Phase feeding of urea after feeding soybean meal to dairy cows.
Urea-free control, medium-, and high-urea concentrates containing 0, 1.6, and 2.3% urea, respectively, were applied as main treatments, each to a group of nine lactating cows during three 8-wk periods. Split plot treatments consisted of feeding each concentrate normally or the urea portion in phase 2 or 4 h after feeding the soybean meal component. Dry matter intake, milk yield, milk lipid composition of butyric through capric acids were decreased, but milk linoleic acid was increased with high-urea rather than medium-urea or control concentrate. Ammonia in blood serum was reduced with 2-h phase feeding and urea was reduced with 2-h phase feeding and urea was reduced with 2- or 4-h phase feeding as compared to normal feeding. Ammonia was unaffected by normal or phase feeding of the control concentrate. Normal feeding of high-urea concentrate increased ammonia in serum, but phase feeding reverted concentration comparable to the control group (160 to 122 microgram/100 ml). Ammonia was nearly the same with normal or phase feeding of medium-urea concentrate.
D000596:Amino Acids / Q000097:blood; D000641:Ammonia / Q000097:blood; D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000097:blood; D004435:Eating / Q000187:drug effects; D005260:Female; D007774:Lactation / Q000187:drug effects*; D011247:Pregnancy; D013025:Glycine max; D014508:Urea / Q000494:pharmacology*
D000596:Amino Acids; D000641:Ammonia; D014508:Urea