The more we research, the less we know. Frankly, when working with complicated systems like living and breathing animals, we will never have it all figured out. One of the more fascinating research areas is epigenetics- the study of changes due to gene expression from environmental factors rather than altering the genetic code. Whether genetics or environment is more important is still a valid question because, as we are finding out, the environment can have an effect.

A team from the University of Wisconsin published a paper in 2023 covering more than five years of sheep research focusing on whether they could influence the phenotype of ram lambs born of ram lines fed an altered diet (specifically supplemented with methionine). The results were that the F2 generation (the grandchildren of the rams fed the special diet) showed changes in their genetic code (extra methyl groups attached to the DNA) and phenotypic changes in scrotal circumference and loin muscle depth. (https://grow.cals.wisc.edu/departments/features/ewe-are-what-your-grandparents-ate)

A large body of work has examined the effects of heat stress in dairy cattle. We know that heat stress reduces feed intake and conception rates, decreases milk production, changes milk components, and causes various other issues. What has become more apparent is that heat stress not only affects the cow, but her fetus and the future offspring of that daughter as well. While males don’t begin to produce sperm until puberty, females are born with their lifetime quota of eggs- so anything that affects a female fetus in utero has the potential to affect her future offspring (and their future off spring) as well. In dairy cattle, heifers affected by heat stress in utero have been shown to have a lower lifetime milk yield, reduced growth and conception rates, and changes in skin and hair (shorter, thicker hair with thinner skin and smaller sebaceous glands).

Nebraska and Oklahoma have done some studies following the impact of fetal nutrition on the performance of the calves, and no surprise, they found that growth and health were higher in calves that had adequate protein and energy in their diet, as well as increased reproductive performance. Several famous studies have been done in humans (Dutch starvation) that follow generations of families to see what changes have occurred.

It’s a fascinating rabbit hole to fall down, and I expect we will see more research in the future as we try to pinpoint how the choices we make now affect future generations of our flocks and herds. I think Wisconsin said it best when they said “Ewe are what your grandparents ate.”