Effect of nutrition, temperature and photoperiod on the rate of sexual maturation of the field vole (Microtus agrestis).

Weanling male and female field voles were placed in long or short photoperiods, kept at 18 degrees C or 4 degrees C, and fed (ad libitum) diets containing 24%, 16%, 8% and 4% protein, for 6 weeks. Animals in the long photoperiod were more sexually mature than were animals in the short photoperiod. Temperatures had no effect on females, but did affect males: those kept at 4 degrees C had heavier testes and wider seminiferous tubules than those kept at 18 degrees C. There was little difference between the animals on 24%, 16% and 8% protein diets. Animals on 4% protein diets had retarded growth rates and were significantly less sexually mature than those on the other 3 diets, males having smaller testes and seminal vesicles and narrower seminiferous tubules and females having smaller ovaries and uteri.