Weaning and post-weaning performance by fall-born calves weaned on different dates from endophyte-infected tall fescue pastures managed with two different rotation frequencies

Weaning and post-weaning performance by fall-born beef calves weaned on different dates in the spring from Neotyphodium coenophialum-infected tall fescue pastures

“…In the present study, heifer weight at breeding increased linearly across weaning dates. These data are in agreement with those of Coffey et al (2008) who reported numerically greater heifer weight at breeding in 2 years and significantly greater weight at breeding in 1 year of a 3-year study. However, subsequent calving rates were not different in either study.…”

“…Antibody titers to BVD and IBR before calves received their initial vaccination at the time they were weaned decreased linearly, likely because of advanced age of the calves and less influence of maternal antibodies instead of prolonged exposure to E+ toxins. A similar response in BVD and IBR antibody titers was shown previously from fall-born calves weaned either mid-April or early June from E+ pastures managed with two different rotation frequencies (Coffey et al, 2008).…”

“…Serum Cu concentrations on each weaning date were at concentrations that would not be considered as Cu deficient (Underwood and Suttle, 1999). Others have reported reduced serum Cu in calves grazing E+ pastures (Stoszek et al, 1979;Saker et al, 1998;Oliver et al, 2000), but in the present study, Cu levels were comparable with those from fall-born calves weaned from E+ in mid-April or early June (Coffey et al, 2008). Although, Cu appears to play a significant role in the maintenance of immune function (Stabel et al, 1993), calves weaned on any of the weaning dates were apparently not immunocompromised due to Cu deficiency.…”

“…Grazing E+ pastures have been shown to negatively impact calf weaning weights (Peters et al, 1992), but reports of other measurements at weaning and post-weaning are limited, particularly when pertaining to fall-born calves. Fall-born calves grazing E+ fescue using a twice-weekly rotation schedule and weaned in early June had higher weaning weights and final feedlot weights compared with calves weaned in mid-April and rotated twice monthly (Coffey et al, 2008). In the present study, fall-born calves were weaned from E+ pastures on four different weaning dates from midMarch through early June to more accurately determine the optimum weaning date for fall-born calves grazing E+ pastures.…”

“…The perception by cattle buyers that calves weaned from E+ pastures will exhibit carry-over effects during other phases of cattle production (Coffey et al, 2008) may reduce the price buyers are willing to pay for calves that appear to have grazed E+ previously. In the present study, heifer weight at breeding increased linearly across weaning dates.…”