Performance and bunk attendance of cattle fed steam-rolled or ground corn supplemented with laidlomycin and chlortetracycline or monensin and tylosin

Gibb. D. J., Streeter, M., Schwartzkopf-Genswern, K. S. and McAllister, T. A. 2008. Performance and bunk attendance of cattle fed steam-rolled or gound corn supplemented with laidlomycin and chlortetracycline or monensin and tylosin. Can. J. Anim. Sci. 88: 499-506. British cross steer calves (n = 240; 332 +/- 23 kg) in 16 pens were fed,round (G) or steam-rolled (SR) corn-based finishing diets medicated with 12 mg kg(-1) laidlomyein propionate and 42.2 mg kg(-1) chlortetracycline hydrochloride (LC) or with 30.4 mg kg(-1) monensin sodium and 10.5 mg kg(-1) tylosin phosphate (MT) in a 2 x 2 factorial experiment. Individual bunk attendance was monitored using radio frequency identification in one pen per diet. Finishing diets were fed for 125 d following a 27-d adaptation from 65 to 91%, concentrate diet. In the first 56 d and overall. daily dry matter intake (DMI) was greater (P < 0.05) with LC than with MT (8.8 vs. 8.3 kg), but did not differ (P = 0.97) between 6 and SR diets. There was a trend (P = 0.11) towards greater ADG for cattle fed LC than those fed MT (1.54 vs. 1.47 kg d(-1)). but gain:feed was similar (0.169: P = 0.80) between antibiotic supplements. Processing method did not (P = 0.29) affect rate of gain, but SR tended (P = 0.06) to improve gain:feed compared with G (0.171 vs. 0.165). Steers fed LC spent more (P < 0.001) time at the bunk than those fed MT (125 vs. 120 min d(--1)). Oil G diets, cattle fed LC made fewer daily visits (93 vs. 9.5 visits d(-1): P = 0.03), but spent more tune at the bunk (135.9 vs. 124.0 min d(-1): P < 0.001) resulting In greater duration per meal (15.4 vs. 13.7 min meal(-1): P < 0.001). These cattle also had the greatest deviation in daily duration at the bunk (37.3 vs. 33.7 min: P < 0.001). The prevalence of liver abscesses was 13.2% with LC and 6.5% with MT (P = 0.09). However. the prevalence of severely abscessed livers (2.9%) was unaffected (P = 0.45) by treatment. The prevalence of foot Lot was greater (P = 0.02) for cattle Fed NIT (7.5%) than for cattle Fed LC (0.8%). Compared with feeding, MT. feeding, LC may enhance ADG, possibly due to greater DMI.