The Effect of Soaking on Carbohydrate Removal and Dry Matter Loss in Orchardgrass and Alfalfa Hays

The objective of this research was to determine the impact of water temperature and soaking length on removal of nonstructural carbohydrate (NSC) fractions and dry matter (DM) from legume and cool-season grass hays. The experimental design was a randomized complete block with six replications. Hay types included bud and flowering alfalfa (Medicago sativa L.) and vegetative and flowering orchardgrass (Dactylis glomerata L.). Flakes were submerged for 15, 30, and 60 minutes in 25 L of cold (22°C) water, warm (39°C) water, and 12 hours in cold water, respectively. Water temperature at each soaking duration did not affect residual NSC fractions in alfalfa hays. Flowering and vegetative orchardgrass hays soaked for 30 and 60 minutes, respectively, in warm water had greater (P < .001) amounts of NSC fraction removal compared with soaking in cold water. Soaking bud and flowering alfalfa and vegetative orchardgrass hays for ≥15 minutes removed more NSC fractions compared with the control (P ≤ .005); however, soaking for 15-60 minutes resulted in similar NSC fraction removal. Conversely, in flowering orchardgrass hay, longer soaking times resulted in greater (P < .001) NSC fraction removal. Fructan removal in orchardgrass hay was greatest (P < .001) after soaking for 12 hours. DM losses were similar among hays after soaking for 15-60 minutes, but were greatest after soaking for 12 hours (P < .001). Soaking grass hay for 15-30 minutes is recommended to remove sufficient NSC fractions while minimizing DM losses.