Seasonal and age effects on energy requirements in domestic short-hair cats (Felis catus) in a temperate environment

There is little information known about the energy requirements of cats in temperature climates. Energy requirement of domestic short-haired cats was determined using three groups of mixed gender old kept outside (approximately 9.9years of age; 4.8kg; n=9), young kept outside (approximately 3.1years of age; 3.9kg; n=8) or young kept inside (approximately 3.1years of age; 3.9kg; n=8). Cats were housed individually for 5weeks during summer (18.5 +/- 0.5 degrees C) and winter (8.5 +/- 0.4 degrees C) and were fed a commercially available maintenance diet ad libitum. In both periods, energy expenditure was determined from the rates of 2H and 18O elimination for blood H2O over a 12day period, from a doubly labelled water bolus 2H2O (0.7g/kg BW) and H218O (0.13g/kg BW) administered intravenously. During the summer period, macronutrient digestibility was determined. Older cats had a reduction (p<0.05) in apparent digestibility of dry matter (approximately 9%), energy (approximately 8%) and protein (6%). There was a significant effect of age and season on energy intake and energy expenditure. While lean mass was affected by age and season, there was no effect of age or season on energy expenditure when expressed as a proportion of lean mass. Possible seasonal differences in nutrient digestibility may explain these results.