Abstract #M175

# M175
Effects of a yeast-derived microbial protein supplement on transition dairy cow performance.
G. Mazon*1, M. R. Campler1, J. H. C. Costa1, 1Dairy Science Program, University of Kentucky, Lexington, KY.

The objective of this study was to evaluate the effects of partial substitution of soybean meal with yeast-derived microbial protein (YMP) on transition dairy cow performance. The study was conducted at the UK Coldstream Dairy from August 2017 to June 2018. Seventy-one Holstein dairy cows were enrolled in the study from 28 ± 3 d before expected calving until 21 d post-calving. At enrollment, cows were randomly assigned to either a treatment (YMP) or a control (CON) diet. Isonitrogenous and isoenergetic diets were formulated with corn silage, alfalfa silage, grass hay, cottonseed, and a grain mix with or without YMP. Treatment diets were formulated to supply animals with 100 and 300 g of YMP/d (DEMP; Alltech Inc., Nicholasville, KY) during the dry and fresh periods, respectively. Dry and fresh cows were housed in a compost bedded pack barn equipped with automatic feed bins that recorded individual feed intake of which DMI was calculated. Milk yield and composition were recorded daily using an automatic meter until 100 DIM; 4% fat corrected milk (FCM) and energy corrected milk (ECM) were also calculated. A mixed linear model was used to determine the effects of YMP on milk yield, 4% FCM, ECM, and DMI. The model included the fixed effects of treatment, parity, body weight, milk yield, and disease occurrence, with lactation wk as a repeated measure. There were no significant differences in milk yield between YMP and CON cows during the fresh period (0 to 21 DIM) (YMP = 30.91 ± 1.34, CON = 28.87 ± 1.32 kg/d; P = 0.14) and for ECM (YMP = 35.36 ± 1.43, CON = 32.98 ± 1.40 kg/d; P = 0.11). However, cows fed YMP tended to produce more 4% FCM (YMP = 33.15 ± 1.32, CON = 30.81 ± 1.30 kg/d; P = 0.09). During the first 3 wk of lactation, YMP cows had lower DMI compared with CON cows (YMP = 17.04 ± 0.63, CON = 20.91 ± 0.61 kg DM; P < 0.01). Total milk produced until 100 DIM was not different between treatments (YMP = 4,020 ± 170.83, CON = 4,122.15 ± 165.49 kg; P = 0.56). Overall, feeding YMP during the transition period did not affect daily milk yield but cows fed YMP had decreased DMI when at a similar production level as CON cows.

Key Words: protein supplement, bypass protein, microbial CP