Growth Curve and Energy Intake in Male and Female Cats

The aim of this study were (1) to characterize the growth curve in male and female cats, (2) to associate the growth and metabolizable energy intake (MEI) as an indirect measurement of the energy requirements, and (3) to determine the short-term effects of neutering on energy intake to maintain the bodyweight in young adult cats. Eighteen 5-months-old mixed breed cats were used in this study (males, n = 7 and BW = 2.2 ± 0.21 kg; females, n = 11 and BW = 2.0 ± 0.16 kg). The cats were fed to supply their metabolizable energy requirement for growth, adjusting the amounts to maintain an ideal body condition score. The animals were weighed every 15 days for 10 months (from 5 to 15 months old). At 12 months old, the cats were gonadectomized and the MEI was recorded for 3 months, up to 15 months old. Second-order, Gaussian, and spherical models were fitted to growth data. Male cats had higher energy intake for growth (MEI = 176.27^-0.037t, R² = 0.79) than females (MEI = 166.86^-0.044t, R² = 0.62), where t is the age in months. Male cats also reached mature weight later than female cats (16 and 13 months old, respectively). Neutering reduced the energy requirements of male (intact - 116.43 kcal/kg^0.67; gonadectomized - 98.65 kcal/kg^0.67; P < .01) and female cats (intact - 98.65 kcal/kg^0.67; gonadectomized - 76.16 kcal/kg^0.67; P < .01) on average 17.6%. This study suggests that in cats, males and females present different energy requirements since the early growth phases and, this difference remains after neutering in young adults. Female cats reach adult weight earlier than males.