Analysis of the financial and physical data for a range of NZ dairy farms using RedSky (a software programme for measuring farm performance available through Intelact), indicates that the biggest driver of profit on a dairy farm is pasture harvest. Probably not a big surprise!
Given that pasture harvest is linked so strongly to profitability and that profit is so important in the current economic environment, the bigger surprise is that more farms are not taking the opportunity to measure and monitor pasture growth and harvest rates.
The recently developed "3-leaf principle" can be used to estimate how fast the grass is currently growing on your farm and then to set a rotation to match. When carefully applied, this principle will maximise potential growth rates and pasture harvest and improve tiller persistency.
In pasture, ryegrass plants are actually a collection of tillers, each tiller living for a maximum of around one year, regardless of how long the pasture has been established. Each ryegrass tiller produces three green leaves; as the fourth leaf appears, the first dies. In sunlight, leaves produce sugars and these are used as an energy source by the plant. What the plant doesn't use immediately is stored in the base (bottom 4cm) of the tiller.
When a ryegrass plant is grazed, the roots stop growing; new tillers stop emerging and the plant uses its energy reserves to grow its first leaf. This new leaf begins to make energy from the sun as it grows but it is not until the second new leaf has grown that energy stores are replenished and root growth and tillering are active again.
If the plant is grazed before this critical 2-leaf stage, yield will be reduced (as will milk production) and the plant will be less likely to survive successive grazings due to depleted energy reserves. The 2-leaf stage thus sets the minimum grazing interval for ryegrass pastures.
If we let the ryegrass plant grow beyond the 3-leaf stage, leaves start to die, pasture is wasted and pasture quality deteriorates. Milk production from these pastures will also be reduced. The 3-leaf stage thus sets the maximum grazing interval for ryegrass pastures.
For more information about the "3-leaf principle," please contact Lindsay Rowe at the Feilding branch of Totally Vets. He has been using the principle for several years now and can help you apply the technique to your property.