Multivariate analysis of factors associated with calving interval and calving rate in dairy cows.

We collected data on reproductive events of cows (n = 2116) that included dates of calving, first service, last artificial insemination before pregnancy examination, pregnancy examination, abortion, diagnosis of cystic ovary, and treatment with prostaglandin. We used multivariate analysis to evaluate the relationship between the interval from insemination to pregnancy examination and the length of calving interval, adjusting for other factors affecting the calving interval. The effect of the interval from insemination to pregnancy examination on calving rate was estimated using logistic regression analysis.

Calving outcomes for cows diagnosed pregnant or nonpregnant by per rectum examination at various intervals after insemination.

Early pregnancy diagnosis could be associated with decreased diagnostic accuracy or increased fetal loss, which might lead to increased culling. We determined the relationship between pregnancy diagnosis at various intervals after artificial insemination and subsequent calving for cows from five dairy herds in California. Palpations were done by either of two experienced veterinarians.

Optimal time postbreeding for pregnancy examination in dairy cattle.

The objective of this study was to determine the relationship between calving interval and the interval from artificial insemination to pregnancy examination. Cows examined for pregnancy at 30 or more days postbreeding were followed to determine the calving interval for cows examined at sequential intervals postbreeding (e.g.

Milk progesterone concentration and production in superovulated Holstein cows.

Six Holstein cows in a commercial herd (three superovulated and three controls) and eight Holstein cows superovulated a total of 12 times in an experimental herd were studied. Superovulation was induced primarily by treatment with follicle stimulating hormone and prostaglandin F2 alpha. Milk was weighed twice daily for 30 days following treatment in the commercial herd with no effect on production.