A zinc deficiency can negatively impact your levels of testosterone. Studies have shown that zinc supplementation can help increase testosterone levels. Zinc supplements, oysters, beef, pork, crab and fortified cereals offer great sources of this mineral.
Do not breed unless you own healthy animals with excellent breed characteristics, and you are very committed to these kittens preferably for their lifetime. For each home you find for your kittens, there is a kitten at the shelter being euthanized. Age at breeding. A female cat should be allowed to attain her adult size before breeding. If bred early, she will put her energy into feeding the unborn/newborn kittens instead of finishing her growth. She will be 18-24 months old before she is ready for breeding. A male should be 18 months of age prior to being allowed to breed. This allows time to determine if he is healthy and suitable for breeding. Temperaments are passed to the offspring as are genetic diseases.
Breeding Age: Female rats can get pregnant very young. Its best never to keep males and females together past the age of 6 weeks. Best breeding age should be based on the size of the female: As long as the female is sufficiently grown, 4 months at the earliest with 6  7 being optimal. Females in good health and body structure can be as bred as late as 10 months and later depending on the genetic line. If you are not familiar with the line you are breeding, it might be best to breed the doe earlier. Male rats are generally good breeders at the age of three months.