Effects of Climatic and Management Factors on Conception Rate of Dairy Cattle in Subtropical Environment

Abstract

Breeding records, representing 12,038 inseminations at Bassett's Dairy Farm (Monticello, FL), were analyzed to document effects of environmental and management factors on fertility of dairy cattle from January 1, 1975 to December 31, 1977. Conception rates of lactating cows decreased sharply when maximum air temperature on day after insemination exceeded 30 degrees C. In contrast, conception rates for heifers did not decline until 35 degrees C. Virgin heifers had higher conception rates for all services (50%) than lactating cows (34%) and suffered only slight depression of fertility during summer months. Heifers required 1.5 services per conception compared with 2.3 for lactating cows. Relationship between conception rate and rainfall on day after insemination was negative and curvilinear. Jerseys had higher conception rates (45%) than Holstein (39%) and Brown Swiss (41%). Services per conception were 1.7, 2.0, and 1.9. Substantial decreases of fertility were associated with advancing service number. Estrous status (standing; positive heat detection patch; mounting activity), inseminator, and year of service were related to variation of conception rate. Seasonal effects on fertility of lactating cows were marked. Thus, environmental management of the postpartum cow during hot summer months is warranted to maximize fertility.

The effect of some seasonal conditions on oestrus occurrence in cows

“…During the course of domestication, both dairy and beef cattle were selected against seasonality, facilitating them to ovulate and conceive throughout all the year (JAUNIDEEN and HAFEZ, 1987). However, it is reported that seasonal changes are still affecting reproductive performance in cows and heifers (BADINGA et al 1985). In this study, a distinct seasonal variation in the oestrus occurrence was determined.…”

Unexpected detrimental effect of Insulin like growth factor-1 on bovine oocyte developmental competence under heat stress

“…Heat stress is a worldwide problem, which inflicts heavy economics losses and effect about 60% of the cattle population in the world [3]. Field fertility data in cattle revealed the conception rates of 10-20% in the hot summer vs 50-55% in non-hot seasons [5]. While the exact causes for the lower embryonic viability and reduced conception rates are not yet clear, heat stressinduced damages to oocytes prior to fertilization might contribute, in part, to the low reproductive performance of the cows during the hot seasons.…”

Alleviating Heat Stress Leads to Improved Cow Reproductive Performance

“…The magnitude of the depression depends on the geographical location and the milk yield [20][21][22]. In tropical climates, high ambient temperatures and humidity are important determinants of reproductive performance.…”