Journal of Equine Veterinary Science
Original ResearchThe Effect of Feeding Two or Three Meals Per Day of Either Low or High Nonstructural Carbohydrate Concentrates on Postprandial Glucose and Insulin Concentrations in Horses
Introduction
The inclusion of starch-rich concentrate feeds is a common practice among horse owners in an effort to increase the caloric density of the horse's diet [1], [2]. The inclusion of meals high in nonstructural carbohydrate (NSC) is associated with increased risk of colic [3] and reduced tissue sensitivity to insulin [4], [5]. If a horse is fed ample concentrate (>2 kg/d), feeding these concentrate meals only one or two times per day may result in larger meal sizes and may result in altered postprandial metabolite concentrations [6], [7], [8], [9], fluid balance [10], and behavior [10], [11].
Repeated postprandial increases in insulin concentration (such as those observed after the intake of large amounts of NSC) appear to decrease the tissue sensitivity to insulin [4], [12]. Insulin resistance (IR) is defined as a decrease in the sensitivity to insulin at tissues such as the liver, skeletal muscle, and adipose tissue [13]. Because of the association of IR with equine laminitis [14], [15] and equine metabolic syndrome [16], [17], it is of interest to identify feeding and managerial practices to reduce the risk of IR development.
Despite potential negative health consequences associated with the feeding of large meals rich in NSC, concentrate feeding is often a necessary component of the diet, particularly for those horses with elevated nutritional needs. Further, concentrate often provides amino acids, vitamins, and minerals lacking in the forage. Therefore, it is of interest to investigate methods that attenuate the risks associated with feeding concentrates. The inclusion of fat and fiber calorie sources to replace NSC calories is one method of decreasing the NSC load for a horse [13], and such a practice may decrease the risk of IR [4]. Decreasing the rate of feed intake by use of obstacles in the feed tub is another method that may be used to minimize the insulinemic response to a high (26%; 52 g/100 kg body weight [BW]) NSC feed [18]. Increasing the number of meals per day (MPD) (if total caloric intake from concentrate is held constant) may have a similar effect, as horses would receive smaller amounts concentrate at each meal and would likely have smaller NSC loads. Smaller meals tend to result in smaller postprandial metabolite changes [6], [8], [19].
The present study was designed to investigate if both meal frequency and dietary energy source affect postprandial changes in glucose and insulin concentrations in horses. It was hypothesized that increasing meal frequency and thus decreasing meal size would have additive benefits to feeding meals with a greater proportion of the calories coming from fat and fiber, rather than from NSC.
Section snippets
Materials and Methods
All research techniques were approved by the North Carolina State University Institutional Animal Care and Use Committee.
Results
All horses maintained BW and condition throughout the study and consumed all feed offered with no complications.
There were no significant interactions between MPD and NSC for any variable assessed. Therefore, the effects of MPD and NSC on metabolite concentrations were not additive and could be considered independently. Glucose and insulin concentrations are shown in Fig. 1.
Discussion
The results of this study show that concentrate feeds rich in NSC have an impact on both baseline and postprandial insulin responses in horses. Horses fed 0.5% of their BW per day of a high NSC concentrate (43% NSC) resulted in elevated baseline insulin concentrations, elevated baseline GIRs, and larger postprandial insulin responses, including the AUCI and the peak insulin concentration after feeding, compared with those fed 0.5% of their BW of a lower NSC concentrate (18% NSC).
The number of
Conclusions
For horses at risk of developing IR and/or equine metabolic syndrome and/or laminitis, it is important to limit NSC intake, by decreasing the concentration of NSC in the feed (hay, pasture, and concentrate) and potentially by decreasing the NSC load at each meal [31]. The results of this work and of others suggest that there may also be some benefit to reducing meal size and consumption rate to reduce the postprandial insulin concentrations [18], [19], [32]; however, more work is required in
Acknowledgments
This article was funded in part by the North Carolina Horse Council.
References (32)
- et al.
Survey of feeding practices, supplement use, and knowledge of equine nutrition among populations of horse owners in New England
J Eq Vet Sci
(2009) - et al.
Responses of blood glucose, insulin and cortisol concentrations to common equine diets
J Nutr
(1988) - et al.
Digestibility of a complete ration in horses fed once or three times a day and correlation with key blood parameters
Vet J
(2007) - et al.
Effect of meal frequency on fluid balance and behavior in ponies
Physiol Behav
(1988) - et al.
The short-term effects of increasing meal frequency on stereotypic behaviour of stabled horses
App Anim Behav Sci
(2005) High-insulinogenic nutrition–an etiological factor for obesity and the metabolic syndrome?
Metabolism
(2003)- et al.
Insulin resistance in equids: possible role in laminitis
J Nutr
(2006) Equine metabolic syndrome
Vet Clin North Am Equine Pract
(2011)- et al.
The effects of non-structural carbohydrate content and feeding rate on glucose and insulin response to meal feeding in equine
J Equine Vet Sci
(2007) - et al.
Colonic fermentation of indigestible carbohydrates contributes to the second meal effect
Am J Clin Nutr
(2006)
Variation of insulin sensitivity estimates in horses
J Equine Vet Sci
Assessment of resting insulin and leptin concentrations and their association with managerial and innate factors in horses
J Eq Vet Sci
Metabolic syndrome-From human organ disease to laminar failure in equids
Vet Immunol Immunopathol
Dietary management of obesity and insulin resistance: countering risk for laminitis
Vet Clin North Am Equine Pract
The effects of feed form on consumption time and glucose and insulin response to a concentrate meal in equine
J Equine Vet Sci
The effect of current grain feeding practices on hindgut starch fermentation and acidosis in the Australian racing Thoroughbred
Aust Vet J
Cited by (3)
Evaluation of glucose and insulin response to haylage diets with different content of nonstructural carbohydrates in 2 breeds of horses
2018, Domestic Animal EndocrinologyCitation Excerpt :From this relationship it can be estimated that a 50% reduction in NSC content would result in roughly a 25% reduction in insulin response. Several studies in horses have evaluated the postprandial glucose and insulin response after intake of diets rich in starch and/or NSCs [10–12,26,31,32]. To the best of our knowledge, this is the first study that investigates the effect of different NSC content in haylage diets on the glucose and insulin response for horses of different breeds.
A one-health lens offers new perspectives on the importance of endocrine disorders in the equine athlete
2023, Journal of the American Veterinary Medical Association