Dairy Pipeline: November 2004
Ray L. Nebel
Dairy Extension Coordinator
Reproductive Management Scientist
(540) 231-4432 email: email@example.com
Prevention of excessive mobilization of body fat in the first 4 weeks of lactation is of primary importance for subsequent fertility. Cows will tolerate a loss of approximately 1 body condition scoring unit in the first 4 weeks after calving; more extreme condition loss will predispose her to lower conception rates at first service One unit change in body condition score represents about 120 lbs of body weight change and about 400 Mcal of energy. Feeding management that maximizes DMI is also essential to minimize body condition loss and to re-initiate ovarian cyclicity within approximately 3 weeks after calving. Ideally, the second ovulation will occur by 50 days postpartum when uterine involution and repair will also be complete. Increased negative energy balance may delay first ovulation 60 to 75 days or longer extending the postpartum effects and recovery of the uterine environment. The stimulation of appetite to ensure adequate DMI in normal, healthy cows is essential to provide nutrients for maximum milk production, follicular growth, ovulation, uterine involution, and the initiation of pregnancy. First ovulation usually occurs approximately 10 to 15 days after the point of greatest NEBAL and sometime before the peak in daily milk secretion. Nevertheless, dairy cows with greater DMI, despite having a NEBAL, produced more milk, lose less body weight, and ovulated earlier postpartum than those with lower intakes. Additionally, cows with greater intakes also reached their low point of energy balance earlier and experienced a more severe, but shorter, period of NEBAL, suggesting that when cows are more efficient in partitioning dietary and stored nutrients toward milk synthesis, they are also better able to recover ovarian cyclicity. Increased feeding frequency and better feed bunk management to maintain a fresh, adequate supply of feed and multiple sources of clean water are critical for stimulating appetite and maximal DMI.