Farming in Mount Temple, Moate, Co. Westmeath, Irvine Allen has been running a dairy calf-to-beef operation for the past eight years, alongside a contracting business.

Now a participant in the Teagasc Green Acres Calf to Beef programme, Irvine aims to buy 150 calves – 60 in the autumn and 90 in the springtime – each year direct from dairy farmers.

The Westmeath-based farmer purchases Aberdeen Angus, Hereford and Friesian calves. 80% of the steers and heifers purchased will be slaughtered under 24 months, while the remaining 20% will be brought to beef at 28 months-of-age.

In terms of carcass weights, a target of 330kg has been set for steers, while heifers are aimed to hit a 280kg carcass.

Housing is complete with the exception of March 2019-born calves, which are currently grazing Redstart – a hybrid of forage rape and kale – and will remain on this crop for the winter, before being turned onto grass in February 2020.

Prior to housing, Irvine’s dedicated programme advisor, James Fitzgerald, carried out a silage quality analysis. The results were satisfactory; first-cut silage came back at 75% dry matter digestibility (DMD), while second-cut silage hit 64% DMD.

Redstart out-wintering system

Irvine has now entered his third year growing and grazing a hybrid brassica. Prior to growing the crop, poor-performing paddocks were identified, which will be reseeded back to grass in the spring of next year.

Redstart offers the highly beneficial combination of rapid growth ability and good all year round performance.

It was a hugely popular choice on farms in 2018 to increase feed availability as a result of the drought. The forage rape genes in the hybrid allow the crop to grow quickly, while the kale genes deliver excellent winter hardiness.

The crop is mainly used as a high-energy protein crop for out-wintering cattle and sheep.

Some 60 weanlings – split into two groups of 30 – are currently grazing the brassica in two separate paddocks – amounting to 9ac in total.

Also, Irvine will only sow the crop in well-sheltered (high ditches), dry paddocks. This provides a good environment for the lighter cattle which will graze the crop over the winter period.

“The paddocks I have chosen have great shelter. I find the weanlings perform very well on the crop and it saves me on winter housing for 60 cattle,” Irvine explained, adding that it is a very efficient way of reseeding a proportion of the farm each year.

As you can see from the photos, grazing conditions are favourable and a clean, dry, lie-back area is provided for the weanlings, with optimum utilisation achieved.

Before the crop was sowed, Irvine disc-harrowed the paddocks a number of times to provide the perfect seedbed – before sowing on August 13.

While this forage crop is ideal for out-wintering stock, animals grazing hybrid brassicas must receive approximately 30% of their dry matter (DM) requirement from silage, hay, or straw; to provide this, Irvine feeds baled silage in the paddocks; this results in the remaining 70% coming from the hybrid crop itself.

Irvine turned the weanlings onto the crop 10 days ago and introduced the feed to the animals gradually – allowing fresh daily breaks while the animals adapt to the crop over a period of time; fresh water is available at all times.

In addition to the gradual introduction, a mineral bolus was also administrated to the weanlings as their iodine levels may become imbalanced from grazing these crops.

These crops contain goitrogens; these are substances that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland and – after a series of biological reactions – lead to goiter.

In addition to iodine, the brassica is also low in minerals like: selenium; copper; and cobalt, hence it is essential that stock are given a bolus to correct imbalances.

There can also be dangers associated with toxicity. When you hit mid-February, these crops can become reproductive and farmers ideally would want to have them gone and utilised at that stage.

In addition, strip grazing will maximise utilisation and minimise wastage. Irvine is grazing the crop – downhill – in long narrow strips to ensure all animals can graze at the same time; this will minimise trampling of the crop at feeding.

Restart should not be fed in frosty conditions; where this is the case, frost should be allowed to thaw prior to moving the strip wire.

Measuring demand

One of the first steps farmers should take before grazing forage crops is to measure how much of the crop is available. This can be achieved by taking a quadrant cut from the paddock and weighing the resulting sample.

From the results, farmers will be able to judge the daily forage crop allowance, whilst also allowing them to budget how many days grazing the crop will provide.

Items needed:

  • Quadrant (0.5m x 0.5m);
  • Shears;
  • Weighing scales;
  • Plastic bag.

Using the quadrat, a number of representative samples should be taken to get an accurate estimation of yield.

All material within the quadrat should be cut with the shears to a residual height of 10cm; all harvested material should be placed in the plastic bag and weighed on a scales – making sure the weight of the bag is subtracted.

To calculate DM yield/ha, multiply the fresh weight per m² by 40,000 and then multiply by the expected DM percentage; the forage rape/kale hybrid has a DM value of approximately 12%.

  • Total DM yield (kg/ha) = Fresh weight (kg) x 40,000 x DM%;
  • Total DM yield (kg/ha) = 1kg x 40,000 x 0.12 = 4,800kg DM/ha.

Generally speaking, out-wintered animals have a daily DM intake requirement of 3% of liveweight.

For example, a 270kg animal will require 8.1kg of DM/day. But, only 70% of this can be made up of the hybrid brassica leaving the crop requirement at 5.6kg of DM/day; the outstanding 2.5kg of DM being made up of silage, hay or straw.