High fat diet prevents over-crowding induced decrease of sex ratio in mice.

Area of Science:

• Reproductive Biology
• Behavioral Ecology
• Mammalian Physiology

Background:

• Adaptive theory suggests parental manipulation of offspring sex ratio (SR) based on future reproductive success.
• Overcrowding is a significant environmental stressor that can impact reproductive outcomes.
• Dietary factors, such as fat content, may modulate the effects of environmental stress on reproduction.

Purpose of the Study:

• To investigate the impact of crowding on the sex ratio of offspring in mice.
• To determine if dietary fat content influences pregnancy outcomes under crowded conditions.
• To test the Trivers-Willard (TW) hypothesis in relation to maternal stress and diet.

Main Methods:

• Female mice were housed under varying degrees of crowding and fed either a normal fat diet (NFD) or a high-fat diet (HFD).
• Outcomes of pregnancy, including dam body weight (DBW), litter size (LS), and sex ratio (SR), were analyzed.
• Statistical analyses were performed to assess the effects of crowding and diet.

Main Results:

• High-fat diet (HFD) dams exhibited higher average dam body weight (DBW), litter size (LS), and sex ratio (SR) at conception.
• In the normal fat diet (NFD) group, male-biased litters declined with increasing crowding.
• Litter size (LS) and sex ratio (SR) decreased with crowding in the NFD group, while only LS was reduced in the HFD group.

Conclusions:

• Female mice under overcrowding stress shift offspring sex ratio (SR) in favor of daughters, supporting the TW hypothesis.
• High-fat diet (HFD) consumption mitigates the influence of overcrowding on offspring sex ratio (SR).
• Dietary interventions may offer a strategy to counteract the negative reproductive consequences of environmental stressors.