Each individual tiller produces three fresh live leaves. The oldest leaf (first to emerge) starts to die when the fourth leaf begins to emerge and grow.

The leaves are the plant’s factory – they use photosynthesis to

produce energy for growth that farmers measure as ‘Dry Matter’ (DM).  DM is pasture minus the water.

Pasture begins to grow slowly again after grazing, as each ryegrass plant has to start putting out new leaves again.

Growth rate then increases with each new leaf bigger than the previous one.

So during:

• Week one you get 10% of pasture growth
• Week two growth produces 35% of potential
• Week three growth produces 55% of potential.

Feeding value (digestibility) is generally similar for leaf one and leaf three.

If pasture is allowed to grow beyond the three-leaf stage, leaves die; feed value falls as dead material builds up.

These tall pastures should be grazed before the canopy closes over and you can’t see the ground among the individual plants, or the clover will suffer from shading.  It may look as if you have a lot of good green feed, but open up the pasture and see the large areas of bare ground at the base.

Pastures should be grazed leaving about four centimetres as a ‘residual’ for dairy cattle, and about three centimetres for sheep.

Don’t graze below three and a half to four centimetres for dairy cows and two centimetres for sheep otherwise pasture regrowth will be delayed, and stock will eat more dead matter, causing ‘ill-thrift’.

Leaving pasture behind reduces pasture quality in the long term, so graze when the three leaves have grown. Weeds grow where bare ground has been exposed, and the soil can dry out and reduce subsequent pasture growth. 

Cutting, like grazing, will stimulate pasture plants, forcing them to start growing leaves again.

The plant will remain in ‘negative nutritional balance’ until two leaves have grown.

Repeated grazing weakens the plants and could kill them all. So prevent pastures growing out of control and reaching this ‘canopy closure’ stage by earlier grazing or taking them out of the rotation for a silage cut.

Leaves take 13-30 days in autumn/winter (39-90 days for all three).

Pick ten ryegrass tillers across the paddock that the stock are about to graze. Count the number of new leaves/tiller – ignoring leaves previously grazed (with cut ends).

Work out the average number of leaves/tiller.  Divide the number of days since the last grazing by the average number of leaves/tiller.

This gives the leaf appearance rate, which if multiplied by three, gives the average time for a plant to produce three leaves – and hence should be ready for grazing.

Then you can see how long it’s going to take for the pastures to reach an optimal grazing time.