Effect of Supplemental Feeding of Cows on Pasture on Milk Composition and Yield

Abstract

Thirty-five cows were used to study the effects on milk composition and production of supplementing medium-quality pasture with ground-shelled corn or corn silage.Rations were: 1) Corn; 2) corn plus silage; 3) corn (1 lb/6 lb milk) plus silage; and 4) silage.Except for corn in Ration 3, feeds were fed ad libitum for 3 hr twice daily.Trial A compared Rations 1 and 4 and employed a reversal design with 40-day treatments.Trial B was a continuous study with 12-wk treatments.In Trial A, significant ration effects were noted for SNF, protein and fat in milk, and milk yields.Values for cows on corn and silage, respectively, were: 8.65, 3.22, 3.05%, and 39.9 lb; 8.44, 3.11, 3.65%, and 35.8 lb.In Trial B, persistency of production was over 80% for all groups.Cows on grain and silage had highest milk yields.SNF decreased as level of corn decreased (9.16, 8.92, 8.66, and 8.42% for consecutive groups).Milk protein accounted for nmst of the change in SNF.Fat in milk was lower on high-corn rations (2.53, 3.23, 3.50, and 3.59% for consecutive groups).Corn silage alleviated milk fat depression noted on high-corn rations.Treatment effects on milk composition were not complete until the 6th to 8th wk of treatment.