Interval exercise alters feed intake as well as leptin and ghrelin concentrations in standardbred mares.

The research explores how high intensity interval exercise affects the food intake and certain hormonal concentrations in standardbred horse mares, specifically ghrelin and leptin. It uncovers that such exercise seems to decrease food intake and alter the levels of these hormones.

Research Objective and Methodology

The study aims to understand why horses in training often become inappetant, or lose their appetite, and whether this has any correlation with changes in hormonal or biochemical responses induced by rigorous training and/or health conditions like ulcers. The hormones under consideration are ghrelin (related to hunger), leptin (associated with satiety), glucose, insulin, and cortisol, as these can potentially influence appetite and overall health.

Across the three-phase testing stage, eight standardbred mares participated. The stages covered:

• An initial exercise test (IET1) prior to any training
• A follow up test after 8 weeks of high-intensity training (IET2)
• Another follow-up test post ulcer treatment (IET3).

Three respective control tests (CON) were performed in parallel. Blood plasma samples were collected at different time intervals before, during, and after exercise to measure the hormonal and biochemical parameters. The subject horses underwent physical training involving 70% of Heart Rate maximum for 30 minutes per day, 5 days a week, during which their food intake was recorded.

Key Findings and Conclusions

The control trials did not show any significant changes in the variables. However, when it came to the exercise regime, there were interesting findings.

The horses undergoing exercise did not meet their Digestible Energy requirements, implying a troubling gap between energy intake (food) and expenditure (exercise). During all the three IETs, significant increases (P<0.05) were noted in the concentrations of ghrelin, glucose, and cortisol during exercise. Leptin concentrations significantly increased only in the post-training IETs, and insulin remained low during exercise but started to surge post-exercise.

These results underscore the fact that high-intensity exercise seems to cause a decrease in food intake and alter the hormonal balance, particularly in terms of ghrelin and leptin. It calls for more detailed research into whether these hormonal changes are indeed responsible for weight loss in horses undergoing training.