The objective of this study was to estimate the effect on calving risk of interval from AI date until scheduled date of pregnancy examination. First AI (n = 7105) from 65 dairy herds in the United States and Canada were followed for 294 d to determine whether cows calved. Calving was modeled as a function of the number of days in the interval, herd, season, and breeding at PGF2α-induced estrus by multivariate logistic regression. The main effects of herd and AI following PGF2α-induced estrus were significantly associated with calving rate from first AI. The main effects of interval and season were not significantly associated with calving. The effects of PGF2α, season, and interval between AI and pregnancy testing varied significantly among herds. These effects appear to be symmetric in their distributions about their means. The risk of day of palpation on calving is herd dependent and small compared with other herd factors.
- pregnancy attrition
- rectal palpation
- the length of interval (days) from AI date until scheduled date of pregnancy examination
- the outcome of calving (1 = yes, 0 = no)
ASJC Scopus subject areas
- Food Science
- Animal Science and Zoology