Impact of feeding level on digestibility of a haylage-only diet in Icelandic horses.

The research article explores how the level of feed intake affects the digestibility of a haylage-based diet in mature Icelandic geldings. The study found that the digestibility and energy value of early cut haylage in the horses significantly varies with the feeding level.

Study Design

• The study used a sample of eight mature Icelandic geldings and was structured as a change-over design experiment. This specific design was chosen to evaluate changes in one variable (in this case, the feeding level) while other factors remained constant (the same group of horses, same feeding type).
• Each horse was subject to two feeding levels: a low level of 10.7 g dry matter (DM) per kg body weight (considered as the maintenance level) and a higher level of 18.1 g DM per kg body weight, equivalent to 1.5 times the maintenance level.
• Both feeding levels were administered over two experimental periods, each lasting 23 days.

Data Collection

• Data was collected with the total collection of faeces for six days at the end of each feeding level period to determine the coefficient of total tract apparent digestibility (CTTAD).
• The CTTAD values for various constituents such as dry matter, organic matter, neutral detergent fibre (NDF), acid detergent fibre, and energy were compared at different feeding levels.

Findings

• The CTTAD for most constituents, excluding crude protein, was higher when horses were fed at the lower intake level, suggesting better digestibility at lower feeding levels.
• The largest difference in digestibility between the feeding levels was found for NDF. This indicates that high levels of feeding may particularly affect the digestion of fibrous components.
• Measurements also showed that the digestible energy content of the haylage per kilogram of dry matter was higher at the lower feed intake level (11.3 MJ) compared to the high level (10.6 MJ).

Conclusions

• In conclusion, the feeding level significantly influences the digestibility and energy value of an early cut haylage diet in Icelandic geldings.
• The results of this study hold importance for proper nutritional management and planning in horse feed programs, particularly highlighting the need to consider the balance between feeding levels and digestibility.