Changes in heat production by sheep of Guirra breed after increase in quantity of barley grain on the diet

Abstract

The heat production (HP) from CH4 and CO2 production and O-2 consumption was determined by the respirometry quotient (RQ) method and by C-N balance measurements (CN method). Twelve dry and none pregnant Guirras sheep were fed with 3 diets consisting in the same quantity of alfalfa hay (2 kg/d offered) and increasing quantities of barley grain (150,300 and 450 g/d). The experimental design was completely random with 4 replication by treatment. Fasting HP was determinate in one sheep from each group. Ewes were allocated to individual metabolism cages at thermoneutrality. After 10 d of adaptation, feed intake, and total fecal and urine output were recorded daily for each ewe during a 5 d period, as well as BW at the beginning and end of the period. Gas exchange measurements were recorded by open-circuit face mask respirometry system. Average HP measured by RQ method was in agreement with the average HP determined by CN method accounting for 395.6 and 393.4 kJ/kg(0.75) BW/d, respectively. The metabolizable energy requirement for maintenance (MEm) was estimated by linear regression at 352.3 kJ/kg(0.75) BW. (C) 2012 Elsevier B.V. All rights reserved.