Utilization of Pasture by Lactating Cows

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Abstract
Pasture was evaluated for eight seasons in Holstein cows for milk production and milk composition. For 3 yr, cows received either continuous pasture plus 7.3 kg/d of corn-mineral mixture, a continuous corn silage complete diet (no pasture), or alternately greater than 2 wk one of the two treatments. Milk production did not differ for the combined 3 yr. Fat and solids-not-fat content of milk were less for pasture. Milk production was affected little by abrupt changes of diet. For 2 yr, ground corn-mineral mixture was fed at either 3.6, 5.4, or 7.3 kg/d to cows grazing a common pasture. Milk production increased only modestly with corn feeding. Milk fat content decreased and milk protein content was affected little by increased corn. In subsequent seasons, a supplement to pasture of 22.7 kg of total mixed ration based on corn silage supported milk production as well as 7.3 kg of corn-mineral mixture. Corn silage was not as effective in maintaining milk production but enhanced fat test. Limited hay (1.4 kg) or hay available in paddocks did not increase milk production or milk fat concentration. Application of the results to forage management systems are discussed.