The influence of the amount of starch on the utilization of urea by sheep

Abstract

A study was made of the effect on the wool production of Merino sheep following the addition of urea to a ration which was low in protein but contained varying amounts of dehydrated potatoes as a source of starch. The low-protein ration contained 7 to 9 g. nitrogen, the urea supplement was given at the rate of 15 g. daily, equivalent to approximately 7 g. N, and the potatoes were supplied at levels of 50, 100, 150, and 200 g. daily. With 100 g. or more of potatoes an increase occurred in the amount of wool produced which was proportional to the amount of potatoes in the ration. The increases were 7, 19, and 23 per cent. with 100, 150, and 200 g. potatoes respectively. In a second series in which a mixture of red palm oil and peanut oil was added to the diet in order to increase the calorific value of the lower rations, the increases in wool production were 9, 15, and 15 per cent. with 100, 150, and 200 g. potatoes respectively. No increase occurred in wool production when 50 g. potatoes were used, either with or without oil. The increases in total wool production were accompanied by increases in fibre diameter. The maximum increase in the latter was 6 per cent.; this was attained when 200 g. potatoes were fed.