Nutrient digestibility, visceral organ changes and carcass yield of rabbits fed with diets containing graded levels of rumen filtrate-fermented rice offal

A total of twenty-five crossbred rabbit bucks with a mean weight of 628.73g were utilized to investigate their nutrient digestibility, visceral organ changes, and carcass yield when fed with diets containing graded levels of rumen filtrate-fermented rice offal (FRO) for 10 weeks. Five rabbits were grouped into five treatments with each rabbit serving as a replicate in a completely randomized design experiment. The control group was fed with a diet containing no rumen filtrate fermented-rice offal meal while the other four groups were fed with diets in which the FRO replaced the maize at 5%, 10%, 15%, and 20%, respectively. The results of the analyzed nutrient composition and energy content of the experimental diets showed no trend across the treatments except for crude protein and metabolizable energy whose values appeared to increase across treatments as the levels of FRO increased from 0% to 20%. Dry Matter (DM), Crude Fiber (CF), Ether Extract (EE) and Nitrogen Free Extract (NFE) digestibility values were affected by the inclusion level of the fermented rice offal in the diets of the rabbits, except Crude Protein (CP). Crude fiber values appeared to increase across the treatments as the levels of FRO increased from 0% to 20%. Dressed weight showed significantly (p<0.05) higher values for rabbits fed with diets containing 20% FRO and prime cuts were significantly (p<0.05) influenced by treatments. The result of visceral organ and GIT weights showed treatment effect (p<0.05), except fasted live weights, spleen, and visceral fats. Of the visceral organ lengths, only the esophagus and stomach were similar (p>0.05) across treatment groups. It was therefore concluded that the digestibility of nutrients was not adversely affected; such that 20% inclusion of rumen filtrate-fermented rice offal showed no modification on visceral organ changes and a better carcass yield observed in rabbits on the diets. It was suggested that up to 20% rumen filtrate-fermented rice offal meal can be integrated into rabbit diets without impairing their digestibility, visceral organ characteristics, and carcass yield.