Nutrition studies on protein and energy in domestic cats

The effects of three diets varying in their protein, fat and carbohydrate contents and of physical activity on energy and protein metabolism were investigated in eight domestic cats. The diets were based on canned food with addition either of minced cattle heart, melted swine fat or polenta. The activity-induced heat production was measured in a respiration chamber using the Doppler effect of radio-waves reflected from moving bodies. In the group receiving the high-protein diet, urinary nitrogen concentration was higher which was reflected in higher urinary loss of energy without affecting the amount of energy retained. Nitrogen utilization was not significantly influenced by nitrogen intake. Mean daily total heat production ranged between 163 and 187 kJ/kg BW/day or 215 and 270 kJ/kg BW(0.75)/day. The daily crude protein requirement of adult cats was determined to be 2.7 g/kg BW/day. The daily requirement of metabolizable energy for maintenance was estimated to be 153 kJ/kg BW/day or 226 kJ/kg BW(0.75)/day. The activity-induced heat production was 25.1 kJ/kg BW/day which corresponded to 13.5% of the total daily heat production. The daily requirement for metabolizable energy was thus reduced by 20.9 kJ/kg BW/day or 13.7%. The activity pattern of the cats was not characterized by a circadian rhythm.