Effects of coconut meal or fish meal supplementation on performance, carcass characteristics and diet digestibility in growing St. Croix lambs fed a tropical grass-based diet

Abstract

Performance and carcass characteristics of St. Croix lambs fed chopped forage, predominantly guineagrass ( Panicum maximum), was evaluated in three 60-d trials. Treatments in trial 1 were chopped guineagrass ad libitum only (CONT), CONT plus coconut meal (COCO) and CONT plus fish meal (FISH). Supplements (SUPP) were offered at the rate of 9 g CP·kg body weight (BW) −1·d −1. Treatments in trial 2 were guineagrass fed ad libitum and molasses fed at the rate of 10 g·kg BW −1·d −1 (MCONT), MCONT plus coconut meal (MCOCO) and MCONT plus fish meal (MFISH), SUPP offered at the rate of 4 g CP·kg BW −1·d −1. Treatments in trial 3 were MCONT and MCONT plus a 3:1 (C3F1) or 1:3 (C1F3) mixture of coconut meal and fish meal offered at 1o g·kg BW −1·d −. In trial 1, CONT (forage only) lambs lost weight (−0.056 kg/d), while SUPP lambs gained slightly (0.024 to 0.133 kg/d). Apparent digestibilities, particularly for N, were improved with SUPP, but were not different between COCO and FISH. With the addition of molasses to all diets in trial 2, weight gains were all positive, were higher in SUPP compared with MCONT ( P<0.01), and were higher in MCOCO compared with MFISH ( P<0.10). Apparent digestibility of N again was increased by SUPP ( P<0.001) and was greater for MFISH than for MCOCO ( P<0.05). In trial 3, CONT lambs again lost weight because of poor forage quality despite addition of molasses to the diets. Performance was improved by SUPP as expected, but weight gains were similar between the two ratios of coconut meal and fish meal that were fed. Throughout all three trials, quality of chopped pasture appeared to have a large effect on lamb performance that was favorably affected by SUPP, particularly with coconut meal.