Pregnant heifers can be reared on intensively grazed pastures with no adverse effects on growth or first-lactation milk production, say University of Maryland researchers.

In a two-year study, Holstein heifers rotationally grazed endophyte-infected tall fescue and also were fed 1 lb/day of ground shelled corn with minerals and monensin. They were rotated to new paddocks daily from spring to summer. Their performance was compared with that of heifers fed a conventional TMR of corn and rye silage, grass hay and a monensin-supplemented grain mix.

Average daily gain, wither and hip heights, calving dates and projected first-lactation milk, milkfat and protein production were the same for the two groups, the researchers report.