Dairy management notes

Calves: Any calves that were dosed in May with a long-acting worm dose will be due another dose in the coming weeks as the cover period of four months comes 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 and, instead, use the time to weigh the calves while they are in the crush.

Get your hands on a weighing scales or a weighband and weigh the lot and separate the lightest. February-born calves should be 33% of their mature body weight now, so Holstein Friesian calves should be between 190kg and 200kg, while smaller crossbred type calves should be between 180kg and 190kg. Many of the farmers in the Heifer Rearer of the Year competition 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 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 the target weight and keep them at it.

Body Condition Score: While many herds are being scanned at present to see the fertility results for this year, management for next year’s fertility begins now. Condition score at mating is the biggest indicator of fertility performance. The target is to have cows at a condition score of 2.9 at mating (a range of 2.75 to 3.25). To achieve this, they must calve down at 3.25 (range 3 to 3.5) and be dried off at condition score 3 (range 2.75 to 3.25). Some farmers will condition score the cows as they are being scanned or vaccinated and identify the ones under 2.75 and give them special treatment. This could mean a longer dry period or putting them on once-a-day milking from now until dry-off. It may only be 5% to 10% of the herd, but it will make a big difference. Some farmers with automated feed systems can feed these cows more meal, but as these cows tend to be the higher yielding ones, I think more meal will just mean more milk and it won’t do anything for condition score. Once a day is my preference. A 20% reduction in milk solids should be expected for those cows put on once-a-day milking, but the improvement in condition should be fast. Put tape on their tail or a band on their leg and don’t milk them in the evening. Condition score should be a focus at every discussion group meeting. Get your facilitator to organise a demo on a host farm to familiarise yourself with the scores.