The effect of restricted diet and slow-feed hay nets on body weight and morphometric measurements in adult horses
Horses evolved to consume several small, frequent meals throughout the day. However, modern horse care has resulted in many horses being stalled for large portions of the day, and meal fed, therefore decreasing their ability to forage. This management scheme has likely contributed to the increase in obesity in the equine population. The use of slow-feed hay nets represents an opportunity to extend foraging time while restricting forage intake. Therefore, the objective of this study was to determine if restricted feeding coupled with increased time to forage consumption would lead to weight loss in over-weight adult horses. Eight adult Quarter horses (BW 562 kg ± 2 kg) were used in a completely randomized design, with 4 horses assigned to a control (C) of feeding hay off the stall floor, and 4 horses assigned to feeding from a slow feed (3.2 cm openings) hay net (SN). Horses were fed at 1.08% BW, split evenly between two meals. A ration balancer was fed at recommended levels during the morning feeding. Body weight, via a livestock scale, and BCS were measured on d 0, 7, 14, 21, 28, and 35. Morphometric measurements, including neck and girth circumference and cresty neck score, a system developed to estimate the level of adiposity on the crest of the neck using a 0 to 5 scale, were taken on d 0, 14, 21, and 35. Ultrasound measurements of average rump fat, longissimus dorsi (LD) depth and LD thickness were taken on d 0, 21, and 35. Data were analyzed using the Proc Mixed procedure of SAS. All horses lost weight over the 35 day period (P < 0.0001), however; no difference was observed between the SN and control. Horses on the SN lost an average of 40 kg, while horses on the C lost an average of 32 kg. There was no difference observed in BCS, neck and girth circumference, or cresty neck score during the study or between treatments (P ≥ 0.25). Additionally, no differences were observed in rump fat, LD depth, or LD thickness during the study or between the treatments (P ≥ 0.32). While all horses lost weight on the restricted diet, the use of a slow feed hay net did not have an effect on weight loss or morphometric measurements during the 35 d study.
Keywords: restricted diet, weight loss, slow-feed hay net