Effect of rumen protected carbohydrate supplementation on performance and plasma glucose concentrations in growing heifers

J. P. RUSSI; P. DAVIES; N. DILORENZO; A. E. RELLING,

Congreso; 2014 Joint anual meeting; 2014

Fass

The objective of this study was to evaluate the inclusion of a ruminally protected carbohydrate (RUPCA) on performance and blood metabolites in growing heifers. One hundred thirty-five cross-bred heifers (136 ± 14kg) were used in an 84-d experiment. Heifers were blocked according to initial BW and placed (nine per pen) into 15 dirt floor pens (12 × 50 m). Heifers within blocks were randomly assigned to one of three treatments: T0) Control (100% basal supplement), T1) 50% RUPCA and 50% basal supplement, and T2) 100% RUPCA. Diets were (DM basis): 38.8% corn silage, 41.5% dry corn (finely ground), 2% minerals and vitamins mix, and 17.7% supplement (58.1% soybean meal, 39.9% carbohydrates, 2% urea, and 1% minerals). RUPCA and the basal supplement consisted of the same ingredients, differing on the processing of the carbohydrate (i.e., protected or not from ruminal degradation). Heifers had ad libitum access to feed and water during the study. Body weights were measured on d 0, 21, 42, 63, and 84. Dry matter intakes were measured every 7 d from d 21 when the adaptation to the diets finished. Blood samples were taken every 21 d and analyzed for glucose concentration. Back fat on the 12th Rib (BF) was measured on d 1 and 84. Data was analyzed as a randomized complete block design with repeated measures using a mixed model in SAS. There were no significant differences (P > 0.10) amongst treatments on initial BW, final BW, or ADG; however, cattle fed T1 had the lowest DMI (P < 0.01) and the greatest G:F ratio (P < 0.02). There were no differences in glucose concentrations (P > 0.96) or BF on d 84 (P > 0.72). In conclusion, including RUPCA at a rate of 8.87% of the diet DM improved G:F ratio by reducing DMI and not affecting ADG