Interval from calving to conception in high producing dairy cows treated with recombinant bovine somatotropin.
Intervals from calving to conception in cows treated for two lactations with recombinant bST were ascertained using survival analysis methods. Daily intramuscular administration of placebo, 17.2, 51.6, or 86 mg of bST per cow started at d 70 postpartum and ended at culling or drying off. Breeding began at d 70 postpartum. Multiparous cows treated during the first lactation had significantly longer intervals from calving to conception. Cows treated during the previous lactation, but not during the second lactation, had significantly shorter intervals from calving to conception. Cox proportional hazards regression analysis was used with adjustment for the confounding effect of serum metabolites, milk production, energy balance, and body condition.
Esteban
E
E
Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California, Davis 95616.
Kass
P H
PH
Weaver
L D
LD
Rowe
J D
JD
Holmberg
C A
CA
Franti
C E
CE
Troutt
H F
HF
D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D005306:Fertilization; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007774:Lactation / Q000502:physiology*; D010298:Parity; D011247:Pregnancy; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D012044:Regression Analysis; D013997:Time Factors
D011994:Recombinant Proteins; D013006:Growth Hormone