Late gestation hyperthermia: epigenetic programming of daughter's mammary development and function.

Area of Science:

• Reproductive Biology
• Developmental Biology
• Animal Science

Background:

• Early-life stress, particularly prenatal, can permanently affect animal health and productivity.
• The bovine mammary gland develops in utero and is susceptible to fetal programming.
• Limited research exists on the impact of prenatal heat stress on mammary development and subsequent productivity in livestock.

Purpose of the Study:

• To review mammary gland development in cattle during pre- and postnatal stages.
• To examine how intrauterine heat stress affects mammary development and synthetic capacity.
• To elucidate the mechanisms underlying permanent productivity detriments following prenatal heat exposure.

Main Methods:

• Review of existing literature on bovine mammary gland development.
• Analysis of histological, cellular, and molecular changes in mammary tissue.
• Examination of effects across key postnatal stages: birth, weaning, and first lactation.

Main Results:

• Intrauterine heat stress disrupts normal mammary gland development from fetal stages to lactation.
• Prenatal heat exposure leads to impaired mammary gland synthetic capacity and reduced milk yield.
• Epigenetic programming of the udder by in utero heat stress results in less resilient and productive cows.

Conclusions:

• Prenatal hyperthermia significantly compromises mammary gland development and function in cattle.
• Early-life heat stress induces lasting epigenetic changes, impacting long-term productivity.
• Understanding these mechanisms is crucial for improving dairy cow resilience and productivity.