Comparison of grass haylage digestibility and metabolic plasma profile in Icelandic and Standardbred horses.

The research studied and compared the digestive ability and metabolic responses of Icelandic and Standardbred horses when fed two different types of grass haylages. The results suggested Icelandic horses may have a greater tendency to maintain a positive energy balance compared to Standardbred horses, although there was no suggested indication of superior digestive capacity in Icelandic horses.

Introduction and Methodology

• This research aimed to explore differences in how Icelandic and Standardbred horses digest and metabolize two different types of grass haylages, harvested at various maturity stages.
• Six horses from each breed participated in a 24-day change-over design study, which allowed each horse to act as its own control, minimizing variability and increasing statistical power.

Data Collection and Analysis

• Total fecal collection was made on two periods (days 15-17 and 22-24) to evaluate the digestibility of crude protein, neutral detergent fiber, energy, and organic matter in the horse’s diet.
• Blood samples collected on the 24th day of each period were analyzed to determine levels of total plasma protein (TPP), plasma urea, non-esterified fatty acids, cortisol, and insulin concentration. The levels of these markers indicate each horse’s metabolic response.

Findings

• No significant differences were found in the digestibility coefficients of crude protein, neutral detergent fiber or energy between the two breeds. However, the Standardbred horses showed higher organic matter digestibility than the Icelandic horses.
• Weight gain was recorded in the Icelandic horses on both types of haylages, while the Standardbred horses lost weight. This suggests a stronger ability to maintain positive energy balance in Icelandic horses.
• The blood analysis results demonstrated that Icelandic horses had higher total plasma protein (TPP) levels and insulin concentrations but lesser plasma urea concentrations than the Standardbred horses.

Interpretation and Conclusion

• The results indicate that, although there is no significant difference in overall digestive capacity, the Icelandic horses seem to have a greater propensity to maintain a positive energy balance compared to the Standardbred horses. This could potentially influence the selection of horse breeds for various equestrian disciplines or breeding.
• However, it is important to note that further comprehensive studies may be required to fully understand the potential breed-specific variations in metabolism and digestion in horses.