Grass growth is gradually improving with milder and damper conditions in store, but many farmers are getting tight on grass supplies as re-growths from the first rotation are proving very slow to return.
As soil temperatures have improved, it is important to react by getting out fertiliser and ideally spreading nitrogen (N) with sulphur, aiming for 35 units N/ac if no fertiliser has been spread.
Your phosphorus and potassium fertiliser applications should follow for the second application on paddocks with no slurry received.
Fertiliser and slurry is crucial, and you should aim for 60 units N/ac by the first week of April to drive on grass growth and ensure good opening covers for the second rotation.
When farmers get tight on grass supplies, the first thing they think of is to get more silage or concentrates into the diet to slow up the rotation, rather than prioritising grass in the diet by implementing different grazing measures to compliment silage feeding.
However, when is the best time in lactation to feed silage or concentrates without impacting on milk supplies or body condition?
Studies show that increasing concentrate allocation beyond 3kg/cow will result in reduced grass dry matter intake (DMI) and reduced total diet digestibility, which indicates that supplementing through silage to compliment grazing may be more favourable.
Tight grass supplies
The grass demand on farms in the spring determines the availability of grass per cow which is influenced by the stocking rate on the grazing platform, the calving pattern, opening farm cover, and grass growth.
Ideally, farmers would have opened with an average farm cover of around 1,000kg dry matter (DM)/ha in order to ensure that grass is in the diet from early spring until the the start of the second rotation.
Farmers need to ensure that the average farm cover (AFC) does not fall below 500kg DM/ha as otherwise grass availability in the second rotation will be limited.
Where a grass deficit is identified, supplementing with high-quality silage in the diet has less of an impact on performance in the first six weeks of the lactation, in comparison to when the cows are at or approaching peak milk production.
This is something to consider as, for many herds, only a few cows might be calved six weeks at this stage with the majority of the herd only calved down about four weeks.
It is advised to continue grazing low grass covers which will compliment silage feeding and increase grass available to feed the cows as demand increases.
On/off grazing in tougher conditions should be implemented or when grass is tight as cows can achieve up to 90% of their dry matter intake (DMI) over two grazings of three hour allocations.
If conditions are very poor, cows should be housed for a short period and fed 75% DMD silage if it is available, and 4-6kg of concentrates in the parlour before they can return to grass.
Drier and easier accessed paddocks should be targeted in more difficult grazing conditions to maintain grass in the diet.
Before cows are housed during the spring, the farm needs to be walked to see what paddocks are accessible, to ensure grazing is a higher priority rather than housing being the norm and getting opportunities to graze thereafter.
Grazing conditions are not the issue at the minute, the issue is re-growths and ensuring decent covers for the second round.
Remember, you are better off going in with silage supplementation in the early lacation without impacting milk as long as you keep grass in the diet.
When cows get closer to their peak lactation, having high opening covers in the second rotation and little silage supplementation will lead to improved milk yield, solids production and body weight in comparison to feeding 3kg of silage with low covers, according to a Teagasc Moorepark study.
The best time to go in with silage supplementation is in the first six weeks of the lactation if grass supply is inadequate to meet herd demand throughout the first rotation and to replenish grass supplies for when cows are peaking.
When grass supply is tight, it is important to continue with grass in the diet as grazed grass in the diet has a positive effect on milk production due to the high nutritive value. Don’t limit grazing but implement measures which will compliment silage feeding.
