Growth performance, organ weight and histology of rabbits fed graded levels of bitter kola (Gracinia kola)

Abstract

The effect of varying levels (0%, 2.5%, 5% and 7.5%) of Garcinia kola on the carcass, organ weight and growth performance of growing rabbits were investigated using twenty four rabbits of mixed breed (New Zealand white and Chinchilla) and mixed sexes of average weight1+ 0.49kg. The rabbits were randomly assigned to four dietary treatments comprising Garcinia kola: T₁ (0%), T₂ (2.5%), T₃ (5%) and T₄ (7.5%) for 56 day period of the experiment. The experiment was based on Completely Randomized Design with each treatment having six rabbits in three replicates of two rabbits per replicate. During the 56 days period of the experiment, the rabbits were subjected to similar managerial and sanitation conditions such that the only source of variation is the level of Garcinia kola inclusion. At the end of the 56 days treatments, three rabbits were randomly selected from each treatment, weighed, slaughtered, skinned and eviscerated. The carcass weight and organ weight were also taken. Thereafter, the internal organs precisely the liver and kidney were prepared for histological analysis and taken to Nnamdi Azikiwe University, Awka Teaching hospital histological section for analysis. Results showed no significant differences (P > 0.05) in most of the parameters measured except for the carcass weight and kidney weight but the differences did not take any particular trend that could be attributed to the effect of the bitter kola (G. kola). There was also no significant difference (P<0.05) for feed intake level, feed conversion ratio and specific growth rate. Weight gain however differed significantly (P<0.05) with treatments (T₁ < T₂ < T₃ < T₄ ) meaning that body weight gain decreased as the level of bitter 4 3 2 1 kola inclusion increased. The kidneys of rabbits fed bitter kola all had different degrees of damage. Similarly, the histology of the liver organs of rabbits fed different levels of bitter kola showed that rabbits on T₁ (0%) bitter kola was normal, while the liver of those that had the test ingredient bitter kola all had defects. We therefore recommend large doses of G. kola should be given to rabbits else the negative effects will outweigh the gains of its phytobiotic properties.