Livestock Production Science 64 2000 215–223 www.elsevier.com locate livprodsci
A comparative study of nutrient digestibility, kinetics of degradation and passage and rumen fermentation pattern in
goats and sheep offered good quality diets
´ ´
E. Molina Alcaide , A.I. Martın Garcıa, J.F. Aguilera
´ ´
´ Unidad de Nutricion Animal
, Estacion Experimental del Zaidın CSIC. Camino del Jueves, s n. Armilla, Granada, Spain Received 2 November 1998; received in revised form 15 June 1999; accepted 17 August 1999
Abstract
The in vivo digestibility, the rates of fermentation and passage and the rumen fermentation pattern were compared in ˜
Granadina goats and Segurena wethers fed alfalfa hay AH, alfalfa hay sugar beet pulp, 4:1 AH SB and alfalfa hay sugar beet pulp oat grain, 3:1:1 AH SB OG at approximately maintenance level. The animals were at stall and no selectivity
was practised. The nylon bag technique was used to estimate the extent and fractional rate of degradation of the feed in the rumen. The fractional outflow rate of particles was determined with chromium as a marker. No significant interspecies
differences in the nutrients digestibility were found. Values of potential and effective degradability and rates of degradation of both dry matter and protein were similar in goats and sheep. Also, the calculated values of the fractional rate of passage of
the digesta out of the rumen were not significantly different between animal species. Ammonia-N concentrations were higher in the rumen liquor of goats than in sheep. No clear trend in the concentration of total and individual volatile fatty acids was
observed when comparing goats and sheep with the exception of an increased proportion of valeric acid in the rumen liquor of sheep. From present and previous trials it is concluded that goats and sheep show equal capacities of digestion of medium
to good quality diets when fed at energy maintenance level and feed selection is absent. This would validate extrapolations of feed evaluations, what implies a unique energy value.
2000 Elsevier Science B.V. All rights reserved.
Keywords : Alfalfa hay; Sugar beet pulp; Oat grain; Rumen degradation; Passage rate; Digestibility; Goat; Sheep
1. Introduction AFRC, 1997. It devotes a section to comment on
the digestive physiology of this animal species ‘in The Agricultural and Food Research Council’s
view of the frequent suggestions in the literature that Technical Committee on Responses to Nutrients has
in goats, digestive processes may differ in important very recently published a review on the current state
aspects from those of cattle and sheep’ and another of knowledge with respect to the nutrition of the goat
section to interspecies comparisons for feed intake for validation of between species extrapolations. The
review on these specific subjects covers published
Corresponding author. Tel.: 134-958-57-2757; fax: 134-958-
data up to 1991. Some years later we published a
57-2753. E-mail address
: molinaeez.csic.es E.M. Alcaide
number of papers in which interspecies comparisons
0301-6226 00 – see front matter
2000 Elsevier Science B.V. All rights reserved. P I I : S 0 3 0 1 - 6 2 2 6 9 9 0 0 1 4 9 - 9
216 E
.M. Alcaide et al. Livestock Production Science 64 2000 215 –223
between goats and sheep concerning the digestive forages than sheep, they were able to maintain a
´ physiology were made Isac et al., 1994; Garcıa et
larger rumen fill without increasing ruminal disten- al., 1994, 1995; Molina Alcaide et al., 1997 when
sion. This fact would contribute to increased vol- low to medium quality diets were offered. Partially
untary intakes with respect to sheep. However, our this home information refers to non-producing ani-
results are opposite to the information reported by mals fed at maintenance level and confined in
AFRC 1997 as far as kinetics outflow is concerned metabolic crates Isac et al., 1994 and, therefore,
as they indicate shorter mean retention times of the minimizing differences in selective behaviour be-
digesta in the rumen of the goats in comparison with tween animals which might account for unequal
sheep. They are also contradictory concerning the digestive efficiencies. In these experiments we failed
rumen fermentation pattern, although observed dif- to find interspecies differences in digestibility and
ferences were of minor importance. The evidence in degradation rate when medium quality forages were
this aspect is inconclusive. offered. However, most of the data from our labora-
With this background and given the dearth of tory were obtained in non-producing animals grazing
comparative digestion studies with sheep and goats low to medium quality pastures in semi-arid lands of
fed on good quality forages under conditions which ´
the South of Spain Garcıa et al., 1994, 1995; Molina prevent selective intake AFRC, 1997, the aim of
Alcaide et al., 1997. In these trials some contro- the present work was to widen the range of observa-
versial results were observed concerning interspecies tions from medium to high quality diets for which
differences for in vitro digestibility: when grasses the hypothesis of a similar digestion capacity was
were the main component 78 of the pasture stated, implying a unique energy value for both goats
consumed and differences in chemical composition and sheep.
between the material selected were negligible, the in vitro digestibility of dry matter DM and organic
matter OM of the material ingested by sheep was
2. Material and methods
