116 Effects of Moxidectin/Oxfendazole and Long-Acting Eprinomectin Treatment on Fecal Egg and Fly Counts, Adg, and Blood Parameters in Newly Received Stocker Calves

Abstract The objectives of study were to evaluate effects of various anthelmintic treatments on fecal egg counts (FEC), ADG, fly counts, and blood parameters in newly received stocker calves. Upon arrival to the Murray State University Beef Unit, steers (n = 30) were allow a 1 wk adjustment period prior to allocation of treatment. Steers were randomly allocated to treatment based on BW (297.77 ± 16.53 kg) and FEC (43.10 eggs/gram; EPG). Treatments included: control (n = 10; no anthelmintic treatment; CON); moxidectin/oxfendazole combination (n = 10; COMBO); and a long-acting eprinomectin (n = 10; LAE). Steers were comingled and allowed to grazed mixed grass pastures with rotation occurring based on forage availability. Body weight, fecal and blood samples were collected on d 0, 27, 56, and 101 and the following blood parameters evaluated: white blood cell count (WBC), platelets (PLA), neutrophils (NEU), lymphocytes (LYM), monocytes (MON), basophils (BASO), and eosinophils (EOS). Fly counts were estimated on d 0, 31, 61, and 100. Data was analyzed using the PROC MIXED procedure of SAS with steer as the experimental unit and d as a repeated measure. Two preplanned orthogonal contrasts were used to determine effects and included comparisons between: 1) CON vs. treated steers, and 2) COMBO vs. LEA steers. Strongyle EPG were similar between CON and treated steers (P > 0.1) but EPG were higher (P = 0.02) for COMBO vs. LAE steers (22.97 vs. 5.61 EPG, respectively). A treatment × d interaction was found for EPG (P = 0.02). Body weight and ADG was similar (P > 0.1) between treatments; however, ADG from d 27 to 56 was greater (P = 0.04) for LAE vs. COMBO steers (1.29 vs. 0.54). An effect of d (P < 0.01) was observed for fly counts and the following blood parameters: WBC, NEU, LYM, MON, BASO, and EOS. Esonophils were greater (P = 0.03) in LAE vs. COMBO steers (0.32 vs. 0.19, respectively) while MON tended to be greater (P = 0.06) for LAE and COMBO steers (0.82 vs. 0.65, respectively). Data suggests that anthelmintic use may have affected FEC, ADG, and blood parameters in newly received stocker calves.