83  Acceptability of red clover hay and associated eating behaviors of horses when compared to timothy hay

Forage preference and eating behaviors are influenced by prior exposure to a forage species and forage maturity. Therefore, introducing new forages to horses can be challenging. This study aimed to compare horse behavior and acceptance of hay, when given a choice between timothy hay (TH) and red clover hay (RCH); a subobjective of a study also evaluating in vitro fermentation. Twelve Thoroughbred horses were blocked by weight and sex and randomly assigned to TH (n = 8) or TH+20% RCH (n = 4) diet, the unbalanced design due to a dietary treatment not reported here. The study included 2 periods of 4 weeks (n = 6/period) to accommodate the 12 horses. Horses were housed and fed in partially covered individual runs (3 × 12m) and turned out daily in paddocks with muzzles (9:00–15:00) that allowed water consumption. Horses participated in 3 preference tests (PF): one in wk 2 and 2 in wk 4. Horses were on pasture before the study, and transitioned to hay only diets during wk 1. Each successive PF served to test acceptability with continued exposure. On PF days horses were brought inside from turnout, but instead of receiving a full allotment of hay, were provided with a pre-weighed amount of hay in bins and observed for 1 h. Orts was weighed back. Horses (n = 8) allocated to TH diet received TH in both bins, serving as controls. Horses (n = 4) allocated to TH+RCH treatment received TH in one bin, and RCH in the other. Each PF occurred over 2 consecutive days, where hays were switched between bins and results averaged between days. Behavior assessment included the first bin approached, sniffed and consumed from, drinking water, switching bins, or no eating. Data were analyzed as repeated measures ANOVA (SAS 9.4). Bin placement had no effect (P > 0.05). The PF total hay intake did not differ between TRT or time (P > 0.05). Consumption of RCH decreased from PF 1 to 2 (P < 0.01) and then remained the same (P = 0.71). Horses consumed 47%, 26%, and 20% of total intake as RCH during each PF respectively, therefore replacing RCH with TH over time. Horses first approached and sniffed RCH 86% and 79% of the time, but only consumed RCH first 50% of the time. Horses on average drank twice, the first drink within 27 min of PF. Horses stopped eating (>1 min) on average 3 times. Behavior observations indicated a willingness to eat both hays, but TH was preferred over the long-term, whether due to differences in maturity or other sensory factors. Average voluntary RCH intake was 30.7%. In practice RCH will likely be fed at 15–20% of total intake. Thus, willingness to consume RCH at these reported levels is a valuable outcome for practical application.