Management Factors Affecting Reproductive Performance of Dairy Cows in the Northeastern United States

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Abstract
Dairy herds (476) in 7 states in northeastern USA were surveyed to determine effects of various management factors on reproductive performance. Error of estrus detection (> 1 ng/ml milk progesterone) on the day of service was 5.1% for 4558 cows but was as high as 60% in some herds. Error was not affected by herd size but was greater in freestall (6.8%) than in conventional (5.2%) housing. Standing and riding other cows were the most accurate signs of estrus. Of cows in or near estrus when serviced, 28.1% were open 3 wk later, 12.9% were probably open and 59% were probably pregnant based on analysis of milk progesterone. Conception rate, not affected by herd size or housing type, was greater for cows in estrus during the morning and serviced the same afternoon (52.2%) than for cows observed in the afternoon and serviced the next morning (47.1%). Of cows open to 1st service, 55%were serviced again within 3 days of expected return to estrus. Days to 1st service and conception rates were correlated positively. Milk progesterone concentration 21-24 days after service prediced a cow would calve with 88.6% accuracy and that she would not with 93.9% accuracy. Veterinarians predicted a calf with 92.5% accuracy by rectal palpation.