Nutritive value for high-yielding lactating cows of barley silage and hay as a substitute for wheat silage and hay in low-roughage diets

•Grown for forage in dryland farming in semiarid region, barley had higher yield than wheat.•Barley found to be adequate substitute to wheat as a sole source of roughage in high yielding lactating cows TMR.•Cows fed barley silage and hay had higher rumen pH than cows fed wheat silage and hay.•Barley-fed cows showed higher DM total tract apparent digestibility and higher production efficiency than wheat-fed cows.•Milk yield and daily gain were not affected by the silage and hay source. We assessed the effects of replacing wheat silage and hay with barley silage and hay in total mixed rations (TMRs) on: eating behavior, digestibility, and performance of individually fed high-yielding lactating cows. The barley cultivar Ma’anit and the wheat cultivar Omer were grown by dryland farming (210 mm precipitation) in a commercial field with sandy loam soil. The two cultivars were harvested simultaneously for silage or hay at a similar dry matter (DM) content (35.6%). Barley yields exceeded wheat yields by 19% (5.68 vs. 4.79 t DM/ha, P = 0.01). Two-thirds of each crop's DM yield was chopped and transferred for direct ensiling in polyethylene-wrapped bales, and one-third was wilted in the field for 2 weeks and then pressed into hay bales. The chemical composition and in-vitro DM digestibility of the wheat and barley silages and hays were similar. The two experimental TMRs contained either barley silage (280 g/kg DM) and hay (60 g/kg DM) or similar contents of wheat silage and hay, as the sole source of roughage. High-yielding multiparous Israeli Holstein cows were paired into two experimental groups of 21 cows each and fed either wheat- or barley-based TMR ad libitum for 28 days. DM intake of cows fed the wheat TMR was higher than that of the barley TMR-fed cows (28.0 vs. 27.5 kg/day) due to a faster eating rate (137.9 vs. 132.9 g DM/min) and larger meal size. Energy corrected milk production was similar in the two groups (42.4 and 42.8 kg/day), while milk fat yield was higher in barley-fed cows than wheat-fed cows (1.62 vs. 1.57 kg/day). Daily rumination time of the barley-fed cows was longer (577 vs. 537 min/day) and their rumen pH higher during the day and night (P