Impact of grazing pastures containing a high percentage of Epichloë coenophiala-infected tall fescue on ovarian blood flow and activity in beef cows subjected to a Fixed-time artificial insemination protocol.

The objective of this study was to evaluate the impact of grazing pastures with low (Low group) and high (High group) percentages of Epichloë coenophiala-infected tall fescue on ovarian blood flow and activity in beef cows subjected to a Fixed-Time Artificial Insemination (FTAI) protocol. Cows in the Low group (n = 18) grazed for 79 days on a pasture where fescue accounted for 13% of the available forage, with an endophyte infection rate of 96%. Meanwhile, cows in the High group (n = 18) grazed for the same period on a pasture where fescue represented 73% of the available forage, with an endophyte infection rate of 94%. Consumption of pasture with a high percentage of endophyte-infected (E+) fescue was associated with an increase in the rectal temperature, a decrease in the size and the blood flow of the dominant follicle, lower plasma progesterone (P4) concentration, and an increased number of cysts. In addition, the plasma concentration of metabolic hormones, namely triiodothyronine and cortisol, was similar between groups. In conclusion, consuming pastures with a high percentage of endophyte-infected fescue affected the ovarian blood flow and activity without affecting the metabolic hormones in beef cows.