Serum triiodothyronine and thyroxine concentrations in weanling horses fed carbohydrate by direct gastric infusion.

This study measured the blood glucose and hormone levels in young Thoroughbred horses after being directly fed solutions containing sucrose or casein. They found significant rises in glucose and hormone levels only after administering high amounts of sucrose, and these effects depended on the quantity of carbohydrates.

Objective of the Research

The research aimed to explore the effect of direct gastric infusion of carbohydrate solutions, particularly sucrose or casein, on serum hormone and plasma glucose levels in weanling Thoroughbred horses. The goal was to assess the physiological responses triggered by carbohydrates in the digestive tract of these young horses, focusing on blood glucose and hormones such as insulin, thyroxine, and triiodothyronine.

Methodology

• The study involved 6 weanling Thoroughbred horses.
• These horses were subjected to direct gastric infusion with varying solutions: water, 326 or 424 g of casein per 250 kg of body weight, or 649 or 844 g of sucrose per 250 kg of body weight.
• Following the infusions, the researchers regularly checked and recorded the horses’ plasma glucose levels and serum concentrations of insulin, thyroxine, and triiodothyronine.

Findings of the Study

• Neither the infusion of water nor casein influenced the plasma glucose or serum hormone levels of the participants significantly.
• The researchers found that there was a significant increase (P less than 0.001) in plasma glucose and serum hormone concentrations when the horses were infused with 649 or 844 g of sucrose per 250 kg.
• The rate of increase in these levels was faster, and the subsequent reversal was also more rapid when the horses were infused with 844 g of sucrose rather than 649 g.
• This study revealed that soluble carbohydrates in the digestive tract initiated specific responses in the serum thyroid hormone levels of weanling horses.
• Furthermore, the team noticed that the magnitudes and durations of these responses seemed to depend on the quantity of the carbohydrate introduced.

Conclusion

This research has shed new light on the physiological responses of young Thoroughbred horses to ingested carbohydrates. It has shown that high quantities of sucrose directly fed to the stomach have significant effects on plasma glucose and serum hormone levels – findings that may be crucial in understanding horse nutrition and health. Future research needs to be done to find out how this fluctuation in hormone levels might affect the growth and metabolism of weanling horses.