Chemical composition, ruminal kinetic parameters, and nutrient digestibility of ammonia treated oat hulls

Abstract

A study was conducted to determine the effects of ammoniation (3 or 5% by dry weight) on the nutritive value of oat hulls. Ruminal nutrient kinetic parameters and degradability of untreated and ammoniated oat hulls were determined using two non-lactating cows fitted with rumen cannulas. Eighteen steers were used in a digestibility trial to determine nutrient utilization of three diets consisting of 100% barley silage, 50% untreated oat hulls plus 50% barley silage, and 50% ammoniated oat hulls plus 50% barley silage (DM basis). Ammoniation at both levels increased (P < 0.05) total N and reduced (P < 0.05) neutral detergent fibre levels of oat hulls. Most of the N added due to ammoniation was in the form of non-protein N. The results of the in situ trial showed that ammoniation at the 3% level increased the potentially degradable NDF and ADF fractions as well as their rates of degradation. Ammoniation at the 3% level improved (P < 0.05) effective ruminal degradability of NDF and ADF of oat hulls by 41 and 35%, respectively. Dry matter intake was highest (P < 0.05) for steers fed the ammoniated oat hull diets, intermediate for those fed the untreated oat hull diets and lowest (P < 0.05) for those fed the 100% barley silage diet. Steers fed the ammoniated oat hull diet had higher (P < 0.05) total tract digestibility of NDF and lignin relative to steers fed the untreated oat hull diet. However, total tract digestibility of dry matter was not affected by ammoniation. It was concluded that ammoniation is a viable method for improving the feeding value of oat hulls to ruminant animals. Relative to the 3% level, ammoniation at 5% resulted in a marginal improvement in the nutritive value of oat hulls. Key words: Ammonia treatment, oat hulls, ruminal degradation, nutrient utilization