Calves that were dosed back in May with a long-acting worm dose will be due another dose in the coming weeks as the cover period of four months is coming to an end. Most farmers will use either a short-acting ivermectin-type product or a white drench as opposed to a long-acting dose again to allow animals build up some resistance to worms and because of cost.

Contrary to some opinion, there should be no issue with resistance when using ivermectin products provided that the correct time interval between doses is adhered to and the right amount of product is used. Dose rates depend on weight. Time can be saved by using a pour-on dose. Instead use the time to weigh the calves while they are in the crush.

Separating the lightest

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Get your hands on a weighing scales or a weighband and weigh the lot and separate out the lightest. At the Tullamore Show yesterday, we had a demonstration at the Irish Farmers Journal stand with heifer calves. One of the calves was well below target weight at 115kg. The lesson was to remove the lighter calves and give them preferential treatment – better-quality grass, not asking them to clean out paddocks fully and giving an extra one or two kilogrammes of meal.

Calves should be 30% of their mature body weight now, so Holstein Friesian calves should be around 180kg, while crossbred types should be around 150kg.

On-target heifers

Many farmers will be starting back feeding meal to the on-target heifers over the coming weeks as grass growth slows and the weather becomes more changeable. In a Moorepark study from a few years ago it was found that heifers that are too heavy at mating produced less milk solids and had poorer fertility in their first lactation than those on target weight at mating, so there’s no point in pushing them on too hard for the sake of it – just get them to target weight and keep them at it.

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