Milk. Cows were milked twice daily (0400 and 1600 h) in a double-17 parallel milking parlor with sampling devices. Milk production was recorded daily. All daily milkings were totaled for each cow within pen on study for the same day in lactation. Total daily milks were calculated to represent mean daily milk per cow for comparative purposes. Milk samples for composition were collected and composited from each cow at p.m. and a.m. milkings (two 50:50, 30-mL aliquots) on a weekly basis. Samples were preserved, frozen, and thawed slowly after all trial cows in each group