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

Feeding colostrum on farm

3-2-1 Rule:

1: Offer milk from the dam’s first milking

2: Within the first two hours of birth

3: Offer at least three litres (approx. 10% of birthweight)

Typically, there is large variation in quality within a herd, with Teagasc research showing that approximately 20% of a herd may have poor quality colostrum, i.e., insufficient antibodies for the calf. Many farmers have started to test colostrum quality using a refractometer to ensure calves are receiving a high-quality first feed, with the threshold of a Brix value > 22% being the quality standard.

Pooling colostrum is often practiced on farm due to labour constraints, however combining colostrum from several cows will increase the risk of disease spread (e.g., Johnes), reduce passive transfer and dilute high-quality colostrum. Where possible, aim to otter calves a ‘one-dam-to-one’ calf system to avoid such issues occurring.

High standards of hygiene are necessary when collecting, feeding and storing colostrum, with research indicating that clean (no dirt contamination) colostrum allows for increased antibody absorption. Bacterial contamination will compete with antibodies at gut level, resulting in reduced passive transfer. Recent results from a Teagasc Moorepark survey of 48 commercial farms highlighted that stomach tubes and bottles with teats had the greatest quantity of bacteria present.

Boosting colostrum quality

If an issue with colostrum quality on farm is identified, feeding soyabean meal to the in-calf cow in the final two weeks pre-calving can boost overall quality. Feeding rates will be silage quality-dependent but typically range from 0.25-0.75 kg/head/day.

Further Advice

For further calf rearing advice or to learn more about our milk replacer range, contact your local Agritech Sales Advisor.

Firstly, weaning should only ever occur once calves are consuming at least 1.5 kg of concentrate per head per day in group scenarios. Alongside this, gradual weaning is advised to minimise stress levels in young calves and to allow them to increase dry matter intakes over a prolonged period.

During the first grazing season, heifer calves should have a good consistent growth rate of 750g /day or 20kg/month. Calves should always have access to high-quality grass, and depending on target weight gain and grass availability, a quality concentrate supplementation may be required. Typical advice is to feed meal at least 6 weeks post-weaning/turnout and reintroduce meal again in autumn if desired weights are not being met.

Setbacks that occur now or over the first grazing season will result in heifers struggling to meet target weights in the future and can result in these heifers not making it to the parlour.

What is Summer Scour? 

Year on year, in the proceeding weeks after turnout to grass, cases of calves suffering from setbacks are reported, typically described as Summer Scour Syndrome or calf wastage.
Lush grass is very high in oils like CLA (conjugated linoleic acid), sugars and potentially nitrogen, and to a young undeveloped rumen this can be hard to adjust to. In addition, low covers of grass have very little fibre, which is a key substrate for good rumen health.

It’s often asked why Summer Scour Syndrome was not an issue until recent years, and the short answer is that we are victims of our own success. Grassland management has dramatically improved over the past number of years. Calf rearing has also improved, and we are typically weaning calves at 8-10 weeks of age. It is also worth noting that ditches are now typically fenced off to youngstock where historically they would have been used as a source of fibre by calves.

In severe cases or if prolonged, rumen function can be severely impaired and B vitamins may no longer be manufactured by the rumen, resulting in blindness and ‘star-gazing’.

Note: Where poor thrive/scouring is an issue at grass post-turnout, Coccidiosis should be the first port of call to rule out.

Avoiding the issue: 

Ideally, the rumen is developed over the milk feeding period/pre-weaning by offering ad lib access to concentrates (18% Crude protein crunch/nut), and clean fresh straw to reduce your risk of Summer Scour Syndrome.

Below are several management practices that can help combat against the onset of Summer Scour Syndrome symptoms this season, a few which will be farm/system dependent:

1. Offering concentrates in the weeks post-turnout will help to avoid overindulging on rapidly digestible lush grass. Hungry calves are more likely to gorge on lush covers.
2. During periods of rapid growth, avoid letting calves into low covers of grass. Until rumens are well developed and luxury uptake of nitrogen is not a problem, target covers of at least 1,200-1,400 kg DM/ha for 8-10 weeks after turnout.
3. The use of Agritech’s Rumicare in meal pre and post-weaning will help the buffering capacity in the rumen, decrease the risk of acidosis/ruminal upsets during the transition period and promote positive bacteria populations in the rumen (typically included at 2%).
4. Give access to grass and indoor accommodation simultaneously prior to full-time turnout to ease the transition to grass.
5. Offer a fibre source post-turnout. Round feeders are an option to allow access to clean dry straw.
6. Use strip-wire allocations. Strip-wires allow for less selective grazing and force calves to eat stem content along with the leaf.

More Information: 

For more information on reducing the stress of weaning on your calves, contact your local Agritech Sales Advisor.