ABSTRACT
Comparisons were made between 24 Ethiopian rams and 24 Galla goats for voluntary intake, feed selectivity and growth performance when offered three levels of sorghum stover. The levels observed were 25,50 and 75 g/kg live weight per day. Measurements of intake, growth and feed selectivity were taken over a period of 10 weeks.
Both sheep and goats consumed more stover (P<0.001) as rate of offer was increased (22, 31, 32 gDM/kg live weight per day; 19,26,29 g/kg live weight per day, respectively, for sheep and goats). Increasing the level of offer beyond 50g/kg live weight per day did not, however, promote a substantial increase in intake. No difference (P>0.05) was observed in the pattern of feed selectivity between sheep and goats. Both species showed a similar preference for leaf and sheath matter as the level of offer was increased.Sheep gained weight faster (P<0.001) than goats at all rates of offer, (28.0 vs 9.0; 54.0 vs 23.0; 62.0 vs 31.6 in favour of sheep). Those on a higher level of offer showed a faster rate of gain than those on a lower level of offer.
It was concluded that both species can benefit from generous offers and that the benefit, judged by improved intake and growth, is due to selective feeding.
CHAPTER ONE
1.0 INTRODUCTION
Previous studies (Aboud et al, 1992) clearly indicate the value of selective feeding. Sheep were shown to perform better and consume more digestible matter through selective intake of leaf and sheath fractions of sorghum stover as a result of liberal offers. This observation is of practical value for small ruminants in the tropics because the traditional feeding systems depend largely on crop residues. However, there is little evidence in the literature that the approach adopted by Aboud et al (1992) would be as effective for goats as it was for sheep. Results from comparative studies between sheep and goats of selective efficiency are generally conflicting (Huston, 1978; Devendra and Bums, 1983). Goats in the tropics are more able than sheep to consume feed fractions of higher nutritional quality when offered the opportunity to eat selectively (Devendra and Burns, 1983; Hoppe et al, 1977; Huston, 1978). This observation does not agree with studies carried out in temperate countries, where sheep have been shown to perform better than goats under most practical feeding systems. A comparative feeding and performance study on Small East African goats and the Red Maasai sheep in Tanzania (Shoo, 1986) was inconclusive, although sheep appeared to perform better than goats when offered a basal diet of Chlorisgayanahay with Leucaenaas a supplementary forage. However, observations in Shoo’s (1986) study did not include an assessment of selective feeding ability between the two species. The inclusion of a supplementary forage may have confounded the results, as it is known that goats would preferentially consume browse species (Lu, 1988). Most of the comparative studies in the tropics were made under grazing conditions, whereas those in the temperate countries involved comparisons under stall-feeding conditions in which feed was offered at restricted levels, usually at 35 g dry matter M(D)/kg live weight per day or to achieve 10-20% rate of refusal. Comparative studies under grazing or in stalls at restricted levels of offer may give misleading results (Demment and Van Soest, 1983). Restricted levels of offer do not usually provide sufficient opportunity for selective feeding (Aboud et al, 1993). This is particularly serious where low-quality crop residues are used in comparisons.
No performance comparison has been made between sheep and goats that have been fed untreated crop residues at levels that would allow selective intake. Alimon (1989) only measured the digestible organic matter (OM) intake of goats offered increasing levels of feed, but did not measure any related growth performance. Aboud et al (1993) showed that certain levels of offer encouraged sheep to eat selectively. By offering goats and sheep the same type of sorghum stover at these levels both species may perform similarly.
OBJECTIVES OF THE STUDY
The general objective of the studies was to find better methods of feedingsugar cane and some protein-rich foliage species to get the highest feedintake and the best performance in small ruminants.
The specific objectives were:
• To assess the effect of animal factors such as animal species(sheep and goats) and group size (single and group pens) on feedintake, behaviour and growth rate.
• To test the effect of some feed factors such as
– processing method of sugar cane and Acacia foliage
– Level of feed offered of sugar cane
– Supplementation with concentrate
– Method of presentation of foliage and mixtures of foliages
-Utilization of bamboo charcoal to reduce the antinutritionaleffect of tannins in Acacia foliageon feed intake, behaviour and growth rate.
• To identify the intake potential of sugar cane and three tropicalfoliage species by small ruminants.
