Evaluating a novel automatic feeding device for hay provision in horses: behavioral outcomes in group and individual housing.

INTRODUCTION

This study evaluated a novel Automatic Feeding Device (AFD) for hay provision in group-housed and individually housed horses.

METHODS

In Phase 1 (P1), behavioral responses to ground hay feeding (Control-Hay) and to hay delivery through the AFD were assessed in three group-housed mares under two conditions: AFD continuously open (O-AFD) and AFD alternating between open and closed periods (OC-AFD). In Phase 2 (P2), four individually housed horses were used to evaluate the behavioral effects of three AFD opening-closing schedules: long opening (LO-OP), medium opening (ME-OP), and short opening (SH-OP). Behavioral data were collected by continuous video recording. Data were analyzed using linear mixed-effects models, with treatment as fixed effect and horse as random effect (experimental unit). Principal component analysis was used to explore variability in agonistic behaviors among group-housed horses.

RESULTS AND DISCUSSION: In P1, individual differences in foraging activity and agonistic behaviors were observed. Exploratory behaviors increased significantly when the AFD alternated between open and closed periods compared with when it remained open (3.93 ± 3.36 vs. 1.72 ± 3.86 min/h; p = 0.010). Compared with Control-Hay, which resulted in no residual hay, AFD delivery increased residual hay, averaging 3.98 ± 0.77 kg in O-AFD and 4.88 ± 1.00 kg in OC-AFD (p < 0.001). Social hierarchy strongly influenced access to the AFD in group-housed horses. In P2, foraging from the AFD declined progressively from LO-OP and ME-OP to SH-OP (46.91 ± 0.81, 42.80 ± 1.65, and 38.84 ± 0.89 min/h, respectively; p < 0.001). Stress-related behaviors directed toward the AFD were most frequent during SH-OP: pawing occurred up to seven to eight times more often than in LO-OP and ME-OP, while rubbing and teeth or tongue use were approximately two to three times higher. Residual hay increased progressively as access duration decreased (p < 0.001), accompanied by a slight reduction in hay intake rate. Behavioral responses to the AFD were influenced by social dynamics in group-housed horses and feeder access schedule in individually-housed horses. The medium opening interval (40 min open, 20 min closed) appeared to provide the most appropriate balance between regulating hay intake, maintaining feeding behavior and limiting stress-related behaviors.