62 Feeding steamed or soaked hay affects water intake and preference compared to dry hay

Abstract

Stalled horses frequently experience respiratory disease. Soaking or steaming hay before feeding is a common strategy to reduce exposure to irritants. However, the effects of hay treatments on water intake and fecal dry matter (DM) are not well understood. We hypothesize that water intake is higher when feeding dry hay compared with feeding soaked or steamed hay and that fecal DM is related to water intake and DM intake. This study also evaluated preference for steamed, soaked, or dry hay when given a choice. Six mature horses (>3yr; 3 mares and 3 geldings, avg weight 558 kg, range 528–624) of mixed breeds were used. Horses were randomly assigned to either soaked, steamed, or dry hay for 5 d then treatments were rotated weekly with a 2 d washout between treatments. Hay (1.3% of BW, DM) was soaked for 30 min at room temperature or steamed (reaching 76°C by 90 min). Hay treatments were grab sampled weekly. Water intake and hay intake were measured gravimetrically each morning after horses were stalled overnight. Each morning, recently voided feces were collected from each horse. Hay and fecal samples were dried to a steady weight (24 h at 55°C) to determine DM. A preference study was conducted with the 6 adapted horses and 6 new horses. Horses were offered all 3 hay types simultaneously (1 kg each type for 1 h) and remaining hay was recorded. Data were analyzed using mixed model ANOVA with day as arepeated measure and treatment and day as main effects (SAS 9.4). There was a main effect of treatment on water intake (P = 0.0001). Horses fed dry hay drank more water compared with horses fed soaked hay (2.57 ± 0.290 and 1.10 ± 0.290 L/100 kg BW, respectively; P < 0.05). Moreover, DM intake was not influenced by hay treatment (P = 0.4463) but there was a change in DM intake over time (P = 0.0019). DM intake was the lowest on d 1 then increased by d 5 (0.96 ± 0.024 and 1.05 ± 0.034 kg/100 kg BW, respectively; P < 0.05). There was a positive relationship between DM and water intake (r = 0.2106; P = 0.0464) and a negative relationship between DM intake and fecal DM (r = −0.2395; P = 0.0230). The preference study revealed that non-adapted horses tended to consume more steamed hay compared with horses adapted to steamed hay (P = 0.0676), whereas horses adapted to treatments tended to consume more soaked hay compared with non-adapted horses (P = 0.0946). Overall, these results indicate that water is an important management consideration when feeding horses dry, steamed, or soaked hay. Moreover, when modifying hay types or treatments in a horse's diet, time for adaptation is necessary to ensure adequate intake to meet nutrition requirements.