While cats cycle more frequently than dogs, it is unusual to have a queen produce more than two litters per year. It is equally uncommon for a queen to be intentionally rebred during estrous cycles while lactating. Generally the cat breeder will wait months between litters. This hiatus provides the queen time to fully recuperate physically after the pregnancy and delivery, and to restore her internal nutrient levels to normal.

A unique characteristic of cats is the almost immediate need for higher levels of energy and nutrients as soon as a queen is bred.  Most species have a "lag" time before the growth of the fetuses and maternal tissues require a nutritional increase. However cats need to establish body stores of various nutrients well in advance of the rapid growth weight gain observed when fetal kittens develop during the last three weeks of pregnancy. The reasons are that the nutritional drain on the dam in late pregnancy, and during peak lactation are such that she can't take in enough food to satisfy those needs at the time, necessitating proactive nutrient stores.

Even with adequate stores in place, by the time the queen has completely weaned her kittens her body reserves are deficient again. For optimal health and breeding performance, queens are allowed several months on a quality diet to bounce back after weaning a litter, before breeding again. However, the special nutritional needs during this interim period are not always recognized. While the queen is back to maintenance levels of energy, other specific nutrients need to be provided in higher levels in anticipation of rebreeding. Lower quality food can lead to breeding issues such as failure to settle, and smaller litters, as well as higher incidences of pregnancy toxemia and eclampsia.

The concept of "eating for two" is widely recognized in association with pregnancy. Typically this phrase refers to necessary nutrition for the mother and the babies, but the nutritional needs during pregnancy go well beyond just the maintenance needs of the dam and the developmental needs of the fetuses. In addition to those needs are the generation of uterine tissue, miles of blood vessels, placental tissue, and development of mammary tissue.

If the queen carried an average size litter (typically 4 kittens) and successfully nursed to complete weaning at 8 weeks after birth, she not only utilized every gram of nutrient provided in the diet, but also drew on her own body reserves in her bones to some extent. In the case of a larger litter, that use of body stores is exacerbated.

Nutrients that typically need to be restored include calcium and phosphorous, omega-3 and omega-6 fatty acids, zinc, copper, manganese, taurine, arginine, and tyrosine.

A vitally important component of lactation is the production of colostrum, rich in maternal antibodies, to provide immune protection for the newborns. The wear and tear on the queen bred repeatedly with less-than-optimal nutrition between litters, will result in a compromised immune system, meaning lower levels of antibodies in the colostrum resulting in unprotected kittens. So not only are litters smaller and the kittens less vigorous, they are much more vulnerable to viruses, bacteria and parasites.

NRC 2006 Nutrient Requirements of Dogs and Cats - Feline values

Nutrients expressed in amounts per 1,000 Kcal metabolizable energy (ME), called a caloric basis, are not generally provided on the bags or in brochures. This manner of expression allows the direct comparison between diets for specific nutrients without different percentages of protein, fat, moisture and fiber content throwing off the numbers. In a cat requires 300 Kcals ME per day, how many grams of protein are recommended for gestation? Diet 1 will provide X number of grams, and diet 2, Y grams. Which is closer to the target value needed? The pet food manufacturer's technical service center should be able provide these details. Depending on the manufacturer, the values may be reported as the amount of nutrient per 100 Kcal ME, rather than 1000 Kcal. As long as you adjust accordingly, making sure all the information on the various diets is expressed on the same basis, either 100 or 1,000, you'll have realistic numbers to compare diet to diet. With cats being small animals they typically require Kcals in hundreds per day rather than thousands. If the technical services center for the manufacturer doesn't know the values of nutrients on a caloric basis, they haven't done their homework.

If the owner is intending to breed a queen more than once per year, they need to plan on using a "maintenance" diet that provides nutrient levels closer to those required for gestation and lactation for that time period between the litters. The table above shows the recommended levels of key nutrients for maintenance. The repeat breeder should be on a diet that has higher levels than that, but not necessarily at the gestation/lactation level (depending on the specific nutrient).

A breeder must resist the temptation to save money by feeding a lesser quality food between breedings if they want to promote optimal health and reproductive performance for each queen.  The few dollars saved will eventually manifest in smaller litters and less vigorous kittens.

References available upon request.