Managing Fertility While Grazing Fescue
Toxic endophytes can lower milk production and fertility.
November 19, 2024
If you want to bash tall fescue or find a silver bullet for the production ills it can cause, don’t call Neal Schrick. For starters, the University of Tennessee animal scientist likes the forage. He told attendees at the Applied Reproductive Strategies in Beef Cattle symposium in Athens, Ga., Sept. 4-5, “It’s a good, hardy grass, a grass that will grow on a piece of rock with no rain.”
Yes, the original Kentucky 31 tall fescue is hardy, but it usually contains a toxic endophyte that can hammer gains in young cattle and lower milk production and fertility. It can also cause vasoconstriction, making cattle more susceptible to heat stress. In extreme cases it can even cause their tails, hooves and ears to slough off. Still, Schrick said, you already have the answers.
“Usually when we see fescue issues, it’s a combination of fescue and heat, not just the endophyte.” — Neal Schrick
“If you have fescue, I guarantee you have managed around it,” Schrick said. “You know how to fix it. Our producers have selected animals that can handle it. The ones that don’t grow well, you don’t keep as replacements.”
No doubt, you’ve seen photos of a shaggy ol’ cow grazing toxic fescue. You might even have one yourself.
“You know she ain’t gonna work. Don’t keep heifers out of her,” he emphasized, noting producers can plant clover or supplement with feed to dilute the effects of toxic fescue.
Even with good management, however, the toxin can sneak up on you, he added. “If you have a weed issue and you spray for weeds, you may wipe out all your clover. You’ve got problems.”
Fescue and drought are a nasty combination, Schrick said. “If you went in and fertilized in September to get some stockpiled fescue, and it doesn’t rain, it doesn’t rain, it doesn’t rain. It rains in December, and you put those cows on there, and their switches start dropping off. The pastures are hot. Get some extra feed out there. You can dilute this issue.”
With fertility, the reproductive physiologist said it typically isn’t an all-or-none deal. Cows do get pregnant. With an artificial insemination (AI) or embryo transfer (ET) program, though, where precision counts, it can show up.
Schrick split a group of cows between pastures that contained fescue and those that grazed Bermuda grass pastures. When they were superovulated, bred and the embryos removed on Day 7, all was good. However, apparently the follicle-stimulating hormone (FSH) used in the super ovulation helped mask fescue-related problems. When he repeated the trial, he didn’t superovulate those females. The lone embryos he removed on Day 7 from the cows that were on fescue were behind on development and lower in quality compared to the control group.
Endophyte-infested fescue doesn’t do bulls any favors, either, especially when their semen is frozen, thawed and undergoes a three-hour post-thaw stress test. The semen from bulls on a non-toxic pasture had 58% motility before the post-thaw stress test, then dropped to 51%.
“I’ll take that,” said Schrick. With the semen from bulls on endophyte-infested fescue pasture, post-thaw they were 53%, then dropped to 23% three hours later, which is not acceptable. No matter, Schrick still preached management over plowing up fescue. He’s seen producers move to a fall-calving season so breeding takes place in the cooler winter months.
“Usually when we see fescue issues, it’s a combination of fescue and heat, not just the endophyte,” he added. “There are benefits to tall fescue. Like I said, it is very drought tolerant, pest resistant, easy to establish and has a longer growing season.”
As for the downside of the perennial, Schrick repeated, “I have no silver bullets. Several ‘cures’ have been discussed, but don’t pan out long term.” He also stated, “Our producers in the Southeast understand fescue and know how to manage their cattle reproduction and select their replacements to minimize the overall effects.”
Editor’s note: Becky Mills is a freelance writer and cattlewoman from Cuthbert, Ga. [Lead photo by Shauna Hermel.]
Angus Beef Bulletin EXTRA, Vol. 16, No. 11-B
Topics: Feedstuffs , Health , Management , Reproduction
Publication: Angus Beef Bulletin
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