Effects of composite probiotics on growth performance, diarrhea rate, and serum indicators in newborn Holstein calves

The present study aimed to determine the effects of compound probiotics on growth performance, diarrhea incidence, fecal pathogenic microorganisms, and serum parameters in newborn calves.

A total of 48 healthy newborn calves with similar body weights (BWs; mean±standard deviation: 37.0±2.0 kg) were randomly assigned to three groups (n = 16 per group). Control group (CON), yeast group (CP1), Bacillus licheniformis+yeast group (CP2). The feeding trial lasted for 60 days. Growth performance, diarrhea incidence, fecal scores, and serum parameters were assessed on days 1, 30, and 60 of the trial, while fecal samples obtained on days 15 and 30 were analyzed for pathogenic microorganism positivity.

Compared with CON group, calves in the CP2 group had higher BW (day 30; p<0.05), average daily gain (days 1-30; p<0.05), and feed efficiency (days 1-30; p<0.05). Compared with CON group, the incidence of diarrhea and fecal scores (days 1-60) were lower in both CP1 and CP2 groups (p<0.05). Fecal samples from these groups also exhibited reduced positive rates of pathogenic microorganisms (rotavirus, coronavirus, cryptosporidium). Notably, compared with CON group, serum antioxidant and immune markers, total antioxidant capacity, superoxide dismutase, and immunoglobulin A levels were elevated (p<0.05), whereas malondialdehyde and tumor necrosis factor-alpha levels were decreased (p<0.05), and serum diamine oxidase levels were also reduced in the CP1 and CP2 groups (p<0.05). Furthermore, compared with the CON group, calves in the CP2 group exhibited lower serum cortisol and higher growth hormone (GH) levels (p<0.05). No interactions between treatment and period were observed.

The combination of Bacillus licheniformis and yeast exerts promotes newborn calves' growth and development, reduces diarrhea incidence, enhances antioxidant and immune functions, and improves overall health.