Effect of ensiled hop (Humulus lupulus L.) residues on plasma acetate turnover rate in sheep

Abstract

An isotope dilution method using [1-(13)C]sodium acetate was applied to determine the effect of feeding ensiled hop (Humulus lupulus L.) residues on plasma acetate turnover rate in six adult crossbred sheep. The sheep were fed 63 g/kg body weight (BW)(0.75)/day of either mixed hay of orchardgrass (Dactylis glomerata L.) and reed canarygrass (Phalaris arundinacea L.) and round bale silage at 3:1 ratio (Hay-diet), or another where round bale silage was replaced by ensiled hop residues (Hop-diet) with a crossover design each of a 3-week period. The isotope dilution method was performed on day 21 of each dietary treatment. Dry matter digestibility was similar between diets, and nitrogen (N) digestibility was lower (P = 0.001) for Hop-diet than Hay-diet. However, N retention did not differ between diets. Plasma acetate concentration was lower (P = 0.04) for Hop-diet than Hay-diet, and the turnover rate of plasma acetate did not differ between diets. Plasma concentration of lactate and non-esterified fatty acids were similar between diets. Hop-diet was found almost comparable to Hay-diet on plasma acetate turnover rate in the present experimental conditions. Therefore, it could be concluded that hop residues partially could be used as an alternative to traditionally used round bale silage for rearing sheep.