By Jennifer Whitlock
Field Editor

Any rancher knows live births and healthy calves are what drives profit. The loss of pregnancy or a calf not only represents a potential issue with the cow but represents loss of income, too.

A postdoctoral research associate at Texas A&M University’s Animal Science department launched a study on beef cattle’s reproductive tract microbiomes to investigate reproductive failure, its causes and potential solutions.

“It’s like a fertility clinic for humans. The same idea, just bringing it to the beef cattle world,” Dr. Rebecca Poole, the study’s author, said. “They have found there are a lot of relationships between the microbiome of the reproductive tract and fertility in women, so the research has continued from there to establish the understanding of microbiomes in other species like livestock.”

Previously, microbiome research was limited to studying bacteria that can be cultured in a lab setting. But only about 1 percent of the microbiome’s bacteria can be cultured in petri dishes, according to Poole.

“Now, using a sequencing-type approach, we are able to determine all the bacteria in a certain environment,” she said.

Symbiotic bacteria in the reproductive tract have an unknown effect on fertility in cattle. Poole’s theory is variations in reproductive hormone secretion or immune function direct bacterial species diversity in the uterus, and that’s what causes beef cattle to experience infertility issues like inability to establish or maintain pregnancies.

“My research will take the concepts [ranchers] understand along the lines of the estrous cycle, estrous synchronization protocols and reproductive hormones,” Poole said. “I will see how those relate to the microbiome so that we can find ways to potentially manipulate it, from a hormonal standpoint, to create a healthy microbiome to establish a pregnancy.”

In her research, she will implement standard estrous synchronization protocols using hormone therapy to see how those hormones affect bacterial species in the reproductive tracts and uterus.

Differing levels of reproductive hormones and bacteria in the microbiome prior to breeding, as well as the relationship between the immune system and reproductive biome, will be studied.

“We have found differences between cattle that are essentially able to establish a pregnancy versus those that do not, differences in their uterine microbiome before breeding,” Poole said. “So really, we are just trying to figure out if there are other mechanisms that are controlling that microbiome, like reproductive hormones, and also the immune system is another component that is most likely involved with changes in the microbiome.”

In addition to her main research project at Texas A&M, Poole is participating in another project studying nutritional effects on the biome. She hopes to develop a greater understanding of how these factors work better together to promote fertility, which could then be used to inform decisions on cow-calf operations.

“So, our suggestions to [ranchers] could be based on nutrition or it could be a hormonal thing, which means we suggest they take a blood sample at a certain point in time to see where a cow stands. Is she a good contender for breeding based on her hormone concentrations?” she said. “It may mean, for example, suggesting the use of cattle heat detection patches, which is an indication of estrogen concentrations at breeding.”

Using this information, ranchers already using estrous synchronization and artificial insemination would be able to more precisely target a specific time frame with the highest chances of success for pregnancy.

“Based on my results, I can provide suggestions for [ranchers] and say, ‘You need to take a blood sample at this time,’ and, ‘Let’s look at her reproductive hormone concentrations or her immune cell levels and see if her uterine microbiome environment is acceptable for breeding,’” Poole said. “Again, it is like the human fertility clinic, and we can estimate likelihood of establishing a pregnancy.”

The Texas A&M study is funded by a two-year grant from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA).