Reproductive Traits of Holsteins and Jerseys. Effects of Age, Milk Yield, and Clinical Abnormalities on Involution of Cervix and Uterus, Ovulation, Estrous Cycles, Detection of Estrus, Conception Rate, and Days Open

Abstract

Holstein and Jersey cows (212) were in a study to determine factors that affected reproductive traits. First ovulation occurred about 3 wk postpartum, and interval to 1st ovulation was greater in cows that had clinical abnormalities postpartum than in normal cows. Jerseys producing more milk ovulated sooner postpartum than lower producing herdmates. Involution of cervix and uterus occurred later postpartum in cows that had clincal problems postpartum. Involution of genital tract occurred later postpartum in older cows and sooner postpartum in cows that had higher milk yields. Duration of 1st postpartum estrous cycle was 4 days less than for 2nd postpartum cycle. Percentages of estrous cycles detected by standing estrus were 43 and 73% for Holsteins and Jersey. Estrous detection rates were highest for cows that produced slightly above the mean milk yield and did not differ between cows in highest and lowest milk production quartiles. First detected estrus and days to 1st insemination occurred later postpartum in Holsteins as milk yield deviation from herdmates increased, regardless of sign. In Jerseys, days to 1st insemination and days open increased linearly as milk yield increased. Day to 1st insemination and conception were greater in cows with postpartum clinical problems. Conception rate at 1st insemination postpartum increased in proportion to concentration of progesterone in blood samples collected during 12 days before 1st insemination. Clinical problems at parturition and postpartum lowered reproductive performance in both breeds. There was a slight antagonism between milk yield and reproductive performance (days open) in Jerseys but not in Holsteins.