Location: Forage-animal Production ResearchTitle: Effects of tall fescue endophyte type and dopamine receptor D2 genotype on cow-calf performance during late gestation and early lactation
|WILBANKS, SARAH - Clemson University|
|JUSTICE, S. MAGGIE - Clemson University|
|WEST, THOMAS - Clemson University|
|ANDRAE, JOHN - Clemson University|
|DUCKETT, SUSAN - Clemson University|
Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2021
Publication Date: 3/9/2021
Citation: Wilbanks, S.A., Justice, S., West, T., Klotz, J.L., Andrae, J.G., Duckett, S.K. 2021. Effects of tall fescue endophyte type and dopamine receptor D2 genotype on cow-calf performance during late gestation and early lactation. Toxins. 13(3). Article 195. https://doi.org/10.3390/toxins13030195.
Interpretive Summary: Grazing tall fescue infected with the common toxic endophyte has an overall negative effect on bovine reproductive success and productivity. At an individual level, there are cows that appear more and some that appear less sensitive to the negative effects of ergot alkaloids produced by the fungus that is found in toxic tall fescue. This study sought to assess this variation in sensitivity to the toxins by sorting cows by a specific genotype that has been previously shown to indicate bovine tolerance or susceptibility to the toxins of interest. Cattle were grazed on common toxic tall fescue or a novel endophyte-infected tall fescue that does not produce the ergot alkaloid toxins. This study did not find any increased tolerance associated with the cows genetics when using the specific markers selected for in this experiment. However, cows did perform better from a reproductive standpoint when on the novel endophyte-infected tall fescue pasture. This study will be of interest to both researchers and producers seeking information regarding how to select for genetic tolerance to ergot alkaloids as well as how to manage the reproducing cow when on toxic tall fescue.
Technical Abstract: Pregnant cows (n = 75) were randomly assigned to fescue endophyte type: 1) endophyte-infected ergot alkaloid producing tall fescue (E+) or 2) novel endophyte-infected, non-toxic tall fescue (NOV) within maternal (A|A, n = 38 and G|G, n = 37) DRD2 genotype to examine changes in cow/calf performance and milk production during late gestation and early lactation. Grazing E+ fescue pastures during late gestation reduced cow body weight gain but did not alter calf birth weight compared to NOV. Milk production and calf ADG during the first 30 d of lactation were lower for E+ than NOV. Calving rate was reduced but not calving interval for E+ cows. Adjusted 205-d weight of calves was lower in those grazing E+ with their dams compared to NOV. There were no interactions between DRD2 genotype and fescue endophyte type indicating that genotype was not associated with response to E+ fescue in this study. Overall, grazing NOV tall fescue pastures instead of E+ during critical stages of production improved cow gain during late gestation, calving rate, early milk production and calf growth.