It’s vitally important that the next generation of milking cows don’t fall between two stools in the quieter part of the year. Now that breeding season is drawing closer to its completion, the focus should be on the class of 2025 to ensure replacement heifer target weights are achieved over the next number of months.

Hitting target weights at certain milestones is crucial to ensure replacement heifers are on course to achieve the main goal of being 60% of their mature weight when bred at 15 months. Ideally at this point, 2024 born calves will have adjusted to a grass based diet without set-backs and the transition period has gone smoothly.

For many the decision on reducing or removing supplementary concentrates will be made shortly ~ end of June, early July. However, this decision should hinge on current weights relative to target, grass availability/quality and/or their transition to grass and grazing. Abrupt changes should be avoided, and gradual reductions advised.

Weighing scales are by far one of the most underutilised management tools on farm. Timing of weighing can also be beneficial. By weighing mid-season, compared to just at the point of housing, allows farmers to identify heifers that are behind target. The best advice is to group accordingly and make alternative plans for those heifers under target weights.

The threshold figure for 2024 spring born weanling heifers is approximately 200kg in mid-September (33% of an assumed mature weight of 600kg). Heifers that are lighter than this should be separated and given priority access to the highest quality grass and re-introduce concentrates depending on their weight relative to the herds target. Parasite burdens and their control can have a major influence on performance mid-summer for 1st season grazers. A herd health plan for parasite issues/control
should be discussed on a herd-by-herd basis with your veterinary practitioner.

For further advice, contact your local Agritech Sales Advisor or visit www.agritech.ie

Another target weight to keep in mind with February and early born March calves is to weigh 180 – 190 kgs by the 1st of September, equating to an average daily gain of 0.7-0.8kg/head/day.

In an ideal world calves would be weighed regularly over their first season at grass to track average daily gains. This will allow for informed decision making regarding decreasing concentrate feeding rates at grass. 2kg of a low protein (<16%), high fibre concentrate should be offered while grazing for the first 3-4 weeks of grazing and only considered to be reduced thereafter, to approx. 1 kg. Where early born (Late Jan/Feb born) calves are on target and adjusted to grazing well, supplementation can be reduced further or removed – but this should not happen until late June; supplementation will need to be reintroduced when grass quality declines (late summer) and/or if targets are not being met.

Within groups, there will always be outliers that should be prioritized, calves failing to achieve the above outlined weights (especially younger born March calves). This lighter group needs to be offered a higher rate of supplementation, supplemented for later into the summer and prioritised for grass availability.

Replacement heifers struggling to achieve target weights in the first season at grass, typically results in a heifer too light at housing, and if not fed appropriately and returned to grass early, results in a heifer too light at the point of bulling – negatively effecting her longevity within the herd as a mature cow. With calf-to-beef situations a poor first season at grass will result in prolonged days to slaughter at a significant cost.

Parasite control

Stomach worms and lungworms (hoose) are the most common parasites of calves at grass – with burdens typically building during May-July (weather dependant). Although burdens may be building, clinical signs/symptoms are not experienced or seen typically until mid-summer onwards and this is when action will be required.

Warm humid conditions followed by heavy rainfall can result in rapid multiplication and a close eye will need to be kept on youngstock at grass over the next number of weeks. A dosing protocol should be discussed on a herd-by-herd basis with your veterinary practitioner, as conditions/grazing management & resistance in herds will vary hugely. Dung sampling is also advised to pinpoint issues. Stomach worms will typically present as scouring, and poor thrive while lungworm will need to be dealt with where husky coughing occurs (especially when being moved). Where poor thrive and loose dung is an issue, dung sampling to rule out coccidiosis is also required. It is important that poor thrive caused by parasites is not to be wrongly self- diagnosed as summer scour syndrome.

For further information, contact your local sales advisor