RUMINAL AMMONIA AND BLOOD UREA METABOLISM IN SHEEP FED HAY WITH OR WITHOUT CONCENTRATE SUPPLEMENT

Metabolism of ruminal ammonia and blood urea was investigated in West African Dwarf ewes and wethers, fed a low quality hay with or without concentrate supplementation, using single injection of [15N] ammonium chloride (HN4Cl) or [15N] urea into the rumen and blood respectively. The percentages of 15N administered intraruminal as HN4Cl recovered in the urine, faeces and milk of the ewes were 4.3, 9.0 and 3.1, Also 32.3 and 28.7% of [15Nl urea administered into the blood were recovered in the urine of the wethers. Ruminal ammonia contributed 50.6% or protozoal-N in sheep fed hay and 14.2 78.7 and 35.0% respectively in sheep fed hay and concentrate. Also, 59.0 and 7.9% of ruminal ammonia-N was derived from blood urea of sheep fed hay and hay plus concentrate respectively. The inclusion of concentrate in the diet increased the extent of ruminal bacteria protein synthesis but not that of the protozoa, However, the contributions of ruminal ammonia to blood urea synthesis and of blood urea to ruminal ammonia were Sharply decreased in the presence of the concentrate.