Dietary starch level and rumen-protected methionine, lysine, and histidine: Effects on milk yield, nitrogen, and energy utilization in dairy cows fed diets low in metabolizable protein
Yu Zang, L.H.P. Silva, Yifan Geng, M. Ghelichkhan, N.L. Whitehouse, Makoto Miura, A.F. Brito
Abstract
Our objective was to investigate the interactions between starch level and rumen-protected Met, Lys, His (RP-MLH) on milk yield, plasma AA concentration, and nutrient utilization in dairy cows fed low metabolizable protein diets (mean = -119 g/d of metabolizable protein balance). Sixteen multiparous Holstein cows (138 46 d in milk, 46 6 kg/d in milk) were used in a replicated 4 4 Latin square with a 2 2 factorial arrangement of treatments. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Dietary starch level varied by replacing (dry matter basis) pelleted beet pulp and soyhulls with ground corn resulting in the following treatments: