Effects of diet and type of nesting material on the reproduction and lactation of the rat (1966)

Nolen, G. A., Alexander, J. C.

Abstract

Reproductive improvements due to paper nesting material were dramatic. The 10.8 pups per litter weaned by mothers nested in paper was very significantly higher than the 7.0 pups weaned by those with wood shaving. A more sensitive measure of the improvement was the lactation index [percentage of number of pups weaned that are alive at day 5] , which showed a 76% increase for paper-nested mothers over wood shaving-nested mothers. ... Females nested in shavings simply 'dried up'; those nested in paper had full milk glands. Access to paper nesting material reduced infant mortality from 45 to 3%. We suggest that the use of shredded paper for nesting, which incidentally makes a nest similar to that of the wild rat, allows the female with her young to borrow and insulate themselves from disturbing environmental factors, thus enhancing the mother's feeling of security.