Effects of Background Procedures and Probiotic Administration on Weight Gain in Growing Heifers

Angus sired heifers (n=96; initial BW 200 kg) were used to evaluate the effects of background procedures and probiotic administration on weight gain in growing heifers. Heifers were stratified by arrival BW into a 2×2 factorial arrangement where treatments consisted of direct fed microbials (DFM) (yes or no), and High Ruminal Ammonia or Control (HRA or CTR). Heifers were acclimated for 7 d, and treatments were applied for 77 d. Rectal temperatures were taken and any heifer with a temperature >40°C was determined to have pyrexia (fever). Overall, heifers that did not exhibit signs of pyrexia had an ADG of 0.973 kg which translates into a 0.085 kg/d greater ADG (P < 0.05). For the first 21 days (Period A), CTR fed heifers experienced higher ADG than the HRA fed heifers. Heifers fed the HRA diet had a higher ADG than those fed the CTR diet for Period B and C.