Effect of shearing on lamb growth and carcase performance

摘要

A study was undertaken on three properties throughout New Zealand to determine the impact of shearing on lamb performance and whether this offered any economic benefit to farmers as a farm-management tool. A total of 1,183 lambs were randomly allocated to one of four treatments, shorn fasted, bellied fasted, woolly fasted and woolly not fasted. Shorn fasted lambs grew 12 g/d faster than woolly fasted lambs (P<0.05), but at similar rates to bellied lambs and woolly not fasted lambs. There were no differences among treatments for carcase weight, meat yield or proportion of lambs killed at slaughter. The difference observed in average daily gain between the shorn fasted and the woolly fasted lambs, and the lack of difference observed between shorn fasted and woolly not fasted lambs, indicated that while shearing improved lamb growth rates, the weight loss due to fasting overnight was not overcome by the increased growth rate associated with shearing. While there was no economic benefit associated withlamb carcase weight or time to slaughter, at a wool price of $5.40 per kg clean, shorn lambs were still of a greater value to farmers compared to lambs from all other treatments.