Influence of body fat content on digestible energy requirements of exercising horses in temperate and hot environments


Six mature horses were used to determine the energy requirements of exercising horses during different seasons and in different body conditions. Horses were conditioned to work 7.2 km in 30 min 5 d/wk and fed to either a fleshy or moderate body condition during both hot (temperature mean 32.4 C, with a 23.9–36.1 C range) and temperate (temperature mean 17.4 C, with a 3.9–27.8 C range) seasons. Horses were fed average quality Bermuda grass hay at .75% of body weight sufficient concentrate to maintain body weight and condition. During each combination of body condition and season when body weight, condition and feed intake were stable for 14 d horses were declared at energy equilibrium and a digestion trial was conducted. Horses in fleshy body condition (7.5) required 2.3 kg/d more total feed than horses in moderate (5.2) body condition. When expressed in terms of digestible energy (DE) intake, fleshy horses required 11.12 kcal/kgBW/d more than horses in moderate flesh. When DE for maintenance (DEM) was calculated as the difference between DE intake and DE for work (DEW), DEM for horses in fleshy condition exceeded that of horses in moderate condition by 11.3 kcal/kgBW/d (P<.01). Seasonal effects on feed and DE intake were not as apparent as the effect of body condition. These data indicate that body condition is a significant consideration when estimating DE requirements for the performance horse in all seasons and that optimum body condition for the performance horse may vary according to ambient temperature and humidity at the time of performance. © 1990, William E. Jones, All Rights Reserved. All rights reserved.

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Journal of Equine Veterinary Science