The inclusion of high levels of barley in rations for dairy cows and calves

Rations containing high, levels of barley were evaluated in seven experiments (I-VII) with dairy cows and calves.I. Twenty-one Holstein heifer calves and 21 Holstein bull calves were maintained from birth to 84 days on rations containing 1) 100% barley, 2) 50% barley-50% oats or 3) 100% oats as the cereal grain.Grain consumption (kg), gain (kg/day) and feed efficiency (kg feed/kg gain) for the three rations were 1) 54.72, .54 and 1.88, 2) 55.60, .55 and 1.79 and 3) 65.94, .51 and 2.03.II.Twelve eight-week-old Holstein steer calves were used to determine the digestion coefficients for the calf rations.Digestion coefficients (%) of dry matter, crude protein, ether extract, crude fiber and nitrogen free extract for the three rations were 1) 83.15a, 80.71, 47.87a, 47.54 and 88.65a, 2) 81.29a, 81.19, 72.71b, 43.23 and 86.71a and 3) 78.16b, 82.31, 85.13c, 42.46 and 83.35b.Corresponding values with a different superscript differ significantly (P<.05).III.Two trials with 15 12-week-old Holstein calves showed the calves would accept any of the three rations if given no other choice, but the calves preferred the 100% barley over the 100% oats ration if given a choice.IV.Twenty-four lactating Holstein cows were used in two trials to compare rations containing 1) 100% barley, 2) 75% barley-25% oats or 3) 50% barley-50% oats as the ceral grain.Grain consumption (kg), fat corrected milk (kg), milk fat (%), and total volatile fatty acid (mM/1) production for the three rations were 1) 8.2, 18.1, 3.2 and 63.3, 2) 8.5, 19.9, 3.2 and 62.3 and 3) 8.7, 19.6, 3.1 and 59.0.V. Six 15 to 20-month-old Holstein steers were used to determine the digestion coefficients for the rations used in Experiment IV.Digestion coeffif-cients (%) of dry matter, crude protein, and nitrogen free extract for each of the rations, when calculated by difference, were 1) 80.16, 63.02 and 90.28, s) 75.95, 73.58 and 85.93 and 3) 78.32, 71.18 and 85.92.Digestion coefficients of ether extract for the rations plus hay were 1) 1.82a, 2) 45.48ab, and 3) 56.53b.All other digestion coefficients for the complete rations were similar.VI.Two trials with nine dry Holstein cows showed that the cows would accept all of the rations if given no choice, and showed-no preference for any of the three rations when given a choice.VII.In vitro dry matter digestibilities (%) calculated from the grains alone and by difference from grain and hay samples for each of the rations from the lactation trial were 1) 80.60a and 86.18a, 2) 77.97b and 83.02b and 3) 72.10c and 75.92c.