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Developing for Longevity in the Southwest

Management decisions affecting reproduction and longevity in the southwest

RUIDOSO, NEW MEXICO (Aug. 29, 2018) — “Profitability of the beef cow producer is directly tied to the longevity of the cow,” said Adam Summers, New Mexico State University assistant professor of animal science. Cows need to produce a calf yearly for at least three years to recoup their cost of development as a heifer.

Adam Summers

“Heifer development is key in the longevity of a cow,” said Adam Summers, New Mexico State University. “For our region, we have to figure out what is the most effective, and usually a drylot is not.”

The “ideal” cow is developed at a low cost to reach puberty early and breed at the earliest opportunity. She is expected to produce a calf unassisted every year and to take care of that calf by teaching it and providing adequate nutrition while remaining sound, sane, disease-resistant and thriving in her environment. Producers also expect her to retain her value when she is culled at the end of her productive life.

“We expect a lot out of our cows,” Summers said, leading into a discussion of the influence calving date plays on cow longevity during the Applied Reproductive Strategies in Beef Cattle workshop hosted in Ruidoso, N.M., Aug. 29-30. Though these data were not statistically significant, looking at the bottom line of an operation, it proved otherwise.

Summers presented data showing heifers calving earlier for their first six calves also had higher weaning weights. He shed light on the important role nutrition plays in a management system and the productivity of animals, specifically in New Mexico and similar environments.

“We analyzed 45 years of data to find that high levels of rain and good forage over the entire gestation period proved a cow would have a higher-weight calf,” Summers said. “As expected, when we have large amounts of rain, the calf growth and performance was improved. However, with low precipitation the longevity of the cow in the herd was improved and increased the total calf crop produced by that one animal.”

The first of two theories for why this occurred hypothesized that calves born during low precipitation were programmed to enter a harsh environment. This was backed up by research conducted at the University of Wyoming on a herd of sheep. The second theory pertained to protein supplementation.

“Heifer development is key in the longevity of a cow,” Summers continued. “For our region, we have to figure out what is the most effective, and usually a drylot is not.”

Typically, there is a cardinal rule against implanting a heifer intended to keep as a replacement. However, in a region like New Mexico a drought can create a high level of uncertainty pertaining to what animals will be kept or sold based on the unpredictable weather patterns.

In his research, heifers implanted with Synovex® C when they were 2 months old saw a gain advantage of 25 pounds each time they were weighed, Summers explained, emphasizing the early administration of the product. “If it started to rain and a producer wanted to keep those animals as replacements, he could. Subsequent pregnancy rates were no different between heifers that were implanted and those that were not.”

Longevity was also not affected by the implants. Summers noted that implanting any later than 2 months of age could easily have an effect on puberty and fertility. He is conducting a study on this topic currently.

In conclusion, Summers discussed some other reproductive technologies available to producers to improve the fertility and longevity of their herds. In his region, extensive artificial insemination (AI) protocols are not always a feasible practice. Summers shared research by Larson et al. evaluating administration of a single shot of prostaglandin 108 hours after bull turn-in in a natural-service program. While there was no increase in overall pregnancy, the treatment resulted in a 13% increase in calves born in the first 21 days of the calving season.

Summers also recommended the lesser-known technology of counting antral follicles. Moderately to highly heritable, the trait has been shown to be positively associated with fertility in Bos taurus cattle. The trait could be used to identify animals with improved fertility traits to breed and calve earlier in the season.

“Management of fertility and longevity in any region is not a single-phase event,” he continued. “Proper nutrition management will increase cow stayabilty. We may be capable of improving reproductive performance and longevity through fetal programming. Many reproductive technologies may be adapted and integrated into management systems to improve heifer fertility and longevity.”

For details on Summers’ presentation — including the proceedings, PowerPoint and video of his presentation — visit the Newsroom at

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