Effective parasite control is an especially vital part of rearing dairy heifer calves. They need to be achieving a Daily LiveWeight Gain (DLWG) of at least 0.7kg/day to hit their liveweight targets for breeding next year.
Where calves, 6-8 weeks after turnout have an adequate supply of good quality grass, the most likely cause of poor weight gain is parasites.
There are a variety of different approaches to worm control, including new innovative very long-acting wormers, which save a lot of labour.