Location: Cell Wall Biology and Utilization Research
Title: Effects of sericea lespedeza supplementation on steers grazing wild-type endophyte-infected tall tescueAuthor
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POUDEL, SANJOK - Virginia Tech |
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PENT, GABRIEL - Virginia Tech |
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FIKE, JOHN - Virginia Tech |
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Zeller, Wayne |
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Davis, Brittany |
Submitted to: Animals
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/25/2025 Publication Date: 1/28/2025 Citation: Poudel, S., Pent, G.J., Fike, J.H., Zeller, W.E., Davis, B.E. 2025. Effects of sericea lespedeza supplementation on steers grazing wild-type endophyte-infected tall tescue. Animals. https://doi.org/10.3390/ani15030373. DOI: https://doi.org/10.3390/ani15030373 Interpretive Summary: Tall fescue is a cool season perennial pasture forage species, key for livestock production in temperate regions of the world. In the U.S. alone, tall fescue pasture and hay land covers 14 million hectares (35 million acres) and is a highly valued forage in the “fescue belt”, land which stretches from eastern Kansas and Oklahoma eastward to the Atlantic coast. The positive agronomic traits of tall fescue include: easy to establish, little management required, high persistence, drought tolerance, and insect and pest tolerance. Many of these positive agronomic traits have been attributed to a symbiotic relationship this forage has with an endophyte fungus that produces alkaloids. However, when livestock graze on wildtype endophyte-infected tall fescue they can suffer from what is referred to as fescue toxicosis. Symptoms of fescue toxicosis include lower average daily weight gain (ADG), retention of winter hair coat, and heat stress due to reduced blood circulation to the extremities. Fescue toxicosis presents a substantial challenge to the U.S. beef industry, causing considerable economic losses ($2 billion/year, 2015 dollars) through reduced weight gain and reproductive performance. Condensed tannins (CTs) are known to bind to and precipitate alkaloids and a few studies have shown that concurrent feeding of CT-containing forages mitigates fescue toxicosis symptoms in cattle. Despite the potential of CTs found in specific forage legumes to mitigate the absorption of toxic alkaloids causing fescue toxicosis, use of CT-containing supplements in the treatment of fescue toxicosis remains relatively unexplored. This study investigated the potential of sericea lespedeza (Lespedeza cuneata) pellets, a CT-containing feed supplement, to mitigate the post-ingestive effects of fescue toxicosis. Steers grazing on wildtype endophyte-infected tall fescue pastures were supplemented with either sericea lespedeza (LES) or LES mixed with polyethylene glycol (LPEG), a substance which neutralizes the effects of CTs. Steers on the LES diet tended to have greater ADG, retained less hair, had hotter tail skin temperatures and cooler rectal temperatures and had a 21% larger caudal artery lumen area than those fed LPEG. These temperature differences appear to be driven by a reduction in vasoconstriction. This also seems to lower stress in animals on toxic fescue, as steers fed LES tended toward lower hair cortisol, a marker of chronic stress. These findings support the hypothesis that CT may reduce the post-ingestive effects of fescue toxicosis, but they do not answer the question of CT's potential to reduce alkaloid absorption. Further research is needed to elucidate the mechanisms underlying these effects and establish the long-term efficacy of interventions such as CT-supplementation. Technical Abstract: Condensed tannins (CTs) in certain leguminous forages can mitigate toxic alkaloid absorption linked to fescue toxicosis due to their high affinity towards various steroidal and protein-like alkaloids. However, their use as feed supplements remains underexplored. This study evaluated the impact of CT-rich sericea lespedeza (Lespedeza cuneata) pellets on the post-ingestive effects of fescue toxicosis. Twelve steers on wild-type endophyte-infected tall fescue pastures received either sericea lespedeza pellets (LES) or LES with polyethylene glycol (LPEG; negative control) for 12 weeks over three consecutive summers. Body weight, hair coat scores, temperatures (rectal and extremity), cortisol levels, and caudal artery lumen area were measured every four weeks. Steers fed LES showed trends toward higher ADG (p = 0.0999) and reduced hair retention (p = 0.0547) compared to those fed LPEG. Steers on LES also showed hotter tail skin temperatures (p = 0.0053) and cooler rectal temperatures (p < 0.0001) compared to those fed LPEG. LES-fed steers had a 21% larger caudal artery lumen area (p < 0.01), suggesting reduced vasoconstriction. Additionally, LES-fed steers tended to have lower hair cortisol (p = 0.0746), indicating reduced chronic stress. These results suggest that supplementation with CTs may alleviate the post-ingestive effects of fescue toxicosis, potentially by improving blood flow and reducing stress. However, further research is needed to determine whether CTs directly reduce alkaloid absorption, as well as to validate the long-term efficacy of CT supplementation. |