Effect of supplementation on the digestibility of roughage diets

Supplementation of low quality Mongolian hay and barley straw with urea, minerals and a small quantity (11 - 14% of total DM) of easily digestible carbohydrate had a positive influence on in vivo digestibility, increasing the net energy value of the low quality roughages by up to 34%. The rumen ammonia concentration was maintained above the critical level by the recycling of N to the rumen. Supplementation with a concentrate increased the retention time of hay in the digestive tract when compared with feeding hay alone. NaOH-treatment of barley straw increased the digestibility and rate of passage through the digestive tract.