Breakthrough in human medicine could help produce more beef


A recent breakthrough in human medicine research could help a Texas A&M Department of Animal Science researcher find a way to increase beef production to help meet the demands of the world’s growing population.

Bos indicus cattle breeds are important to global beef production because of their adaptability to tropical and subtropical climates, including those found in Texas and other southern states of the United States.

But a big challenge or disadvantage for Bos indicus, or Brahman, cattle is that their overall reproductive performance is lower than that of Bos taurus cattle breeds such as Angus and Hereford, which predominate in the Midwestern and Northern states.

Dr. Rodolfo Cardoso, an assistant professor and reproductive physiologist in the Department of Animal Science at the College of Agriculture and Life Sciences, is leading a four-year project funded by a $500,000 grant from the U.S. Department of Health. Agriculture from the National Institute of Food and Agriculture. Collaborators include Gary Williams, Texas A&M AgriLife Research Professor Emeritus, and graduate students Viviana Garza and Sarah West.

Cardoso said groundbreaking advances in neuroendocrine research have defined the mechanisms controlling the secretion of the gonadotropin-releasing hormone, GnRH. According to him, the new knowledge can help his team determine neuroendocrine differences between Bos taurus and Bos indicus bovine genotypes and use them to improve reproductive output in cattle influenced by Bos indicus.

“Very recently, there has been a significant breakthrough in understanding how GnRH secretion is regulated in rodents and primates,” he said. “Our preliminary research suggests that similar mechanisms are also important in cattle and could explain the differences in reproductive performance between Bos taurus and Bos indicus animals.

“If confirmed, these findings may have practical implications for reproductive management of Bos indicus cattle. In human medicine, several pharmacological strategies to improve fertility in women have already been developed based on these new findings.

Rodolfo Cardoso leads the new research.

Laura McKenzie/Texas A&M AgriLife Communications

Timing of calving is important

Up to 70% of the world’s livestock is raised in tropical and subtropical regions, and approximately 30% of US beef cattle herds have some Bos indicus influence, particularly in southern and southeastern regions.

A major challenge is that Bos indicus and cattle influenced by Bos indicus reach puberty significantly later than Bos taurus breeds. This late puberty essentially means one less calf in a cow’s life and also presents challenges when breeders try to time estrus cycles for the annual breeding season.

Cardoso said Bos taurus heifers typically hit puberty at 10-12 months, while Bos indicus heifers often don’t hit puberty until 15-17 months.

“This five-month delay prevents them from reaching puberty in time for their first breeding season, so they have to wait another whole year to be mated and have their first calf,” Cardoso said.

With more than 4 million replacement beef heifers entering the US cow herd each year, the difference between having a calf when the heifer is two years old and three years old can make a big difference in beef production. In Texas and Florida, less than 50% of beef heifers reach the two-year calving goal due to the influence of Bos indicus.

Cardoso said heifers that first calved at two years old produced about 300 pounds more weaned calf weight over their lifetime, a difference of $500, compared to heifers that calved at three years old.

This project will use recent findings to determine if the distinct differences observed in reproductive function in Bos indicus and Bos taurus breeds can be attributed to functional differences in the region of the brain that controls GnRH hormone secretion.

Predetermined breeding seasons are the key to efficiency

A predetermined breeding season typically lasts between 45 and 90 days and allows for more efficient management of a beef cattle operation, Cardoso said.

“You can have a very even crop of calves, which makes managing those calves a lot easier – vaccinate and follow all the health protocols at the same time,” he said. “You can wean and sell the calves at the same time because you have a uniform group, which makes management much, much more efficient in a cow-calf operation. It also allows animals that are not efficient to be culled.

In addition to better understanding the reproductive function of cattle, Cardoso said, a second goal of a pharmacological strategy is to develop timing protocols for artificial insemination suitable for Bos indicus heifers. Most of the protocols currently used in the United States were developed specifically for Bos taurus breeds.

“These Bos indicus heifers already have, at 12 to 14 months of age, the skeletal size and maturity to support a safe and healthy pregnancy,” he said. “There is no doubt about it. They don’t ride a bike yet. We don’t want to cause these heifers to reach what we call precocious puberty (puberty before 10 months). That’s not desirable, and that’s not what we’re trying to accomplish here.

A key benefit, Cardoso said, of more effectively synchronizing the breeding season is being able to use more artificial insemination in cattle influenced by Bos indicus.

“Artificial insemination is the most powerful tool we have to improve the genetics of beef cattle herds,” he said. “Artificial insemination is a way for a beef cattle farmer to begin, over time, to improve the genetics of the herd.”

But currently, the ability of breeders to synchronize the estrus of animals influenced by Bos indicus for artificial insemination is not optimal, Cardoso said.

“We hope that by the end of this four-year project we will have a very good understanding of the neuroendocrine differences between heifers influenced by Bos taurus and Bos indicus,” he said. “And, more importantly, we believe that at this point we will have good strategies to pharmacologically control the estrus cycle in heifers influenced by Bos indicus.”


About Author

Comments are closed.