Is striking the optimum stocking rate really that important?

Under Irish grazing systems, dairy farmers try to achieve the perfect balance between cow and land performance.

Cow performance is judged on grass intake and milk production. The quantity of milk produced (milk solids kg/ha) and grass utilised (t/ha) are key parameters for measuring how well farmers are utilising their land.

Earlier this week, Teagasc’s Emma-Louise Coffey spoke about optimum stocking rates at the Moorepark ’17 open day.

For farmers trying to identify the optimum stocking rate, the Teagasc Walsh Fellow said it’s important to consider the following:

  • How much grass are you growing;
  • How much supplement are you going to feed your cows.

For a farmer feeding 0.5t of concentrate per cow and growing 10t of grass per hectare, the optimum stocking rate is 1.8 cows per hectare, Coffey stated.

“If we ramp up grass production, we can stock the farm at higher rates. If 16t/ha of grass is grown, we can carry a stocking rate of three cows per hectare.

Grazing days per hectare have massive implications for grass utilisation and milk solids production.

“When we increase the number of grazing days per hectare (grazing season length x stocking rate), we see an increase in both grass utilisation and the quantity of milk solids produced per hectare,” Coffey explained.

Each additional grazing day per hectare corresponds to an increase in grass utilisation of 11kg/ha and milk solids production of 1.7kg/ha.

“The more grazing days, the more milk solids we’re producing per hectare. Grass is the driver of milk production.

“Milk solids production per cow is important. But, with no quotas, we’re looking to maximise the amount of milk we produce from the grazing platform,” Coffey said.

Curtins trial results

Recent research, carried out at Curtins Farm, investigated a range of stocking rates and the results were compared to the national average stocking rate of two cows per hectare.

Range of stocking rates investigated:
  • Low stocking rate: 2.5 cows per hectare;
  • Medium stocking rate: 2.9 cows per hectare;
  • High stocking rate: 3.3 cows per hectare.

Coffey said that increasing stocking rate by 0.8 of a cow per hectare, with a minimal increase in supplementation, produced an extra 264kg/ha of milk solids.

“This was mainly driven by increased grass utilisation,” she added.

At the high stocking rate, the volume of milk solids produced per cow dropped by 8-10%. However, the quantity of milk solids generated per hectare increased by about 20%, Coffey said.

The results from the trial at Curtins Farm show that there is potential to increase grass and milk productivity on commercial Irish dairy farms in Ireland.

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