Effect of period, water temperature and agitation on loss of water-soluble carbohydrates and protein from grass hay: implications for equine feeding management

The effects of different water-soaking treatments on removal of water-soluble carbohydrates (WSC), WSC constituents and protein from four UK hays were determined. Hays were soaked in water for up to 16 hours at mean temperatures of 8°C, 16°C, in hot tap water (initially 49°C) or agitated and rinsed in clean water at 16°C. Initial hay WSC contents ranged from 154 to 216 g/kg dry matter. Losses of WSC from hays after 16 hours soaking at 8°C, 16°C, 16°C plus agitation and 49°C averaged 28, 46, 49 and 44 per cent, respectively. Corresponding percentage losses of fructan were 16, 37, 39 and 33. Percentage losses of sucrose averaged 55 (8°C), 86 (16°C), 91 (16°C+agitation) and 82 (initial temperature 49°C), those of glucose were 60, 85, 75 and 75, and of fructose were 41, 52, 54 and 46. Hay crude protein contents were not significantly changed by any of the soaking treatments. Soaking at 8°C generally resulted in reduced losses of WSC compared to when soaked at the higher temperatures. Thus, in cold weather using warmer water to soak hays may effect greater WSC loss, although very prolonged soaking at warm temperatures might encourage the proliferation of unwanted micro-organisms in the soak liquor.