192±229.
Naidoo, G., Delatiere, C., Preston, T.R., 1977. Effect of maize and
®sh meal supplements on the performance of steers fed steamcooked bagasse and urea. Tropical Animal Production 2, 117±
124.
N'dlovu, L.R., Buchannan-Smith, J.G., 1985. Utilisation of poor
quality roughages by sheep: effect of alfalfa supplementation
on ruminal parameters, ®ber digestion, and rate of passage from
the rumen. Can. J. Anim. Sci. 65, 693±703.
Noller, C.H., White, J.L., Wheeler, W.E., 1980. Characterization of
cement kiln dusts and animal response. J. Dairy Sci. 63, 1947±
1952.
NRC, 1981. Nutrient Requirements of Goats. National Research
Council. National Academy Press, Washington, DC, USA, 76
pp.
érskov, E.R., 1991. Manipulation of ®ber digestion in the rumen.
Proc. Nutr. Soc. 50, 187±196.
érskov, E.R., 1994. Recent advances in understanding of microbial
transformation in ruminants. Livestock Prod. Sci. 39, 53±60.
Pethick, D.W., 1984. Energy metabolism in skeletal muscles. In:
Baker, Gawthorne, Purser (Eds.), Ruminant Physiology:
Concepts and Consequences, Perth, Australia, pp. 277±287.
Poppi, D., McLennan, S., 1995. Protein and energy utilization by
ruminants at pasture. J. Anim. Sci. 73, 278±290.
Preston, T.R., 1995. Tropical Animal Feeding. A Manual for
Research Workers. FAO Animal Production and Health, Paper
No. 126. Rome, Italy, 305 pp.
Puga, C., 1998. Mejoramiento de un sistema de alimentacioÂn
parcialmente biosostenible en cabras bajo pastoreo racional
tecni®cado movil. (Improvement of a partial biosustainable
feeding system in goats with rational technological mobile
grazing). Master Thesis. University of Colima, MeÂxico, 174 pp.
42
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Purroy, A., Jaime, C., MunÄoz, F., Treacher, T.T., 1993. A note on
change in body condition in Raza Aragonesa ewes given
ammonia-treated barley straw after weaning. Anim. Prod. 56,
409±412.
Rihani, N., Garret, N.N., Zinn, R.A., 1993. In¯uence of level of urea
and method of supplementation on characteristics of digestion
of high-®ber diets by sheep. J. Anim. Sci. 71, 1657±1665.
Robinson, C.H., 1984. Metabolismo EnergeÂtico. Fundamentos de
NutricioÂn Normal (Energy Metabolism. Nutritional Normal
Bases). CECSA, MeÂxico, pp. 100±102.
Russell, J., Wilson, D., 1996. Why are ruminal cellulolytic bacteria
unable to digest cellulose at low pH? J. Dairy Sci. 79, 1503±
1509.
Russell, J.R., Young, A.W., Jorgensen, N.A., 1979. Effect of
sodium bicarbonate and limestone addition to high grain diets
on feedlot performance and ruminal and fecal parameters in
®nishing steers. J. Anim. Sci. 51, 996±1002.
Sanson, D.W., 1993. Effect of increasing of corn or beet pulp on
utilization of low-quality crested wheatgrass hay by lambs and
in vitro dry matter disappearance of forages. J. Anim. Sci. 71,
1615±1622.
SAS, 1996. Statistical Analysis System. User's Guide: Statistics,
Version 6th ed. SAS Institute Inc. Cary, NC, USA.
Silva, A.T., Greenhalgh, J.F.F., érskov, E.R., 1989. In¯uence of
ammonia treatment and supplementation on the intake,
digestibility and weight gain of sheep and cattle on barley
straw diets. Anim. Prod. 48, 99±108.
Silva, A.T., érskov, E.R., 1988. The effect of ®ve different
supplements on the degradation of straw in sheep given
untreated barley straw. Anim. Sci. Technol. 19, 277±287.
Smith, R.H., 1984. Mineral and rumen function references. In:
Nuclear Techniques in Tropical Animal Disease and Nutrition
Disorders. International Atomic Energy Agency, Vienna,
Austria, pp. 79±96.
Sudana, I.B., Leng, R.A., 1986. Effects of supplementing a wheat
straw diet with urea or urea±molasses block and/or cottonseed
meal on intake and liveweight changes in lambs. Anim. Feed
Sci. Technol. 16, 25±35.
ValdeÂs, G., Delgado, A., 1990. SuplementacioÂn proteõÂco energeÂtica
para la ceba de ganado en pastos y forrajes (Protein and energy
supplementation in cattle fattening with pasture and forages)
ProduccioÂn de carne en el troÂpico. EDICA. Instituto de Ciencia
Animal, La Habana, Cuba.
Van Soest, P.J., Wine, R.H., 1967. Use of detergents in the analysis
of ®brous feeds. IV. Determination of plant cell-wall constituents. J. Assoc. Of®cial Anal. Chem. 50, 50±55.
Weimer, P., 1996. Why don't ruminal bacteria digest cellulose
faster? J. Dairy Sci., 79, 1496±1502.
Wells, J., Russell, J., 1996. Why do many ruminal bacteria die and
lyse so quickly? J. Dairy Sci., 79, 1487±1495.
Wheeler, W.E., 1979. In¯uence of cement kiln dust on reticulorumen parameters of beef steers fed complete diets. Journal of
Animal Science 49(5), 1364±1370.
Wheeler, W.E., Noller, C.H., White, J.L., 1981a. In¯uence of rate
reactivity of calcitic limestone and level of calcium addition on
utilization of high concentrate diets by beef steers. J. Anim. Sci.
53, 1120±1134.
Wheeler, W.E., Noller, C.H., White, J.L., 1981b. Comparison
between limestone and cement kiln dusts of similar rates of
reactivity used in high concentrate diets for beef steers. J.
Anim. Sci. 52, 873±881.
Zinn, R.A., Barajas, R., MontanÄo, M., Sean, Y., 1996. Protein and
energy value of dehydrated poultry excreta in diets for feedlot
cattle. J. Anim. Sci. 74, 2331±2335.
Effect of complex catalytic supplementation with non-protein
nitrogen on the ruminal ecosystem of growing goats
pasturing on shrub land in Mexico
M.A. Galinaa,b,c,*, M. Guerreroa,b, G. Serranob, R. Moralesb,c, G.F.W. Haenleind
a
Facultad de Estudios Superiores Cuautitlan, UNAM, 54000 Cuautitlan, Mexico
Posgrado Interinstitucional en Ciencias Pecuarias, Universidad de Colima, 28000 Colima, Mexico
c
Granja Puma, Municipio del Marques, QuereÂtaro, Mexico
d
Department of Animal and Food Sciences, University of Delaware, Newark, DE 19717-1303, USA
b
Accepted 20 August 1999
Abstract
Thirty-eight young Alpine goats, 16.1 (0.370) kg body weight (BW), were reared at QuereÂtaro, Mexico, grazing on a
semi-arid woody brush (Caducifolio espinoso) range land. The experimental goats (n 20) were pastured daily and
supplemented with 200 g/day of a complex catalytic feed (CCF). It consisted of molasses (14±18%), urea (8±10%), salt (3±
4%), limestone (3±4%), cottonseed meal (13±18%), rice polishing (10±13%), corn (11±12%), poultry litter (9±10%),
commercial mineral salt (1.3%), ammonium sulfate (0.3±0.5%), cement kiln dust (1.5%), and animal lard (10±15%). The
control goats (n 18) were supplemented daily with 300 g of a balanced concentrate (BC), containing 1.5% commercial
mineral salt, 60% corn, 32.5% wheat bran, and 4% soybean oil meal. Stocking rates varied from 1.45 to 1.85 AU/ha and daily
stocking rate from 36.4 to 58.6 AU/ha. At all times, ®brous forages were available exceeding the voluntary dry matter intake.
One ®stulated goat was kept in each group. Growth of the experimental goats averaged 95 g/day (3) compared to 76 g/day
(5) of the controls (P < 0.005) in 150 days from June to November. Supplementation per kg BW was from 17.5 to 10.4 g BC/
day for the control goats; the experimental goats received 12.2±6.5 g CCF/day. Weight gain in response to fermentable
carbohydrates (FC) averaged 8.95 g BW gain/g FC/day for the control BC goats, compared to 28.2 g BW gain/g FC/day for
the experimental CCF goats. Daily supplies of FC to goats on CCF supplementation were always below the limits for
celullolysis at 6 g/day, while FC supplies of BC rations to the control goats always exceeded them. After 2 h of shrub land
pasture, the ruminal pH rose when CCF was offered and stayed above 6.6 during 12 h, while the ruminal acidity in BC goats
went down to pH 5.57 at 6 h and rose to 6.5 by 12 h. Ammonia (NH3 mg/l) in ruminal liquid of CCF goats was higher
(P < 0.01) in average and all but one sample. Total cost per animal per day including shrub land pasture, management,
medicine and salaries was US $0.06 for experimental goats and US $0.09 for controls (market price for goat meat was US
$1.15/kg; US $1.00 10 Mexican Pesos, November 1998). Daily gain varied during the study period from 77 to 85 g/day in
BC control goats compared to 92±97 g/day in experimental CCF goats. CCF supplementation to shrub land pasturing resulted
in signi®cantly greater weight gains apparently due to elevated ruminal pH, higher availability of fermentable carbohydrates
and ruminal ammonia, augmenting ruminal ecosystem, digestibility and voluntary feed intake. The use of local shrub land
*
Corresponding author. Tel.: 0052-331-411-33; fax: 0052-331-275-81.
E-mail address: galina@cgic.ucol.mx (M.A. Galina).
0921-4488/00/$ ± see front matter # 2000 Published by Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 1 1 5 - 7
34
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
resources and complex catalytic supplementation with non-protein nitrogen provided greater pro®tability from this feeding
system for growing goats than the traditional balanced concentrate feed supplementation. # 2000 Published by Elsevier
Science B.V. All rights reserved.
Keywords: Nutrition; Goats; Growth; Ruminal ecosystem; Supplementation; Shrub land; Urea
1. Introduction
Goats raised on shrub range land, which is rich on
®brous forages, have low performance in body weight
(BW) gain of no more than 50 g/day (Galina et al.,
1993). Forages and crop residues, rich in ®ber and low
in protein are the most abundant feeds for ruminants in
third world nations (Preston, 1995). Recent studies in
Mexico with large ruminants aimed at achieving better
performance from local forages by using complex
catalytic feed (CCF) supplementation (Galina et al.,
1997). Strategies to improve utilization with CCF
feeds in dairy goats have been reported (Morales
et al., 2000).
Utilization of high ®ber diets with CCF needs to
develop new feeding standards, because ruminal protein and energy will add to the nutritional offer in the
feed to the animal (Jackson, 1980; Galina, 1994;
Graham, 1983; Preston, 1995). Goat requirements
have been reviewed (AFRC, 1998), after the work
of Morand-Fehr and Sauvant (1988) and NRC (1981).
Energy requirements for goats are 104.7 kcal/kg
BW0.75 for maintenance plus 25±50% increase to
cover cost of walking, grazing and other activities,
and 13.8 Mcal/kg BW gain (AFRC, 1998). Present
information on energy and protein contents of a feed
has little bearing on how animals utilize their feed,
when digestibility is improved due to bacterial augmentation from favorable energy contents in ration,
resulting in more intestinal true protein. It have even
been suggested that traditional nutritional approaches
should be abandoned for forage-based diets under
®brous forage management (Leng, 1990).
Nutritional utilization of ®brous forages requires
that the imbalance of nutrients for both rumen microorganisms and the host animal must be corrected for
better nutrition of rumen bacteria by providing energy
and nitrogen, which then results in improved bypass
nutrients to reach the intestines for higher production
by the host animal with lowered cost (érskov, 1994;
Wells and Russell, 1996; Russell and Wilson, 1996;
Weimer, 1996).
Better understanding of rumen function and the role
of CCF supplementation has been tested in Mexico
(Galina et al., 1997). Recent studies lead to the concept of ``balancing nutrients'' by providing high protein to energy ratios in absorbed nutrients, and
improving productive ef®ciency (Leng, 1990). Goats
can be considered as animals with a two-compartment
system (Morales et al., 2000). Ef®cient microbial
fermentation relies on the products of the rumen
and those digestible feed components that escape
fermentation (Preston, 1995). Under laboratory conditions, many factors can be isolated and studied in
detail, but few studies have attempted to elucidate
simultaneously the interaction of many factors that
result in the ef®ciency of end-product utilization by
the animal in production trials (Leng, 1990). The
importance of the type of supplement used when
evaluating forages has been emphasized by many
studies (Sanson, 1993). The addition of soluble carbohydrates to diets can have a negative effect on
forage intake and ®ber digestibility (Purroy et al.,
1993). The hypotheses for this decrease in intake
include decreased ruminal pH, a substitution effect,
competition for essential nutrients among cellulolytic
and non-cellulolytic bacteria, and the possible use of
alternative energy sources by cellulolytic bacteria
(Mould, 1989). Many workers found that supplementing basic forage diets of low digestibility with small
quantities of feed that are rich in digestible cellulose or
hemicellulose will increase forage digestibility (JuulNielsen, 1981).
The effect of supplementation with feeds balanced
in easily digestible carbohydrates in complex catalytic
feeds while pasturing on shrub land is unknown. The
objective of the present study was to examine the
effect of a complex catalytic supplementation with
non-protein nitrogen as urea on the utilization of shrub
land by growing goats. The study was to be performed
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
in QuereÂtaro, Mexico, with 38 goats pasturing brush
land and supplemented with complex catalytic feeds.
The study should allow balancing the nutrients needed
by the rumen bacteria and measure the effects of
modifying the ecosystem with suf®cient bypass nutrients on goat growth and economic feasibility. Traditionally balanced supplementation (Morand-Fehr and
Sauvant, 1988) was to be employed for control goats.
2. Material and methods
The study was conducted on the ``Puma'' farm in
the Cerro Prieto region, QuereÂtaro, Mexico, at 208350
latitude North and 1008180 longitude West. The altitude was 1950 m above sea level. Climate is classi®ed
as Bs 1 kw (w) (e), described as dry semiarid with
isolated rains in the winter and a total of 460 mm of
average precipitation per year (GarcõÂa, 1973). The
research was performed on 40 ha of shrub range land
with grasses: Bouteloua curtipendula, Chloris virgata,
Bothriochloa saccharoides, Leptochloa saccharoides,
Leptochloa dubia, Rhyncheltythurum roseum, Panicum obtusum, Bouteloua repens, Aristida adscensionis, Setaria parvi¯ora, Urochloa fasciulata;
leguminous trees: Prosopis laevigata, Acacia farnesiana, Acacia schaffneri, Mimosa biuncifera; and
shrubs: Celtis pallida, Jatropha dioica, Zalazania
augusta, Verbasina serrata, Opuntia spp.
A production of 800 kg DM/ha/year was calculated
(Galina et al., 1998). Grazing management and techniques for shrub land evaluation was published by
Puga (1998). Stocking rates varied from 1.45 to
1.85 AU/ha and daily stocking rate from 36.4 to
58.6 AU/ha. At all times, ®brous forages were available exceeding the voluntary dry matter intake.
Thirty-eight young Alpine goats, 16.1 (0.37) kg
BW, were allocated into two treatment groups in a
production function design. Animals were weighed
every 15 days. On experimental group of 20 goats
were pastured daily and supplemented with 200 g/day
of a complex catalytic feed mixture (CCF) consisting
of molasses (14±18%), urea (8±10%), salt (3±4%),
limestone (3±4%), cottonseed meal (13±18%), rice
polishing (10±13%), corn (11±12%), poultry litter (9±
10%), commercial mineral salt (1.3%), ammonium
sulfate (0.3±0.5%), cement kiln dust (1.5%), and
animal lard (10±15%). The control group of 17 goats
35
was kept on similar management but fed 300 g/day of
a traditional balanced concentrate (BC) composed of
1.5% commercial mineral salts, 60% corn, 32.5%
cottonseed meal, and 4% soybean oil meal. Chemical
feed analyses were performed according to AOAC
(1995); determination of ®ber contents according to
Van Soest and Wine (1967) and Goering and Van Soest
(1975) methods; total energy with a calorimetric bomb
after Hill et al. (1958) and Robinson (1984); shrub
land forages were combined for chemical analyses
with the method of Puga (1998).
Cellulolysis and rumen eco-environment was determined by using one ®stulated goat in each treatment
group to measure pH and ruminal ammonia (N±NH3)
levels. Each goat was sampled every 2 h after supplementation every 15 days, as described by Beatman
(1970), with a portable recorder (Orion 250-A)
equipped with an ion selective electrode for ammonia
(Orion 95-12). From the chemical analyses of the two
supplements the contents and supplies of fermentable
carbohydrates were calculated in g/day. Supplementation in g/day was also recorded monthly in g/kg BW.
Daily voluntary intake was determined for both supplements and for the forages in pasture according to
INRA (1988).
Statistical analyses for pH and ammonia were
performed comparing means with SAS (1996)
procedures (P < 0.05). The statistical model was:
Yij m ti Eij, where Yij is pH or NH3 jth observation of the ith treatment; m the overall mean; t the
treatment effect; i the ith treatment (i 1, 2 supplement type); j is the jth observation (j 1, 2, . . ., 4
(pH); 1, 2, . . ., 4 (NH3) observation); and Eij is the
error.
Statistical analyses of the 4 4 Latin square design
were performed with ANOVA (SAS, 1996), and
differences between means were analyzed according
to Tukey (P < 0.05). The model was: Yijkl m Ai
Bj Tt Eijkl; where Yijkl are variables such as goat
growth, supplementation g/kg BW, fermentable carbohydrates in g/kg BW, and supplementation g/day/g
BW gain; m is the overall mean; Ai the effect from the
ith line (goat); Bj the effect from the jth column (time);
Tt the effect of treatment shown in the jth line/column;
and Eijkl is the error associated with the experimental
unit line/column (ij).
Statistical analyses were also performed by multiple regression comparing variables (SAS, 1996).
36
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Monthly consumption and nutrient requirements as
suggested by Morand-Fehr and Sauvant (1988) were
dependent variables. By regression equation, the nutrient density of the feeding treatments and the total
requirements of the grazing goats were the determinants of probable consumption.
3. Results
Table 1 shows monthly BW of the control and
experimental groups. The amounts of voluntary intake
of BC supplementation went from 17.5 g/day/kg BW
at the beginning of the trial in control goats to 10.4 g/
day/kg BW at the end, when the 300 g/day were
offered. The intake of CCF supplementation went
from 12.2 to 6.5 g/day/kg BW, when 200 g/day were
offered. At the end of the trial, BC supplementation
was 59% lower from initial consumption, CCF supplementation 53% lower. While the amounts offered
remained constant throughout the trial, the BW
increased almost two-fold. Total dry matter intake
(DMI) by the CCF group increased from 3.1% to
3.8% of BW, while the DMI of the BC group
decreased from 3.3% to 2.9% of BW. Forage intake
increased from 265 to 536 g/day in BC, while in CCF
goats it changed from 311 to 973 g/day. Goats in the
CCF group consumed signi®cantly more forage than
the BC controls.
Experimental CCF goats showed an average growth
of 95 g/day (3) compared to 76 g/day (5) (Table 1)
for BC controls during 150 days from June to November (P < 0.005). The rotationally grazed shrub land
pasture consistently had more total forage available
during midsummer and late summer. However, once
the period of plant regrowth ®nished in early autumn,
the rotational pasture had similar or less total forage
standing, while grass was available at all times
exceeding the voluntary dry matter intake. Experimental CCF feeds were consumed for 6±8 h after
offering, in comparison with BC rations, which were
eaten in 15±30 min after supply.
Fig. 1 shows the amounts of fermentable carbohydrates consumed daily/kg BW calculated from the
chemical analyses of the feeds. Response to fermentable carbohydrates in terms of grams BW gain/day/g
FC averaged 8.95 for BC, compared to 28.27 for CCF
goats (P < 0.05) (Table 1). Daily supplies of FC to
goats on CCF supplementation were always below the
limits of 6 g/day for cellulolysis (Mould, 1989), while
FC supplies of BC rations to the control goats always
exceeded them.
Table 1
Monthly BW, supplement fed/kg BW/day, fermentable carbohydrates supplied/kg BW/day and gain/day in each period for CCF and BC
supplement treatments (BW: body weight; FI: forage intake; BC: balanced concentrate; CCF: complex catalytic feed; DMI: dry matter intake;
d: day; FC: fermentable carbohydrates; ab: statistical difference (P < 0.05) among pairs with same shading)
Days
0
30
60
90
120
150
Mean
BW (kg), BC goats
BW (kg), CCF goats
BC total (g/day)
CCF total (g/day)
FI±BC group (g)
FI±CCF group (g)
Total DMI BC (g)
Total DMI CCF (g)
DMI (%) BW±BC
DMI (%) BW±CCF
BC (g/kg) BW
CCF (g/kg) BW
FC (g/day) BC
FC (g/day) CCF
FC (g/g) BW BC gain
FC (g/g) BW CCF gain
BC gain (g/day)
CCF gain (g/day)
17.14
16.41
300
200
265
311
565
511
3.3
3.1
17.50
12.18
11.02a
4.62b
19.45
19.29
300
200
387a
536ab
687
736
3.5
3.8
15.42
10.36
9.71a
3.93b
7.92a
24.42b
77a
96b
21.55
22.19
300
200
400a
617ab
700a
817b
3.2
3.7
13.92
9.01
8.76a
3.42b
7.99a
28.36b
70a
97b
21.40
25.06
300
200
346a
752ab
646a
952b
3.0a
3.8b
12.44a
7.98b
7.83a
3.03b
10.85a
31.68b
85a
96a
26.60
27.93
300
200
478a
832ab
778a
1032b
2.9a
3.8b
11.27ab
7.16ab
7.10a
2.72b
11.69a
35.29b
83a
96a
28.84
30.68
300
200
536a
973ab
836a
1173b
2.9a
3.8b
10.40ab
6.51ab
6.55a
2.47a
11.45a
37.24b
75a
92b
22.44 4.4
25.59 5.35
300
200
402 95.7a
670 234b
702 95.7a
870 234b
3.1 0.24a
3.7 0.28b
13.39 2.66
8.97 2.31
8.49 1.67a
3.36 0.80b
8.95a
28.27b
76a
95b
37
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Fig. 1. Total supplementation g per day, total fermentable carbohydrates g/day and limit of carbohydrate supplementation g/day for
Cellulolysis according to Elias (1983).
Table 2 shows the chemical composition of forages,
CCF and BC supplements. Crude protein contents for
both forages were 7.68% and 8.10%, respectively;
metabolizable energy was 2.12 and 2.49 Mcal for
BC and CCF forages, respectively. Supplements contained 19.8% crude protein for BC and 26.13% for
CCF, due in part to the amount of urea. The table also
shows crude ®ber, NDF, ADF, cellulose, hemicellulose and lignin contents, the later above 8% in both
forages.
Table 3 summarizes the ruminal kinetics of pH
over time in goats fed CCF or BC while pasturing
shrub land. After 2 h on CCF the pH rose and stayed
above 6.6 for 12 h, while the ruminal acidity in
Table 2
Chemical composition of forages, BC and CCF supplements (CCF: complex catalytic feed; BC: balanced concentrate; CCF forage: mixture of
forages consumed by CCF goats; BC forage: mixture of forages consumed by BC goats)
Dry matter (%)
Ash (%)
Ether extract (%)
Crude protein (N 6.25) (%)
Crude fiber (%)
Neutral detergent fiber (%)
Acid detergent fiber (%)
Cellular content (%)
Cellulose (%)
Hemicellulose (%)
Lignin (%)
Nitrogen free extract (%)
Total digestible nutrients (%)
Metabolizable energy (Mcal)a
Digestible energy (Mcal)a
Total energy (Mcal)a
a
Mcal/kg dry matter.
BC forage
CCF forage
BC
CCF
93.69
5.08
2.70
7.68
36.04
75.17
39.73
34.83
32.90
67.27
8.54
61.50
95.49
2.12
3.59
4.37
99.65
9.21
1.08
8.10
35.81
68.82
45.75
31.17
31.67
65.37
9.48
60.80
92.91
2.49
3.35
4.08
90.53
5.60
4.07
19.83
12.56
68.40
13.16
31.59
7.84
55.23
4.86
57.94
99.89
2.83
3.61
4.39
93.12
18.89
9.88
26.13
5.00
37.84
16.66
62.15
8.01.
21.18
4.90
40.10
99.99
3.05
3.71
4.53
38
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Table 3
Ruminal kinetics of pH over time in goats fed CCF or BC on shrub
land pasture (CCF: complex catalytic feed; BC: balanced
concentrate; *A,B: means with different letters indicate statistical
signi®cance (P < 0.01); a,b: means with different letters indicate
statistical signi®cance (P < 0.01))
Hours
0
2
4
6
8
10
12
Average pH
CCF
BC
ab
6.75 0.50
6.98ab 0.09
6.80ab 0.16
6.60b 0.26
6.61b 0.29
6.66ab 0.16
6.69ab 0.29
6.72*A 0.10
6.58a 0.30
5.93ab 0.36
5.59b 0.06
5.57b 0.24
6.00b 0.22
6.12ab 0.28
6.50b 0.23
6.04*B 0.39
BC goats went down to pH 5.57 at 6 h and rose to 6.5
by 12 h.
Table 4 shows the ruminal kinetics of ammonia
(NH3 mg/l) over time in goats fed CCF or BC while on
shrub land pasture. Ammonia was higher (P < 0.01) in
the CCF group on an average and in all but one
sample.
Total cost per animal per day including grass,
management, medicine and salaries was US $0.06
for the experimental CCF goats but US $0.09 for
control BC goats. Market price per kg meat was US
$1.15 calculated in Mexican Pesos per dollar
exchange rate of November 1998 (1 US $ 10 Pesos).
Daily gain varied during the trial from 70 to 85 g/day
in control BC goats to 92 to 97 g/day in experimental
CCF goats (Table 1).
Table 4
Rumen kinetics of ammonia over time (NH3 mg/l); ruminal liquid
from goats pastured on shrub land supplemented with CCF or BC
(CCF: complex catalytic feed; BC: balanced concentrate; a,b:
means with different letters have statistical signi®cance (P < 0.01)
Hours
0
2
4
6
8
10
12
Average NH3
CCF
BC
a
11.04 15.0
27.49a 25.0
24.40a 24.1
13.24a 15.7
13.99a 14.2
16.74a 15.6
14.73a 12.7
17.37a 16.3
7.98a 4.8
16.50b 8.9
14.02ab 9.1
14.10ab 8.5
9.95a 2.67
5.89a 0.91
4.07a 0.99
10.30b 4.0
4. Discussion
Results showed differences in growth rate
(P < 0.05) for experimental over control goats, suggesting that daily gains of 100 g (AFRC, 1998) can be
obtained with good nutritional management. The protein needs of the experimental goats for growth were
met by correcting the nutrient imbalance of the grasses
and providing a continuous non-protein nitrogen
source of urea (Hennessay and Williamson, 1990)
or ammonium sulfate to the rumen bacteria (Leng,
1990; Silva et al., 1989). Ruminal bypass protein, e.g.
®shmeal, and bypass carbohydrates in corn and rice
polishings have proven important in cattle performance when fed ®brous forages (Elliot et al., 1978;
Leng et al., 1977; Naidoo et al., 1977; Galyean, 1996;
Poppi and McLennan, 1995). Bypass protein in our
experiment was supplied by the legume tree leaves
(Puga, 1998). Growth in the control goats was supported mainly by the high protein content in the BC
ration, which hand a substitution effect for the poor
forages (Tables 1 and 2). Low rumen pH and less
ammonia contents in the control goats explained the
effects of concentrate intake in pastured goats. The
high amounts of fermentable carbohydrates also
affected cellulolysis (Elias, 1983; Madrid et al.,
1998). When microbial protein is the main source
of nitrogen for growth, there must be considerable
concern covering the requirements by rumen microbes
for ef®cient growth. Meang et al. (1989) suggested
that microbial growth ef®ciency was improved in
washed rumen microbes by including amino acids
as well as urea in the incubation medium. Amino
acids such as leucine, lysine, threonine and tryptophan
were supplemented in the CCF experimental diet by
the addition of poultry litter as also demonstrated by
Zinn et al. (1996).
Previously, Elias (1983) has shown that small
amounts of easily available energy from fermentable
carbohydrates like in molasses, sugar cane or starch
could increase cellulose digestibility because ruminal
microorganisms are not capable to obtain energy from
cellulose for their cellular functions until the molecule
is digested. Therefore, goats, sheep and cattle supplemented with low levels of sugars between 2 and 6 g/kg
BW/day could improve cellulose digestibility because
rumen microorganisms now have energy for their
cellular functions. Similar ®ndings have been reported
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
when low amounts of citrus by-products were supplemented at 100 g/day and improved digestibility and
intake of DM of urea±NaOH treated straw based diets
(Madrid et al., 1998). The explanation was that at low
levels the supplementation with degradable carbohydrates such as from citrus by-products supplied energy
for ruminal microorganism and improved the ruminal
ecosystem for cellulolysis and straw digestion
(Madrid et al., 1998). However, at more than 6 g of
fermentable carbohydrates (FC) per kg of BW, cellulose digestibility diminished because concentrate supplementation substituted for forage. It has been shown
that moderate amounts of cellobiose added to pure
cultures of cellulolytic bacteria inhibit cellulose
hydrolysis, which suggests an enzyme depressing
system based on less speci®c activity for cellulose
from microorganisms growing in a cellobiose-rich
environment (Elias, 1983). Similar results have been
published by Madrid et al. (1998), when higher levels
of digestible carbohydrates in supplements depressed
the digestion of straw. This is also explained by the
negative effects on cellulolytic activities of the rumen
micro¯ora, when high levels of energy supplements
decrease ruminal pH (Rihani et al., 1993). In our study,
CCF fermentable carbohydrates were always below
the above limits (4.62±2.47 g FC/day) (Table 1) favoring the ruminal ecosystem to stimulate feed intake and
BW gain, while FC from the BC ration was always
above the limits (11.02±6.55 g/day) apparently affecting cellulolysis.
Daily weight gain in the present work apparently
did not equal the levels of metabolizable energy in the
forages (Table 2). Increased voluntary dry matter
intake supplied more energy, because of improved
digestibility from the improved action of cellulolytic
bacteria (Fibrobacter succinogenes, Ruminococcus
albus, R. Flavefaciens) favored by the continuous
presence of non-protein nitrogen (Leng, 1990; Fondevila and Dehority, 1995; Preston, 1995; Brown et
al., 1988). This is indicated by the higher levels of
ruminal ammonia (17.37 mg/l; P < 0.01) (Table 4) in
CCF supplemented goats compared to the BC goats
(10.30 mg/l), creating a favorable protein/energy ratio
for bacterial protein formation (Leng, 1991). The
experimental CCF supplement was consumed over
a period of 6±8 h, while the commercial BC supplement was ingested in less than 30 min after offering
(15±30). This mixture could have insured suf®cient
39
ammonia for microbial growth (50±80 mg NH3±N/l
rumen ¯uid) (Leng, 1991), but the level of ammonia
needed is dependent on the pH of the rumen (Smith,
1984).
Forage offer was kept high all time through the
rational technological mobile grazing (RTMG) system
developed by Puga (1998), boosting digestibility of
the basal diet (Juul-Nielsen, 1981; N'dlovu and
Buchannan-Smith, 1985). Grass was allowed to regrow before returning to be pastured (Puga, 1998).
Sudana and Leng (1986). Showed that supplements
must provide continuous adequate levels of ammonia
for persistent growth of both ®brolytic and saccharolytic microorganisms, by providing in the supplement high concentrations of salt±urea and molasses±
urea to aviod fast intake. Supplementation with
branched-chain VFA has been reported to increase
the apparent ¯ow of microbial-N to the duodenum
(Silva and érskov, 1988). Ruminal pH supported by
calcitic limestone and cement kiln dust could have
played a key role of maintaining cellulolytic bacteria
in our experimental animals (Wheeler, 1979; Wheeler
et al., 1981a, b; Noller et al., 1980).
Rumen acidity is produced by high intake of
starches. Amylose and amylopectin are broken down
early under the in¯uence of amylases. Ruminal pH
environment for microbial activity was lower in the
BC supplemented goats (Table 3). CCF supplementation kept pH above 6.6 all the time, while BC
decreased pH to 5.57 inhibiting celullolysis (Leng,
1991). This may explain the lesser growth of the BC
control goats, depending on energy and protein from
their supplementation, because of less bacterial protein formation. As rumen pH is depressed below 6.2
(Istasse et al., 1986), cellulolysis progressively
decreased and ceased altogether at rumen pH of
around 5.9 (érskov, 1994; Russell and Wilson,
1996; Russell et al., 1979; Weimer, 1996).
Sulfur and phosphorus have been proven to be
essential for bacterial growth (Leng, 1990) as was
assured in our experimental diets. In general practice
there is either no mineral supplement provided or a
``shot gun'' mixture is given as salt licks (McDowell
et al., 1984). In this study, molasses, which is already
rich in minerals was suitably forti®ed with minerals
(Kunju, 1986). Acetic acid does not seem to be a major
constrain to oxidation, because the ruminant reacts to
excess supplies by excreting acetate in the urine
40
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
(érskov, 1991). Long-chain fatty acids in animal lard,
as provided in the CCF supplement, potentially generate reduced nicotinamide adenine dinucleotide
(NADPH) and electron acceptors (NAD) for
increased use of acetate. This and the high energy
density of the animal lard may explain the better
growth performance of the CFF goats on less supplement (200 vs 300 g/day) than the BC controls
(Houtert, 1993).
Molasses as a cheap source of FC, and the buffer
effects of limestone and cement kiln may explain the
complex relationships established by this feed in
manipulating ®ber digestion in the rumen (érskov,
1991). High levels of molasses±urea have been successfully used for fattening of cattle on pasture in
Australia (Anon, 1984), Colombia (Huerta and GonzaÂlez, 1987) and Cuba (ValdeÂs and Delgado, 1990).
It could be suggested from the present results that
goat kids adequately supplemented with small quantities of essential nutrients performed equally well on a
lower digestibility feed, as animals on higher digestibility forage. Pasture management was the other key
to obtain gains from grass offered throughout the study
(Puga, 1998). Heat increment of added acetogenic
substrates will depend on the pattern of fermentation
in the rumen, VFA and the balance of protein available
from the intestine. Goats need to oxidize acetate, the
major thermogenic substrate. Ruminants con®ned to
calorimeters are usually maintained at what is supposed to be thermoneutrality, however, in our study,
animals were exposed to heat and cold (rain) stress and
they responded metabolically according to the insulative properties of their skin. Variances in weekly
gains were related to environmental effects. Acetogenic substrate is the major source of ATP for muscle
metabolism (Pethick, 1984), therefore acetate formation in this study could explain the growth of the
supplemented goats (Leng, 1990).
5. Conclusion
Utilization of ®brous diets by ruminants can be
manipulated in various ways. Digestibility and intake
was improved as evidenced by superior weight gain of
95 g/day for CCF goat kids compared to 76 g/day by
BC goats. This was apparently due to elevated rumen
pH and ammonia levels augmenting the bacterial
ecosystem by offering essential amino acids, longchain fatty acids, non-protein nitrogen, calcium, sulfur
and phosphorus, which in turn improved cellulose
digestion. Direct bypass protein and glycogenic carbohydrates from the rumen are other key ingredients
to the present results. Use of the local resources of
shrub land pasture provided the economical feasibility
and pro®tability of the diet.
Acknowledgements
This research was supported by projects SIMORELOS CONACYT 9501075, 970301029 and PAPIIT
217798 UNAM.
References
AFRC, 1998. The nutrition of goats. AFRC Technical Committee
on Responses to Nutrients, Report 10. CAB International, UK
and New York, 118 pp.
Anon, 1984. Molasses 8% urea. The supplement that saved
North Queensland cattle in the big drought of 1982 and 1983.
Beef cattlemen's Union. Mackay region. Australia 35 pp.
AOAC, 1995. Of®cial Methods of Analysis. Association of Of®cial
Agricultural Chemist, 16th ed. Washington, DC, USA, 600 pp.
Beatman, J.V., 1970. In: Herrero-Hernandez (Ed.), NutricioÂn
Animal. Manual de MeÂtodos AnalõÂticos (Animal Nutrition.
Manual for Analytic Methods). Mexico, 60 pp.
Brown, W.F., Pitman, W.D., Mislevy, P., 1988. Intake and
digestibility and performance by cattle grazing Cynodon
varieties. Nutr. Rep. Int. 38(6), 1201 ±1209.
Elias, A., 1983. DigestioÂn de pastos y forrajes tropicales (Digestion
of tropical pastures and forages). In: Los Pastos en Cuba.
Instituto de Ciencia Animal, Cuba, pp. 187±247.
Elliot, R., Ferreriro, H.M., Priego, A., Preston, T.R., 1978. Rice
polishing as a supplement in sugar cane diets: the quantities of
starch (glucose polymers) entering the proximal duodenum.
Trop. Anim. Prod. 3, 30±35.
Fondevila, M., Dehority, B.A., 1995. Interaction between Fibrobacter succinogenes, Prevotella ruminicola, and Ruminococcus
¯avefaciens in the digestion of cellulose from forages. J. Anim.
Sci. 74, 678±684.
Galina, M.A., 1994. Sistemas Pecuarios biosostenibles y biodiversos. Una alternativa de produccioÂn animal ante el deterioro
ambiental y la contaminacioÂn. (Biodiverse and biosustainable
livestock production systems. An alternative to animal production and deterioration of the environment and pollution). Av. en
InvestigacioÂn Agropecuaria, Mexico 3, 48±75.
Galina, M.A., Morales, R., Hummel, J., 1993. ComparacioÂn de dos
modelos de manejo alimenticio para la produccioÂn de leche de
caprinos. (Comparison of two models for nutritional management of dairy goat production). Pastos y Forrajes, Cuba 16,
263±270.
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Galina, M.A., Pineda, J., Rosado, J., Aguilar, A., Puga, D.C.,
Rubio, C., Murillo, J.C., 1997. Fattening of steers Zebu F1
cross fed high fermentable carbohydrate diet of a continuous
non-protein nitrogen and bypass protein supplement. Adv.
Agric. Res. MeÂxico. 6, 22±32.
Galina, M.A., Puga, D.C., HernaÂndez, A., Haenlein, G., 1998.
Biodiverse and biosustainable system with goats in
Mexico: importance of the forage bank. Small Rumin. Res.
27, 19±23.
Galyean, M.L., 1996. Protein level in beef cattle ®nishing diets:
industry application, University research and systems results. J.
Anim. Sci. 74, 2860±2870.
GarcõÂa, E., 1973. Modi®caciones al sistema de clasi®cacioÂn
climaÂtica de KoÈppen (Modi®cations of KoÈppen climatic
classi®cation system). Instituto de Geogra®a, Universidad
Nacional AutoÂnoma de MeÂxico, MeÂxico, DF, 33 pp.
Goering, H.K., Van Soest, P.J., 1975. Forage Fiber Analyses
(Apparatus, Reagents, Procedures, and Some Applications).
Agriculture Handbook No. 379. United States Department of
Agriculture, Agricultural Research Service, Washington, DC.
Graham, N.Mc., 1983. Feeding standards: an outmoded concept in
ruminant nutrition. In: Farrel, Pran Vohora (Eds.), Recent
Advances in Animal Nutrition in Australia. University of New
England, Armidale, Australia, pp. 184±191.
Hennessay, D.W., Williamson, P.J., 1990. Feed intake and
liveweight of cattle on subtropical native pasture hays. I. The
effect of urea. Aust. Journal Agric. Res. 41, 1169±1177.
Hill, W.H., Seals, J., Montiegel, E., 1958. Destruction of animal
and vegetable tissue by combustion in the Parr oxygen bomb.
Am. Ind. Hyg. Assoc. J. 19, 378.
Houtert, M.F.J., 1993. The production and metabolism of volatile
fatty acids by ruminants fed roughages. A review. Anim. Feed
Sci. Technol. 43, 189±225.
Huerta, H., GonzaÂlez, H., 1987. Ceba de bovinos en pastoreo
suplementados con urea (Fattening of cattle on pasture
supplemented with urea). Bol. Sugerencias de investigacioÂn y
transferencia. SeccioÂn ganado de carne. CRI. La Libertad.
Instituto Colombiano Agropecuario ICA, Colombia.
INRA, 1988. Alimentation de bovines, ovins and caprins (Nutrition
of cattle, sheep and goats), INRA Paris France, 880 pp.
Istasse, L., Reid, G.W., Tait, C.A.G., érskov, E.R., 1986.
Concentrates for dairy cows: effects of feeding method
proportion in diet and type. Anim. Feed. Sci. Technol. 15,
167±182.
Jackson, M.G., Who needs feeding standards? Anim. Feed Sci.
Technol. 6, 101±104.
Juul-Nielsen, J., 1981. Nutritional principles and productive
capacity of the Danish straw-mix system for ruminants. In:
Maximum Livestock Production From Minimum Land in
Bangladesh. Bangladesh Agricultural University, pp. 287±299.
Kunju, P.J.G., 1986. Urea molasses block lick: a feed supplement
for ruminants. In: Ibrahim, Schiere (Eds.), Rice and Related
Feeds in Ruminant Rations. Wageningen, Pudoc, Netherlands,
pp. 261±274.
Leng, R.A., 1990. Factors affecting the utilization of ``poor
quality'' forages by ruminant animals particularly under
tropical conditions. Nutr. Res. Rev. 3, 277±303.
41
Leng, R.A., 1991. Application of Biotechnology to Nutrition of
Animals in Developing Countries. FAO, UN, Rome, No. 90,
146 pp.
Leng, R.A., Kempton, T.J., Nolan, J.V., 1977. Non-protein
nitrogen and bypass proteins in ruminant diets. AMRC Rev.
33, 1±21.
Madrid, J., HernaÂndez, F., Pulgar, M.A., Cid, J.M., 1998. Effect of
citrus by-product supplementation on the intake and digestibility of urea sodium hydroxide-treated barley straw in
goats. Small Rumin. Res. 28, 241±248.
McDowell, L., Conrad, J.H., Ellis, G.L., 1984. Mineral de®ciencies
and imbalances and their diagnosis. In: Gilchrist, Mackie
(Eds.), Herbivore Nutrition in the Subtropics and Tropics. The
Science Press, Craighall, South Africa, pp. 67±88.
Meang, W.J., Chang, M.B., Yun, H.S., Choi, I., 1989. Dilution rates
on the ef®ciency of rumen microbial growth in continuous
culture. Asian±Australian J. Anim. Sci. 2, 477±480.
Morales, A.R., Galina, M.A., JimeÂnez, S., Haenlein, G., 2000.
Improvement of biosustainability of a goat feeding system with
key supplementation. Small Rumin. Res., in press.
Morand-Fehr, P., Sauvant, D., 1988. Alimentation des caprins
(Goat feeding). In: R. Jerrige (Ed.), Alimentation des bovins,
ovins et caprins. Institut National de la Recherche Agronomique, Paris, France, pp. 282±304.
Mould, F.L., 1989. Associative effects of feeds. In: E.R. érskov
(Ed.), Feed Science. Elsevier, The Netherlands, pp. 192±229.
Naidoo, G., Delatiere, C., Preston, T.R., 1977. Effect of maize and
®sh meal supplements on the performance of steers fed steamcooked bagasse and urea. Tropical Animal Production 2, 117±
124.
N'dlovu, L.R., Buchannan-Smith, J.G., 1985. Utilisation of poor
quality roughages by sheep: effect of alfalfa supplementation
on ruminal parameters, ®ber digestion, and rate of passage from
the rumen. Can. J. Anim. Sci. 65, 693±703.
Noller, C.H., White, J.L., Wheeler, W.E., 1980. Characterization of
cement kiln dusts and animal response. J. Dairy Sci. 63, 1947±
1952.
NRC, 1981. Nutrient Requirements of Goats. National Research
Council. National Academy Press, Washington, DC, USA, 76
pp.
érskov, E.R., 1991. Manipulation of ®ber digestion in the rumen.
Proc. Nutr. Soc. 50, 187±196.
érskov, E.R., 1994. Recent advances in understanding of microbial
transformation in ruminants. Livestock Prod. Sci. 39, 53±60.
Pethick, D.W., 1984. Energy metabolism in skeletal muscles. In:
Baker, Gawthorne, Purser (Eds.), Ruminant Physiology:
Concepts and Consequences, Perth, Australia, pp. 277±287.
Poppi, D., McLennan, S., 1995. Protein and energy utilization by
ruminants at pasture. J. Anim. Sci. 73, 278±290.
Preston, T.R., 1995. Tropical Animal Feeding. A Manual for
Research Workers. FAO Animal Production and Health, Paper
No. 126. Rome, Italy, 305 pp.
Puga, C., 1998. Mejoramiento de un sistema de alimentacioÂn
parcialmente biosostenible en cabras bajo pastoreo racional
tecni®cado movil. (Improvement of a partial biosustainable
feeding system in goats with rational technological mobile
grazing). Master Thesis. University of Colima, MeÂxico, 174 pp.
42
M.A. Galina et al. / Small Ruminant Research 36 (2000) 33±42
Purroy, A., Jaime, C., MunÄoz, F., Treacher, T.T., 1993. A note on
change in body condition in Raza Aragonesa ewes given
ammonia-treated barley straw after weaning. Anim. Prod. 56,
409±412.
Rihani, N., Garret, N.N., Zinn, R.A., 1993. In¯uence of level of urea
and method of supplementation on characteristics of digestion
of high-®ber diets by sheep. J. Anim. Sci. 71, 1657±1665.
Robinson, C.H., 1984. Metabolismo EnergeÂtico. Fundamentos de
NutricioÂn Normal (Energy Metabolism. Nutritional Normal
Bases). CECSA, MeÂxico, pp. 100±102.
Russell, J., Wilson, D., 1996. Why are ruminal cellulolytic bacteria
unable to digest cellulose at low pH? J. Dairy Sci. 79, 1503±
1509.
Russell, J.R., Young, A.W., Jorgensen, N.A., 1979. Effect of
sodium bicarbonate and limestone addition to high grain diets
on feedlot performance and ruminal and fecal parameters in
®nishing steers. J. Anim. Sci. 51, 996±1002.
Sanson, D.W., 1993. Effect of increasing of corn or beet pulp on
utilization of low-quality crested wheatgrass hay by lambs and
in vitro dry matter disappearance of forages. J. Anim. Sci. 71,
1615±1622.
SAS, 1996. Statistical Analysis System. User's Guide: Statistics,
Version 6th ed. SAS Institute Inc. Cary, NC, USA.
Silva, A.T., Greenhalgh, J.F.F., érskov, E.R., 1989. In¯uence of
ammonia treatment and supplementation on the intake,
digestibility and weight gain of sheep and cattle on barley
straw diets. Anim. Prod. 48, 99±108.
Silva, A.T., érskov, E.R., 1988. The effect of ®ve different
supplements on the degradation of straw in sheep given
untreated barley straw. Anim. Sci. Technol. 19, 277±287.
Smith, R.H., 1984. Mineral and rumen function references. In:
Nuclear Techniques in Tropical Animal Disease and Nutrition
Disorders. International Atomic Energy Agency, Vienna,
Austria, pp. 79±96.
Sudana, I.B., Leng, R.A., 1986. Effects of supplementing a wheat
straw diet with urea or urea±molasses block and/or cottonseed
meal on intake and liveweight changes in lambs. Anim. Feed
Sci. Technol. 16, 25±35.
ValdeÂs, G., Delgado, A., 1990. SuplementacioÂn proteõÂco energeÂtica
para la ceba de ganado en pastos y forrajes (Protein and energy
supplementation in cattle fattening with pasture and forages)
ProduccioÂn de carne en el troÂpico. EDICA. Instituto de Ciencia
Animal, La Habana, Cuba.
Van Soest, P.J., Wine, R.H., 1967. Use of detergents in the analysis
of ®brous feeds. IV. Determination of plant cell-wall constituents. J. Assoc. Of®cial Anal. Chem. 50, 50±55.
Weimer, P., 1996. Why don't ruminal bacteria digest cellulose
faster? J. Dairy Sci., 79, 1496±1502.
Wells, J., Russell, J., 1996. Why do many ruminal bacteria die and
lyse so quickly? J. Dairy Sci., 79, 1487±1495.
Wheeler, W.E., 1979. In¯uence of cement kiln dust on reticulorumen parameters of beef steers fed complete diets. Journal of
Animal Science 49(5), 1364±1370.
Wheeler, W.E., Noller, C.H., White, J.L., 1981a. In¯uence of rate
reactivity of calcitic limestone and level of calcium addition on
utilization of high concentrate diets by beef steers. J. Anim. Sci.
53, 1120±1134.
Wheeler, W.E., Noller, C.H., White, J.L., 1981b. Comparison
between limestone and cement kiln dusts of similar rates of
reactivity used in high concentrate diets for beef steers. J.
Anim. Sci. 52, 873±881.
Zinn, R.A., Barajas, R., MontanÄo, M., Sean, Y., 1996. Protein and
energy value of dehydrated poultry excreta in diets for feedlot
cattle. J. Anim. Sci. 74, 2331±2335.