Impaired fertility is the main reason for involuntary culling of dairy cows in Sweden. The objective of this study was to map quantitative trait loci (QTL) influencing fertility and calving traits in the Swedish dairy cattle population. The traits analyzed were number of inseminations, 56-d nonreturn rate, interval from calving to first insemination, fertility treatments, heat intensity score, ...

A 1-yr calving interval (CInt) is usually associated with maximized milk output, due to the calving-related peak in yield. Extending CInt could benefit cow health and production efficiency fewer transition periods per unit of time. can affect lactation performance by days dry year, delayed pregnancy effect on yield, greater solid yield late lactation. This study first investigated effects 3 dif...

the reproductive performance of a dairy herd has a significant effect on the profitability of that herd. common measures of reproductive performance are days to first service, days to conception, calving interval, services per conception, conception rate, estrus detection rate, and pregnancy rate. most cow operations would benefit economically by reducing the number of operational days, decreas...

Fertility and reproductive performance of Landim and Africander females were compared using data collected from 1968 to 1981 at the Chobela Research Station in Mozambique. Breeds were managed together and grouped by age and sex, except when separated for breeding. Traits were relative fertility (probability of fertile females calving from the first breeding season), age at first calving, first ...

A bivariate censored threshold-linear model was used to study genetic parameters of number of services to conception (STC) and days open (DO) in first-lactation Norwegian Red (NRF) cows. Records of 1,454,916 NRF cows, with a first insemination from 1980 to 2004, were analyzed. It was assumed that every cow had at least a first insemination. The number of inseminations was recorded until a cow c...

Over 18% of cows returning to service within 49 days of first insemination were remated within the first 17 days. A distinct peak representing 31.4% of all short return intervals occurred from 8 to 10 days after first insemination. Because nonreturn rates to second insemination following these service intervals were equal to nonreturn rates for first inseminations, it is probable that some cows...

When the voluntary waiting period (VWP), defined as days between calving and when cow is eligible to receive first insemination, extended, high-yielding dairy cows may have better opportunities regain energy balance before insemination. This study investigated effect of an extended (145–215 DIM, n = 280) or conventional (25–95 251) VWP treatment on fertility, disease incidence, culling rate in ...

Two experiments were conducted on postpartum suckled beef cows synchronized with Syncro-Mate B and artificially inseminated approximately 48 h after implant removal. In Exp. 1, cows (> or = 42 d postpartum at the timed AI) were randomly assigned to treated (n = 101) and control (n = 85) groups on d 12 after the timed AI. Treated cows received norgestomet/silicone implants that were left in situ...