A study conducted by John Speakman and colleagues at the University of Aberdeen, UK, has suggested that 'nude' female mice have chubbier
offsprings than females with whole body fur. The research team found
that shaving the backs of nursing mice allowed them to produce more
milk hence producing healthier litters than their fully fur covered
The study, led by John Speakman at the University of Aberdeen, UK, found that shaving the backs of nursing mice allowed females to produce more milk and wean heavier litters than their fully fur coated peers.
Speakman said that normally mice need their fur to keep warm, but while nursing, making more milk and digesting the extra food needed for the production of it, generates so much waste heat that the mouse risks overheating.
In the study, the researchers measured and subtracted the energy intake and expenditure of nursing mice mothers.
The calculation found that a whopping 55 percent was made into milk to nurse on average 11 babies each. But shaved mice mothers ate 12 percent more food, made 15 percent more milk and had litters that were 15 percent heavier than their fully coated counterparts.
"If prevention of overheating is important for animals that need to keep a constant body temperature, like mammals and birds, then this could for example explain why litter and clutch sizes are bigger in cooler regions," New Scientist quoted Speakman, as saying.
However, Polly Phillips, a physiologist at Florida International University in Miami, US, cautioned that since mice are small, and have a large surface to volume ratio, that they more commonly struggle to keep warm rather than to lose heat.
"Nursing females with their high metabolism may be a special case, but the idea that excess heat from digestion or milk production may limit food intake is more valid in large animals. I would like to see how this applies to sheep or bison", Phillips said.
According to Phillips, humans' ability to sweat makes heat loss easier for them, but Speakman said that some women mention feeling flustered when nursing.
"If that applies, and the woman worries about milk supply, then cooling down a little may be worth trying", Speakman said.
The study is published in The Journal of Experimental Biology.