A study of the efficiency of feed utilization in young Friesian bulls fed cut pasture : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University

Abstract

An investigation was undertaken into the efficiency of feed utilisation of Friesian bulls. Of major interest was the comparison of efficiency of feed utilisation in two groups of bulls selected for extreme differences in liveweight gains at pasture. Data for yearling, Friesian bulls run at pasture over a period of six months at the Awahuri and Newstead Artificial Breeding Centres were analyzed. Nine bulls with the highest liveweight gain were placed in a high (H) group, and nine bulls with the lowest liveweight gains were placed in a low (L) group. A standardisation period of four weeks was used to measure the voluntary intake of cut pasture of the two groups of bulls. At the end of this period the bulls were assigned to blocks on the basis of liveweight and one of three intake levels randomly allocated within blocks. Intake levels one, two and three were designed to give liveweight gains of 0.1, 0.5 and 1.0 kg/day respectively. Each bull within intake level one or two was allocated cut pasture in direct proportion to their metabolic liveweight (W3/4). During the eight week comparison pariod, a concentrate meal was offered at the rate of 3.6 kg/day to those bulls on intake level three, together with ad libitum cut pasture. Digestible energy intake and liveweight gain were measured in the comparison period, and measures of total and partial efficiency calculated from the data. In the selection period the mean liveweight gains of the high and low liveweight gain groups were 1.35 and 1.00 kg/day respectively. However, in the standardisation period there were no significant differences between the high and low liveweight gain groups in either, voluntary intake or liveweight gain.