Gluconeogenesis from caecal propionate in the horse

Area of Science:

• Equine nutrition
• Gastrointestinal physiology
• Metabolic studies

Background:

• The caecum plays a crucial role in hindgut fermentation in horses.
• Understanding volatile fatty acid production, like propionate, is key to equine energy metabolism.
• Dietary components can influence caecal fermentation and nutrient absorption.

Purpose of the Study:

• To quantify caecal propionate production in ponies fed different diets.
• To assess the contribution of caecal propionate to total glucose production.
• To determine the impact of diet on these metabolic parameters.

Main Methods:

• Two Shetland-type ponies were fitted with caecal and colonic cannulas.
• Intracaecal infusion of 14C-labelled sodium propionate and intravenous infusion of [2-3H]glucose were employed.
• Samples were collected from the right ventral colon to measure propionate and glucose production rates.

Main Results:

• Caecal propionate production was significantly higher on a hay and wheat bran diet (34.0 mg/h/kg BW) compared to a hay-only diet (19.6 mg/h/kg BW).
• Total glucose production rates were consistent across both diets and between ponies.
• Approximately 7% of total glucose production was derived from caecal propionate, irrespective of diet.

Conclusions:

• Diet composition, specifically the inclusion of wheat bran, influences caecal propionate production in ponies.
• Despite dietary effects on propionate production, overall glucose homeostasis appears maintained.
• Caecal propionate contributes a small but consistent fraction to the total glucose pool in horses.