Effects of Yeast-Derived Rumen Escape Microbial Protein on Lactational Performance and Metabolic Status of Transition Dairy Cows

In dairy cows, the transition period is the most critical time that is often marked by negative nutrient balance due to high nutrient demands but low dry matter intake. Ruminal-escape protein derived from yeast (YMP) has shown to increase DMI and milk fat percentage in midlactation cows. However, the effects of YMP in transition cows are still unknown. Therefore, the objectives of this study were to evaluate the effects of YMP on dry matter intake, milk yield and components and blood metabolites in transition cows. Twenty seven primiparous and multiparous Holstein cows were blocked according to anticipated calving date and parity (1 to 7) and randomly assigned to receive either a control (0g YMP) or treated (50g YMP prepartum followed by 200g YMP postpartum) pellet containing molasses and beet pulp. The pellets were given to individual cows 30mins prior to morning feeding. The experiment started 21 d prior to predicted calving date and ended 28 d postpartum. Blood samples were collected on d -21, -14, -7, -3, -1, 1, 3, 7, 14, 21 and 28 and were analyzed for metabolites, macrominerals and proteins. In addition, DMI was recorded daily throughout the experimental period. Milk yield was measured daily and milk samples were collected twice weekly on two non-consecutive days and were analyzed for fat, protein, lactose, somatic cell count and urea. Supplementing YMP significantly lowered (P< 0.05) serum concentrations of non-esterified fatty acids from d 3 postpartum until the end of the study. Serum concentrations of β-hydroxybutyrate were also lower (P < 0.05) in YMP supplemented cows at d 3 and 7 postpartum. Moreover, YMP supplementation increased (P < 0.05) serum glucose levels at d 3 and 7 postpartum and lowered (P < 0.05) serum aspartate transaminase levels at d 14 and 21 postcalving. Both groups had similar DMI and lactational performance. Overall, our results suggest that YMP supplementation to transition cows may not influence their lactational performance but may significantly improve cow metabolic status during the postpartum period.