Authors : A. Plascencia , E. Alvarez and R.A. Zinn
Abstract: Four Holstein steers (406 kg) with cannulas in the rumen and proximal duodenum were used in a 4x4 Latin square design to evaluate the influence of acetate infusion on characteristics of ruminal and total tract digestion. The basal diet contained 51.3% steam-flaked corn and 33.8 % of forage (alfalfa and sudangrass hay). Dry matter intake was restricted to 2.0% of BW (8.24 kg d 1). Acetic acid was dissolved in distilled water to produce four treatment solutions of 0, 0.333, 0.666and 1.000 M. Treatment solutions were infused into the rumen via the ruminal cannula at the rate of 11.1 mL min 1 (16 L d 1). There were no treatment effects (p>0.20) on ruminal pH, lactate and ammonia concentrationand estimated methane production. Acetate infusion increased (linear effect, p< 0.10) total ruminal VFA molar concentrationand molar proportion of acetate, but decreased molar proportion of butyrate (linear effect, p< 0.01) and valerate (linear effect, p< 0.05). There was a quadratic effect of acetate infusion on ruminal tonicity (p< 0.05) and molar proportion of isovalerate, being maximal with the 0 and 960 mL d 1 acetate infusion rate. There were no treatment effects (p>0.20) on ruminal microbial efficiency and ruminal and total tract digestion of N . However, acetate infusion decreased (linear effect, p< 0.05) ruminal and total tract NDF digestion. Ruminal VFA concentration explained 48% (p< 0.01) of the variation in ruminal NDF digestion. In contrast, ruminal pH had limited value (r2= 0.03; p>0.20) as a predictor of NDF digestion.
A. Plascencia , E. Alvarez and R.A. Zinn , 2007. Influence of Intraruminal Infusion of Acetate on Ruminal Characteristics and NDF Digestion in Feedlot Steers. Journal of Animal and Veterinary Advances, 6: 986-990.