A transgenerational study on the effect of great-granddam birth month on granddaughter EBV for production traits in Italian Simmental cattle

Heat tolerance is a key feature of resilient animals. Offspring of animals that suffer environmental stress during pregnancy could show physiological, morpho-logical, and metabolic modifications. This is due to a dynamic reprogramming of the epigenetics of the mam-malian genome that occurs in the early life cycle. Thus, the aim of this study was to investigate the extent of the transgenerational effect of heat stress during the pregnancy of Italian Simmental cows. The effects of dam and granddam birth months (as indicator of preg-nancy period) on their daughter and granddaughter estimated breeding values (EBV) for some dairy traits as well as of the temperature-humidity index (THI) during the pregnancy were tested. A total of 128,437 EBV (milk, fat, and protein yields, and somatic cell score) were provided by the Italian Association of Sim-mental Breeders. The best birth months (of both dam and granddam) for milk yield and protein yield were May and June, whereas the worst were January and March. Great-granddam pregnancies developed during the winter and spring seasons positively affected the EBV for milk and protein yields of their great-grand-daughters; in contrast, pregnancies during summer and autumn had negative effects. These findings were con-firmed by the effects of maximum and minimum THI in different parts of the great-granddam pregnancy on the performances of their great-granddaughters. Thus, a negative effect of high temperatures during the preg-nancy of female ancestors was observed. Results of the present study suggest a transgenerational epigenetic inheritance in Italian Simmental cattle due to environ-mental stressors.

Automated summary

Heat stress during pregnancy can lead to physiological and metabolic changes in the offspring of animals, as a result of epigenetic reprogramming of the genome. This study investigated the transgenerational effects of heat stress in Italian Simmental cows. The birth months of the dam and granddam, as well as the temperature-humidity index during pregnancy, were found to affect breeding values for dairy traits in the daughters and granddaughters. The findings suggest an epigenetic inheritance due to environmental stressors in Italian Simmental cattle.