Nutrient Intake, Digestion and Utilization by Rabbits Fed Cowpea Hull and Soybean Hull Based Diets

Abstract

A study involving two experiments was conducted to investigate the growth performance of rabbits fed diets containing graded levels of cowpea hull (CPH) and soybean hull (SBH). Thirty-two weaner rabbits of about 6 weeks old were used for the study. In experiment1, sixteen 6-week old hybrid (Chinchilla x New Zealand white) weaner rabbits of both sexes with initial average weight of 730-790g were randomly divided into four groups of 4 rabbits each. The groups were randomly assigned to four treatment diets containing 0, 10, 20 and 30% levels of cowpea hulls. Each treatment group was replicated four times with a rabbit constituting a replicate placed in a four –tier rabbit cages that had a total of 16 hutches per tier. In experiment two, 16 six-week old hybrid (Chinchilla x New Zealand white) weaner rabbits of both sexes with initial average weight of 730-790g were randomly divided into four groups of 4 rabbits each. The groups were randomly assigned to four treatment diets containing 0, 10, 20 and 30% levels of soybean hulls. Each treatment group was replicated four times with a rabbit constituting a replicate placed in a four –tier rabbit cages that had a total of 16 hutches per tier. The experiments lasted for 8 weeks during which the daily feed intake body weight gain, feed conversion ratio, protein efficiency ratio and feed cost per kg weight gain were determined. The haematological parameters, digestibility coefficients, carcass and organ weights were also determined. Results (experiment I) showed that while increasing levels of CPH in the diets had no significant effect (P>0.05) on the average daily feed intake, daily protein intake and protein efficiency ratio, they had significant effect (P<0.05) effect on average final body weight and average daily weight gain of rabbits. Differences between the treatments in nutrient digestibility coefficients were significant (P<0.05). Generally, digestibility coefficients decreased with increasing level of CPH in the diets. The inclusion of CPH in the rabbits’ diet resulted in the reduction of the cost of feed per kg gain. Dietary treatments did not have any adverse effect on such haematological values as the Hb, PCV, RBC, MCH, MCHC and MCV of rabbits. However, the WBC was observed to decrease at the 30% level of inclusion. While dietary treatments had no significant effect (P>0.05) on organ weights of rabbits, they had significant (P<0.05) effect on live body weight, dressed carcass weight and dressing percentage. In experiment 2, dietary treatments had significant effect (P>0.05) on final body weight, feed conversion ratio, and daily protein intake. However no significant (P>0.05) differences were observe among rabbits in daily feed intake and average daily weight gain. The effect of treatments on nutrient digestibility coefficients were significant (P<0.05). Both DM, CP, crude fibre, ether extract and nitrogen-free extract digestibility coefficients were significantly (P<0.05) decreased beyond 10% SBH inclusion level. The inclusion of SBH in the diets reduced significantly the cost of feed per kg weight gain. Inclusion levels of SBH did not have any adverse effect on such haematological values as the Hb, PCV, RBC, MCH, MCHC and MCV of rabbits. However, the WBC was significantly (P<0.05) decreased at the 30% SBH inclusion level. While dietary treatments had no significant effect (P>0.05) on organ weights of rabbits, they had significant (P<0.05) effect on live body weight, dressed carcass weight and dressing percentage. The results obtained in the present study show that up to 10% cowpea hull and 30% soybean hull can be included in rabbits’ diet without any deleterious effect on growth performance, haematology and internal organs of rabbits.