In an effort to expand the knowledge base on the use of non conventional feedstuff in rabbit nutrition, the nutritional potential and the cost effectiveness of using rice offal fermented with rumen filtrate for 48 hours was investigated using twenty five (25) growing crossbred rabbit bucks weighed between 625.34 g-631.21 g for 10 weeks. The rabbits were divided into five (5) treatment groups of five (5) rabbits each with each rabbit serving as a replicate in a completely randomized design experiment. The control group was fed with a diet containing maize as the main energy source while the remaining four groups were fed with diets in which the maize was replaced with 5%, 10%, 15% and 20% Rumen filtrate fermented-rice offal meals respectively. Final weight was similar (P>0.05) in rabbits fed maize-based control diet and those fed diet containing 5% to 20% Rumen Filtrate Fermented Rice Offal Meals (FRO). The experimental diets had significant (P<0.05) effect on the daily feed intake, and daily body weight gain with rabbits on 20% having superior weights of 93.88 g and 20.54 g respectively, and a better feed conversion ratio of 4.57 g. The cost of feed per kg of weight gain was lowered progressively from N446/kg for the control diet to N307/kg for the 20% FRO diet, where the lowest feed cost was observed, with a concomitant improvement in overall production profitability. It was concluded that fermenting rice offal with rumen filtrate had high potential as a possible replacement for maize in rabbit diet at inclusion levels of up to 20%. The use of this agricultural by-product can reduce the cost of rabbit production, increase the availability of cheaper animal protein for the populace, generate higher profit margins for the livestock farmer and reduce environmental pollution. It was therefore recommended that feed manufacturers and rabbit farmers can incorporate up to 20% of bovine rumen filtrate-fermented rice offal meal in the diets of rabbits without compromising performance.

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.