Impact of an extended-release dewormer on fetal development and subsequent calf performance. Conference Paper uri icon


  • Abstract Parasitism decreases the nutrients available for cow and fetal/calf performance. The objective of this study was to evaluate the impact of an extended-release dewormer [LongRange (eprinomectin)] compared to a traditional dewormer [Dectomax (doramectin)] on fetal/calf performance. Postpartum suckled beef cows (n = 349) were grouped by age and randomly allotted to one of two treatments over a two year period 1) treatment with LongRange at AI and calves treated with Eprinex or 2) cows and calves treated with Dectomax. In year 2, half of each treatment was switched to the opposite treatment and half remained on the same treatment to result in a 2x2 design (calf sex was included in the statistical model). Cow weight was determined at AI, d60, d135, and d365 (treatment year 2). Calves born in year 2 were weighed at time of AI and at weaning. Pregnancy rates (determined at 60 and 135 d after AI) did not differ in year 1 (P = 0.85, 0.29) or in year 2 (P = 0.44, 0.98). Both treatments lost weight from AI to d60 of the breeding season (P = 0.98); however, there was a weak tendency (P = 0.15) for LongRange cows to gain more from d60 to 135 compared to Dectomax cows. Performance did not differ from d135 to AI in year 2 (P = 0.79). Calves that were in utero during year 1 when their dam received LongRange treatment had increased weight per day of age at year 2 AI (mean calf age =58d) compared to Dectomax treatment (P = 0.05; 2.2 0.09 vs 2.0 0.07kg). Furthermore, year 2 treatment tended (P = 0.09) to impact weight per day of age at weaning (LongRange=1.4 0.03kg, Dectomax=1.3 0.02). There was no year 1 by year 2 interaction (P = 0.87). In summary, administering an extended-release dewormer at AI did not impact pregnancy success, but increased calf performance both at 50d of age and at weaning.

published proceedings


author list (cited authors)

  • Reiner, A. M., Perkins, S. D., Rich, J., Northrop, E. J., & Perry, G. A.

citation count

  • 0

complete list of authors

  • Reiner, Ashley M||Perkins, Stephanie D||Rich, Jerica JJ||Northrop, Emmalee J||Perry, George A

publication date

  • January 2019