Milking frequency, estradiol cypionate, and bST alters milk yield and reproductive outcomes in dairy cows

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Show simple item record Blevins, C.A. Aberle, J.J. Hensley, B.A. Tiffany, S.M Shirley, John E. Stevenson, Jeffrey S. 2010-12-01T16:59:03Z 2010-12-01T16:59:03Z 2010-12-01
dc.description.abstract The objective of this study was to determine how milking frequency, estradiol cypionate (ECP) postpartum therapy given at 1 week after calving, and biweekly bovine somatotropin (bST) administration alter lactational and reproductive outcomes in dairy cattle. Holstein cows (n=144) were randomly assigned to eight treatments (18 cows per treatment): 1) twice daily milking frequency (2x), 10-mg injection of ECP at 1 week after calving (ECP), and bST (given biweekly according to label beginning in the ninth week of lactation); 2) 2x milked, oil (cottonseed oil vehicle for ECP), bST; 3) 2x milked, ECP, and no bST; 4) 2x milked, oil, and no bST; 5) four-times daily milking frequency (4x; first 30 days in milk then 2x thereafter), ECP, and bST; 6) 4x milked, oil, and bST; 7) 4x milked, ECP, and no bST; and 8) 4x milked, oil, and no bST. Milk yields were recorded at each milking during the first 90 days of lactation. Milk samples were collected weekly at each milking and composited to determine milk components (percentages of fat, protein, lactose, solids-not-fat [SNF], milk urea nitrogen [MUN], and somatic cell count [SCC]). Energy-corrected milk yields were calculated for the first 90 days and for whole lactation yields (305-2x- ME standardized lactation records). Ovulation before first AI was synchronized beginning between 59 and 72 DIM using 100 :g of GnRH given 7 days before 25 mg of PGF2", followed in 24 hr by 1 mg of ECP. Cows were inseminated after detected estrus or at 48 hr after ECP. Pregnancy rates were assessed by transrectal ultrasonography 28-30 days after AI. Postpartum ECP therapy increased milk production for first-lactation 2x cows, but decreased milk yields of the multiparous 4x cows until bST restored those yields. Pregnancy rates were greater for the 4x cows given the postpartum ECP therapy injection, despite fewer cows cycling before AI. In conclusion, postpartum ECP therapy increased pregnancy rates in 4x cows, but had a detrimental effect on milk yields of 4x milked cows unless bST was administered. en_US
dc.publisher Kansas State University. Agricultural Experiment Station and Cooperative Extension Service en_US
dc.relation.isPartOf Diary Day, 2002 en_US
dc.relation.isPartOf Kansas Agricultural Experiment Station contribution; no. 03-121-S en_US
dc.relation.isPartOf Report of progress (Kansas State University. Agricultural Experiment Station and Cooperative Extension Service); 898 en_US
dc.subject Dairy en_US
dc.subject Estradiol cypionate en_US
dc.subject bST en_US
dc.subject Milking frequency en_US
dc.subject Fertility en_US
dc.title Milking frequency, estradiol cypionate, and bST alters milk yield and reproductive outcomes in dairy cows en_US
dc.type Conference paper en_US 2002 en_US
dc.citation.epage 80 en_US
dc.citation.spage 71 en_US
dc.description.conference Dairy Day, 2002, Kansas State University, Manhattan, KS, 2002
dc.contributor.authoreid jss en_US

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