Date on Honors Thesis

Fall 12-10-2016




Objective of study was to evaluate effects of anthelmintic treatments on fecal egg counts (FEC), average daily gain (ADG), fly counts, and blood parameters in stocker calves. Upon arrival at MSU Beef Unit, steers were allowed one-week adjustment period before allocation to treatment, were comingled, and grazed on mixed-grass pastures. Steers were randomly allocated to treatment based on initial body weight (BW) and FEC. Treatments included: control (n = 10; CON); moxidectin/oxfendazole combination (n = 10; COMBO); and long-acting eprinomectin (n = 10; LAE). BW, fecal and blood samples were collected on d 0, 27, 56, 101. Blood parameters evaluated were white blood cells, neutrophils, lymphocytes, monocytes, basophils, and eosinophils. Fly counts were estimated on d 0, 31, 61, and 100. Data was analyzed using PROC MIXED procedure of SAS. Two preplanned orthogonal contrasts were used and included comparisons between: 1) CON-treated, and 2) COMBO-LAE. Strongyle EPG were similar between CON and treated (P > 0.1), but EPG were higher (P = 0.02) for COMBO-LAE. Treatment by d interaction was found for EPG (P = 0.02). BW and ADG were similar (P > 0.1) between treatments; ADG from d 27 to 56 was greater (P = 0.04) for LAE-COMBO. An effect of d (P < 0.01) was observed for fly counts and blood parameters. Eosinophils were greater (P = 0.03) in LAE-COMBO, while MON tended to be greater (P = 0.06) in LAE and COMBO. Data suggests anthelmintic use may have affected FEC, ADG, and blood parameters in stocker calves.