Milk Yield and Metabolic Measures of Cows Fed Grain Free Choice During Early Lactation

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Abstract
Holstein cows were assigned at parturition to 3 treatments of 2 intakes of concentrate. In treatment 1, 14 cows were fed 7 kg concentrate and hay free choice the entire 16 wk experimental period. In treatment 2, 14 cows were fed 7 kg concentrate on day 2 postpartum and an additional 1 kg concentrate every 2 days until free choice feeding of concentrate was achieved. Alfalfa hay was restricted to 5 kg/day. In treatment 3, 14 cows were fed 7 kg concentrate and alfalfa hay free choice for 4 wk postpartum, then fed an additional 1 kg concentrate every 2 days until free choice feeding of concentrate was achieved. Alfalfa hay was restricted to 5 kg/day after wk 4. Cows fed limited concentrate for 16 wk consumed less total dry matter than cows in treatment groups 1 and 2 (17.8-20.4 kg/day). Milk yield was lower for cows fed restricted concentrate rations (30.0-33.5 kg/day). There were no differences in daily intake of dry matter and milk yield between cows fed limited concentrate the first 4 wk and cows fed concentrate free choice the entire period. Molar percentages of propionate in rumen fluid were increased by feeding large amounts of concentrate. Glucagon immunoreactivity in plasma was elevated in cows fed high concentrate rations whereas insulin was increased slightly. Neither P nor urea N in plasma were affected by treatment. Compared to cows fed concentrate free choice, limited feeding of concentrate to cows for 4 wk postpartum did not affect milk yield but did reduce concentrate consumption by 10% over 16 wk.