THE EFFECTS OF ANHYDROUS AMMONIA TREATMENT OF WHEAT STRAW AND STEAM COOKING OF ASPEN WOOD ON THEIR FEEDING VALUE AND ON RUMINAL MICROBIAL ACTIVITY. I. FEEDING VALUE ASSESSMENTS USING SHEEP

Abstract

Steam-cooked aspen wood, anhydrous ammonia-treated and untreated wheat straw each made up 64% of high roughage rations, the remainder being composed of 25% alfalfa, 10% cottonseed meal plus minerals and vitamins. The three experimental diets, medium quality alfalfa hay and 50% grain ration were individually fed to four mature wethers, one diet at a time to all wethers, to assess intake, digestibility and nitrogen balance. The same diets were group-fed to lambs in a growth trial. Steam cooking of the wood resulted in an energy digestibility near that of the alfalfa but intake of the ration was lower than would be expected from the digestibility. Anydrous ammonia treatment of the wheat straw increased (P <.05) its energy digestibility dramatically. Performance of lambs in a growth trial indicated that the rations containing steamed wood and untreated straw were capable of sustaining only slight gains above maintenance, whereas the ammoniated straw ration contained considerable productive energy resulting in gains 86% higher than those on untreated straw and nearly equivalent to those obtained with the alfalfa.