Effects of Peripartal Supplementation of Yeast-Based Products on Performance, Rumen Fermentation Profile, and Circadian Rhythms in Dairy Cows

Yeast-based products have been investigated, and they have shown beneficial results on performance and rumen fermentation profile in dairy cows. This study aimed to evaluate the effects of a yeast-derived postbiotic prototype (PB) on lactation performance in dairy cows supplemented during the transition period until 60 DIM. Sixty-one Holstein dairy cows were enrolled in a randomized complete block design from -35 to 60 DIM and blocked according to expected calving day, parity, and previous lactation energy-corrected milk. At -35 DIM, cows were assigned to either a basal diet plus 100 g/d of ground corn and 25 g/d of placebo (CTL; n = 30) or a basal diet plus 100 g/d of ground corn and 25 g/d of PB (PB; n = 31). Cows were fed 1X/d with TMR, and treatments were top-dressed. From -35 to -22 DIM, cows were fed a far-off diet; from -21d until calving, cows received a close-up diet. From calving to 30 DIM, cows received a fresh cow diet, and from 31 to 60 DIM, cows were fed a post-fresh diet. Blood samples and rumen fluid were collected at various time points from −35 to 60 d relative to calving (DRC). Frequent blood and fecal samplings were performed during pre- and postpartum to represent 24-hour circadian rhythms over 3-day periods and evaluate the presence of rhythmicity of each variable. Data were analyzed using the MIXED procedure of SAS. The daily rhythms of blood biomarkers and rumen fermentation profiles were further evaluated by fitting to cosinor model. The initial mean for BW was greater (P < 0.01) in CTL cows compared with PB; therefore, pretrial BW was used as a covariate. Prepartal energy balance and postpartal DMI (as % of BW) were greater in PB cows than CTL. An increased milk yield (+2.8 kg/d) and milk protein yield (+0.09 kg/d) were observed in PB cows compared with CTL. We observed treatment × time interactions for daily percentages of lactate, associated with a lower proportion at 28 DRC; propionate, associated with a greater proportion at 28 DRC; and isovalerate, associated with a trend for a greater proportion at 7 DRC, for PB cows compared to CTL. For blood biomarkers, PB cows had a greater concentration of γ-glutamyltransferase and a lower concentration of paraoxonase than CTL cows. Regarding daily rhythms, we observed a lower mesor (i.e., rhythm-adjusted mean) in prepartal isovalerate, valerate, isobutyrate, and NEFA in PB cows compared with CTL. Lower postpartal mesor for ruminal pH, lactate, acetate, acetate:propionate ratio, as well as blood BHB and NEFA, was observed in PB cows compared with CTL. In contrast, greater postpartal mesor for ruminal propionate, valerate, blood glucose, and blood urea were observed in PB cows compared with CTL. Most blood biomarkers and ruminal parameters evaluated presented daily rhythmicity during pre- and postpartum. These results indicate potential enhancement in ruminal fermentation profile along with increased gluconeogenesis and reduced lipolysis. The effects of supplementation of PB during the transition period are reflected in enhanced lactation performance in dairy cows.