|VILLALBA, JUAN - Utah State University|
|SPACKMAN, C - Utah State University|
|GOFF, BEN - University Of Kentucky|
|GRIGGS, T - West Virginia University|
|MACADAM, JENNIFER - Utah State University|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2015
Publication Date: 12/30/2015
Citation: Villalba, J.J., Spackman, C., Goff, B.M., Klotz, J.L., Griggs, T., MacAdam, J.W. 2015. Interaction between a tannin-containing legume and endophyte-infected tall fescue seed on lambs’ feeding behavior and physiology. Journal of Animal Science. 94:845-857. doi: 10.2527/jas.2015-9790.
Interpretive Summary: Millions of acres seeded with tall fescue in the US are infected with the fungal endophyte Neotyphodium coenophialum which produces an array of ergopeptide alkaloids that are toxic to grazing animals. Condensed tannins have a strong binding affinity for proteins and may bind other nitrogen-based compounds like alkaloids. This interaction could reduce absorption of alkaloids thus reducing their toxic effects in livestock. A study was conducted to determine whether a tannin-rich legume like sainfoin reduces the negative post-ingestive effects of ergot alkaloids in tall fescue. Sheep that consumed sainfoin had increased intake of the endophyte-infected tall fescue and reduced rectal temperatures relative to the no-tannin control. These results suggest that the effects mediated by the condensed tannins in sainfoin binding to and inactivating the ergot alkaloids. However, this interaction appears to be dependent upon plant maturity. These results will benefit other researchers looking to identify natural products to mitigate the effects of ergot alkaloids as well as producers who supplement livestock with condensed tannin-containing legumes.
Technical Abstract: It was hypothesized that a tannin-rich legume like sainfoin reduces the negative post-ingestive effects of ergot alkaloids in tall fescue. Thirty-two 4-month-old lambs were individually penned and randomly assigned to a 2X2 factorial arrangement with two legume species (1-sainfoin [SAN; ' 3% condensed tannins] or 2-cicer milkvetch [CIC; no tannins]) and a diet (seed:beet pulp:alfalfa, 50:30:20) containing tall fescue seed with two levels of endophyte infection (endophyte-infected [E+; 3,150 ppb ergovaline] or endophyte-free [E-]). For a 10-d baseline period, all groups were fed SAN or CIC (average amounts 19.8 and 15.1 g/Kg0.75, respectively) and ad libitum amounts of E-. In an ensuing 10-d experimental period, the protocol was the same except half of the lambs received E+ instead of E-. Daily food intake and rectal temperatures were measured for both periods. Jugular blood was extracted at the beginning and end of the experimental period. Subsequently, all lambs had choices between their respective legume (SAN; CIC) and seed-containing diets (E+; E-). Finally, an in vitro radial diffusion assay was conducted to determine whether condensed tannins extracted from sainfoin have the potential to bind to alkaloids in E+. All groups consumed similar amounts of E- during baseline (P > 0.10). However, lambs ate more E- than E+ during the experimental period (P < 0.05) and lambs offered SAN ate more E+ than lambs offered CIC (P < 0.05). Groups fed E- during baseline and experimental periods had similar rectal temperatures (P > 0.10). However, lambs fed E+ had lower rectal temperatures per g of food ingested when supplemented with SAN than with CIC (P < 0.05). Lambs fed E+ had a greater concentration of hemoglobin and number of red blood cells than lambs fed E- (P < 0.05) but plasmatic concentrations of cortisol and prolactin did not differ between treatments (P > 0.10). All lambs preferred their respective ration treatment over their respective legume treatment and they preferred E- over E+ (P < 0.05). Ergovaline in the E+ seed extract reduced the binding of the tannins with protein suggesting a tannin-alkaloid complexation but only from tannins extracted from sainfoin during the beginning of the experimental period. In summary, SAN supplementation increased intake of E+ and reduced rectal temperatures relative to CIC supplementation. Our results suggest that these effects were mediated by the condensed tannins in SAN through alkaloid inactivation. However, this interaction appears to be dependent upon plant maturity.