Abstract #T388

# T388
Effects of corn silage hybrids on metabolic parameters and lactational performance of transition dairy cows.
A. W. Kelley1, K. Neal1, J.-S. Eun*1, A. J. Young1, 1Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT.

Developing solutions to lessen metabolic stress experienced by transition dairy cows is very critical to improve lactational performance. The objective of this study was to determine metabolic parameters [concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) and lactational performance of dairy cows fed brown midrib corn silage (BMRCS)-based diets during the transition period when compared with conventional corn silage (CCS)-based diets. At 4 wk before parturition, 40 dry multiparous Holstein cows were randomly assigned treatments. The treatment groups consisted of 2 close-up transition diets (CCS-based and BMRCS-based diets) offered to 2 groups of 20 cows each. After calving, 10 cows from each prepartum group were individually fed either a CCS-based lactation diet or a BMRCS-based lactation diet. Four dietary treatments tested postpartum included: 1) CC = CCS-based close-up diet + CCS-based lactation diet; 2) CB = CCS-based close-up diet + BMRCS-based lactation diet; 3) BB = BMRCS-based close-up diet + BMRCS-based lactation diet; and 4) BC = BMRCS-based close-up diet + CCS-based lactation diet. Statistical analysis during the pre- and postpartum period parameters were performed by a split-plot-in-time design with repeated measures procedure using the Proc Mixed procedure of SAS with a model that included effects of treatment and week and their interaction and a random effect of cow within treatment. During the dry period, there was a tendency (P = 0.09) for a diet × test week interaction for DMI; initially, CCS-based diet had greater DMI, but as parturition neared, BMRCS-based diet increased DMI, resulting in greater DMI than CCS-based dirt at parturition. Postpartum concentrations of BHBA and NEFA were lower for BB and BC diets, with CC and CB diets having the greatest concentrations of both BHBA and NEFA (P < 0.05). In contrast, cows fed BB and BC diets increased milk yield compared with those fed CC and CB diets. There was a tendency for BB to have greater milk yield than CB on wk 1 (32.7 vs. 27.9 kg/d, P = 0.09) and greater milk yield on wk 4 (45.1 vs. 38.5 kg/d). Overall data in the present study indicate that cows fed BMRCS-based diet in the dry period but CCS-based diet in lactation had positive carry-over effects on metabolic parameters and lactational performance possibly due to a consistent pattern of feed intake during dry period.

Key Words: brown-midrib corn silage, dairy cow, transition period