Interpretive Summary: Development of a mathematical model for predicting digestible energy intake to meet desired body condition parameters in exercising horses.
By: Jackie Walling
A new article coming soon in the Journal of Animal Science used DE intake as a nutritional model to predict changes in body condition score (BCS) of exercised horses. Currently, nutritionists have revised a model used on cattle to predict the BCS of sedentary horses, and are determining if applying exercise energy expenditure estimates to the existing model will accurately predict changes in the BCS of exercising horses.
Twenty-four horses with similar condition were divided by intention to increase (I) or decrease (D) BCS and by exercise level: no exercise, light exercise, and high exercise. Exercise was conducted under a structured regime with an assigned rider to ensure uniformity. Researchers evaluated BCS, BW, and rump fat thickness (RFT) every two weeks over a period of 60 days. Three independent appraisers scored BCS.
For I and D groups, there was an expected change in BCS by day interaction for body fat (BF), RFT, and BW. There was also a BCS by exercise interaction for all three parameters which suggests the equations for measuring exercise energy expenditure are not adequate for predictions. A statistical linear regression analysis found a 16.47kg change in BW was needed to make a change in BCS. While a linear model is not practical to predict all situations, it estimated a mean change in BW per change in BCS was 3.4% of the overall mean BW.
In conclusion, the current study fine-tuned the previous model when predicting DE requirements to alter BCS in sedentary horses because of the high precision and accuracy of observed results when compared to predicted results in non-exercised horses. Precision was less reliable when the model was applied to horses in exercise, especially for those under heavy work. It is possible that horses under heavy work adapted, increasing their fitness and improving their heart rate. Moreover, this adaptation could have altered the use of DE. These results suggest that determining the amount of DE to maintain a BCS in exercised horses is need before a model can be applied.
For the full article, visit the Journal of Animal Science.