The effect of environmental conditions on food utilisation by sheep.

摘要: 1. A series of calorimetric experiments was conducted with sheep which had fleeces ranging in thickness from 0·1 cm. to 12 at environmental temperatures between 8 and 32° C. Heat production, heat loss by radiation, convection conduction, vaporisation water due warming food body temperature were measured together losses energy faeces, urine as methane. 2. The effects a rise on digestion the or methane resulted slight metabolisable ration 6 Cal./° 3. Environmental marked effect particularly when fleece short. critical (i.e. production minimal) closely-clipped varied 24° high level feeding 38°C. sub-maintenance feeding. These are similar that naked, resting man but much higher than pig fed similarly. 4. As grew fell. Thus, maintenance feeding, C.; grown 2·5 13° while 0° 5. Below increase more rapidly light fleeces. Thus heavy not only depresses also reduces rate falling under sub-critical conditions. 6. At well below critical, per unit surface identical. Under such conditions, whole is used keep animal warm, criterion adequacy content meta-bolisable small bulk. 7. above constant increased, being greatest highest Consequently net value declined these temperatures. 8. supplemented two comparative trials normal outdoor conditions weight groups Cheviot Blackface measured. Control kept indoors heated pens. 9. During mild winter 1956-7 out-wintered wethers i n full did loose any those same rations indoors. 10. severe 1957-8, Cheviot, in-lamb ewes diet gained 2·3 lb.; outside lost 3·3 lb. With Blackface, in·lamb difference 0·3 favour indoor group. 11. utilisation affected considerably little even an cold can be demonstrated practical