Evaluation of Sorghum (Sorghum bicolor) as a Substance for Maize in the Diet of Growing Rabbits (Oryctolagus cuniculus)

Abstract

Two experiments were carried out at Tatton farm, Egerton University, between February and August 2000 to evaluate the suitability of sorghum as a substitute for maize in the diet of growing rabbits. In the first experiment, Thirty-six (36) young New Zealand white rabbits, aged five weeks, were used in a 3x2 factorial arrangement of treatments in a randomised complete block design (RCBD) experiment. Six different diets were formulated to contain one of the three grains (maize, white sorghum or brown sorghum) and one of the two levels of crude protein (16 or 18.5%). Weaning weight at 35 days of age was used as the blocking criterion. Results indicated that white sorghum was not significantly different (P > 0.05) from maize in any of the parameters considered (feed intake, weight gain, feed conversion efficiency, feed digestibility, as well as the blood parameters). Animals fed on diets containing brown sorghum had a lower average daily gain (ADG) and a poorer feed conversion efficiency (FCE) (P < 0.01) in comparison with those fed on diets containing maize or white sorghum. The 18.5% CP level gave a better FCE (P < 0.05) compared with the 16% CP level. However, increasing the level of CP did not improve the utilisation of any of the grains to any extent greater than it did for the other grains. In the second experiment, twenty five (25) New Zealand white rabbits of 35 days of age were used in a completely randomised design to evaluate the effect of substituting maize with varying levels of brown sorghum, in the diet, on the performance of growing rabbits. The control diet contained 40 g of maize per 100 g of diet. In the other four diets, this maize portion was substituted with brown sorghum at the rate of 25, 50, 75 and 100% respectively. Results indicated that the use of brown sorghum in these diets significantly (P < 0.05) depressed the average daily gain, feed conversion efficiency, crude protein digestibility, crude fiber digestibility, the level of packed cell volume, haemoglobin concentration, as well as the erythrocyte and leucocyte counts in the experimental animals. From the two experiments, it was concluded that white sorghum can effectively replace maize in the diet of growing rabbits. On the other hand, the use of brown sorghum in the diets of growing rabbits may depress their growth rate. This may be due to the high concentration of tannins in the b1'OWI1 sorghum.