The feed requirements of weaned lambs : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Agricultural Science in the University of Canterbury

In recent years interest has centred around the maintenance requirement of sheep, as these animals spend much of the year at maintenance. For some time it was thought that the energy maintenance requirement (MR) was constant for a given live-weight, but work during the last ten years has now established that the various muscular activities and climatic stresses cause quite large variations in the maintenance requirement. The magnitude of these differences varies with the feed availability, size of enclosure, terrain, length of wool, degree of exposure and climate. It is desirable to obtain more information on this subject in order to make more precise estimates of potential productivity of pasture and gross efficiency of food utilisation. Most of the studies have been conducted with mature sheep and estimates of the MR of a penned 100 lb sheep are about 1.0 lb DOM per day, increasing by 10-100% under different grazing conditions. The purpose of this trial was to carry out similar investigations with lambs, and to attempt to estimate the magnitude of differences in MR under different conditions of pen feeding and grazing. The effect or shearing in relation to MR and the estimation of the cost of live-weight gain were also integral parts of this project. Estimation of intake under grazing conditions was intimately associated with this problem. For this reason literature on the various methods of determining grazing intake has also been reviewed. It appeared that under the conditions of New Zealand pastoral sheep farming that the Chromic oxide - faecal Nitrogen technique was the most suitable, and so for this reason was used in the trial