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Saner: Reproductive efficiency provides important consideration to the bottom line

by Wyoming Livestock Roundup

Heifers that become pregnant within the first 21 days of the breeding season are 80 percent more likely to be in the cowherd nine years later, a University of Nebraska beef specialist tells producers. 

Because pregnancy has four times more impact on the cow than any other production trait, producers should continue to find ways to improve the reproductive efficiency in their cowherds, according to Randy Saner.

Research has shown that heifers bred 22 to 42 days into the breeding season are only 60 percent likely to be in the herd nine years later. 

“Depreciation is significant. We are losing money if we can’t keep cows in the herd long-term,” Saner says.

Early breeding

Getting the heifer bred within the first 21 days of the breeding season will likely improve the herd’s reproductive efficiency. 

Saner shares the results of research using a CIDR (controlled internal drug release) with progesterone in a timed artificial insemination (AI) program. The pregnancy rate of heifers in this program increased from 81 percent to 93 percent. This increase caused a trickle down impact, producing heavier calves at weaning and increasing the value per calf by $169. 

Saner figures, by getting these cows bred earlier, the calves were 50 pounds heavier at weaning. In a 300-head cowherd, this increased the value of the calf crop from $26,000 to $51,000, he says.

Fall-born heifers

Saner shares with producers studies looking into how to increase the value of fall-born heifers. 

“Usually, fall-born heifers selling in the spring are not worth as much as spring-born heifers selling in the fall,” he says. “If we can get them bred before they are two-year-olds, they could be a cheaper source of replacements.”

Research at the University of Nebraska looked at breeding 311-day-old heifers using MGA (melengestrol acetate) or CIDRs. The two methods didn’t produce a lot of difference in estrus response, age of breeding or pregnancy rate, Saner says, but he noted there are cost differences because the CIDRs are more expensive.

The beef specialist thinks these heifers can be developed from weaning to pregnancy diagnosis for around $1,550 a head. 

“It is pretty reasonable to develop them, but producers need to realize they may have a higher number of opens because they are younger,” he says. 

If producers try to breed fall-born heifers, Saner notes the importance of using a calving-ease bull because these heifers will be smaller and have smaller pelvic areas. 

Pregnancy rates

Comparing pregnancy rates using fixed time AI with MGA or CIDRs, a study of 5,000 heifers at Ainsworth, Neb. produced similar results. Overall, pregnancy rates were 93 percent using MGA versus 90 percent with CIDRs. 

However, using MGA can result in savings, since CIDRs are more expensive. 

“MGA is cheaper, but if they won’t eat it, we will have a problem. The benefit of using a CIDR is once it’s in there, we’re set,” Saner says.

Producers can also add value to non-pregnant females by synchronizing them with a seven-day CIDR-PG (prostaglandin) protocol, prior to a 60-day natural service breeding season with a one-to-25 bull-to-cow ratio, Saner continues. 

In a University of Nebraska study, these cows were pregnancy checked by ultrasound 30 days after the bulls were removed, and two weeks later, on March 1, the open cows were sold. 

The pregnant cows were sold two months later, in mid-April, when grass was more readily available. 

“Holding the cows over until spring may increase their value,” Saner explains.

Cow considerations

Producers should also consider a crossbred cow breeding program to increase the longevity of the herd. Saner says a crossbred cow averages 1.3 times longer in the herd, one more calf during her lifetime and weans an additional 600 pounds over a straight-bred cow. 

“At today’s costs, that is about $3,000 more income,” he notes. “As things get tighter, this may be one way to improve profitability.”

Matching cow size to available resources can also improve herd efficiency. 

“Managing cow size is important. As the cow gets bigger, she needs more feed, more protein and more energy. There is nothing wrong with a bigger cow if we have an abundance of grass and corn. However, the bigger cow may be more suitable to a producer in Illinois than in short grass prairie, where our resources are more limited,” Saner says.


Saner reiterates the importance of reproductive performance, calling it a crucial part of the breeding program. 

“Building a heifer is not cheap. It is important to match cow size to the forage resources we have available. Higher milking cows have higher forage needs and greater maintenance requirements. It takes bigger organs to produce more milk,” he explains.

Saner encourages producers to know their costs and keep good records so they can evaluate changes they make to their operations. 

The key is to improve stocking rates, while decreasing costs and improving revenue, he explains. 

“We might consider things like implementing a rotational grazing program or adding the crossbred cow to improve herd longevity,” he says. “Don’t do things like selecting for excessive growth or milk or chase only post weaning and carcass traits.”

Gayle Smith is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to 

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