Supplementation of cottonseed meal on fe (1)
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Livestock Science 119 (2008) 137 – 144
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Supplementation of cottonseed meal on feed intake, digestibility,
live weight and carcass parameters of Sidama goats
Matiwos Solomon a , Solomon Melaku b,⁎, Adugna Tolera c
a
Dilla ATVET College, P.O. Box, Dilla, Ethiopia
Department of Animal Sciences, Haramaya University, P.O. Box 138, Dire Dawa, Ethiopia
Department of Animal and Range Sciences, Hawassa University, P.O. Box 5, Awassa, Ethiopia
b
c
Received 4 January 2008; received in revised form 15 March 2008; accepted 17 March 2008
Abstract
The experiment was conducted at Dilla Agricultural Technical Vocational Education and Training (ATVET) College in Ethiopia
using twenty-four yearling intact male Sidama goats with a mean body weight (BW) of 16.8 ± 1.14 kg (mean ± SD). The objective
of the experiment was to examine the effect of different levels of cottonseed meal (CSM) supplementation on the feed intake,
digestibility, BW gain, and carcass parameters of Sidama goats. The experiment consisted of 90 days of feeding trial and 10 days of
digestibility trial followed by evaluation of carcass parameters at the end of the experiment. The treatments included ad libitum
feeding of hay (T1, control) and daily supplementation of CSM at 200 g (T2), 300 g (T3) and 400 g (T4) per head on dry matter
(DM) basis. The experimental design was a completely randomized block design. The experimental goats were blocked on initial
BW and six goats were randomly assigned to each treatment. Hay DM, crude protein (CP) and neutral detergent fiber (NDF) intake
were higher (P b 0.001) in the non-supplemented than in the supplemented goats, however, the contrary was true for total CP
intake. Total DM intake was higher (P b 0.001) for goats supplemented with the high level of CSM than those on the control
treatment. Among CSM supplemented goats, the intake of CSM DM, CP, NDF (P b 0.001) and total CP (P b 0.01) were higher in
the order of T4 N T3 N T2. The high level of supplementation with CSM resulted in better (P b 0.05) apparent digestibility coefficient
(DC) of DM and organic matter (OM) compared to the non-supplemented goats. The apparent DC of CP was higher (P b 0.01) for
supplemented than non-supplemented goats. The non-supplemented goats had lower daily BW gain, empty BW, dressing
percentage on slaughter weight base, rib-eye muscle area (P b 0.01), BW change (P b 0.001), final BW (P b 0.05) and higher feed
conversion ratio (P b 0.01) than the supplemented ones. The medium level of supplementation resulted in higher daily BW gain
(P b 0.01), BW change (P b 0.001), final BW (P b 0.05) and lower feed conversion ratio (P b 0.01) than the lower level of
supplementation, but with no differences (P N 0.05) in these parameters with the high level of supplementation. Therefore, it is
concluded that supplementation of CSM at 300 g DM per head per day resulted in better animal performance parameters in Sidama
goats.
© 2008 Elsevier B.V. All rights reserved.
Keywords: Feed intake; Digestibility; Body weight; Cottonseed meal; Sidama goats
⁎ Corresponding author. Tel.: +251 915 74 72 18.
E-mail address: solmelay@yahoo.com (S. Melaku).
1871-1413/$ - see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.livsci.2008.03.011
138
M. Solomon et al. / Livestock Science 119 (2008) 137–144
1. Introduction
Goats are among the important domestic animals of
value to man in the drier regions of the tropics. They
have multiple functions and display a unique ability to
adapt to harsh environments with wide ecological
range. In the tropics, goats serve mostly as a source of
meat and skins (Devendra and Burns, 1983), while in
the temperate zone they are primarily reared for milk
and to a lesser extent for meat production. Feeding
behaviour, prolificacy, small body size are important
characteristics of goats that enable them to be easily
integrated in pastoralist as well as mixed crop
livestock production systems in the tropics. Consequently, about 52% of the world's goat population is
found in the developing countries of the tropics (FAO,
2003) due to their concentration in dry tropical areas
of poor agricultural potential and even on marginal
lands (Morand-Fehr and Boyazoglu, 1999). Indeed,
mutton and goat meat as compared to beef account for
a large share of the domestic meat consumption in
many tropical countries (Gryseels and Anderson,
1983).
However, the meat production potential of goats is
low compared to the population size. This low level of
productivity of goats in tropical countries could be
attributed to animal diseases, poor genetic potential, lack
of proper management, and poor nutrition, among
which the latter plays a significant role. Generally,
goats reared by smallholder farmers and pastoralists in
the tropics rely entirely on poor quality natural grassland, crop residues with crude protein (CP) contents of
less than 8% and neutral detergent fiber (NDF) content
of more than 55%. Feedstuffs of such composition
hardly meet the maintenance requirements of goats
throughout the year. Hence, supplementation with agroindustrial by-products such as oil seed meals that are
produced abundantly in tropical countries and rich in CP
(200–500 g/kg DM) is among the possible measures to
improve the productivity of goats. Among the various
oil seed residues, cottonseed meal (CSM) is one of the
protein supplements commonly used in animal feeding,
though its utilization may be limited by its content of
gossypol, the main anti-nutritive factor in CSM.
However, according to Wolf et al. (1980), gossypol in
CSM cannot present problems to animals with a
functional rumen. Therefore, this experiment was
conducted with the objective to examine the effect of
different levels of CSM on feed intake, weight change
and carcass parameters of Sidama goats.
2. Materials and methods
2.1. Description of the experimental area
The experiment was conducted at Dilla Agricultural Technical Vocational Education and Training (ATVET) College, Ethiopia.
The study site is located at 6° 27′ N and 38° 30′ E and at an altitude of 1550 m above sea level, and receives annual precipitation of
1200–1800 mm with annual temperature range between 13 and 23 °C.
2.2. Management of animals
Twenty-four yearling male Sidama goats with mean initial body weight (BW) of 16.78 ± 1.14 kg (mean ± SD) were used for the
study. The goats were quarantined for 3 weeks, and during this period they were de-wormed and sprayed against internal and
external parasites, respectively. They were also vaccinated against pasteurelosis and anthrax, and penned individually.
2.3. Experimental design and treatments
The experimental goats were blocked into six blocks of four animals based on initial BW and randomly assigned to one of the
four dietary treatments in a randomized complete block design giving six animals per treatment. The dietary treatments consisted of
sole grass hay (control, T1), and supplementation with 200 g (low, T2), 300 g (medium, T3) and 400 g (high, T4) CSM on DM basis.
The natural grass hay used in the study consisted of mainly Digitaria nodosa, Sporobolus natalensis and Eragrostis papposa
species.
2.4. Feed intake and body weight
The respective CSM supplements for each treatment were offered twice a day at 800 h and 1600 h in two equal portions. Hay was
offered ad libitum after the consumption the first CSM offer. Daily feed offer and refusals were weighed and recorded for each goat
to determine daily feed intake. Water and mineral lick were available free choice. Representative samples of feed offer per batch and
refusals per goat were collected and pooled on treatment for determination of chemical composition. The feed conversion ratio
M. Solomon et al. / Livestock Science 119 (2008) 137–144
139
(FCR) was calculated as a proportion of daily DM intake to daily BW gain. The substitution rate (SR) of the basal feed by the
concentrate mix was calculated using the following equation (Ponnampalam et al., 2004).
SR ¼
Tef straw intake of control treatment ðgÞ tef straw intake of the supplemented treatment ðgÞ
Concentrate mix intake ðgÞ
Initial BW of each goat was determined by taking the mean of two consecutive weights after overnight fasting, and BW was
subsequently measured every 10 days after overnight fasting. The mean daily BW gain was calculated by regressing BW
measurements on days of feeding.
2.5. Digestibility trial
Four animals from each treatment were randomly selected and fitted with faeces collection bags to measure the digestibility of the
treatment feeds they were fed on during the feeding trial. After allowing an adjustment period of 3 days to carrying the faeces
collection bags, daily total faecal excretion per animal was collected for seven consecutive days. The daily collected faeces was
weighed, 20% sub-sampled and stored frozen at − 20 °C. The digestion coefficient of nutrients was calculated as a proportion of
nutrients consumed and not recovered in the faeces.
The digestibility of CSM was estimated by difference as described by McDonald et al. (2002) using the equation:
Nutrient DC ¼
Nutrient in test f eed
ðNut: in f aeces of mixed diet Nutrient in f aeces of basal f eedÞ
Nutrient in test f eed
2.6. Carcass parameters
Five goats from each treatment were randomly slaughtered after overnight fasting. Blood, head, skin, feet, heart, lungs and
trachea, liver with gall bladder, spleen, testis, penis, kidneys, abdominal gut, reticulo-rumen, omasum–abomasum, small and large
intestine were weighed and recorded. Empty BW was determined by difference between BW at slaughter and gut content. Hot
carcass weight was computed by excluding edible and non-edible offals. Dressing percent was calculated as proportion of hot carcass
weight to slaughter as well as empty BW. The rib-eye muscle area was measured by tracing the cross section area of the 10th and 11th
ribs after cutting perpendicular to the back bone (Kyomo, 1978 cited in Legesse, 2001). The left and right rib-eye muscle area was
traced on a water proof transparent plastic foil and the area was measured using a planimeter.
2.7. Chemical analysis
Samples of feed offered, refused and faeces were dried at 55°C in a forced draft oven to constant weight and ground to pass 1 mm
mesh screen size and used for determination of chemical composition. Dry matter (DM), organic matter (OM), CP, ether extracts
(EE) and ash were analysed according to the AOAC (1990). The NDF, acid detergent fiber (ADF), and acid detergent lignin (ADL)
were analysed by the procedures of Van Soest et al. (1991).
2.8. Statistical analysis
The data collected were subjected to the analysis of variance using the general linear model procedure of SAS (1998). Treatment
means were separated by least significant difference (LSD). The model used for feeding trial was Yij = μ + Ti + Bj + eij, while the model
used for the digestion trial and carcass parameters was Yij = μ + Ti + eij.
Where; Yij is response variable, μ overall mean, Ti is treatment effect, Bj is block effect, and eij is random error.
3. Results
3.2. Feed intake
3.1. Chemical composition of the treatment feeds
The total DM intake of experimental goats supplemented with the high level of CSM was higher
(P b 0.001) as compared to that for non-supplemented
goats (Table 2). Hay DM, CP and NDF intakes were
higher (P b 0.001) in non-supplemented than in supplemented goats. The DM, CP and NDF intakes of hay
decreased numerically as the level of CSM increased,
The CP content of hay used in this study was
markedly lower than CP contained in CSM, whereas the
NDF and ADF contents were higher in the grass hay
(Table 1). The CSM contained more ADL than the grass
hay.
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M. Solomon et al. / Livestock Science 119 (2008) 137–144
Table 1
Chemical composition of treatment feeds
Feed
Hay
CSM
DM (g/kg)
OM (g/kg DM)
CP (g/kg DM)
EE (g/kg DM)
NDF (g/kg DM)
ADF (g/kg DM)
ADL (g/kg DM)
Hemicellulose (g/kg DM)
Cellulose (g/kg DM)
944.0
897.3
92.3
6.0
779.4
427.0
56.9
352.4
370.1
957.0
939.2
253.4
54.6
605.8
406.7
76.4
199.1
330.3
ADF = acid detergent fiber; ADL = acid detergent lignin; CP = crude
protein; CSM = cottonseed meal; DM = dry matter; EE = ether extract;
NDF = neutral detergent fiber; OM = organic matter.
while the total DM intake increased. There was no
significant difference (P N 0.001) in total DM intake
among supplemented goats. The total CP intake
increased (P b 0.01) with increasing level of supplementation. The daily DM, CP and NDF intakes of CSM
increased (P b 0.001) with level of supplementation.
Treatment differences (P N 0.05) were not observed in
NDF and ADF intake as well as in total DMI as percent
of BW. Supplementation with CSM caused a partial
substitution of the grass hay with the CSM, which was
Table 2
Daily feed intake of Sidama goats fed grass hay supplemented with
different levels of cottonseed meal
Feed intake
(g/kg W0.75)
T1
Hay DM intake
CSM DM intake
Total DM intake
Hay CP intake
CSM CP intake
Total CP intake
Hay NDF intake
CSM NDF intake
Total NDF intake
ADF intake
Total DM intake
(g/day)
Total DM intake
(%BW)
Substitution rate
(g/kg)
42.0b
35.1b
58.8a
30.7b
–
23.1c
b
ab
65.11
65.8ab
58.8
3.9b
3.2b
5.5a
c
7.8b
–
5.7
9.5c
11.0b
5.5d
32.7b
27.6b
45.9a
18.2b
–
13.5c
45.9
46.3
46.0
25.1
27.0
27.5
482.0b 568.5ab 569.6ab
abcd
2.8
–
T2
2.8
0.28b
T3
2.7
0.41ab
T4
SEM SL
32.8b
37.0a
69.9a
3.0b
9.4a
12.4a
26.0b
21.6a
48.0
29.1
651.9a
1.90
0.76
1.90
0.18
0.15
0.20
1.53
0.60
1.48
0.81
18.42
2.9
0.44a
***
***
***
***
***
**
***
**
ns
ns
***
Table 3
Nutrient digestion coefficient in Sidama goats fed grass hay
supplemented with different levels of cottonseed meal
Treatments
DM
T1
T2
T3
T4
SEM
SL
Means in the same row with different superscripts differ significantly (P b 0.05);*** (P b 0.01); ** (P b 0.01); * (P b 0.05); ADF =
acid detergent fiber; BW = body weight; CP = crude protein; CSM =
cottonseed meal; DM = dry matter; NDF = neutral detergent fiber; ns =
not significant; SEM = standard error of mean; SL = significance level;
T1 = sole grass hay; T2 = grass hay + 200 g DM CSM; T3 = grass
hay + 300 g DM CSM; T4 = grass hay + 400 g DM CSM.
OM
b
0.62
0.63b
0.68ab
0.72a
0.022
*
CP
b
0.65
0.69ab
0.70ab
0.75a
0.012
**
b
0.41
0.62a
0.67a
0.73a
0.022
**
NDF
ADF
0.65
0.66
0.67
0.71
0.06
ns
0.67
0.62
0.61
0.67
0.020
ns
ab
Means with different superscripts in column are significantly different; *** (P b 0.001); ** (P b 0.01); * (P b 0.05); ADF = acid detergent fiber; CP = crude protein; DM = dry matter; NDF = neutral
detergent fiber; ns = not significant; OM = organic matter; SEM =
standard error mean; SL = significance level; T1 = sole grass hay; T2 =
grass hay + 200 g DM CSM; T3 = grass hay + 300 g DM CSM; T4 =
grass hay + 400 g DM CSM.
higher (P b 0.05) at the highest than the lowest level of
supplementation.
3.3. Apparent digestibility of nutrients
The apparent digestibility of CP in supplemented
goats was higher (P b 0.01) as compared to that in nonsupplemented goats, even though there was no difference (P N 0.01) among the supplemented treatments
(Table 3). The high level of supplementation resulted in
higher (P b 0.01) apparent OM digestibility compared to
the control treatment. Moreover, the high level of
supplementation promoted higher (P b 0.05) apparent
digestibility of DM as compared to the control and the
low level of supplementation. Organic matter, CP and
NDF digestibility increased numerically with level of
CSM supplementation, though statistically non significant (P N 0.05). The apparent digestibility of NDF and
Table 4
Nutrient digestion coefficient determined by difference for different
levels of cottonseed meal in Sidama goats fed hay basal diet
Treatments
0.13 ns
0.32 *
Digestion coefficient
T2
T3
T4
SEM
SL
Digestion coefficient
DM
OM
CP
NDF
ADF
0.77
0.75
0.82
0.33
ns
0.75
0.75
0.83
0.27
ns
0.75
0.78
0.82
0.18
ns
0.69
0.70
0.78
0.37
ns
0.54
0.55
0.67
0.38
ns
ADF = acid detergent fiber; CP = crude protein; DM = dry matter;
NDF = neutral detergent fiber; ns = not significant; OM = organic
matter; SEM: standard error of mean; T1 = sole grass hay; T2 = grass
hay + 200 g DM CSM; T3 = grass hay + 300 g DM CSM; T4 = grass
hay + 400 g DM CSM.
141
M. Solomon et al. / Livestock Science 119 (2008) 137–144
Table 5
Body weight parameters of Sidama goats fed grass hay supplemented
with different levels of cottonseed meal
Table 7
Edible carcass offals of Sidama goats fed grass hay supplemented with
different levels of cottonseed meal
Parameters
Edible offals (g)
Initial BW (kg)
Final BW (kg)
BW change (kg)
Daily BWG
FCR (g DMI/g BWG)
T1
16.0
16.9c
0.9c
10.2c
47.9a
T2
16.6
20.3b
3.8b
41.7b
13.7b
T3
17.3
23.2a
5.9a
65.3a
9.7b
T4
17.2
22.2ab
5.0ab
55.6ab
12.3b
SEM
0.54
0.65
0.27
3.10
1.62
SL
ns
*
***
**
**
abc
Means with different superscripts in the same row are significantly
different (P b 0.05);*** (P b 0.001); ** (P b 0.01); * (P b 0.05); BWG =
body weight gain; DMI = dry matter intake; FCR = feed conversion
ratio; ns = not significant; SEM = standard error of mean; T1 = sole
grass hay; T2 = grass hay + 200 g DM CSM; T3 = grass hay + 300 g
DM CSM; T4 = grass hay + 400 g DM CSM.
ADF were not different (P N 0.05) between the control
and supplemented goats and among different levels of
supplementation. The apparent digestibility of nutrients
in CSM was similar (P N 0.05) for the different levels of
CSM supplementation (Table 4).
Heart
Head
Liver
Kidney
Kidney fat
Reticulo-rumen
Omasum–
abomasum
Small and large
intestine
Tail
Abdominal fat
Testis
Blood
Total edible offals
T1
T2
b
T3
ab
T4
a
a
SEM
SL
65
1081b
251b
53b
12b
428
123b
85
1298ab
316ab
64ab
64a
405
129ab
99
1409a
361a
72a
78a
459
155a
89
1324ab
362a
72a
70a
369
119b
3.85
54.08
18.87
3.89
4.12
24.58
5.37
**
**
*
**
***
ns
**
491
598
567
561
37.74 ns
23b
108c
128b
867b
7312b
34ab
343b
169ab
986ab
9866a
39a
662a
194a
1061a
10925a
33ab
2.85
450b
30.56
186a
10.35
979ab
40.82
10371a 421.63
*
***
**
*
**
abc
Means with different superscripts in rows are significantly different
(P b 0.05); *** (P b 0.001); ** P b 0.01); * (P b 0.05); ns = not significant; SEM = standard error of mean; SL = significance level; T1 =
sole grass hay; T2 = grass hay + 200 g DM CSM; T3 = grass hay+ 300 g
DM CSM; T4 = grass hay + 400 g DM CSM.
3.4. Body weight parameters
The final BW, total BW change and daily BW gain
were higher (P b 0.01) at medium than at low level of
supplementation and all these variables were lower
(P b 0.01) in the non-supplemented than in the supplemented animals (Table 5). The BW of the experimental
goats in all the treatments increased through time with
more prominent increase in animals supplemented with
the medium and high level of CSM supplementation.
The grass hay used in this study also promoted positive
daily BW gain. On the other hand, the feed FCR was
Table 6
Carcass parameters of Sidama goats fed grass hay supplemented with
different levels of cottonseed meal
Parameters
T1
T2
T3
T4
SEM
SL
BW at slaughter (kg)
Empty BW (kg)
HCW (kg)
16.7b
12.0b
6.2b
20.0ab
16.6ab
9.2ab
23.0a
19.1a
10.6a
21.5a
17.8a
9.7a
0.92
0.79
0.54
**
**
***
Dressing percentage
BW at slaughter basis
Empty BW basis
Rib-eye area (cm2)
ab
37.2b
51.6
3.5b
45.8a
55
5.1a
45.9a
55.2
5.6a
45.1a
54.5
5.4a
1.17
1.35
0.21
**
ns
***
Means with different superscripts in rows are significantly different
(P b 0.05);*** (P b 0.001); ** (P b 0.01); BW = body weight; HCW =
hot carcass weight; ns = not significant; SEM = standard error of mean;
SL = significance level; T1 = sole grass hay; T2 = grass hay + 200 g
DM CSM; T3 = grass hay + 300 g DM CSM; T4 = grass hay + 400 g
DM CSM.
higher (P b 0.01) in the non-supplemented than the
supplemented animals.
3.5. Carcass components and offals
The medium and high level of supplementation resulted in higher BW at slaughter, empty BW (P b 0.01)
and hot carcass weight than the control treatment. Moreover, supplementation with the different levels of CSM
promoted higher dressing percent on BW at slaughter
basis (P b 0.01) and higher rib-eye muscle area (P b
0.001) compared to non-supplemented animals
(Table 6). In the current study, small intestine and large
intestine, reticulo-rumen, lungs and trachea and penis
were not affected by different levels of supplementation
Table 8
Non-edible carcass offals of Sidama goats fed grass hay supplemented
with different levels of cottonseed meal
Non-edible offals (g)
T1
T2
T3
T4
Skin with feet
Lungs and trachea
Spleen
Penis
Total non-edible offals
1590b
186
20b
31
1828b
2400a
201
33ab
34
2668a
2560a
231
36a
35
2863a
2580a 155.8
207
11.7
31ab
3.45
40
3.34
2859a 162.0
ab
SEM
SL
**
ns
*
ns
**
Means with different superscripts in rows are significantly different
(P b 0.05); ** (P b 0.01); * (P b 0.05); ns = not significant; SEM =
standard error mean; SL = significance level; T1 = sole grass hay; T2 =
grass hay + 200 g DM CSM; T3 = grass hay + 300 g DM CSM; T4 =
grass hay + 400 g DM CSM.
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M. Solomon et al. / Livestock Science 119 (2008) 137–144
(Tables 7 and 8). Heart, head, omasum–abomasum, tail,
abdominal fat and spleen weight were higher (P b 0.05)
in goats supplemented with the medium level of
CSM compared to the non-supplemented goats (Tables
7 and 8). Medium and high level of supplementation
resulted in higher (P b 0.05) liver and kidney weight than
in the control goats. Generally, supplemented goats
produced higher (P b 0.01) total edible offals and total
non-edible offals (P b 0.05) than the non-supplemented
ones.
DM intake and growth rate in Alpine and Nubian goats
increased correspondingly as the level of protein in the
diet increased (Lu and Potchoiba, 1990). The reduction
in hay intake with increasing level of the supplement in
the present study could be due to the substitution effect
of the basal diet with the concentrate feed. Other studies
(Mosi and Butterworth, 1985; Tolera and Sundstøl,
2000) also reported partial substitution of the basal
ration by forage legume supplementation.
4.3. Apparent digestibility
4. Discussion
The CP content of CSM used in the present study was
comparable to the CP content of CSM reported by
McDonald et al. (2002) which was 239 g kg− 1 DM.
Contrary to the result of the current study, high CP
content of 480 g kg− 1 DM was reported for CSM by
Khan et al. (2000). The low CP content of CSM in the
present study could be due to using undecorticated
cottonseed for oil extraction. According to McDonald
et al. (2002), undecorticated CSM contains lower CP
(239 g kg− 1 DM) than CSM produced from decorticated
meal (460 g kg− 1 DM). The NDF and ADF content of
CSM in this study were comparable to the result of
Moges (1992). High NDF and ADF in the CSM used in
the current study are related to its lower CP content.
Indeed, Moges (1992) reported low CP content in oil
seed cakes with high cell wall contents. The CP content
of grass hay used in the present study (92 g kg − 1 DM) is
comparable to the CP content (110 g kg − 1 DM) of good
quality grass hay (McDonald et al., 2002). The relatively
high CP content of hay in the present study is due to the
species composition as well as harvesting at early stage
of growth.
The apparent digestibility of CP observed in this
study agrees with the result of Ash and Norton (1987)
that demonstrated better CP digestibility in goats fed
high protein compared to low protein diet. Generally,
concentrate feed which is rich in protein content
promotes high rumen microbial population (McDonald
et al., 2002) which facilitates rumen fermentation.
Similar to the current study, supplementation with
CSM, leucaena or sesbania to Menz sheep did not
affect the apparent digestibility of NDF and ADF (Bonsi
et al., 1996). The lack of significant difference in
digestibility (P N 0.05) of NDF and ADF between the
treatments in the present study was also in agreement to
the result of McRae and Armstrong (1969) who reported
little or no effect of supplementation on digestibility of
NDF and ADF. The absence of effect of supplementation on NDF and ADF digestibility could be explained
by possible reduction in rumen pH which has a depressing effect on the population of cell wall fermenting
rumen microbes as a result of feeding more digestible
supplement to the animals. Increased CP digestibility in
supplemented treatments might be due to higher dietary
CP supply. Crude protein digestibility of CSM in the
present study was comparable to the value of 77–86%
reported by McDonald et al. (2002).
4.2. Feed intake
4.4. Body weight parameters
The DM intake as percent of BW in the present study
(2.71–2.94%) is in agreement with that reported (1.7–
4.8% BW) for various breeds of goats in the tropics
(Devendra and Burns, 1983). The high NDF and ADF
intake in the non-supplemented than the supplemented
goats could be due to high intake of grass hay in the nonsupplemented goats since NDF content was higher in
the grass hay. The higher total DM intake with the high
level of CSM supplementation in this study was similar
to the result of Bonsi et al. (1996) in which supplementation with a protein source increased total DM
intake in sheep. Consistent with the result in this study,
Positive mean daily BW gain in non-supplemented
goats in the present study indicated that the grass hay
satisfied the maintenance requirement of the goats. This
was expected since the content of CP (9.23%) and
apparent DM digestibility (62.3%) in the grass hay was
more than adequate to meet maintenance requirement of
the goats. Van Soest (1994) demonstrated that BW gain
is not impaired if the level of CP in a given diet is more
than 8%. Similarly, Conrad and Hibbs (1968) reported
that rumen function is impaired, feed intake and animal
performance is markedly reduced when the nitrogen
content of the diet is less than 1.2%. High BW gain in
4.1. Chemical composition of the treatment feeds
M. Solomon et al. / Livestock Science 119 (2008) 137–144
supplemented goats could be due to high energy and
protein intake. The daily BW gain observed in the
present study was comparable to 36–53 g day− 1 BW
gain in Somali goats fed grass hay supplemented with
concentrate mix of 200 g DM day − 1 (Urge et al., 2004).
Shapiro et al. (1985) reported mean daily BW gain of 33
and 70 g during the dry and wet seasons, respectively in
grazing sheep supplemented with 300 g wheat bran and
300 g CSM, which is comparable to the results of the
present study. The decreased FCR with the high level of
supplementation in this study was in agreement to the
results of Zinn et al. (1997) that showed decreased FCR
with increasing level of CSM in cattle.
4.5. Carcass component and offals
The positive effect of supplementation on hot carcass, empty BW, dressing percentage (slaughter basis)
and rib-eye muscle area in the present study was similar
to that reported by Okello and Obwolo (1994) in goats
supplemented with CSM and maize bran. Low dressing
percentage (slaughter weight basis) in the non-supplemented goats could be due to high gut fill which
accordingly reduced the dressing percentage. Slaughter
weight, hot carcass weight, empty BW and dressing
percentage observed for the non-supplemented goats in
the present study was in agreement with the results
reported by Legesse (2001) for mid-rift valley goats in
Ethiopia. The average slaughter weight, empty BW and
hot carcass weight of goats supplemented with 300 g
DM CSM showed heavier weight which was similar to
the trend observed in final BW. Consistent to the present
study, Bhuyan et al. (1996) observed that low and high
protein supplementation had no effect on the rib-eye
muscle area in goats. Zinn et al. (1997) also reported that
different levels of CSM supplementation to cattle did
not affect dressing percentage and rib-eye muscle area.
The lack of significant difference in dressing percentage
on empty BW basis might be due to the exclusion of the
contribution of gut fill. The dressing percent observed in
this study was within the range of dressing percent (37–
55%) for goat carcass (Enseminger, 2002). Similar to the
present study, Legesse (2001) reported that most of the
non-carcass components of supplemented treatments
showed significant difference for extensively managed
goats.
5. Conclusions
The medium level of supplementation resulted in
higher daily BW gain (P b 0.01), BW change (P b 0.001),
final BW (P b 0.05) and lower feed conversion ratio
143
(P b 0.01) than the lower level of supplementation, but
with no differences in these parameters with the high
level of supplementation. Therefore, it is concluded that
supplementation of CSM at 300 g DM per day resulted in
better animal performance parameters in Sidama goats.
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Livestock Science 119 (2008) 137 – 144
www.elsevier.com/locate/livsci
Supplementation of cottonseed meal on feed intake, digestibility,
live weight and carcass parameters of Sidama goats
Matiwos Solomon a , Solomon Melaku b,⁎, Adugna Tolera c
a
Dilla ATVET College, P.O. Box, Dilla, Ethiopia
Department of Animal Sciences, Haramaya University, P.O. Box 138, Dire Dawa, Ethiopia
Department of Animal and Range Sciences, Hawassa University, P.O. Box 5, Awassa, Ethiopia
b
c
Received 4 January 2008; received in revised form 15 March 2008; accepted 17 March 2008
Abstract
The experiment was conducted at Dilla Agricultural Technical Vocational Education and Training (ATVET) College in Ethiopia
using twenty-four yearling intact male Sidama goats with a mean body weight (BW) of 16.8 ± 1.14 kg (mean ± SD). The objective
of the experiment was to examine the effect of different levels of cottonseed meal (CSM) supplementation on the feed intake,
digestibility, BW gain, and carcass parameters of Sidama goats. The experiment consisted of 90 days of feeding trial and 10 days of
digestibility trial followed by evaluation of carcass parameters at the end of the experiment. The treatments included ad libitum
feeding of hay (T1, control) and daily supplementation of CSM at 200 g (T2), 300 g (T3) and 400 g (T4) per head on dry matter
(DM) basis. The experimental design was a completely randomized block design. The experimental goats were blocked on initial
BW and six goats were randomly assigned to each treatment. Hay DM, crude protein (CP) and neutral detergent fiber (NDF) intake
were higher (P b 0.001) in the non-supplemented than in the supplemented goats, however, the contrary was true for total CP
intake. Total DM intake was higher (P b 0.001) for goats supplemented with the high level of CSM than those on the control
treatment. Among CSM supplemented goats, the intake of CSM DM, CP, NDF (P b 0.001) and total CP (P b 0.01) were higher in
the order of T4 N T3 N T2. The high level of supplementation with CSM resulted in better (P b 0.05) apparent digestibility coefficient
(DC) of DM and organic matter (OM) compared to the non-supplemented goats. The apparent DC of CP was higher (P b 0.01) for
supplemented than non-supplemented goats. The non-supplemented goats had lower daily BW gain, empty BW, dressing
percentage on slaughter weight base, rib-eye muscle area (P b 0.01), BW change (P b 0.001), final BW (P b 0.05) and higher feed
conversion ratio (P b 0.01) than the supplemented ones. The medium level of supplementation resulted in higher daily BW gain
(P b 0.01), BW change (P b 0.001), final BW (P b 0.05) and lower feed conversion ratio (P b 0.01) than the lower level of
supplementation, but with no differences (P N 0.05) in these parameters with the high level of supplementation. Therefore, it is
concluded that supplementation of CSM at 300 g DM per head per day resulted in better animal performance parameters in Sidama
goats.
© 2008 Elsevier B.V. All rights reserved.
Keywords: Feed intake; Digestibility; Body weight; Cottonseed meal; Sidama goats
⁎ Corresponding author. Tel.: +251 915 74 72 18.
E-mail address: solmelay@yahoo.com (S. Melaku).
1871-1413/$ - see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.livsci.2008.03.011
138
M. Solomon et al. / Livestock Science 119 (2008) 137–144
1. Introduction
Goats are among the important domestic animals of
value to man in the drier regions of the tropics. They
have multiple functions and display a unique ability to
adapt to harsh environments with wide ecological
range. In the tropics, goats serve mostly as a source of
meat and skins (Devendra and Burns, 1983), while in
the temperate zone they are primarily reared for milk
and to a lesser extent for meat production. Feeding
behaviour, prolificacy, small body size are important
characteristics of goats that enable them to be easily
integrated in pastoralist as well as mixed crop
livestock production systems in the tropics. Consequently, about 52% of the world's goat population is
found in the developing countries of the tropics (FAO,
2003) due to their concentration in dry tropical areas
of poor agricultural potential and even on marginal
lands (Morand-Fehr and Boyazoglu, 1999). Indeed,
mutton and goat meat as compared to beef account for
a large share of the domestic meat consumption in
many tropical countries (Gryseels and Anderson,
1983).
However, the meat production potential of goats is
low compared to the population size. This low level of
productivity of goats in tropical countries could be
attributed to animal diseases, poor genetic potential, lack
of proper management, and poor nutrition, among
which the latter plays a significant role. Generally,
goats reared by smallholder farmers and pastoralists in
the tropics rely entirely on poor quality natural grassland, crop residues with crude protein (CP) contents of
less than 8% and neutral detergent fiber (NDF) content
of more than 55%. Feedstuffs of such composition
hardly meet the maintenance requirements of goats
throughout the year. Hence, supplementation with agroindustrial by-products such as oil seed meals that are
produced abundantly in tropical countries and rich in CP
(200–500 g/kg DM) is among the possible measures to
improve the productivity of goats. Among the various
oil seed residues, cottonseed meal (CSM) is one of the
protein supplements commonly used in animal feeding,
though its utilization may be limited by its content of
gossypol, the main anti-nutritive factor in CSM.
However, according to Wolf et al. (1980), gossypol in
CSM cannot present problems to animals with a
functional rumen. Therefore, this experiment was
conducted with the objective to examine the effect of
different levels of CSM on feed intake, weight change
and carcass parameters of Sidama goats.
2. Materials and methods
2.1. Description of the experimental area
The experiment was conducted at Dilla Agricultural Technical Vocational Education and Training (ATVET) College, Ethiopia.
The study site is located at 6° 27′ N and 38° 30′ E and at an altitude of 1550 m above sea level, and receives annual precipitation of
1200–1800 mm with annual temperature range between 13 and 23 °C.
2.2. Management of animals
Twenty-four yearling male Sidama goats with mean initial body weight (BW) of 16.78 ± 1.14 kg (mean ± SD) were used for the
study. The goats were quarantined for 3 weeks, and during this period they were de-wormed and sprayed against internal and
external parasites, respectively. They were also vaccinated against pasteurelosis and anthrax, and penned individually.
2.3. Experimental design and treatments
The experimental goats were blocked into six blocks of four animals based on initial BW and randomly assigned to one of the
four dietary treatments in a randomized complete block design giving six animals per treatment. The dietary treatments consisted of
sole grass hay (control, T1), and supplementation with 200 g (low, T2), 300 g (medium, T3) and 400 g (high, T4) CSM on DM basis.
The natural grass hay used in the study consisted of mainly Digitaria nodosa, Sporobolus natalensis and Eragrostis papposa
species.
2.4. Feed intake and body weight
The respective CSM supplements for each treatment were offered twice a day at 800 h and 1600 h in two equal portions. Hay was
offered ad libitum after the consumption the first CSM offer. Daily feed offer and refusals were weighed and recorded for each goat
to determine daily feed intake. Water and mineral lick were available free choice. Representative samples of feed offer per batch and
refusals per goat were collected and pooled on treatment for determination of chemical composition. The feed conversion ratio
M. Solomon et al. / Livestock Science 119 (2008) 137–144
139
(FCR) was calculated as a proportion of daily DM intake to daily BW gain. The substitution rate (SR) of the basal feed by the
concentrate mix was calculated using the following equation (Ponnampalam et al., 2004).
SR ¼
Tef straw intake of control treatment ðgÞ tef straw intake of the supplemented treatment ðgÞ
Concentrate mix intake ðgÞ
Initial BW of each goat was determined by taking the mean of two consecutive weights after overnight fasting, and BW was
subsequently measured every 10 days after overnight fasting. The mean daily BW gain was calculated by regressing BW
measurements on days of feeding.
2.5. Digestibility trial
Four animals from each treatment were randomly selected and fitted with faeces collection bags to measure the digestibility of the
treatment feeds they were fed on during the feeding trial. After allowing an adjustment period of 3 days to carrying the faeces
collection bags, daily total faecal excretion per animal was collected for seven consecutive days. The daily collected faeces was
weighed, 20% sub-sampled and stored frozen at − 20 °C. The digestion coefficient of nutrients was calculated as a proportion of
nutrients consumed and not recovered in the faeces.
The digestibility of CSM was estimated by difference as described by McDonald et al. (2002) using the equation:
Nutrient DC ¼
Nutrient in test f eed
ðNut: in f aeces of mixed diet Nutrient in f aeces of basal f eedÞ
Nutrient in test f eed
2.6. Carcass parameters
Five goats from each treatment were randomly slaughtered after overnight fasting. Blood, head, skin, feet, heart, lungs and
trachea, liver with gall bladder, spleen, testis, penis, kidneys, abdominal gut, reticulo-rumen, omasum–abomasum, small and large
intestine were weighed and recorded. Empty BW was determined by difference between BW at slaughter and gut content. Hot
carcass weight was computed by excluding edible and non-edible offals. Dressing percent was calculated as proportion of hot carcass
weight to slaughter as well as empty BW. The rib-eye muscle area was measured by tracing the cross section area of the 10th and 11th
ribs after cutting perpendicular to the back bone (Kyomo, 1978 cited in Legesse, 2001). The left and right rib-eye muscle area was
traced on a water proof transparent plastic foil and the area was measured using a planimeter.
2.7. Chemical analysis
Samples of feed offered, refused and faeces were dried at 55°C in a forced draft oven to constant weight and ground to pass 1 mm
mesh screen size and used for determination of chemical composition. Dry matter (DM), organic matter (OM), CP, ether extracts
(EE) and ash were analysed according to the AOAC (1990). The NDF, acid detergent fiber (ADF), and acid detergent lignin (ADL)
were analysed by the procedures of Van Soest et al. (1991).
2.8. Statistical analysis
The data collected were subjected to the analysis of variance using the general linear model procedure of SAS (1998). Treatment
means were separated by least significant difference (LSD). The model used for feeding trial was Yij = μ + Ti + Bj + eij, while the model
used for the digestion trial and carcass parameters was Yij = μ + Ti + eij.
Where; Yij is response variable, μ overall mean, Ti is treatment effect, Bj is block effect, and eij is random error.
3. Results
3.2. Feed intake
3.1. Chemical composition of the treatment feeds
The total DM intake of experimental goats supplemented with the high level of CSM was higher
(P b 0.001) as compared to that for non-supplemented
goats (Table 2). Hay DM, CP and NDF intakes were
higher (P b 0.001) in non-supplemented than in supplemented goats. The DM, CP and NDF intakes of hay
decreased numerically as the level of CSM increased,
The CP content of hay used in this study was
markedly lower than CP contained in CSM, whereas the
NDF and ADF contents were higher in the grass hay
(Table 1). The CSM contained more ADL than the grass
hay.
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M. Solomon et al. / Livestock Science 119 (2008) 137–144
Table 1
Chemical composition of treatment feeds
Feed
Hay
CSM
DM (g/kg)
OM (g/kg DM)
CP (g/kg DM)
EE (g/kg DM)
NDF (g/kg DM)
ADF (g/kg DM)
ADL (g/kg DM)
Hemicellulose (g/kg DM)
Cellulose (g/kg DM)
944.0
897.3
92.3
6.0
779.4
427.0
56.9
352.4
370.1
957.0
939.2
253.4
54.6
605.8
406.7
76.4
199.1
330.3
ADF = acid detergent fiber; ADL = acid detergent lignin; CP = crude
protein; CSM = cottonseed meal; DM = dry matter; EE = ether extract;
NDF = neutral detergent fiber; OM = organic matter.
while the total DM intake increased. There was no
significant difference (P N 0.001) in total DM intake
among supplemented goats. The total CP intake
increased (P b 0.01) with increasing level of supplementation. The daily DM, CP and NDF intakes of CSM
increased (P b 0.001) with level of supplementation.
Treatment differences (P N 0.05) were not observed in
NDF and ADF intake as well as in total DMI as percent
of BW. Supplementation with CSM caused a partial
substitution of the grass hay with the CSM, which was
Table 2
Daily feed intake of Sidama goats fed grass hay supplemented with
different levels of cottonseed meal
Feed intake
(g/kg W0.75)
T1
Hay DM intake
CSM DM intake
Total DM intake
Hay CP intake
CSM CP intake
Total CP intake
Hay NDF intake
CSM NDF intake
Total NDF intake
ADF intake
Total DM intake
(g/day)
Total DM intake
(%BW)
Substitution rate
(g/kg)
42.0b
35.1b
58.8a
30.7b
–
23.1c
b
ab
65.11
65.8ab
58.8
3.9b
3.2b
5.5a
c
7.8b
–
5.7
9.5c
11.0b
5.5d
32.7b
27.6b
45.9a
18.2b
–
13.5c
45.9
46.3
46.0
25.1
27.0
27.5
482.0b 568.5ab 569.6ab
abcd
2.8
–
T2
2.8
0.28b
T3
2.7
0.41ab
T4
SEM SL
32.8b
37.0a
69.9a
3.0b
9.4a
12.4a
26.0b
21.6a
48.0
29.1
651.9a
1.90
0.76
1.90
0.18
0.15
0.20
1.53
0.60
1.48
0.81
18.42
2.9
0.44a
***
***
***
***
***
**
***
**
ns
ns
***
Table 3
Nutrient digestion coefficient in Sidama goats fed grass hay
supplemented with different levels of cottonseed meal
Treatments
DM
T1
T2
T3
T4
SEM
SL
Means in the same row with different superscripts differ significantly (P b 0.05);*** (P b 0.01); ** (P b 0.01); * (P b 0.05); ADF =
acid detergent fiber; BW = body weight; CP = crude protein; CSM =
cottonseed meal; DM = dry matter; NDF = neutral detergent fiber; ns =
not significant; SEM = standard error of mean; SL = significance level;
T1 = sole grass hay; T2 = grass hay + 200 g DM CSM; T3 = grass
hay + 300 g DM CSM; T4 = grass hay + 400 g DM CSM.
OM
b
0.62
0.63b
0.68ab
0.72a
0.022
*
CP
b
0.65
0.69ab
0.70ab
0.75a
0.012
**
b
0.41
0.62a
0.67a
0.73a
0.022
**
NDF
ADF
0.65
0.66
0.67
0.71
0.06
ns
0.67
0.62
0.61
0.67
0.020
ns
ab
Means with different superscripts in column are significantly different; *** (P b 0.001); ** (P b 0.01); * (P b 0.05); ADF = acid detergent fiber; CP = crude protein; DM = dry matter; NDF = neutral
detergent fiber; ns = not significant; OM = organic matter; SEM =
standard error mean; SL = significance level; T1 = sole grass hay; T2 =
grass hay + 200 g DM CSM; T3 = grass hay + 300 g DM CSM; T4 =
grass hay + 400 g DM CSM.
higher (P b 0.05) at the highest than the lowest level of
supplementation.
3.3. Apparent digestibility of nutrients
The apparent digestibility of CP in supplemented
goats was higher (P b 0.01) as compared to that in nonsupplemented goats, even though there was no difference (P N 0.01) among the supplemented treatments
(Table 3). The high level of supplementation resulted in
higher (P b 0.01) apparent OM digestibility compared to
the control treatment. Moreover, the high level of
supplementation promoted higher (P b 0.05) apparent
digestibility of DM as compared to the control and the
low level of supplementation. Organic matter, CP and
NDF digestibility increased numerically with level of
CSM supplementation, though statistically non significant (P N 0.05). The apparent digestibility of NDF and
Table 4
Nutrient digestion coefficient determined by difference for different
levels of cottonseed meal in Sidama goats fed hay basal diet
Treatments
0.13 ns
0.32 *
Digestion coefficient
T2
T3
T4
SEM
SL
Digestion coefficient
DM
OM
CP
NDF
ADF
0.77
0.75
0.82
0.33
ns
0.75
0.75
0.83
0.27
ns
0.75
0.78
0.82
0.18
ns
0.69
0.70
0.78
0.37
ns
0.54
0.55
0.67
0.38
ns
ADF = acid detergent fiber; CP = crude protein; DM = dry matter;
NDF = neutral detergent fiber; ns = not significant; OM = organic
matter; SEM: standard error of mean; T1 = sole grass hay; T2 = grass
hay + 200 g DM CSM; T3 = grass hay + 300 g DM CSM; T4 = grass
hay + 400 g DM CSM.
141
M. Solomon et al. / Livestock Science 119 (2008) 137–144
Table 5
Body weight parameters of Sidama goats fed grass hay supplemented
with different levels of cottonseed meal
Table 7
Edible carcass offals of Sidama goats fed grass hay supplemented with
different levels of cottonseed meal
Parameters
Edible offals (g)
Initial BW (kg)
Final BW (kg)
BW change (kg)
Daily BWG
FCR (g DMI/g BWG)
T1
16.0
16.9c
0.9c
10.2c
47.9a
T2
16.6
20.3b
3.8b
41.7b
13.7b
T3
17.3
23.2a
5.9a
65.3a
9.7b
T4
17.2
22.2ab
5.0ab
55.6ab
12.3b
SEM
0.54
0.65
0.27
3.10
1.62
SL
ns
*
***
**
**
abc
Means with different superscripts in the same row are significantly
different (P b 0.05);*** (P b 0.001); ** (P b 0.01); * (P b 0.05); BWG =
body weight gain; DMI = dry matter intake; FCR = feed conversion
ratio; ns = not significant; SEM = standard error of mean; T1 = sole
grass hay; T2 = grass hay + 200 g DM CSM; T3 = grass hay + 300 g
DM CSM; T4 = grass hay + 400 g DM CSM.
ADF were not different (P N 0.05) between the control
and supplemented goats and among different levels of
supplementation. The apparent digestibility of nutrients
in CSM was similar (P N 0.05) for the different levels of
CSM supplementation (Table 4).
Heart
Head
Liver
Kidney
Kidney fat
Reticulo-rumen
Omasum–
abomasum
Small and large
intestine
Tail
Abdominal fat
Testis
Blood
Total edible offals
T1
T2
b
T3
ab
T4
a
a
SEM
SL
65
1081b
251b
53b
12b
428
123b
85
1298ab
316ab
64ab
64a
405
129ab
99
1409a
361a
72a
78a
459
155a
89
1324ab
362a
72a
70a
369
119b
3.85
54.08
18.87
3.89
4.12
24.58
5.37
**
**
*
**
***
ns
**
491
598
567
561
37.74 ns
23b
108c
128b
867b
7312b
34ab
343b
169ab
986ab
9866a
39a
662a
194a
1061a
10925a
33ab
2.85
450b
30.56
186a
10.35
979ab
40.82
10371a 421.63
*
***
**
*
**
abc
Means with different superscripts in rows are significantly different
(P b 0.05); *** (P b 0.001); ** P b 0.01); * (P b 0.05); ns = not significant; SEM = standard error of mean; SL = significance level; T1 =
sole grass hay; T2 = grass hay + 200 g DM CSM; T3 = grass hay+ 300 g
DM CSM; T4 = grass hay + 400 g DM CSM.
3.4. Body weight parameters
The final BW, total BW change and daily BW gain
were higher (P b 0.01) at medium than at low level of
supplementation and all these variables were lower
(P b 0.01) in the non-supplemented than in the supplemented animals (Table 5). The BW of the experimental
goats in all the treatments increased through time with
more prominent increase in animals supplemented with
the medium and high level of CSM supplementation.
The grass hay used in this study also promoted positive
daily BW gain. On the other hand, the feed FCR was
Table 6
Carcass parameters of Sidama goats fed grass hay supplemented with
different levels of cottonseed meal
Parameters
T1
T2
T3
T4
SEM
SL
BW at slaughter (kg)
Empty BW (kg)
HCW (kg)
16.7b
12.0b
6.2b
20.0ab
16.6ab
9.2ab
23.0a
19.1a
10.6a
21.5a
17.8a
9.7a
0.92
0.79
0.54
**
**
***
Dressing percentage
BW at slaughter basis
Empty BW basis
Rib-eye area (cm2)
ab
37.2b
51.6
3.5b
45.8a
55
5.1a
45.9a
55.2
5.6a
45.1a
54.5
5.4a
1.17
1.35
0.21
**
ns
***
Means with different superscripts in rows are significantly different
(P b 0.05);*** (P b 0.001); ** (P b 0.01); BW = body weight; HCW =
hot carcass weight; ns = not significant; SEM = standard error of mean;
SL = significance level; T1 = sole grass hay; T2 = grass hay + 200 g
DM CSM; T3 = grass hay + 300 g DM CSM; T4 = grass hay + 400 g
DM CSM.
higher (P b 0.01) in the non-supplemented than the
supplemented animals.
3.5. Carcass components and offals
The medium and high level of supplementation resulted in higher BW at slaughter, empty BW (P b 0.01)
and hot carcass weight than the control treatment. Moreover, supplementation with the different levels of CSM
promoted higher dressing percent on BW at slaughter
basis (P b 0.01) and higher rib-eye muscle area (P b
0.001) compared to non-supplemented animals
(Table 6). In the current study, small intestine and large
intestine, reticulo-rumen, lungs and trachea and penis
were not affected by different levels of supplementation
Table 8
Non-edible carcass offals of Sidama goats fed grass hay supplemented
with different levels of cottonseed meal
Non-edible offals (g)
T1
T2
T3
T4
Skin with feet
Lungs and trachea
Spleen
Penis
Total non-edible offals
1590b
186
20b
31
1828b
2400a
201
33ab
34
2668a
2560a
231
36a
35
2863a
2580a 155.8
207
11.7
31ab
3.45
40
3.34
2859a 162.0
ab
SEM
SL
**
ns
*
ns
**
Means with different superscripts in rows are significantly different
(P b 0.05); ** (P b 0.01); * (P b 0.05); ns = not significant; SEM =
standard error mean; SL = significance level; T1 = sole grass hay; T2 =
grass hay + 200 g DM CSM; T3 = grass hay + 300 g DM CSM; T4 =
grass hay + 400 g DM CSM.
142
M. Solomon et al. / Livestock Science 119 (2008) 137–144
(Tables 7 and 8). Heart, head, omasum–abomasum, tail,
abdominal fat and spleen weight were higher (P b 0.05)
in goats supplemented with the medium level of
CSM compared to the non-supplemented goats (Tables
7 and 8). Medium and high level of supplementation
resulted in higher (P b 0.05) liver and kidney weight than
in the control goats. Generally, supplemented goats
produced higher (P b 0.01) total edible offals and total
non-edible offals (P b 0.05) than the non-supplemented
ones.
DM intake and growth rate in Alpine and Nubian goats
increased correspondingly as the level of protein in the
diet increased (Lu and Potchoiba, 1990). The reduction
in hay intake with increasing level of the supplement in
the present study could be due to the substitution effect
of the basal diet with the concentrate feed. Other studies
(Mosi and Butterworth, 1985; Tolera and Sundstøl,
2000) also reported partial substitution of the basal
ration by forage legume supplementation.
4.3. Apparent digestibility
4. Discussion
The CP content of CSM used in the present study was
comparable to the CP content of CSM reported by
McDonald et al. (2002) which was 239 g kg− 1 DM.
Contrary to the result of the current study, high CP
content of 480 g kg− 1 DM was reported for CSM by
Khan et al. (2000). The low CP content of CSM in the
present study could be due to using undecorticated
cottonseed for oil extraction. According to McDonald
et al. (2002), undecorticated CSM contains lower CP
(239 g kg− 1 DM) than CSM produced from decorticated
meal (460 g kg− 1 DM). The NDF and ADF content of
CSM in this study were comparable to the result of
Moges (1992). High NDF and ADF in the CSM used in
the current study are related to its lower CP content.
Indeed, Moges (1992) reported low CP content in oil
seed cakes with high cell wall contents. The CP content
of grass hay used in the present study (92 g kg − 1 DM) is
comparable to the CP content (110 g kg − 1 DM) of good
quality grass hay (McDonald et al., 2002). The relatively
high CP content of hay in the present study is due to the
species composition as well as harvesting at early stage
of growth.
The apparent digestibility of CP observed in this
study agrees with the result of Ash and Norton (1987)
that demonstrated better CP digestibility in goats fed
high protein compared to low protein diet. Generally,
concentrate feed which is rich in protein content
promotes high rumen microbial population (McDonald
et al., 2002) which facilitates rumen fermentation.
Similar to the current study, supplementation with
CSM, leucaena or sesbania to Menz sheep did not
affect the apparent digestibility of NDF and ADF (Bonsi
et al., 1996). The lack of significant difference in
digestibility (P N 0.05) of NDF and ADF between the
treatments in the present study was also in agreement to
the result of McRae and Armstrong (1969) who reported
little or no effect of supplementation on digestibility of
NDF and ADF. The absence of effect of supplementation on NDF and ADF digestibility could be explained
by possible reduction in rumen pH which has a depressing effect on the population of cell wall fermenting
rumen microbes as a result of feeding more digestible
supplement to the animals. Increased CP digestibility in
supplemented treatments might be due to higher dietary
CP supply. Crude protein digestibility of CSM in the
present study was comparable to the value of 77–86%
reported by McDonald et al. (2002).
4.2. Feed intake
4.4. Body weight parameters
The DM intake as percent of BW in the present study
(2.71–2.94%) is in agreement with that reported (1.7–
4.8% BW) for various breeds of goats in the tropics
(Devendra and Burns, 1983). The high NDF and ADF
intake in the non-supplemented than the supplemented
goats could be due to high intake of grass hay in the nonsupplemented goats since NDF content was higher in
the grass hay. The higher total DM intake with the high
level of CSM supplementation in this study was similar
to the result of Bonsi et al. (1996) in which supplementation with a protein source increased total DM
intake in sheep. Consistent with the result in this study,
Positive mean daily BW gain in non-supplemented
goats in the present study indicated that the grass hay
satisfied the maintenance requirement of the goats. This
was expected since the content of CP (9.23%) and
apparent DM digestibility (62.3%) in the grass hay was
more than adequate to meet maintenance requirement of
the goats. Van Soest (1994) demonstrated that BW gain
is not impaired if the level of CP in a given diet is more
than 8%. Similarly, Conrad and Hibbs (1968) reported
that rumen function is impaired, feed intake and animal
performance is markedly reduced when the nitrogen
content of the diet is less than 1.2%. High BW gain in
4.1. Chemical composition of the treatment feeds
M. Solomon et al. / Livestock Science 119 (2008) 137–144
supplemented goats could be due to high energy and
protein intake. The daily BW gain observed in the
present study was comparable to 36–53 g day− 1 BW
gain in Somali goats fed grass hay supplemented with
concentrate mix of 200 g DM day − 1 (Urge et al., 2004).
Shapiro et al. (1985) reported mean daily BW gain of 33
and 70 g during the dry and wet seasons, respectively in
grazing sheep supplemented with 300 g wheat bran and
300 g CSM, which is comparable to the results of the
present study. The decreased FCR with the high level of
supplementation in this study was in agreement to the
results of Zinn et al. (1997) that showed decreased FCR
with increasing level of CSM in cattle.
4.5. Carcass component and offals
The positive effect of supplementation on hot carcass, empty BW, dressing percentage (slaughter basis)
and rib-eye muscle area in the present study was similar
to that reported by Okello and Obwolo (1994) in goats
supplemented with CSM and maize bran. Low dressing
percentage (slaughter weight basis) in the non-supplemented goats could be due to high gut fill which
accordingly reduced the dressing percentage. Slaughter
weight, hot carcass weight, empty BW and dressing
percentage observed for the non-supplemented goats in
the present study was in agreement with the results
reported by Legesse (2001) for mid-rift valley goats in
Ethiopia. The average slaughter weight, empty BW and
hot carcass weight of goats supplemented with 300 g
DM CSM showed heavier weight which was similar to
the trend observed in final BW. Consistent to the present
study, Bhuyan et al. (1996) observed that low and high
protein supplementation had no effect on the rib-eye
muscle area in goats. Zinn et al. (1997) also reported that
different levels of CSM supplementation to cattle did
not affect dressing percentage and rib-eye muscle area.
The lack of significant difference in dressing percentage
on empty BW basis might be due to the exclusion of the
contribution of gut fill. The dressing percent observed in
this study was within the range of dressing percent (37–
55%) for goat carcass (Enseminger, 2002). Similar to the
present study, Legesse (2001) reported that most of the
non-carcass components of supplemented treatments
showed significant difference for extensively managed
goats.
5. Conclusions
The medium level of supplementation resulted in
higher daily BW gain (P b 0.01), BW change (P b 0.001),
final BW (P b 0.05) and lower feed conversion ratio
143
(P b 0.01) than the lower level of supplementation, but
with no differences in these parameters with the high
level of supplementation. Therefore, it is concluded that
supplementation of CSM at 300 g DM per day resulted in
better animal performance parameters in Sidama goats.
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