Urea, starea, and soybean meal as supplemental nitrogen sources for lactating dairy cows
Jones, G.M.; Stephens, C.
Journal of Dairy Science 57(5): 633
1974
ISSN/ISBN: 0022-0302 Accession: 027820799
A double 4 × 4 Latin square design with eight Holstein cows having an initial average of 34 kg milk daily compared a 14.5% crude protein complete ration to three 15.8% complete rations. The latter. rations contained supplemental nitrogen totally from soybean meal, urea, or Starea at 16 and 22% of total ration nitrogen, respectively. Concentrates were mixed with wilted alfalfa-bromegrass silage (32% dry matter) and the complete rations fed ad libitum. Data were collected during the last week of each 28 days. Low protein, urea, Starea, and soybean rations averaged 23.4, 25.3, 24.6, and 25.8 kg milk daily; 2.7, 2.8, 2.8, and 2.9% milk fat; 3.3, 3.0, 3.1, and 3.6% milk protein; 2.51, 2.66, 2.75, and 2.85 kg dry matter/100 kg body weight; - .05, 0, -3.6, and .91 kg gain/day. Apparent digestion of dry matter and crude protein were similar between rations. Nitrogen retention and utilization did not differ between 15.8% crude protein rations.