Effects of feeding frequency on energy and nitrogen balance in sheep given a ground and pelleted forage

Abstract

Wether sheep were fed at intervals of 3 hr, 24 hr, and 4 days, and their energy utilization studied at several levels of feeding. The diet consisted of ground and pelleted lucerne containing 19% crude protein and 28% crude fibre. Digestibility was a few units lower when feeding was less frequent; crude protein and fibrous constituents were affected most. The relation between methane production and digestible energy was the same for daily as for 3-hourly feeding, but methane production was depressed by feeding every fourth day only. Metabolizable energy was a slightly greater proportion of digestible energy when feeding was infrequent. A larger fraction of metabolizable energy was dissipated as heat when feeding frequency decreased. This was attributed to the cost of alternating between energy storage and oxidation of reserves: activity differences were not a cause. Overall, the net energy value of the food decreased as frequency of feeding decreased. Prediction from chemical composition or digestibility was not reliable. Measurement of hour by hour changes in metabolism indicated that there was an intense phase of fermentation and lipogenesis immediately after feeding. With 3-hourly or daily feeding, the oxygen consumption, carbon dioxide production, and methane production increased respectively by 0.7, 2.5, and 0.3 l/hr/100 g food eaten in the first hour: with the highest level of feeding, these represent increases up to 2.4-fold and an R.Q. of 1.15. With feeding every fourth day the responses were very much less, indicating depressed rumen activity; blood urea levels were also relatively low.