EFFECT OF TEMPERATURE AND FOOD-INTAKE ON METABOLIC-RATE AND POSTURE OF PRERUMINANT CALVES

Influence of feeding level and temperature on posture and posture-rela ted heat production was studied in preruminant calves. Twenty-four you ng calves were assigned in a 2 x 2 factorial design to one of two feed ing levels [high (FH) or low (FL)] and to one of two temperature (7.5 degrees C or 19 degrees C). Heat production (HP) and posture were meas ured per calf every 9 min, during 3 days. HP was dependent on feeding level and temperature. Energy expenditure related to standing was high er at 7.5 degrees C than at 19 degrees C. Time spent standing was high er at FL than at FH, and at 7.5 degrees C than at 19 degrees C. On the contrary, the number of standing periods was lower at 7.5 degrees C t han at 19 degrees C. Consequently, the duration of a standing period w as higher at 7.5 degrees C than at 19 degrees C. Within a standing per iod, HP decreased with time. This decline was largest at 7.5 degrees C . Thus, energy cost of standing was lower in treatments with a longer duration of a standing period. These results demonstrated that the eff ect of temperature on energy cost of standing is influenced by the num ber of standing periods.