Maternal and calf diet supplementation with Saccharomyces cerevisiae fermentation–derived postbiotics: Effects on calf growth performance, health, rumen fermentation, and microbiota

Supplementation with Saccharomyces cerevisiae fermentation-derived postbiotics (SCFP) in calves can improve calf growth and health. This study evaluated the effects of SCFP supplementation in the calf diet on growth, health, rumen fermentation, and rumen microbiota during the first 70 d of life in 2 independent calf experiments conducted under different maternal dietary contexts. The dams of the calves consisted of 400 pregnant Holstein dry cows that received either a basal far-off and close-up TMR without SCFP (n = 200) or the same diets supplemented with SCFP (n = 200) beginning at dry-off. From these dams, 144 female calves were enrolled and allocated within maternal dietary background, blocked by birth date, and randomly assigned to receive SCFP or not in the calf diet, resulting in 2 independent experiments (n = 36 calves per group, 4 groups in total): experiment 1, CC (dam: -SCFP, calf: -SCFP) and CT (dam: -SCFP, calf: +SCFP); and experiment 2, TC (dam: +SCFP, calf: -SCFP) and TT (dam: +SCFP, calf: +SCFP). Growth performance, serum metabolites and antioxidant and anti-inflammatory indicators, diarrhea incidence, and rumen fermentation and microbial composition were measured. In experiment 1, CT calves showed greater weaning weight and preweaning ADG, reduced diarrhea incidence, and altered rumen microbial community structure at 70 d of age, with enrichment of Erysipelotrichaceae_UCG-002 and Sharpea. In experiment 2, TT calves tended to have greater preweaning ADG, whereas weaning weight was unaffected. In both experiments, calves supplemented with SCFP consistently reduced preweaning diarrhea risk. At 70 d of age, rumen microbial diversity was not affected, although calves in the TT group exhibited greater total volatile fatty acid and ammonia-nitrogen concentrations. In conclusion, direct SCFP supplementation to calves during the preweaning period improved growth performance and health and modified rumen fermentation and microbial composition. Differences in calf responses between experiments highlight the need for future studies with replicated maternal treatments to clarify the role of maternal supplementation.