Performance, carcass, organs, haematology and serum biochemical indices of rabbits fed graded levels of mulberry leaf meal in replacement of soybean meal

Abstract

This study examined the nutritional value of Mulberry leaf meal (MLM) as substitute for soybean meal (SBM) at graded levels. Forty cross-bred young rabbits of mixed sexes used for the study were purchased from a reputable farm in Osogbo, Osun State, Nigeria. The animals were balanced for the initial weight and randomly allocated to five experimental dietary treatments of 8 rabbits per treatment. There were 4 replicates of 2 rabbits per replicate. The rabbits were provided with pelletized experimental diets and clean water ad libitum for 2 weeks pre-experimental period and thereafter for 8 weeks during which data were collected. Five (5) diets containing 0 (0.00% MLM, control), 25 (1.25% MLM), 50 (2.50% MLM), 75 (3.75% MLM) and 100% (5.00% MLM) as replacement for SBM were formulated and contained ME ranging from 2617 – 2661 kcal/kg and crude protein ranging from 15.01 – 16.00%. The average daily weight gain (8.71 g/R/d) obtained in control was similar to 8.03 g/R/d (25.00% MLM), and both significantly (P < 0.05) reduced to 6.75 g/R/d (50.00% MLM), 6.73 g/R/d (75.00% MLM) and 5.98 g/R/d (100.00% MLM). The average daily feed intake (60.08 g/R/d) obtained in animals fed the control diet reduced (P < 0.05) to 53.44 g/R/d (25.00% MLM), 53.44 g/R/d (50.00% MLM), 55.36 g/R/d (75.00% MLM) and 51.52 g/R/d (100.00% MLM) respectively. Cost of feed per kg live weight gain were ? 471.39 (0.00% MLM), ? 396.80 (25.00% MLM), ? 459.52 (50.00% MLM), ? 454.67 (75.00% MLM), and ? 473.24 (100.00% MLM). The percentage dressed weight, head, feet, shoulder, loin, thigh and fore legs were significantly (P < 0.05) affected by the dietary treatments. The highest dressed weight (55.12%) was obtained in rabbits fed 0.00% MLM-based diet compared with 45.51, 46.32, 50.28 and 44.88% respectively in animals fed 25.00, 50.00, 75.00 and 100.00% MLM. All the organs (heart, lung, kidney and stomach) except the liver were significantly (P < 0.05) affected by the dietary treatments. All haematological (haemoglobin, packed cell volume, white blood cell and red blood cell); and serum (glucose and total protein) metabolites except albumin investigated were significantly (P < 0.05) influenced by the dietary treatments. It was concluded that MLM can economically replace 75% SBM (5%) in growing rabbits' diets; but 25% (1.25%) level of substitution was the cheapest and most economical level with no deleterious effects on carcass and health status of the animals.