Dietary protein and energy restriction in mares: rapid changes in plasma metabolite and hormone concentrations during dietary alteration.

The research article investigates the effect of dietary changes in horse mares, focusing particularly on the alteration from a full diet to a half diet in protein and energy, and the subsequent impacts on plasma metabolite and hormone concentrations. By examining these changes, the study highlights the importance of early sampling in understanding nutrient alterations and metabolic responses.

Objective and Methodology

• The main objective of this study was to examine how rapidly dietary modifications can affect plasma metabolite and hormone concentrations in mature mares.
• Two dietary plans were adopted for the research. The first was a control diet providing 100% of the protein and energy requirements for horse mares. The second one was a restricted diet offering only half (50%) of the required protein and energy.
• Twelve mares were initially given the control diet for 7 days. Then, six of them were switched to the restricted diet, which was served in two equal portions during the day. After a week on the restricted diet, the six mares were reverted to the control diet.

Key Findings

• Immediately after the transition to the restricted diet, the tested mares had significantly lower plasma concentrations of glucose and insulin.
• This reduction occurred in response to the two restricted meals served on Day 0 of the dietary change.
• However, these concentrations of glucose and insulin normalized, returning to control levels one hour after resumption of the control diet on Day 7.
• Conversely, the researchers observed an increase in plasma NEFA concentrations within the first 24 hours of dietary restriction. These elevated levels persisted until the mares returned to the control diet.
• The study also noted meal-induced increases in plasma concentrations of glucose, insulin, urea Nitrogen (N), glucagon, and thyroxine.

Significance and Implications

• The results of the research emphasize the necessity and significance of early sampling when monitoring plasma constituents during nutrient alterations.
• The findings suggest that the prefed responses of plasma constituents may not be sufficient to encompass the full metabolic consequences of dietary restriction.