Net energy requirements for growing suffolk ewe lambs

Developing feeding systems for efficient use of local resources is currently becoming more important to promote and fix sheep rearing in rural communities in Japan. For supporting such efforts, a feeding standard for sheep was currently compiled. However, experimental data are scarce to show reliable recommendation of nutrient requirements under feeding conditions in Japan. Therefore, we undertook an experiment to measure energy requirement for growing Suffolk ewe lambs which was one of the fields deficient in original data. Eight weaned Suffolk ewe lambs, being allotted equally to one of two groups, were used for a 32-week feeding experiment consisting of three terms of 12 (the 1st), 12 (the 2nd) and 8 weeks (the 3rd). The lambs of each group wee confined in indoor individual pens with diets offered containing an equal amount of Italian ryegrass hay wafer (800 g/day) and one of two different feeding levels, high (HE) or low (LE), of pelleted concentrate mixture. In each term of the feeding experiment, a balance trial (seven days for collection of feces and urine, among which three successive days in an open circuit respiration chamber) was conducted for all the lambs to measure metabolizable energy (ME) intake and heat production (HP). To calculate ME intake during the feeding experiment, ME content of each feed offered was derived from a linear regression of ME content of mixed diets on the ratio of hay or concentrate in the diets. After finishing the feeding experiment, all the lambs were slaughtered as well as another two lambs slaughtered just after starting the feeding experiment. Energy retained (RE) in empty body during the feeding experiment was calculated by the difference in total energy content of empty body with fleece between at the start and end, which was estimated from fat content of carcass, according to Garrett et al. (19959), and growth of fleece