Herbage production and live weight gain in dairy heifers grazing forest habitats in Norway

We examined the herbage production of different vegetation types and the live weight gain of dairy heifers grazing forest habitats over three consecutive years. Thirty-five heifers were grazing at high-grazing intensity (1 animal/ha) and 18 heifers at low-grazing intensity (0.5 animal/ha) in a ca. 15-year-old spruce forest with the vegetation types: bilberry spruce forest (57%); peat bogs (25%); and meadow spruce forest (18%). The herbage production was on average for all years highest in meadow spruce forest (2001 kg DM/ha), while it was similar in bilberry spruce forest and peat bogs (629 and 536 kg DM/ha, respectively). The average weight gain of the heifers was 509 g/d, with means ranging from 385 to 653 g/d for different years and grazing intensities. We conclude that estimates of herbage production were improved when the vegetation types of the grazing areas were taken into account.