Improve pregnancy rate | Cows are more profitable if they produce a calf on time every year
TAMPA, Fla. — Beef supplies are dropping to record low levels in North America, but that could be alleviated if more calves were born to the existing cow herd.
“To produce more beef with a decreasing cow herd, we could im-prove reproductive rates,” said animal scientist Rick Funston from the University of Nebraska-Lincoln.
“If we increased reproductive rates in the United States by one percent, we are going to put 300,000 more calves in the system.”
Funston told the National Cattlemen’s Beef Association meeting held in Tampa Feb. 5-9 that producers who want to get the most out of their cows must ensure they get pregnant every year and wean a good sized calf.
Mike Smith of the University of Missouri’s animal science division said producers should ask three questions when attempting to achieve 85 percent pregnancy rates:
- What is the pregnancy rate among heifers and mature cows for the first 60 to 70 days of the breeding season? Pregnancy rate is defined as the total number of females pregnant during the breeding season divided by the number of females exposed to breeding.
- What proportion of the calves was born by day 21, 42 and 63 of the calving season? “It is well known in some of the highest production herds, approximately 61 percent of the calves are born by day 21, 85 percent by day 42 and 94 percent by day 63,” he said. “A reasonable goal would be to have 70 percent or more of your calves born by the end of the first 30 days of the calving season.”
- What is the calving pattern among two- and three-year-old females? More attention should be paid to the management of first calf heifers and young cows if most of them are calving late or in the middle of the season. More than half the potential crop is lost when cows and heifers fail to get pregnant.
One-third of calf deaths occur from birth to two weeks of age and 11 percent are lost during gestation. Four percent die before weaning.
Smith said proper management can reduce those losses.
Heat stress and drought are causing abortions in the United States this year. Other reasons for infertility include poor estrus detection, heifers that have not reached puberty, poor libido in bulls, low semen quality and poor artificial insemination techniques.
“Reproduction is very unforgiving,” Smith said. “The good things you do management wise don’t compensate for the mistakes or problems you encounter.”
Extending the season does not help when females fail to get pregnant in the allotted breeding period.
The cows may not settle, or they fall behind the rest of the herd if they calve later. These later calving cows don’t have time to return to heat and conceive in the subsequent breeding season.
A calving interval should be 365 days or less.
Gestation is 280 days, and the cow needs 20 days after calving for the uterus to reduce to normal size. It will have a short cycle, ovulate without showing heat and then come into full estrus seven to 10 days later and should be ready to conceive again.
A productivity study showed heifers and steers born in the first 20 days of the calving season have increased weaning weight because they are older.
Steers were heavier and tended to have a higher hot carcass weight and graded better. Heifers had a higher pre-breeding and pre-calving rate, an increased pregnancy rate and increased cycling.
Cows are more profitable if they produce a calf on time every year. They are more likely to produce two or more calves compared to the late calvers.
Smith said the profit from two early calving cows is needed to cover the losses from one late calver.
Adequate nutrition helps keep calving periods on time.
Consider the cow’s body condition after calving. This is the fat cover or energy reserve. The score is from one to 10 with one being emaciated and 10 being too fat. Moderate is a score of five to six. The minimum score at calving is five.
“As condition score increases, so too does pregnancy rate,” Smith said.
Thin cows take a long time to return to estrus while a cow with a score of five to eight can experience a shorter calving interval.
Body condition score is not an absolute, but Funston said pregnancy rates will fall when cows are not getting proper nutrition and they will have lower weaning weights.
The calf could be 100 pounds lighter at weaning, depending on how the cow was treated during pregnancy and lactation.
Calves that were weaned early could be 20 pounds lighter at finishing.