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Virginia Cooperative Extension - Knowledge for the CommonWealth

Strategies for Improving Reproductive Performance:
Part One of Four

Dairy Pipeline: January 2009

John Currin
Extension Dairy Veterinarian
(540) 231-5838,

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Reproductive Performance (RP) in dairy herds continues to be a major issue. While experts suggest that herds should strive for a pregnancy rate of greater than 20%, Virginia’s average for DHIA herds is currently 14.1%, indicating potential for improvement.

Unfortunately, improving reproduction is rarely as simple as improving one thing — usually a variety of factors need attention in order to improve RP. At its simplest, improving the RP of a dairy requires the timely administration of semen to a cow with a healthy uterus at the correct time of the estrus cycle. What sounds simple when boiled down to one sentence actually encompasses most aspects of dairy management.

Days open remains a useful tool in diagnosing the weak link in herd RP and there are four components: the voluntary waiting period, heat detection, conception rate, and culling. This issue discusses the voluntary waiting period (VWP), which is an often overlooked area of reproductive performance.

Sixty days has been the standard VWP for years. As reproductive problems increased on dairy farms an attempt was made to lower the VWP to 45 days to improve reproductive management. While good in theory, this practice rarely lead to improvement in RP. In most cases the conception rate in these herds for cows from 45-60 days in milk (DIM) was less than 15%. One of the main issues this early in lactation is uterine health. In a recent study, 44% of the cows still had subclinical metritis at 45 DIM. Many factors have been blamed for uterine problems post calving. These factors include: subclinical hypocalcemia, dirty calving environment, and selenium deficiency. Recent studies have shown that excessive negative energy balance precalving may be the single most important factor in cows developing metritis post-calving. Putting the information from these studies together reveals that a successful reproduction program must begin even before a cow calves.

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