Growth and reproductive responses of heifers consuming endophyte-infected tall fescue seed with or without sodium bicarbonate supplementation

Objective: The objective of this study was to evaluate growth and reproductive characteristics of heifers consum-ing endophyte-infected (EI) tall fescue seed in a feedlot setting with or without sodium bicarbonate supplementa-tion.Materials and Methods: A total of 48 commercial beef heifers (+/- 1.2 mo; BW = 268 +/- 24 kg) were used in an 84-d experiment. Animals were blocked by BW and as-signed to treatments. Treatments were arranged in a 2 x 2 factorial design with heifers fed either EI fescue seed with 1,320 mu g/kg total ergot alkaloid without sodium bicarbon-ate (E+B-) or with sodium bicarbonate (E+B+), or EI fescue seed with 11 mu g/kg total ergot alkaloid without sodium bicarbonate (E-B-) or with sodium bicarbonate (E-B+). Data were analyzed utilizing R statistical soft-ware (R Foundation for Statistical Computing).Results and Discussion: At d 56, there tended to be an interaction between seed type and bicarbonate supple-mentation for G:F (P = 0.084) and ADG (P = 0.071). Neither fescue seed type nor bicarbonate supplementation affected DMI at d 56 (P >= 0.739). By d 84, bicarbonate supplementation tended to decrease ADG (P = 0.087), and intake of whole seed from E+ fescue tended to de-crease DMI (P = 0.074). Prolactin concentrations tended to be lower in heifers consuming E+ when compared with heifers consuming E- on d 56 (P = 0.09). However, there was no difference in overall prolactin concentrations over the full experimental period (P > 0.05). Implications and Applications: The observations in this study failed to show any noteworthy abnormalities in growth and reproductive performance associated with feeding a whole E+ fescue seed with 1,320 mu g/kg total ergot alkaloid, and as such, there was little positive influ-ence of bicarbonate supplementation on the productive outcomes assessed. The lack of productive performance responses to endophyte-infected fescue seed or to sodium bicarbonate supplementation could be due to low power, whole-seed feeding, a corn-silage basal diet, the lack of thermal stress during the feeding period, or other experi-mental design limitations.