Hair Coat and Steroidal Implant Effects on Steers Grazing Endophyte-Infected Tall Fescue During the Summer

The study involved 60 steers grazing on toxic tall fescue for 104 days to assess the impact of hair coats and steroidal ear implants on physiological responses. The steers were divided into groups based on body weight and hair coat color, and assigned to six pastures. Treatments included clipping and two types of steroidal implants: Synovex-S and Compudose. Results showed that hair growth averaged 0.29 mm/day, and sweating rates decreased over time, with higher rates in steers with estradiol implants. Clipped steers had lower rectal temperatures during high ambient temperatures. The study concluded that winter hair coat retention, continuous hair growth, and reduced sweating impaired thermoregulation, leading to decreased grazing frequency and poor animal performance.