32 Exercise versus feed restriction: What is the most efficient weight loss option for your fat horse?

Abstract

In first world countries, 45–75% of domesticated horses are considered overweight. Accumulation of excessive fat mass puts horses at risk for co-morbidities such as systemic inflammation and osteoarthritis. The objective was to characterize weight loss in overweight horses during 10 weeks of feed restriction, exercise, or both. Thirty-two horses, 4 geldings and 28 mares, mean age of 14 ± 4, with a body condition score (BCS) of at least 7/9, were fed controlled, individualized hay feedings 3 times a day with a concentrate meal. Diets were based on horse's body weight (BW) (kg) and calculated using FeedXL. Horses were randomly allocated into one of 4 treatment groups, Daily Exercise (E), Feed Restriction (FR), Feed Restriction & Daily Exercise (FRE), or unrestricted sedentary Control (C). The C and E horses were fed 100% of their Digestible Energy (DE) requirements, while FR and FRE horses were fed 85%. The E and FRE groups underwent submaximal unridden exercise, with a consistent working heart rate of 150 bpm, for 20 min, 5 times a week, with a walking warm-up and cooldown, with the approximate DE loss of 15% based on the NRC. In wk 1, 5 and 10, morphometric measurements were recorded, including BW (kg, via weight tape), cresty neck score (CN) (/5), whole body BCS (/9) and individual BCS (/9) for 8 different anatomical locations. Original mean BCS for all treatment groups was 7 ±0.2. Original BW (kg) for each of the treatment groups are as follows: C 486 ± 11, E 501 ± 11, FR 485 ± 12, and FRE 469 ± 11. Statistical analysis was performed using SAS Studio. Data were analyzed using 1-Way RM ANOVA for individual treatments and 2-Way RM ANOVA to determine significant (P ≤ 0.05) effects of and interactions between time and treatment. There was a reduction in BW across time for all groups (P < 0.0001). The mean weight loss (kg) for each treatment group are as follows: C 28kg, E 31kg, FR 27kg, FRE 36kg. The CN score was reduced in E and FRE horses (P = 0.01; P = 0.02). Whole body BCS was reduced in E (P < 0.0001), FR (P = 0.001) and FRE (P < 0.0001). Treatment group affected anatomical BCS of the tailhead and shoulder (P = 0.05 and P = 0.01), with FRE having the greatest reduction (P = 0.0005 and P = 0.001,). Anatomical BCS loss at the withers was found to have an interaction between time and treatment (P = 0.02). In conclusion, although all horses lost BW, there were differences in how the treatment groups lost fat mass, with exercise programs having a significant effect on the change in CN, tailhead and shoulder fat mass. Therefore, the most efficient weight loss program, is that of combining both daily exercise and feed restriction.