Abstract #M432

# M432
Effect of rumen-protected carbohydrate supplementation on performance, blood and plasma metabolites in growing heifers.
Juan P. Russi*1, Elias Peruzzo1, Nicolas DiLorenzo2, Alejandro E. Relling1, 1Facultad de Cs Veterinarias, UNLP, Buenos Aires, Argentina, 2University of Florida, Mariana, FL.

The objective of this study was to evaluate the inclusion of a rumen-protected carbohydrate (RUPCA) (US Patent # 8,507,025) on performance, blood and plasma metabolites in growing heifers. Crossbred heifers (n = 135; 136 ± 14kg) were used in an 84-d experiment. Heifers were blocked by initial BW, placed into 15 pens and fed a diet comprised of (DM basis) 38.8% corn silage, 41.5% dry corn, 2% minerals and vitamins mix, and 17.7% supplement or RUPCA, which varied depending on treatments. The supplement and RUPCA consisted of the same ingredients (58.1% soybean meal, 38.9% soluble carbohydrates, 2% urea and 1% mineral salt), differing in the processing of the carbohydrate (i.e., protected or not from ruminal degradation). Heifers within blocks were randomly assigned to 3 treatments: T0) 17.7% supplement (100% unprotected carbohydrate), T1) 8.85% supplement and 8.85% RUPCA, and T2) 17.7% RUPCA (100% protected carbohydrate). Body weight was measured on d 0, 21, 42, 63, and 84. Pen DMI was measured weekly from d 21 to 84. Blood samples were taken on d 0, 42, 63, and 84 from jugular vein prior morning feeding and analyzed for glucose, insulin, urea and NEFA concentrations. Data were analyzed as a randomized complete block design with repeated measures using a mixed model of SAS. Treatment × day interaction were found for DMI (P = 0.02), ADG (P < 0.0001) and G: F (P < 0.0001) and with T1 having the lowest DMI (P < 0.05) and the greatest G:F (P < 0.05). No differences were found in the concentrations of blood glucose (P > 0.91), plasma insulin (P = 0.82), plasma NEFA (P = 0.802) or plasma urea (P = 0.336). Feeding RUPCA to growing heifers improved G:F through lower DMI without altering ADG, blood or plasma metabolites. Results are shown in Table 1. Table 1.
TrtDayTrt × day
DMI, kg/d6.9a5.9b6.8a0.06<0.0001<0.00010.02
ADG, kg1.<0.0001<0.0001
Glucose, mg/dL90.291.691.23.520.91<0.00010.92
Insulin, µg/dL0.
NEFA, mM200.8187.9181.318.740.540.00250.42
Urea, mg/dL14.913.414.81.030.36<0.00010.39
a,bMeans without common superscript differ (P < 0.05).

Key Words: carbohydrate, rumen, bypass energy