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Here's How To Make Cows More Reproductive

Here's How To Make Cows More Reproductive
Reproductive pressure and culling can select more profitable cows and fixed-time AI can help poorer cows cheat the odds.

National statistics tell us many cows aren't pulling their weight, reproductively.

The last study by the National Animal Health Monitoring System showed 33% of cows were culled from the herd for "pregnancy status", plus another 4% for "other reproductive problems."

At the back end of life and production, only one-third stick around long enough to be culled for age or bad teeth (32%).

Furthermore, almost 16% of animals culled by the nation's beef producers were less than 5 years of age and 32% were 5 to 9 years old.

Early = $: When an 84-day breeding season was split into 21-day parcels, the earliest-born calves were vastly more productive.

If you put any stock in the economic analyses that say it takes the net revenue from about six calves to cover the development and production costs of each replacement heifer or that any cow which misses a single calving is not likely to recover the lost revenue of that missed calf, these statistics suggest serious reproductive and financial problems.

Understanding the causes and enacting the right management can begin to solve these issues, say George Perry, South Dakota State University reproductive physiologist, and Michael Smith, University of Missouri reproductive physiologist.

Smith says half of the reproductive losses among all cows are those cows which do not conceive during the breeding season, for whatever reason. Only 11% of the cows that experience reproductive loss lose calves during gestation and another one-third of the loss occurs  during  the first two weeks of the calves' lives, primarily due to dystocia.

The two reproduction specialists say 90-95% of heifers and cows have their eggs fertilized within a couple of days following insemination. HHowever, actual conception rates are usually around 60% to 70% for natural service or artificial insemination. Consequently, a number of embryos are lost within the first two weeks after breeding.

Although nature contributes much of this loss, inappropriate management practices such as inducing stress or transporting your cows at the wrong time following AI can also increase embryonic mortality, they say.

Cows which breed early and calve early are simply more effective. They produce more pounds of calf through their lifetimes and are less likely to miss calving in any given year.

Moreover, this reproductive soundness has profound effects on profitability. Smith says a cow that calves in the first 21 days of a 90-day calving season her entire 8- or 9-year life will produce the weaning weight equivalent of one and a half to two additional calves in her lifetime, compared with one that starts late and stays in the last 21 days of the calving season.

University of Nebraska data says those early calves are themselves better producers. Heifer progeny born early have increased weaning weight, pre-breeding weight, pre-calving weight, percentage cycling before breeding and pregnancy rate.

The most reproductively sound cows are definitely the ones to select and keep but sometimes a cheater bar is called for. One such advantage is estrous synchronization and fixed-time artificial insemination (FTAI), Smith says.

In Missouri some 2,300 postpartum cows were given a progestin-based FTAI protocol. Nearly half (43%) were anestrous when the protocol was administered yet the pregnancy rate for the cycling and anestrous cows following FTAI was essentially the same -- 64.8% and 63.8%, respectively.

Smith says that shows progestin-based FTAI protocols can be effective in inducing a fertile ovulation and increasing the proportion of anestrous cows that become pregnant at the start of the breeding season.

To read the full study by Perry and Smith, download it below.

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