As the grass plant hits the reproductive stage, topping (disc mowing) paddocks to correct grass quality once the cows have grazed might be an option.
At the moment, it is proving difficult for farmers to stay ahead of grass quality as the swards seem to be under a bit of stress with the deficits of moisture in the soil.
Hhopefully with the rain over the last week, with a bit of correction, quality and quantity can be restored.
People will always argue that farmers who manage grass effectively take out surplus bales on high covers, and are in general good grassland and grazing manager, will not need a topper.
I always remember in grassland management lectures in college being told that dairy farmers do not need a topper or a stock bull on the farm, but things do not always work out this way, especially when the plant gets to the reproductive stage quite quickly.
If covers on the farm are struggling to recover and there are no surpluses appearing, farmers should consider topping paddocks after they are grazed to get rid of the untouched stem and encourage re-growths.
Ideally, if there is a surplus on the farm and there seems to be good grass growth on the way – which may be the case for many with good warmth in the soil and with plenty of rain around – a paddock should be cut for surplus bales.
However, if growth is struggling to push on, it might be no harm to top one or two paddocks after grazing, though it is important not to blanket top the whole milking platform as that would slow down growth and waste valuable feed.
Topping
It is important that topping is not be used to replace good grassland management but rather when controlling quality is out of your hands due to weather or stress on the plant.
Farmers need to maintain their pre-grazing yield between 1,300-1,500kg of dry matter (DM)/ha, as grazing over this threshold will have an effect on animal performance, grass recovery, and clean outs.
Farmers should continue walking their farm every five days to see what is ahead of them in order to make the decision whether they need to take out bales or just top after grazing.
Topping paddocks also helps prevent the spread of weeds by making their growth less vigorous and it reduces their competitiveness in the sward.
Topping is most effective when it removes the flower head and upper leaves in dense areas of thistles, docks, and nettles before the bud opens, but will need to be done again in a month’s time to ensure the weed does not persist.
The topper should be set to cut down to 4-4.5cm of a residual to ensure a good clean cut and that grass grows for the next round. The topping needs to be done immediately after grazing.
Topping is associated with poor grass utilisation, which is sometimes out of your control, but anything that can be controlled through improved grazing management needs to be implemented to reduce costs and improve performance.
Pre-mowing
Pre-mowing can be used on paddocks that have gone too strong or have a large amount of stem present. It can also be used where the grass in the paddock is mowed and then cows allowed in to graze the mowed plant.
Pre-mowing encourages the cows to eat all of the plant, including the stem, which will increase intakes as the grass is readily available to the cow.
This method works well if paddocks have gone too strong and you are looking to ensure that grass does not run out.
However, if grass is plentiful on the farm and there is no fear of running out, mowing and baling the paddock is the ideal option.
Sometimes the drawback with this option is that you are taking away the cow’s choice of what grass to eat, as cows are selective grazers and eating too much low quality stem can result in a drop in milk performance.
The best way to correct grass quality is no doubt shortening up your rotation length through reducing extra supplements in the diet or taking out paddocks for bales. Topping or mowing are an alternative when your options are limited.
Good grassland management has to remain the focus, as grazing covers when the plant is at the three leaf stage and achieving target residuals through grazing will save a lot of money and labour on your farm.
