This first 30pc is important because it provides the grass for the first week to 10 days required to start the second rotation. It stimulates grass growth from a grazed residual which is often better than a deferred pasture, and it establishes a low residual to set the season up for grass quality.
However, this 30pc grazed is not the primary objective of the SRP.
The SRP is a rationing tool for a prolonged period of where grass growth is always exceeded by cow demand.
So it's essential that we must not forget the cow in this. To be good at our system of high margin milk solids from low-cost pasture-based farming, one must carefully manage the balance between the grass and the cow.
Grazed grass is an excellent feed for the calved cow once settled into milking.
If fed from the start of lactation, it promotes increasing milk yields of high butterfat and protein levels.
This rising plane of nutrition also promotes the return to oestrus.
We all know what happens at any stage when silage is reintroduced.
Diet quality is significantly reduced and the milk quality crashes, irrespective of how much meal we put in front of these ladies.
So the main priority for the SRP is to keep an ever increasing amounts of pasture in the diet.
This is also the same reasoning as to why the SRP should be used in conjunction with knowing your average farm cover and grass growth rates.
The SRP should be adjusted where necessary when grass growth is slow or grass covers are diminishing quicker than expected.
In these circumstances, it is always important to use slightly longer rotations which makes the grass last longer.
However, in a year awash with grass, this poses a great opportunity to maximise grass intakes to milking cows and reduce the feeding of concentrates.
It's certainly the break we need after having fed so much in 2018. I'm rather baffled why some of this grass is being fed to dry cows, when it's rocket fuel for milkers.
I know the intention is to graze the 30pc, but a small extension of one to three days in April prior to the second rotation will recover the grass growth you may have missed from a grazed sward.
Believe me, farming wet ground makes you wait patiently in spring until ground conditions are worth the degree of damage that's tolerable.
Every time, whether grazing commences on the February 1 or 20 or March 1 or 20, we have managed to graze off the available cover not required to make cuts for silage.
It just means opening the cows up and feeding them more swiftly.
Now I admit I get anxious if cows aren't grazing by March 17, but it's happened and we've still got the grass off. The cows' capacity to graze in spring is notable and ever increasing and we must harness this capacity. I realise that in the era of quotas, there were serious risks of wasting grass.
But if your stocking rate reaches three cows/ha this spring and you monitor pasture regularly and set out to use it by getting cows to pasture, you can leave the silage for the dry cows instead of going from boom to bust on available grass supply.
Mary Kinston is a discussion group facilitator and consultant, and farms with her husband in County Kerry