Digestibility by Dairy Cows of Monosaccharide Components in Diets Containing Either Ground Sorghum or Sorghum Grain Treated with Sodium Hydroxide

Abstract

Five cows in midlactation and equipped with ruminal and abomasal canulas were fed two isonitrogenous diets composed of 46% sorghum grain, either ground or treated with 4% NaOH, plus 39% wheat silage and 15% supplements. The DMI were 16.3 and 15.8 kg/d for cows fed the diets containing ground sorghum and treated sorghum, respectively. The digestibility of NDF polysaccharides was higher for cows fed the treated sorghum, but the digestibility of neutral detergent soluble α-glucans (starch) was higher for cows fed ground sorghum. Digestibility of total carbohydrate was 79% for cows fed the diet containing ground sorghum and 67% for cows fed the diet containing sorghum treated with NaOH. Ruminai pH was higher in cows fed the diet with treated sorghum, but total ruminal VFA concentration was higher in cows fed the diet containing ground sorghum. Profiles of individual ruminal VFA and NH3 concentration were similar for both treatments. Flow of NAN through the abomasum of cows fed ground sorghum was higher than that of cows fed the sorghum treated with NaOH, and N absorption in the intestine followed a similar trend. The data indicated a possible advantage for dairy cows fed ground sorghum than for those fed grain treated with NaOH.