Farm Ireland

Thursday 22 February 2018

Assess quality and quantity of kale and pasture in the wake of the 'freeze'

Dr Mary Kinston

In June 2006, a year after my decision to leave the family dairy farm in England, I was working for Dexcel (now known as DairyNZ) in New Zealand as a consulting officer in Canterbury.

As the seasons are the reverse of ours, for the spring calving herd this was similar to December being the start of the dry period, so drying off, condition score and closing covers had been the topics of discussions with dairy farmers. However, on June 12 there was a snow storm, which today has gone down in history as a notable event, with a few of the older farmers in the area likening it to the snow event of 1945 and 1967.

Depths of snow across Canterbury were substantial, with the most of my region having received around 30cm. As snow does, this caused a big challenge, especially because there had been considerable damage to the electricity distribution system, with many farmers being without electricity for more than a week.

As a result, we at Dexcel worked furiously over the next few days to bring together information which would help farmers cope with the challenging conditions, and launched a series of Snow Response meetings.

It reminded me of a few points that may have relevance for Ireland when faced with this spell of cold weather or the possibility of snow.

Freezing cold weather in Ireland always brings visions of farmers running around with hot water trying to get running water into troughs. This often feels likely a thankless task but animals need access to ample, clean water whether out grazing crops, on a pad or housed. Animals can't supplement their water intake from snow -- 10ga of snow is only equal to 1ga of water -- and water is especially important when feeding concentrates, hay or straw.

For those grazing kale, there are issues to be aware of:

  • Secure stock after a heavy snowfall;
  • How to manage the crop after a heavy fall of snow;
  • Avoiding the risk of nitrate poisoning.


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The first challenge after a heavy snowfall can be fences, as it can disrupt power to electric fences and, in extreme circumstances, even knock fences. So, if cattle are out grazing forage crops in such an event, this needs to be considered. Again, an extra temporary fence through the field of kale can be a saving grace in the event of a break out.

In the event of a heavy snowfall, while kale is under snow, the crop is preserved. Ultimately, if a heavy snowfall was experienced, it could break or uproot most of the plants and, after thawing, you would probably only have a three-week window to use this feed before it rots.

This is an extreme circumstance and it's more likely that only the leaves will be ripped off by snow. Again these leaves will rot and reduce the feeding value of the crop.

However, depending on the variety and sowing rate of kale, around 60-80pc of the energy from the crop is in the stem and therefore only 20-40pc is in the leaves, so just the stem is still a valuable feed resource.

Note that the heavier the crop, the higher the risk of damage. You will also have to account for the fact that the dry matter content of the crop can drop to as low as 8-10pc compared with 10-14pc prior to snow, so extra feed will be required in this instance. It's also important to remove and house any animals struggling with the conditions.

Nitrate poisoning is also something to be aware of and is an issue on dull days combined with frosts earlier in the dry season.

Nitrates are highest in the morning and nitrate poisoning can be considered as a rate of intake problem. So to avoid it, never put hungry animals on to kale first thing in the morning. Give them access to silage, hay or straw so they are less likely to gorge themselves.

When considering the pasture, not much will happen under snow unless it's lying for more than seven days. As with winter burn from frosts, shorter pasture covers will come out with few problems. But with longer pastures (more than 1,500kg DM/ha available), the outcome will be dependent on the weather conditions after a thaw.

The worst scenario is where long pastures are flattened and crushed under snow, with wet weather after a thaw rotting the grass. While it's a catch 22 for poaching, in these circumstances removing a degree of this material as quickly as possible can aid its recovery and re-growth.

So be aware of which paddocks have heavy covers to help when making these decisions.

However, note that grazing off heavy covers during the winter is likely to look unsightly until April/May, though paddocks will recover with time -- but initial growth may be slow.

Dr Mary Kinston is a dairy consultant based in Co Kerry. Email:

Irish Independent