Effects of metaphylaxis on production responses and total antimicrobial use in high-risk beef calves
Alyssa B Word, Tryon A Wickersham, L. A. Trubenbach, Glennon Mays, J. E. Sawyer
Abstract
Our study objectives were to determine the effects of metaphylaxis for control of bovine respiratory disease on measures related to sustainability, including health, antibiotic use, and productivity. Male calves (n = 198; 231 ± 2.4 kg) arriving in 2 groups received either 3.3 mL/100 kg (6.6 mg/kg) ceftiofur crystalline free acid (EXC) or 4.4 mL/100 kg (13.2 mg/kg) tilmicosin phosphate (MIC) or were not treated (CON) in a randomized complete block design. Cattle were observed daily and treated according to clinical presentation of bovine respiratory disease and weighed every 14 d. Feed intake and total antimicrobial use were recorded. Cattle receiving metaphylaxis had 25.2% lower morbidity rates than CON (P = 0.01; 51.5 vs. 76.7%). Differences (P = 0.14) were not observed between MIC (46.4 ± 4.3%) and EXC (56.5 ± 4.3%). Of cattle requiring therapy, the CON group displayed symptoms 5 d earlier than metaphylaxis (P = 0.01); MIC required treatment 4 d before EXC (P = 0.02, 8 vs. 12 d). Metaphylaxis improved ADG (1.63 vs. 1.28 kg/d; P = 0.06) and G:F (0.29 vs. 0.22; P = 0.01) during the first 14 d, without differences between EXC and MIC (P > 0.40). No differences were observed in ADG (P = 0.20) or G:F (P = 0.18) between CON and treatment groups after 42 d. Antimicrobial use was similar (P = 0.88; 6.03 vs. 6.16 g of active ingredient per animal) for CON versus metaphylaxis, and for MIC versus EXC (P = 0.74; 5.99 vs. 6.33). Metaphylaxis enhanced animal well-being. Total number of antimicrobial applications was higher but total mass of antimicrobial use was similar when metaphylaxis was applied in calves with high initial morbidity rates.