Effect of diets containing untreated or processed barley grain [treated with sugar beet pulp extract (SBPE) or double sulphate of aluminium and potassium (ALUM)] and different levels of rumen undegradable crude protein (RUP) on production, rumen fermentation and blood metabolites of lactating Holstein cows were investigated. Untreated soybean meal (SBM) or xylose protected ‘Yasminomax soy® (YAS)’ was included to represent a low (LR, 4.2% DM) and high (HR, 5.4% DM) RUP diets, respectively. Experimental diet was as follows: (a) untreated barley grains with high RUP (HRCON); (b) untreated barley grains with low RUP (LRCON); (c) ALUM-treated barley grain with high RUP (HRAL; (d) ALUM-treated barley grain with low RUP (LRAL); (e) SBPE-treated barley grain with high RUP (HRSE); and (f) SBPE-treated barley grain with low RUP (LRSE). The experiment was conducted as a completely randomized design with lactating dairy cows (n = 36) averaging 215 ± 18 days in milk, milk yield 31.7 ± 5.8 kg/day, 620 ± 61 kg body weight. Diets containing processed barley grain increased feed intake, while decreased both rumination and eating (p < 0.001). Feed intake of dairy cows on Low RUP and High RUP were 23 and 24 kg/day, respectively (p < 0.01). Daily production of milk fat, protein, lactose and total solids was improved when the processed barley grain was included in the diets (p < 0.05). Present study pinpointed that the inclusion of the processed barley grain in diets might improve production indices of dairy cows.

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