Better Performance Through Genetic Selection

– Breed Differences on Endophyte-Infected Tall Fescue

By Brittni Drennan

Tall fescue is the most commonly used grass in the U.S. used to graze and feed cattle. Widespread throughout a majority of the country, fescue grass provides multiple benefits for pasture performance due to its persistence, long growing season, and nutritional quality as well as drought, insect and disease resistance. However, producers have a love-hate relationship with this seemingly desirable plant. The same fungal endophyte that makes the grass so hardy also contains some alkaloids that studies have shown are detrimental to the performance of grazing livestock.

Common side effects of toxicosis include heat stress, suppressed appetite, poor growth or reduced calving rates, ultimately costing the beef industry approximately $500 million to $1 billion annually in losses due to decreased reproductive and growth rates, according to an abstract from Richard Browning, Ph.D., Tennessee State University.

Researchers have determined the endophyte can be alleviated using several forage management practices including replacing endophyte-infected tall fescue with low-endophyte strands, diluting endophyte-infected fescue with other grasses or legumes, ammoniating fescue hay, or increasing stocking rates to prevent plant maturation since the endophyte is highly concentrated in the seedhead. However, due to high costs, vast amount of acreage covered in endophyte-infected tall fescue, along with reluctance to eradicate long-standing pastures, forage management for eradication purposes does not seem likely or advantageous.

A more practical, effective solution for alleviating the negative effects caused by high-endophyte fescue is with animal management practices by genetic selection. Browning pointed out heat stress is a known symptom of fescue toxicosis, causing increased panting, respiration rates, and time spent in the shade, which means cattle spend less time grazing and gaining.

Recently, the University of Kentucky conducted a trial using 120 spring-born calves out of cows with varying degrees of Brahman-influenced genetics bred to Hereford bulls. Roy Burris, Ph.D., Extension Beef Specialist at UKY was the lead researcher on the study.

“There’s five million acres in Kentucky and most of it is high-endophyte fescue. When dealing with fescue endophyte, there’s a lot we don’t know and pastures vary,” Burris said. “What we found from the trial is an improvement in the adjusted weaning weights. We did see better performance on those calves with Brahman influence, and they gave us higher adjusted 205-day weaning weights.”

Burris reported the results from those calves having zero Brahman influence had an adjusted weight of 499.2 pounds, calves out of 3/16 Brahman influenced cows were 512.5 pounds, and calves out of the 3/8 percentage cows were 533.9 pounds. Burris said there was no significant difference between findings on the high-endophyte versus the low-endophyte fescue.

The better performance from Brahman-influenced calves can be attributed to their natural ability to tolerate heat better than Continental breeds. Burris said calves raised on fescue grass tend to be a little woolier and hairier, and Brahman-influenced cattle tend to be slicker hided, allowing them to more effectively dissipate excess body heat caused by fescue toxicosis.

“We sent the resulting calves to the feedlot, and there wasn’t much difference in the results between the different sets of calves out of the feedlot, and there wasn’t any difference in carcass data between the calves.” Burris said. “We did, however, make more money off the Brahman-influenced cattle because they were evaluated lower initially because of their Brahman-influenced characteristics.”

Fescue toxicosis has an impact on more than just performance to weaning in cow-calf operations. Browning also noted studies in which the average daily growth rates (ADG) in Bos indicus crossed steers were less affected by fescue toxicosis (Table 1).

To briefly summarize, Goetsch et al. (1988) demonstrated the reduction in ADG of Brahman cross steers was comparable to the reduction of British cross steers in a 12-week period in the spring as well as fall. An exception was noted during the first half of the fall season when the ADG of Brahman crosses was statistically less affected by the endophyte. McMurphy et al. (1990) tested Angus, Brahman x Angus, and Simmental x (Brahman x Angus) steers and found the half-blood Brahman steers’ post-weaning ADG were less affected by high endophyte levels than the straight Angus or quarter-blood Brahman steers.

“Collectively, a consistent trend is apparent,” Browning said. “High endophyte levels in the tall fescue diets invariably reduced ADG of Brahman-cross steers to a lesser degree than when steers did not posses the Brahman influence. Brahman genetics reduced the adverse effects of endophyte-infected tall fescue on post-weaning ADG by 26 percent on average (range = 10 to 65 percent) across the studies.”

These studies also demonstrate another important factor for producers to recognize. It’s not about fighting fescue and completely eliminating toxicosis; it’s about doing what it takes to reduce loss and decrease the negative impacts caused by high-endophyte fescue.

Having worked with Beefmaster cattle and other Brahman-influenced cattle since 1974, Burris is very familiar with the benefits these kinds of cattle provide, aside from their ability to thrive in areas with high-endophyte fescue. Beefmasters are a stabilized composite breed developed by maintaining 50 percent Brahman influence, 25 percent Hereford and 25 percent Shorthorn. Currently, the UKY cowherd is fall calving, and Burris has found Brahman-influenced cattle perform just as well in the winter months as they do in the summer.

There is a misconception among producers in the beef cattle industry that Beefmaster cattle or cattle with Bos indicus genetics will not perform in colder climates, but that simply could not be farther from the truth. In the colder seasons and environments found in northern areas of the country, Bos indicus cattle thrive just as well in the winter months due to their hardiness and natural adaptability characteristics. Burris said Brahman-influenced females, in particular, are in high demand because of their performance and especially their mothering abilities.

“What we found most of the time in cross-breeding programs, some Brahman influence has proved to work very well in the south as well as the north,” Burris said. “What we see here is that a lot of people like, and there’s a lot of demand for, F1 heifers due to their longevity and their performance. Most people in this area aren’t used to looking at Brahman-type cattle, so they don’t necessarily love the phenotype, but they find they do perform well.”

Regardless of production stage or industry sector, Burris said producers would benefit from evaluating their own cattle and breeding those cattle to genetics that will compliment their herd.

“Breed to improve structure and soundness or breed to improve carcass or performance,” Burris said. “Find those weaknesses within your herd and work to eliminate those weaknesses.”

It comes down to using the tools available to select genetics that will compliment a producer’s herd, coincide with his production goals, and work well in his environment, not against it.

Burris also said disposition of Bos indicus cattle was a concern among cattlemen. Let’s be realistic. Docility was a problem in the past for producers raising Brahman-influenced cattle. Although, since Beefmaster producers in cooperation with Beefmaster Breeders United (BBU) have recognized the issue, they have worked to effectively minimize the problem by selecting for improved disposition within their operations.

“Disposition seems to be more of a problem in some other Brahman-influenced breeds than in the Beefmaster breed,” Burris said. “I always look at docility and disposition and select for that. When I bring a bull in, I want to be sure I’m not bringing in problems, and I do the same thing with Angus cattle. If my herd has a problem, that’s what I’m going to try to take care of first.”

In regards to the perception that all Brahman-influenced cattle have problems with disposition, Burris said it would be a mistake for producers to affirm those negative perceptions and give critics something else to pick apart.

“In my experience, Brahman-type cattle tend to respond better and more quickly to the way they’re handled and the way they’re treated,” Burris said. “There are always some outliers, but they need to be culled and disposition needs to be looked at within all Bos indicus breeds.”

Aside from the herd based at the University of Kentucky Research and Education Center, Burris personally keeps approximately 200 brood cows, and tries to maintain some Brahman-influenced cattle in the herd. He keeps a few purebred Angus and Brahman-influenced bulls and breeds his own replacement females to uphold a 3/16 Brahman-cross. Because of their hardiness and adaptability, longevity is an indirect advantage of Bos indicus cattle.

“Longevity, to me, is the biggest benefit of Brahman-influenced cattle—their ability to stay structurally sound, stay in the herd and continue producing,” Burris said.

Ultimately, implementing Beefmaster and/or Brahman-influenced genetics provides tremendous profit potential for cow-calf producers as well as stockers, introducing benefits from heterosis, more longevity and improved performance on high-endophyte fescue.

“Infusion of Brahman genetics seems to offer an alternative means of reducing the impact of fescue toxicosis on both cow-calf and stocker performance,” Browning said. “Use of Brahman genetics to overcome challenging environmental conditions is not a new concept. Somewhat overlooked, however, may be the potential of Brahman germplasm to enhancing cattle performance in another challenging production environment, the high endophyte-infected tall fescue pasture.”

For more information about Brahman-influenced genetics or to find a Beefmaster seedstock provider, visit www.beefmasters.org.