Effects of Fat Feeding and Energy Level on Plasma Metabolites and Hormones in Shetland Ponies

Abstract

The aim of this study was to investigate the influence of a fat-supplemented diet compared with a carbohydrate diet on the lipid metabolism and the enteroinsular axis of Shetland ponies. The 'crossover' experiment was divided into two parts: in the first 10 weeks the diets comprised the correct number of calories according to requirements and in the following 10 weeks they were hypercaloric, in order to check the effect of a different energy content of the diets. Feeding the fat-enriched diet, independently of its energy content, led to a significant decrease in plasma triglycerides, associated with a mean 50% increase of plasma lipoprotein lipase activity. After oral glucose load the ponies on fat-enriched diets showed higher plasma glucose concentrations. Oral glucose administration after feeding the hypercaloric fat-enriched diet led to a 25-fold increase of plasma insulin levels. Glucose-dependent insulinotropic polypeptide plasma levels were increased in the animals on the fat-enriched diets. The results of this study suggest that fat feeding improves triglyceride clearance. However, the fat supplementation of the diet also led to impaired glucose tolerance. These results are important for a better understanding of the function of the enteroinsular axis. To investigate the influences of fat on lipid metabolism in relation to the aetiopathogenesis of equine hyperlipaemia further studies involving diseased animals are needed.

Plasma Leptin Level in Hyperlipidemic Mares and Their Newborn Foals

“…The normal range for plasma FFA in horses remains unknown, but in several studies, plasma FFA determined in horses at rest did not exceed 0.05 mmol ⁄ l (Schmidt et al 2001;Frank et al 2002;Kędzierski and Kowalik 2009). This amount was much smaller than demonstrated in this study.…”

“…The normal range for plasma FFA in horses remains unknown, but in several studies, plasma FFA determined in horses at rest did not exceed 0.05 mmol/l (Schmidt et al. 2001; Frank et al.…”

Enteroinsular axis response to carbohydrates and fasting in healthy newborn foals

“…The difference noted between these 2 study groups would be 500 mg/kg of galactose or another undetermined variable. Fat‐based diets in adult ponies previously have been demonstrated to stimulate GIP secretion after a PO glucose test when compared to ponies that had the same testing performed and were maintained on a carbohydrate‐based diet …”

Factors affecting clinical assessment of insulin sensitivity in horses

“…When ponies were fed very high levels of fat (23% of daily digestible energy) they showed higher glucose and insulin responses to an oral glucose load compared to ponies fed a nonfat supplemented diet (2% of DE) (Schmidt et al 2001). This was thought to indicate induction of insulin resistance by the fat supplemented diet (Schmidt et al 2001).…”

“…When ponies were fed very high levels of fat (23% of daily digestible energy) they showed higher glucose and insulin responses to an oral glucose load compared to ponies fed a nonfat supplemented diet (2% of DE) (Schmidt et al 2001). This was thought to indicate induction of insulin resistance by the fat supplemented diet (Schmidt et al 2001). Others have suggested that this is indicative of an adaptation to fat supplemented diet resulting in a glucose sparing effect where fatty acids are utilised in preference (Hoffman et al 2003a).…”