Feed forms of different particle sizes: growth response, carcass yield and intestinal villus morphology of growing rabbits

Several studies revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Information on the interaction effect of feed form and feed particle size on rabbit’s growth performance and gut morphology is thereby a growing concern. Hence, the growth response, carcass yield and intestinal villus morphology of thirty-six growing male rabbits of mixed breeds (Chinchilla × New Zealand White) weighing between 550-600g were determined using two feed forms (FF): pellets and crumbs of different particle sizes (PS): 1 and 2 mm. The rabbits were allotted on weight equalization basis to crumbs and pellets composed of 1 and 2 mm PS in a 2 × 2 factorial experimental layout and subjected to Completely Randomized Design. Nine (9) rabbits were assigned to each treatment made of three replicates of three rabbits each. The rabbits were maintained on concentrate diets ad libitum for 10 weeks. Two rabbits per replicate with representative mean live weight were selected for carcass evaluation at the 10th week and the remaining one was used for intestinal villus morphology. FF and PS significantly (P<0.05) influenced the cost/kg feed but did not influence the growth responses. Rabbits on 1mm PS feed had a higher (P<0.05) dressing percentage (65.61 %) than 2 mm. Also, rabbits fed crumbs containing 1 mm PS recorded the highest dressing percentage. Rabbits on 1mm PS feed had a higher (P<0.05) lamina propria depth (172.50 µm) and apical width (52.50 µm) of ileum. Significant (P<0.05) interaction effects were observed for lamina propria depth (LPD) and basal width with rabbits fed crumbs of 1 mm PS having the highest LPD. It was concluded that carcass yield of growing rabbits could be optimized by feeding pellets or crumbs of 1mm particle size.