Nitrogen utilization by dairy goats offered different nitrogen sources as supplements in high isocaloric energy concentrates

Abstract

Twelve growing female goats (Anglo-Nubian) were assigned to a multiple Latin square design experiment to evaluate the effectiveness of additions of nitrogen (N) supplements to a high isocaloric energy ration on N utilization. In this experiment, microbial synthesis and N balance were assessed. The daily rations were either unsupplemented barley meal (BM), or BM supplemented with one of three nitrogen sources. All rations were isocaloric (3.0 Mcal ME/kg DM) and the N supplements were soybean meal (BSBM), cottonseed meal (BCSM) or urea (BU) to provide 2.9% N in the concentrate component. The unsupplemented BM contained 1.7% N. The addition of N supplements to the ration enhanced N utilization in dairy goats. The organic matter (OM) intake, N intake, N balance, and microbial N synthesis for BM, BSBM, BCSM and BU were 660.5 g, 721.9 g, 728.1g and 703.5 g; 13.5 g, 21.5 g, 20.9 g and 20.7 g; 2.7 g; 7.1 g, 5.4 g, and 5.7 g; and 14.1 g 19.1 g, 19.1 g, and 20.0 g, respectively. It can be concluded that when sufficient dietary energy was available for ruminal microbial activities, the source of N did not affect N balance, and microbial N synthesis.