Icelandic horses vs. trotters, who are best at digesting forage?
In this study six Icelandic horses and six Standardbred trotters ability to digest forage was compared. Two grass haylages were used and all horses were tested on both forages. Haylage 1 was harvested after heading and haylage 2 was harvested after seeding.
Figure 1 shows digestibility of organic matter, the fibre fraction NDF and crude protein for the Icelandic horses and the trotters on both the early and the late harvested haylage. Organic matter is dry matter minus ash. There were no differences between the two breeds ability to digest the forage, except for organic matter when they ate the early harvested haylage. The trotters had 2.9 % higher digestibility of organic matter than the Icelandic horses on haylage 1.
This study shows that there does not seem to be a big difference in these two breeds capacity to digest forage. However, during the study the Icelandic horses gained weight and the trotters lost weight. There were no differences in the horses feed intake per kg body weight (the trotters had a slightly higher energy intake on haylage 1) and they were fed based on prior experience of their requirements. The Icelandic horses still had higher body condition scores (BCS) and thicker rump fat than the trotters; they were fatter. This shows that the trotters had higher energy requirements and this can be due to that they had higher voluntary activity and/or that they had higher maintenance requirements because of a more energy requiring body tissue composition (less fat, more muscle).
The Icelandic horses had a bigger appetite and the trotters’ appetite did not correspond to their energy needs (since they lost body weight), which demonstrates the phenomenon of easy keepers and not so easy keepers. The Icelandic horses were in the range of normal to easy keepers and the trotters were in the range of normal to hard keepers.
Sara Muhonen, AgrD
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