Dose effect of Actisaf Sc 47 yeast probiotic () supplementation on production, reproduction, and negative energy balance in early lactation dairy cows.

The study evaluated the dose effect of dietary supplementation with yeast probiotic (CNCM I-4407, 10 CFU/g, Actisaf Sc 47; Phileo by Lesaffre, France) on production, energy metabolism, and reproduction in lactating dairy cows. About 117 multiparous Holstein cows from 3 to 60 d in milk held in a barn with an automatic milking system were enrolled in a randomized complete block design and blocked according to calving day, parity, and previous milk yield. The cows were assigned to a basal diet (15% CP, 22% starch) plus either 5 g (Y5 group,  = 39), 10 g (Y10 group,  = 39), or 0 g (CON,  = 39) of yeast probiotic, presented on top of concentrate fed in the robot. Milk yield and body weight were recorded daily, milk composition, and somatic cell count () every 2 wk, and body condition score () was estimated at days -14, 14, and 40 post-calving. Data were analyzed using a linear mixed model. The Y10 group showed an increased average daily yield of energy-corrected milk () over CON (+3.5 kg,  < 0.05) and Y5 (+0.8 kg). There were no significant differences between the groups in milk fat, milk protein, milk SCC linear score, milk urea, blood beta-hydroxy-butyric acid levels, and BCS. Body weight loss from 3 to 90 d in milk was numerically lower (13.8 kg) in Y5 than in CON (25.3 kg), and the success rate from the first insemination was the highest in YP5 and YP10 groups (39%) than in Control (26%). The yeast probiotic supplementation to early lactation high-producing dairy cows showed a clear effect of the high dose (10 g) on ECM milk production, although the lower dose (5 g) showed only numerical ECM production increase, both doses displayed better use of energy from the diet than the control and suggest a better resource efficiency.