Responses of dairy cows in early lactation to bovine somatotropin and ruminally inert fat.
Bovine somatotropin (0 or 41.2 mg/d bST) and calcium salts of long-chain fatty acids (0 or .77 kg/d Ca-LCFA) were administered to 16 Holstein cows in early lactation. Cows remained on 0 or 41.2 mg/d bST for the entire 10 wk and received 0 or .77 kg/d Ca-LCFA in one of two 5-wk periods. Production data were recorded daily, milk fatty acids, and blood metabolites were determined once each period. Treatments did not affect feed intake. Fat-corrected milk (kg/d) and percentage of milk fat for cows receiving no supplementation, fatty acids alone, bST alone, and fatty acids and bST together were 33.8, 3.2; 33.5, 3.1; 37.4, 3.4; and 40.8, 3.5. Milk fatty acids below C16 were reduced with either bST or dietary fatty acids; C16 fatty acids were lower with bST but higher with dietary fatty acids; C18:0 fatty acids were reduced with dietary fatty acids; and C18:1 fatty acids were higher with either bST or dietary fatty acids. Blood acetoacetate concentrations were higher with both bST and dietary fatty acids, beta-hydroxybutyrate was not different, and FFA and insulin concentrations increased with bST. In this experiment, the energy supplied by Ca-LCFA acids enhanced the lactogenic effect of bST.
Schneider
P L
PL
Real Veal, Inc., Ixonia, WI 53036.
Sklan
D
D
Kronfeld
D S
DS
Chalupa
W
W
D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000097:blood; D000818:Animals; D002417:Cattle / Q000097:blood / Q000378:metabolism*; D004435:Eating / Q000187:drug effects*; D005227:Fatty Acids / Q000097:blood*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006885:Hydroxybutyrates / Q000097:blood; D007328:Insulin / Q000097:blood; D007774:Lactation / Q000187:drug effects*; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism; D013997:Time Factors
D000090:Acetoacetates; D005227:Fatty Acids; D006885:Hydroxybutyrates; D007328:Insulin; C016635:acetoacetic acid; D013006:Growth Hormone; D020155:3-Hydroxybutyric Acid