A novel ammoniation treatment of barley as a strategy to optimize rumen pH, feed degradability and microbial protein synthesis in sheep.

BACKGROUND Meeting the energy and nitrogen requirements of high-performing ruminants while avoiding digestive disturbances (i.e. rumen acidosis) is a key priority in ruminant nutrition. This study evaluated the effect of a cereal ammoniation treatment, in which barley grains are combined with urea and enzymes that catalyze the conversion of urea to ammonia to optimize rumen function. Twelve rumen cannulated sheep were randomly divided in two groups and fed a diet containing 60% of ammoniated barley (AMM), or untreated barley supplemented with urea (CTL) to study the impact on rumen fermentation and feed utilization. RESULTS Ammoniated barley had higher total N content and effective rumen degradable N than untreated barely. AMM sheep had a consistently higher rumen pH throughout the day (6.31 vs 6.03) and tended to have a lower post-prandial ammonia peak and higher acetate molar proportion (+5.1%) than CTL sheep. The rumen environment in AMM sheep favored the colonization and utilization of agro-industrial by-products (i.e. orange pulp) by the rumen microbes leading to a higher feed degradability. AMM sheep also had higher total tract apparent N digestibility (+21.7%) and urinary excretion of purine derivatives (+34%) suggesting higher N uptake and microbial protein synthesis than CTL sheep. CONCLUSIONS The inclusion of ammoniated barley in ruminants' diet represents a valid strategy to maintain rumen pH within a physiological range and to improve N utilization by the rumen microbes which could have positive effects on animal's health and productivity in intensive production systems. These findings warrant further studies under conventional farm conditions. This article is protected by copyright. All rights reserved.