Abstract:
Laboratory mice (strain MF1) were used to investigate the effects of dietary fat intake on lactation
performance. The specific dynamic action (SDA) for high fat (HF), medium fat (MF) and a low fat (LF) diets was
measured using open-flow respirometry at 4.5%, 3.9% and 6.1%, respectively. The same three diets were fed ad
libitum to mice between days 4 and 18 of lactation. Mice fed HF, MF and LF diets reached plateau in their daily food
intake at 14.95±1.14 g day-1, 16.30±0.61 g day-1 and 16.57±0.26 g day-1, respectively between days 12-17 of lactation.
At weaning, litters from HF and MF-fed mice were significantly heavier than pups on LF diet. This was because the HF
and MF-fed mice not only consumed more energy at peak lactation but also delivered more milk energy to their pups
than the LF-fed mice. Evidence suggested that the positive effects of feeding fat to mice were in part due to the low
SDA and probably low heat production for milk synthesis. Probably, the ability of the HF and MF-fed mice to directly
transfer absorbed fat into the milk might have reduced the heat production of lactogenesis. The HF and MF diets had
beneficial effects on lactation because they increased the capacity of mice to generate milk more efficiently and wean
heavier offspring than mice fed LF diet. The daily energy expenditure (DEE) of mice in the three dietary groups was
fixed.
KEY WORDS: Laboratory mouse, dietary fat, specific dynamic action, doubly labelled water, daily energy
expenditure, milk energy output, reproductive performance
