Effects of lasalocid on coccidial infection and growth in young dairy calves

Effects of lasalocid on coccidial infection and growth were examined using 16 Holstein bull calves. Animals were assigned randomly to a 2 x 2 factorial arrangement of starter containing 0 or 40 ppm lasalocid beginning at 3 d of age (SE = .46) and single oral infection with 0 or 30,000 oocysts (Eimeria bovis) at 28 d. Pelleted calf starter was fed for ad libitum consumption from d 1; milk replacer was fed at 3.6 kg/d to 28 d. Average daily gain, dry matter intake, and body weight were increased in calves fed lasalocid and decreased in calves dosed with coccidia. Addition of lasalocid to the feed improved gains by 8% in uninfected calves and by 50% in infected calves. Fecal oocyst numbers were increased by administration of coccidia and decreased by lasalocid. Calves infected with coccidia had greater fecal scores, indicating abnormal or diarrheic feces. Respiration, rectal temperature, hematocrit and serum sodium and potassium concentrations were unaffected by treatment. Data indicated that lasalocid minimized effects of coccidial challenge and increased growth in this study.