Voluntary Energy Intake and Expenditure in Obese and Lean Horses Consuming ad libitum Forage

• Published in: Journal of equine veterinary science Vol. 74; pp. 13 - 20
• Main Authors: Moore, Jennifer L., Siciliano, Paul D., Pratt-Phillips, Shannon E.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.03.2019
• Subjects: Energy expenditure; Horses; Intake; Obese; Energy expenditure; Horses; Intake; Obese
• ISSN: 0737-0806; 1542-7412
• DOI: 10.1016/j.jevs.2018.12.020

Some horses are more prone to obesity than others. This study aimed to compare energy intake and expenditure between obese and lean horses. Ten mature, stock-type geldings (aged 11.8 ± 4.0 years; 577 ± 52 kg) maintained on the same pasture were classified as obese (n = 6, body condition score [BCS] ≥ 7) or lean (n = 4, BCS = 4–5) and adapted to free-choice grass hay over 25 days. Dry matter intake (DMI) was measured for 11 days, with body weight (BW) and blood samples (analyzed for serum leptin) collected on Days 0, 2, 4, 7, 9, and 11. Behavior was observed for 24 hours. Apparent dry matter digestibility and gross energy digestibility were measured using 48-hour total fecal collection. Digestible energy intake was calculated. Activity (distance traveled, average heart rate [HR], and maximum HR) was quantified using HR monitors with GPS tracking. Average HR was used to estimate energy expenditure. Serum leptin, DMI, and BW were analyzed as repeated measures. Other variables were analyzed using unpaired t-tests. P < .05 was considered significant. Serum leptin, intake, digestibility, and activity were not affected by group. Dry matter intake was correlated with average HR (r = 0.70; P = .03). Obese horses spent more time active (interacting with other horses, moving around; P = .003) and less time eating (P = .03). Overall, the results of this study identified some differences in behavior but did not identify any differences in energy intake or expenditure between obese and lean horses. •Horses managed under the same conditions often show large variation in body condition.•Innate differences in energy intake, digestibility, behavior, or energy expenditure may account for some of this variation.•Horses that naturally maintained either obese or lean body condition showed no differences in energy intake, digestibility, or estimated expenditure at maintenance, suggesting that these factors do not significantly contribute to the observed variation in maintained BCS.•Obese horses spent more time interacting with neighboring horses than lean horses, potentially reflecting differences in dominance.