Lactating cats not only increase their total calorie consumption, they also significantly alter the make-up of their diet to meet the demands of feeding a litter, research from the WALTHAM® Centre for Pet Nutrition has shown. The research provides intriguing insights into cats' feeding behaviour and strong evidence that they are able to adapt their macronutrient intake, i.e. their intake of protein, fat and carbohydrate, to meet their physiological requirements.

"It's no surprise that, just like humans, cats require more energy during pregnancy and when feeding their young. However, this research shows that lactating cats, particularly those with large litters, select their foods to alter the proportions of protein, fat and carbohydrate they consume", commented lead scientist Dr Adrian Hewson-Hughes, WALTHAM® Centre for Pet Nutrition. "If given the choice, cats with large litters will significantly alter their diet composition when feeding kittens to ensure a much greater proportion of energy is obtained from fat."

In the study, seventeen adult female cats were offered a choice of three nutritionally-complete wet foods with different proportions of protein, fat and carbohydrate. During pregnancy, the cats significantly increased their total energy intake, and the amounts of protein and fat consumed also increased linearly. When lactating, the cats with large litters of four or five kittens further increased their energy intake, consuming a significantly higher proportion of energy from fat and reducing the proportion of energy from protein and carbohydrate. Total fat intake tripled for the cats feeding large litters, and doubled for cats with smaller litters of one to three kittens.

Previous research has shown that non-reproducing adult cats with normal energy requirements have a limit to the amount of carbohydrate they will consume in a day (Hewson-Hughes et al. 2011). Specifically, cats' "carbohydrate ceiling" was found to be approximately 20g of carbohydrate per day. The present study expanded on these findings and showed that, while cats increased their intake of protein and fat during pregnancy and lactation, their carbohydrate intake did not exceed this limit of 20g per day. The research therefore shows that cats' "carbohydrate ceiling" still applies during the increased physiological demands of gestation and lactation.