Glycaemic and insulinaemic responses to mechanical or thermal processed barley in horses.

This research article explores how different methods of barley processing — mechanical or thermal — impact the blood sugar and insulin responses in horses.

Research Methodology

• The researchers tested five different variations of barley – whole (WB), finely ground (FGB), steamed (SB), steam-flaked (SFB), and popped barley (PB). The aim was to determine how the type of processing affected the pre-caecal starch digestibility (how the barley is digested before it reaches the caecum, a part of the large intestine).
• The barley allowance for each horse was adjusted to provide 630g of starch per day (approximately 1.2 – 1.5g of starch per kilogram of body weight), in addition to 6kg of grass hay per day.
• Over a ten-day period, each horse was exclusively fed one type of barley, in a random order, which allowed for an adjustment period to the new diet. On the final day, blood samples were taken at specific intervals for glucose and insulin analysis.

Findings

• Irrespective of type, barley feed resulted in a significant increase in plasma glucose and insulin levels within 30-45 minutes of feeding.
• The highest glucose and insulin responses were observed after intake of steam-flaked barley (SFB), which had a starch gelatinization (DG) of 28.7%. Starch gelatinization refers to the process by which starch granules swell and rupture, allowing enzymes to break down the starch more easily. It is considered a measure of how processable or digestible the starch is.
• The changes in glucose and insulin were more pronounced with popped barley (PB), having a DG of 95.6%, than with steamed barley (22.2% DG), finely ground barley (14.9% DG), and whole barley (also 14.9% DG).
• The highest peak plasma glucose varied between 5.72 ± 0.67 mmol/l with finely ground barley and 6.52 ± 0.64 mmol/l with steam-flaked barley.

Conclusion

• The results of the study confirm that the type of barley consumed does influence the post-meal changes in blood glucose and insulin levels. However, the study also found that the degree of starch gelatinization in the different barley products did not correlate with the most pronounced glycaemic or insulinaemic response. This suggests that other factors beyond the degree of gelatinization may be involved in influencing these responses.