LAUSR

Many generic anthelmintics are commercially available; however, very little information exists regarding effectiveness of these products compared with pioneer brands. Therefore, the objective of this study was to conduct a fecal egg count reduction test comparing generic eprinomectin (Eprizero) to pioneer eprinomectin (Eprinex), as well as to fenbendazole in grazing beef steers. Naturally infected steers (n = 40; BW = 212±5 kg) were allocated into five treatment groups based on ranked fecal egg counts:. Eprinex (EX), 2. Eprizero (EZ), 3. Safeguard (SG), 4. Eprinex + Safeguard (XS), or 5. Control/No treatment (NT). Fecal samples were collected on days -7, 0, 14, and 29, and body weights were recorded on days -14 and 29. Data were analyzed using the MIXED procedure of SAS 9.4. At day 14 post-treatments, the EX treatment group demonstrated a 50% fecal egg count reduction (FECR), while EZ treatment group had a 79% FECR. Both the SG and XS treatment groups showed a 98% and 100% FECR, respectively. At day 29 post-treatment, EX and EZ treatment groups demonstrated a1% and 5% FECR, while the SG and XS treatment groups displayed a 94% and 89% FECR. The coproculture data indicated that Cooperia punctata, Cooperia oncophora and Ostertagia ostertagi all persisted and comprised at least 90% of the larvae recovered from both the EX and EZ coprocultures performed on days 14 and 29. Haemonchus spp. was recovered from EZ coprocultures on days 14 and 29 (10% and 1%, respectively, of recovered larvae), as well as from the EX coprocultures (4% and%, respectively). Interestingly, the proportions of C. punctata and C. oncophora essentially demonstrated a post-treatment reversal in the both the SG and XS treatment groups when comparing days 0 and 29, possibly indicating a greater efficacy of fenbendazole against than C. punctata. There were no significant differences (P < 0.05) in average daily gains between the treatment groups.