Do the effects of fetal programming reach generationally?

Stephen P. Ford, director of the University of Wyoming’s Center for the Study of Fetal Programming, thinks so.

“We studied F1 offspring from obese ewes after we did feedlot trials. We put obese females on a maintenance diet and got them back down to body condition of pre-feeding levels and bred them.

“We had two groups of adult female offspring (from fat mothers and from control mothers) and fed them maintenance diets all through pregnancy. We found ewes born from obese mothers, even though they themselves were on a normal diet during pregnancy, exhibited insulin resistance, as well as a marked increase in glucose and insulin concentrations in their blood. They had more glucose to shunt into the fetus,” Ford says. In other words, they were passing extra nutrition to the next generation.

When the F2 offspring were born, they exhibited a marked increase in internal fat, as their mothers had, suggesting the F2 generation was perpetuating the same health concerns. Thus, there may be transfer of obesity across generations.

“We don’t know how many generations this might go, once you program these problems. Females born from obese mothers are more insulin resistant because their pancreas has been altered. They feed their own fetus more, even though they are eating less,” he explains.

Another experiment was designed to look for phenotypic differences between two flocks of sheep of similar genotype (Western Whiteface ewes), which had been a single flock maintained by the University of Wyoming 30 years earlier.

“They’d been separated into two flocks, each maintained under markedly different management and feeding systems. One flock was purchased and taken to the Red Desert near Baggs, WY. They were in a nomadic range operation and hadn’t received any supplement. Lambs produced were kept as part of the range flock. The other flock remained at UW and were typical university sheep – fed too much and leading a sedentary life,” Ford says.

Ford bought ewes from each flock and undernourished both groups during early to mid-gestation.

“When I collected fetuses at mid-gestation, I found the fetuses of the UW sheep had significant intrauterine growth retardation. The pancreas was affected, heart enlarged, etc. When offspring from these animals were born, I raised them to adults and put them on full feed. They had increased appetites, became insulin resistant, and developed hypertension,” he says.

“In contrast, fetuses collected from the nutrient-restricted nomadic range flock were of normal weight and body composition, even though they’d been significantly undernourished during fetal development. Their placentae exhibited an altered phenotype and became more efficient in delivering nutrients to the fetus when we reduced the ewes’ feed intake. These undernourished nomadic ewes over a period of 30 years (about 4-5 generations of sheep) had evolved to where they could eat much less feed and yet grow normal, healthy lambs. And, when those lambs were born, they did not show insulin resistance or any unhealthy symptoms. They grew normally,” says Ford.

This suggests that animals can adapt to their environment over time. Producers generally try to buy animals from a similar type of operation, so the cows will fit their ranch environment.

“If you buy animals from another production environment, they may not adapt to your environment for several generations. Our studies suggest that by getting animals that were raised in a similar production setting, there’s more chance they will do well in yours. Epigenetically they are able to adapt their phenotype to a particular production environment, and it takes time to adapt to a markedly different environment,” he says.