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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #275504
Title: The effect of soaking on protein and mineral loss in orchardgrass and alfalfa hays

Author
item MARTINSON, KRISHONA - University Of Minnesota
item HATHAWAY, MARCIA - University Of Minnesota
item Jung, Hans Joachim
item SHEAFFER, CRAIG - University Of Minnesota

Submitted to: Journal of Equine Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2012
Publication Date: N/A
Citation: N/A

Interpretive Summary: Horses suffer from a set of disease conditions that can be caused or aggravated by feeding high-quality hay naturally containing too much sugar. To avoid this risk factor, horse owners will often soak hay in water to reduce the sugar content. However, the impact of soaking hay on removal of other important nutrients required by horses has not been examined. Immature and mature cuttings of alfalfa and grass hays were soaked for various lengths of time in both cold and warm water. Increased soaking time from 15 minutes up to 12 hours did not alter protein content of immature alfalfa and mature grass hays, reduced protein content of mature alfalfa hay, and actually increased protein content of immature grass hay. Calcium concentration was also affected in different patterns due to soaking; no change for mature alfalfa and grass hays but decreased calcium for both immature hays. In contrast, soaking always reduced concentrations of the other major minerals (phosphorous, potassium, and magnesium). Water temperature had little impact on removal of nutrients. However, concentrations of protein and all minerals remained high enough in all hays after soaking to avoid nutrient deficiencies in lightly worked horses. These results will provide guidance and reassurance to horse owners and veterinarians who use hay soaking in water to remove excess sugars to avoid nutritional diseases.

Technical Abstract: Nonstructural carbohydrates (NSC) are usually targeted for removal during hay soaking, however, other essential nutrients may also be lost. The objectives of this research were to determine impact of water temperature and time of soaking on removal of protein and minerals 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) and vegetative and flowering orchardgrass (Dactylis glomerata). Flakes were submerged for 15, 30, and 60 minutes in 25 liters of cold (22 degrees C) and warm (39 degrees C) water, and 12 hours in cold water. Changes in crude protein (CP) concentration after soaking had no effect (P > 0.05) on alfalfa bud or flowering orchardgrass hays, increased (P = 0.02) as soaking length increased in vegetative orchardgrass hay, and decreased as soaking length increased (P < 0.001) in flowering alfalfa hay. Soaking did not affect (P > 0.05) Ca concentrations in flowering alfalfa and orchardgrass hays but resulted in a reduction of Ca (P < 0.001) as soaking length increased in alfalfa bud and vegetative orchardgrass hays. Reductions in phosphorus (P), potassium (K), and magnesium (Mg) concentrations were observed in hays with longer soaking times resulting in greater mineral losses (P < 0.001). Soaking for 15 to 60 minutes did not result in nutrient deficiencies based on requirements of a 500 kg horse in light work. However, supplementation of P after feeding hay soaked for 12 hours would be necessary to address high Ca:P ratios.