One Group Versus Two Group System for Lactating Cows Fed Complete Rations

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Abstract
Both 1st lactation and older Holstein cows were assigned to either a 1 group or a 2 group system of feeding and management. Animals in the 1 group system were fed a complete ration of 56% corn silage: 44% concentrate, dry matter. In the 2 group system, cows were fed a similar ration in early lactation and at higher milk production and then shifted to a ration of 84% corn silage: 16% concentrate at lower production. Dry matter intakes of corn silage and concentrates were 9.9 and 7.8 kg/cow per day for the 1 group system, and 11.5 and 5.5 kg/cow per day for the 2 group system. Cows in the 1 group system averaged .6 kg milk/cow per day greater yield than cows in the 2 group system. The average decline in milk yield the 1st wk after group change was 2 kg/cow per day. Milk loss persisted longer in older cows than in 1st lactations. Magnitude of loss in milk was not related to stage of lactation but to milk production at the time of change. Milk production was greater in the 1 group than the 2 group system. Income over feed costs for the 2 groups was discussed.