Tips for troubleshooting reproductive performance
for The Fence. Post
A high priority for most cow/calf producers is having a high pregnancy rate. So, if the number of pregnant cows disappointingly drops far below expectations, there are important considerations in advance of the next breeding season for cows and bulls. Two prominent beef specialists at Kansas State University recently provided detailed recommendations in an article they wrote called ‘’Troubleshooting Poor Reproductive Performance in Cows.“
Nutrition is at the top of the list for heifers and cows. Heifers need sufficient growth for breeding, and cows need energy reserves to resume normal cycles and re-breed. Pregnancy rate can be affected by several disease issues, and the female needs adequate nutrients to develop immunity following vaccination.
First and foremost, there’s the issue of whether a female achieved appropriate weight and body condition by calving time.
“Bred heifers should reach 85 percent of mature weight by first calving in a body condition of 5.5 to 6,” said Sandy Johnson, Ph.D., Extension beef specialist at K-State. Body condition scores range from 1 to 9, with 1 being extremely thin and 9 being very obese. “For raised replacements, weight of mature cows should be known, and in other cases estimates should be realistic.” Johnson suggests weighing and scoring the body condition of replacement heifers periodically, in order to monitor progress and targets.
Healthy mature cows should gain about 150 pounds in weight of the fetus and fluids before calving, and be in a body condition score of 5 at calving. Johnson said that adequate body condition at calving is paramount to successful re-breeding, especially since meeting total energy demand for milk production with any leftover to increase body condition is challenging with many common feedstuffs.
“It’s important to have a positive energy balance to end postpartum anestrus. So, if cows lose condition after calving, they must still have enough condition that they could lose some weight and still cycle and re-breed in a timely fashion,” Johnson said.
GOOD QUALITY FEED
A good rule of thumb to avoid having to add body condition when nutrient demands are high is to closely monitor body condition year-round. If available feedstuffs are not sufficient to meet needs, low pregnancy rates result. “In extreme cases, calving time brings weak calves, poor colostrum and low milk production,” she said.
To meet nutrition requirements, be sure that feedstuffs were tested to determine nutrient content, and that rations were balanced accordingly, Johnson said. Poor pregnancy performance has often been linked to low quality feedstuffs that don’t meet deficiencies.
It’s important to know if and when the poor reproductive performance was observed. If vitamin or trace mineral imbalances are pinpointed, then often late-term abortions and weak calves might be observed in the same herd, at the same time.
“Vitamin and mineral imbalances may contribute to lowered reproductive performance. However, overall protein and energy status are more likely to explain a large number of open females,” said Gregg A. Hanzlicek, DVM, PhD., associate director of the Kansas State Veterinary Diagnostic Laboratory at K-State and associate professor. If there are a large number of cows cycling late in the breeding season or after the breeding season wraps up, it often is due to Trichomoniasis.
Also important is making notes about whether any open females were in a particular age or management group. Young cows often fail to become pregnant since they are still growing and experience more calving difficulty. If females of all ages are managed as a group, then body weight and dominance may put young growing females at a disadvantage to get their share of supplied nutrients.
The experts say heifers that conceive in the first two cycles of their first breeding season are considered in the best position to re-breed in subsequent seasons and remain in the herd longer.
Health recommendations also include timely and annual vaccinations, which include IBR, BVD, Campylobacter (Vibro) and Lepto. “Consult with your veterinarian regarding the use of killed and modified-live vaccines and timing, to avoid (resulting) abortions,” Hanzlicek said.
Biosecurity practices are advised, including quarantining all purchases. “Also, don’t buy used cows less than 120 days pregnant to avoid Trichomoniasis,” he said. Another biosecurity consideration is that if a neighboring herd has no biosecurity then some type of set back fence might be needed to prevent close contact. “If your bull jumps into a neighboring pasture, be sure to let the neighbor know your bull was in that pasture, and get your bull out soon as you can,” Hanzlicek said. He recommends a good follow-up exam in that case; testing that bull for Trich twice in a few weeks.
A breeding season for a well-managed herd is around 60 days, which should result in a pregnancy rate of 90 percent or more. Johnson and Hanzlicek say if something unexpected occurs to reduce the number of cows pregnant in the first cycle of a shorter breeding season, then the risk for a poor pregnancy outcome is greater than it would be with a longer breeding season. That’s because there would be more time for those cows to conceive.
EARLY PREG TEST
“To manage this risk, you can include an early pregnancy check 30 to 45 days into the season, and consider possibly extending the breeding season or leaving bulls out longer if early pregnancy results are poor,” Johnson said. “The goal should be a tight calving season and optimizing returns from opens or late bred cows that don’t fit the production system.”
On the other hand, it may also be worthwhile to shorten a very long breeding season (a season that is longer than 100 days) with gradual steps to achieve higher pregnancy rates. This is especially so, if cows have poor body condition at calving, and nutrition is of marginal quality or quantity post-calving. In this case, a short breeding season would be disappointing. “This would depend on the individual situation, economic conditions and goals. Step one for some might be not leaving the bull in 12 months/year,” Johnson said.
“Mature cows in good body condition take 45 to 55 days to resume normal cycles after calving, but young and thin cows would take twice this amount of time,” Johnson added.
Make sure the bull/female ratio is appropriate, the experts advise. “The general rule of thumb for bulls under 24 months is one cow per month of age of the bull. Mature bulls can be placed with 25 to 30 cows. Adjustments for a sick or injured bull would depend on how much of the breeding season was left at the time.
Since reproduction drives herd profitability in cow/calf operations, keeping these troubleshooting tips and guidelines can help boost low pregnancy rates in cows and simultaneously help the bottom line.
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