PSXIV-14 - Selenium and Copper Deficiency Associated Decline in Reproductive Performance in Summer Bred, Rotationally Grazed, Forage Fed Beef Cattle

Abstract: This case study reports on selenium and copper deficiency associated decline in reproductive performance in summer bred, rotationally grazed, forage fed beef cattle at the Berea College Educational Farm over a 6-year period (2016 to 2021). The Angus-Hereford crossbred breeding herd (N=45/year) received a significantly lower selenium and copper free fed mineral supplement between 2014 and early 2021 compared with what was provided beginning in mid-2021, in response to veterinary diagnosed selenium and copper deficiency. Supplement was also provided intramuscularly January 20, 2022. Cattle liver biopsies (n=5) and postmortem necropsies (n=3) were performed to determine a mineral panel. Annually, ultrasound guided pregnancy diagnosis and BCS were conducted each fall after a 60-day summer breeding season. Moderate BCS (avg=5.4) were maintained during the first 4 years, including 2021 (5.8) where visibly noticeable weight loss was evident in primiparous heifers during summer. Declining annual pregnancy rates from 2016 (y = -0.0153x + 0.08731) also declined (9.32%) to 73.68% (Fig. 1) in 2021. Manual palpation (n=12) during the Fall 2021 pregnancy examinations and dissection (n=2) of the reproductive tracts of nulliparous heifers 104 days later determined abnormal morphology. In Fig. 2, a cystic corpus hemorrhagicum (1.7 x 1.4 cm) and bilateral oviduct aplasia was discovered in one heifer. In the other heifer, a cystic corpus luteum (0.7 x 0.6 cm), initially detected at the pregnancy examination was discovered (Fig. 3), which resulted in a 53% weight difference between the right and left ovary (6.1, 4.0 g). Mineral panels taken at the end of 2021 confirmed a selenium and copper deficiency with the liver biopsy averaging 2.38 ppm Cu (Table 1). Hence, annual declines in reproductive performance of summer bred, rotationally grazed, forage finished beef cattle at Berea College Educational Farm was associated with selenium and copper deficiency.