The metabolic rate of Merino rams bred for high or low wool production

Abstract

Five rams from a flock bred for high wool production at pasture and six rams from another flock bred for low production were studied. The two groups had also grown differing amounts of wool when rationed to 800 g food per day in pens. The high producers were somewhat larger and heavier than the low producers and had greater fat-free body weights. Both groups had higher metabolic rates (fasting heat production) than ewes and wethers of the same weight, in whatever units metabolism was expressed. The high producers were judged to have higher metabolic rates than the low producers; some of this difference may have been due to the larger skeletal size of the high producers.