The effects of maternal health and body condition on the endocrine responses of neonatal foals.

The study explores how changes in maternal nutrition during pregnancy due to disease affect the hormonal responses in newborn horses. Researchers studied mares infected with Streptococcus equi and found that reductions in nutrients mid-pregnancy may enhance insulin secretion response to glucose in their foals, which could potentially lead to metabolic issues later in life.

Objective and Method

• The study aimed to understand how maternal nutritional restriction due to natural infection alters endocrine function in newborn foals. The research was conducted on ten primiparous (first pregnancy) mares who were either put on a diet to maintain a moderate body condition or a nearly unrestricted feeding to maintain a high body condition throughout pregnancy.
• Interestingly, all the mares unknowingly contracted Streptococcus equi — a bacterium causing strangles, a highly contagious equine disease — during the mid-gestation period and lost about 10% of body mass.

Results

• The results showed a decrease in maternal insulin and glucose levels during and following the weight reduction period. Despite this change, the foals born from both high and moderate nutritional groups were healthy, with no significant differences in terms of gestational age, bodyweights, placental, and post-birth clinical parameters.
• The cortisol and glucose responses in foals to adrenocorticotrophic hormone and insulin, respectively, showed no distinction between the two groups. However, insulin levels during a glucose tolerance test were notably higher in foals from the mares in moderate condition than those in the high condition and previous studies on healthy, well-fed mares.
• This observation indicated that the sensitivity of the foals’ beta cells to glucose was heightened in those mares kept under moderate nutritional conditions during pregnancy.

Conclusions

• The study concluded that acute nutritional restriction caused by maternal illness and poor appetite, superimposed on a maintenance diet throughout pregnancy, amplified the insulin response to glucose in the foals.
• The process of nutritional programming of pancreatic beta cells in the foals appeared to rely on the conditions before and after the weight loss period, but the foals’ hypothalamo-pituitary-adrenal (HPA) axis function wasn’t affected.
• Finally, the research suggests that disturbances in neonatal pancreatic beta cell function programmed during pregnancy could predispose foals to metabolic problems as they grow.