49 Effects of different hay feeders, availability of roughage on abnormal behaviors and time budget of horses kept in dry lots

Abstract

Limited availability of forage may be the main factor related to the development and prevalence of abnormal and stereotypic behaviors in horses. Offering forage ad libitum could be the best option regarding horses’ welfare, but is associated with increases in body weight (BW), BCS, waste of hay and obesity. Devices such as hay-nets/bags, box- and slow-feeders have been developed to decrease food waste, but there is little knowledge on how they can affect the horses' time-budget (TB). TB is the daily amount of time an animal engages in all behavioral activities. Differences in the TB of domesticated horses compared with feral conspecifics in their natural environment can be used to reveal welfare impairment. The objective of this study was to compare the effects of feeding free choice hay (FC), to a slow feeder (SF) and an automated box feeder (BF) on equine behavior by 24-h continuous sampling (CS). The study was designed as a 3 × 3 latin square design with 15 mixed Thoroughbred polo horses (14.9 ± 4.1 years) divided into 3 social groups of 5 horses (cohabited pens for previous 6 mo) randomly assigned to one of the treatments for 15 d. Horses were hept in dry lots, had access to water, salt and mineral blocks. BW and BCS were assessed biweekly. The animals’ behavior was recorded during the last 24 h of the last day of each treatment period and the video analyzed with CS. The time spent in stereotypic,abnormal behaviors and other activities was evaluated second-by-second, averaged in minutes, and used for the determination of the animals’ TB. The effects of the different feeders were analyzed in ANOVA in a mixed model with repeated measures. Horses in FC consumed and wasted more hay (16.6 ± 0.5kg/horse/day) (P < 0.001), compared with BF (10.4 ± 0.5 kg/horse/day), and SF (9.30 ± 0.45 kg/horse day), where BF and SF had similar intake and less waste. Horses on FC had the highest weight gain (P < 0.001, 23.5 ± 4.6kg), whereas BF gained 1.2 ± 5.7 kg and SF 0.37 ± 4.6 kg (P = 0.092). Horses in FC spent 744 ± 26 min, and SF 791.16 ± 27 min (P = 0.21), meaning more than 50% of the TB foraging, generating a time distribution similar to grazing horses. Horses on BF treatment spent the lowest time eating (P < 0.001), 371.6 ± 32.3 min, or 25.81% of their TB, increasing (P < 0.050) the time spent in other activities (standing attentive, sniffing the ground, and practicing coprophagy). The level of aggression between conspecifics became higher as the feed became less accessible, with horses in BF showing highest levels of aggression(P < 0.043). Slow feeders are a good option to mimic natural TB.