Comparative effect of direct-fed microbial regimen on health and performance of neonatal dairy heifer calves

This study was conducted to compare health and performance in neonatal dairy heifer calves supplemented with direct-fed microbial products in milk: (1) Propionibacterium freudenreichii NP24 and Lactobacillus acidophilus NP51 (BVM) or (2) Kluyveromyces m/f B0399 and Saccharomyces c/f 1026 (PBST). A total of 770 individually housed Holstein (n = 528), Jersey (n = 212), and crossbred (n = 30) heifers at a commercial calf-rearing facility were used for the primary group. Body weight was recorded on d 0 and 60 to determine ADG and percentage of daily BW gain, and health was monitored daily from arrival (d 0) through weaning (d 60). A subset group comprising 50 (n = 25 per treatment) Holstein (n = 32) and Jersey (n = 18) heifer calves were weighed periodically and analyzed separately to evaluate interim and overall performance and health. For both groups, heifers between 1 and 3 d of age were assigned randomly to treatment, and treatments were arranged within a single hutch row consisting of 100 heifers. A tendency (P = 0.09) for an improvement in ADG was observed for PBST heifers in the primary group. For the subset group, PBST had improved ADG from d 0 to 10 (0.29 vs. 0.05; P < 0.001), d 0 to 22 (0.31 vs. 0.23; P = 0.003), and overall (0.51 vs. 0.44 kg/d; P = 0.002). The percentage of daily BW gain was increased for PBST from d 0 to 10 (0.45 vs. 0.09%; P < 0.001) and overall (0.78 vs. 0.64%; P = 0.002). Also, PBST had a greater (P = 0.05) percentage of calves requiring a second respiratory disease treatment, but no other health differences were observed in this experiment. Results indicate PBST improved performance compared with BVM, but health was not clearly affected.