Effects of level and source of supplemental protein in a concentrate-based diet on growth performance of Boer × Spanish wether goats

Boer × Spanish wether goats (50; 26.8 ± 4.04 kg initial BW and 7 months of age) were used in a 27 week experiment to determine effects of two levels of CP (13 and 19%) and five protein sources varying in ruminal degradability (blood, corn gluten, feather, fish and soybean meals). Diets were 70% concentrate, had a ratio of ruminally degraded intake protein (DIP) to total digestible nutrients (TDNs) of at least 0.09 and were formulated to maximize ruminally undegradaed protein from supplemental protein sources. There were no interactions between dietary CP level and supplemental protein source. Voluntary DM intake (1043, 1089, 1153, 1086 and 1112 g per day; S.E. = 74.4), ADG (136, 134, 143, 145 and 138 g per day; S.E. = 9.8) and gain efficiency (ADG:DM intake) (131, 124, 125, 136 and 128 g/kg for blood, corn gluten, feather, fish and soybean meals, respectively; S.E. = 5.7) were similar between CP levels and among sources of supplemental protein. In summary, with a dietary concentrate level of 70% and at least 13% CP, differences in amino acid profiles among blood, corn gluten, feather, fish and soybean meals did not impact rate or efficiency of growth by Boer × Spanish wethers. © 2003 Elsevier B.V. All rights reserved.