Dairy Management: ground turns wet in the south

After a lot of rain in the south east and south, ground conditions have turned tricky.

Aidan Brennan

19 February 2025

Dairy Management: ground turns wet in the south

Damage being done to a farm earlier this week.

Grazing: After a dry start, ground conditions weren’t long turning wet. The south is faring worse with Cork Airport recording over 70mm of rain over the last week, while Gurteen in Tipperary and Oak Park in Carlow got just over 7mm. The reality is: if you’re trying to get grass into cows in spring under an Irish sky, some damage will be done. The trick is to try to minimise that damage while at the same time keeping cows well fed. The best way to minimise damage is to use on/off grazing. This is where cows are out for three hours at a time and they go out the field with an appetite so they graze vigorously while they are outside.

The reality is: if you’re trying to get grass into cows in spring under an Irish sky, some damage will be done. The trick is to try to minimise that damage while at the same time keeping cows well fed. The best way to minimise damage is to use on/off grazing. This is where cows are out for three hours at a time and they go out the field with an appetite so they graze vigorously while they are outside.

Most farmers will give them some silage in the shed when they return after their grazing stint. Having them hungry is important and in order to do that, keep them away from silage for a few hours before going out grazing.

By doing on/off grazing, it is likely that overall daily dry matter intake will be higher compared to keeping them on silage all day. Other important tricks are to use multiple access points and graze in square blocks. If cows are only out for a few hours, they do not need access to water.

Milk solids: Tirlán is launching a new milk solids campaign, aimed at raising awareness of the importance of feeding cows well in spring. It has identified the differential between fat and protein percent as a key determinant of cows being consistently underfed in spring and say that this has long-term impacts on milk solids yield.

The first thing is, it has identified that the best diet for cows in spring is grass as this provides the highest amount of energy (ufl). Because it’s highly digestible, cows will eat more of it and so the cows’ overall energy intake increases. Where grass cannot be fed because it is too scarce or land is too wet then the focus needs to be on quality silage with around 75% DMD silage for milking cows. Where silage quality is poor, then meal becomes more important, but still won’t compete with grass in terms of energy intake.

In situations where cows can’t go out grazing – as happened for long periods last spring – then feeding the best silage available and 5kg or 6kg of meal makes sense. It’s important that this message doesn’t turn into a meal-feeding racket, but the reality is that most Irish cows are overfed with meal relative to what they produce. This indicates that the timing of when the feed is fed could be better.

The mistake many make is to feed too much in mid- and late lactation when the cow doesn’t need it. If some of that concentrate was frontloaded to the spring during periods when grass can’t be fed it would be much better.

Milk fever: I’m hearing lots of reports of milk fever this spring. One of the main causes is high potash levels in silage and one of the main defences is to feed additional magnesium pre-calving, or additional calcium post-calving.

Mag flakes or sweetened cal-mag are cheaper options than calcium post-calving. Farmers add this to the water or sprinkle it over the over the silage for a week or so before calving.