Comparison of gamithromycin, tilmicosin and tulathromycin: metaphylactic treatments in high risk calves for bovine respiratory disease

Abstract

Bovine Respiratory Disease (BRD) continues to be one of the largest animal health concerns in the cattle industry. BRD is a multifaceted group of pathogens, both viral and bacterial, that take advantage of an immune compromised calf to cause disease. This study took aim at comparing metaphylactic treatments for BRD in both the feedlot and pasture setting. In the feedlot study, heifers (n=579, 403.7 ± 27.4 lbs) from Southwest Texas were identified as being high risk for BRD and shipped to the Clayton Livestock Research Center in Clayton, NM. Cattle were randomly allocated within truck load lots into 18 to 20 head treatment pens (30 pens; 3 treatments; 10 reps). Cattle were given one of three metaphylactic treatments based on the randomly assigned treatment for their pen within a replicate. The three antibiotic treatments administered at initial processing were: 1) Tulathromycin (2.5 mg/kg), 2) Tilmicosin (13.3 mg/kg), and 3) Gamithromycin (6.0 mg/kg). Cattle were fed a typical commercial starter diet for the first 56-60 d with a step-up ration change at day 28. At the end of the feeding period, pens were weighed and body weights recorded. Dry Matter Intake, morbidity, and mortality were recorded by CLRC personnel daily. Cattle administered tulathromycin had higher daily gains than cattle administered gamithromycin by 0.29 lbs/d (P<.01) and tended (P=0.09) have higher daily gains than cattle that received tilmicosin by 0.18 lbs/d. Tulathromycin treated cattle tended (P = 0.12) to have improved feed efficiency compared to gamithromycin treated cattle. Cattle that received tulathromycin (5.2%) had lower morbidity rates (P < .02) than tilmicosin (14.6%) and gamithromycin (12.79%) treated cattle. There were no treatment differences in dry matter intake or mortality in cattle. For the wheat pasture study, heifers (n=120, 393.2 ± 28.6 lbs) from the same origin and risk were shipped to the CLRC and processed before being trailed to a nearby wheat pasture. Cattle were randomly assigned into three treatment groups (3 treatments, 40 reps), and were given one of three metaphylactic treatments. The three antibiotic treatments administered at initial processing were: 1) Tulathromycin (2.5 mg/kg), 2) Tilmicosin (13.3 mg/kg), and 3) Gamithromycin (6.0 mg/kg). Cattle were allowed to graze on wheat for 54 days with free-choice Hi-Pro mineral mixed with Lasalocid, an ionophore. After 54 days on wheat pasture, the cattle were trailed back to the CLRC facilities and final individual weights were recorded. Morbidity and mortality were recorded daily by CLRC personnel. No differences were identified for ADG (P=0.98), morbidity (P=0.46) or mortality (P=0.36) among the three treatment groups.