The Effect of the Saccharomyces Boulardii Supplement in Combined Feed on the Health, Growth, and Fecal Microbiota of Growing Calves

The aim of this study was to study the effect of a specific strain of yeast, Saccharomyces cerevisiae boulardii T8-3C (SCB), on the growth, health, and bacterial profile of calves' feces. A total of 12 animals were included in the experiment on a commercial calf farm for a total of 90 days. The calves were fed hay and alfalfa twice a day, as well as combined concentrated feed (CP 17%) throughout the experiment and randomly assigned to receive daily SCB supplements of 1% for the first group and 2% for the second group of the combined feed weight. Rumen total bacteria count increased significantly with SCB application in G2. A slight decreasing trend was observed in the total protozoa count. While Entodinium species numerically significantly decreased with SCB application, the percentage of Isotricha+Dasytricha species significantly increased. A notable rise in the fecal count of SCB in calves was observed at the 12th week, compared to the 0th week, with 4.8 × 10^7 colonies of SCB per gram of feces in the 12th week. The addition of SCB showed an improvement in the overall growth status of calves in terms of Average Daily Gain (ADG), final body weight and feed intake. However, a total of 50% of calves had diarrhea that were not fed with SCB, and 25.0% of calves receiving SCB had diarrhea. Regarding the calves of the control group, 25% of the calves registered with diarrhea were treated with antibiotics. In group G2, there was a significant reduction in the Total Oxidant Status (TOS), Oxidative Stress Index (OSI), and Malondialdehyde (MDA) levels. Besides, Glutathione Peroxidase (GPx) concentration significantly decreased with SCB application. Rumen ammonia production was significantly increased in G2, similarly the percentage of acetic acid in the rumen fluid significantly reduced with SCB application.