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

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

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.

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.