Hormonal responses to high and low planes of nutrition in weanling thoroughbreds.

The research article explores the role of nutrition in growth-related skeletal diseases in young horses, specifically Thoroughbreds. It evaluates the hormonal responses and metabolic impacts of two distinctive diet plans on these horses, indicating a clear distinction in their reactions to diets with different energy and protein contents.

Study Overview

• The study monitored the hormonal responses among eight Thoroughbred weanling horses that were provided with two different diet plans for a period of three weeks. The diets contained either 80% (the low diet A) or 160% (the high diet B) of the National Research Council’s recommendations for energy and protein intake.
• The aim of the study was to understand the relationship between nutrition and growth-related skeletal diseases commonly noticed in young horses.
• The researchers acknowledged that while a link between high nutritional intake and these years early diseases has been made, the mechanisms facilitating this association remain unclear.

Hormone and Metabolic Observation

• After 24-hour fasting periods, researchers observed that the prefeeding serum concentrations of hormones thyroxine (T4) and insulin, and plasma concentrations of glucose, total protein, total triglycerides, creatinine, Ca and P were similar regardless of which diet the horses had been consuming.
• However, horses that had been eating the high diet B had higher serum cortisol concentrations when they were fasted.

Post-Meal Observations

• Post-meal, both thyroxine, insulin, and glucose concentrations increased in horses on both diet plans.
• Interestingly, after consuming diet A, T4 concentrations increased to about 150% of fasting concentrations. In contrast, after consuming diet B, T4 concentrations fell to about 85% of fasting concentrations.
• Glucose concentrations rose during the first hour after the meal, but decreased more rapidly among horses that fed on diet B.
• Insulin levels also rose more rapidly in horses that had been on diet B.
• In general, cortisol levels decreased after meals, regardless of the diet, and the concentrations of the other measured metabolites were not affected by diet or meal consumption.

Implications

• The study indicates that the type of diet and its nutritional content can significantly influence the hormonal and metabolic responses in young Thoroughbred horses.
• This can have implications for understanding and potentially mitigating the impact of diet on growth-related skeletal diseases.