John Roche questions part 3

Published 4 July 14

In the last part of our Q&A series with Dr John Roche, he answers questions about stocking rate. These were posed to him by farmers, at a series of grassland meetings this spring.

What is the right stocking rate?

The right stocking rate depends on: the amount of pasture grown per hectare, the size of the cow, the amount of supplement purchased onto the milking platform, and whether the youngstock is reared at home or off-farm. To account for all of these variables, I talk about a comparative stocking rate, which is measured in kg Lwt/t feed DM available.

The optimum comparative stocking rate is 80-85kg Lwt/t feed DM.

This means that a 500kg cow requires 5.9t feed DM available (pasture, conserved silage, plus purchased supplements). If cows receive 500kg DM of purchased supplement and the farm grows 12t DM pasture/ha, this allows a stocking rate of 2.2 cows/ha. Personally, I would prefer a slightly higher stocking rate if farming on dry, free draining land.

How crucial is the stocking rate on heavy farms?

It is crucial but it shouldn’t be used as an excuse not to graze. For heavy, poorly draining soils, in high rainfall areas, the ideal stocking rate is probably 10% less than on dry farms. This offers a degree of flexibility at the beginning and the end of the grazing season.

Remember to consider your calving date when questioning stocking rate. If stocking rate is low, calving date should be earlier. If stocking rate is high, an early calving date will require much more purchased supplement. At an ideal stocking rate (80-85kg Lwt/t feed DM available), planned start of calving should be 60 days before balance date (ie when grass growth = herd demand).

Does too heavy a stocking rate limit the grass growth?

No, it doesn’t as long as you avoid poaching/damaging the paddocks. In fact, at a high stocking rate you are able to have longer rotations. This means that growth rate will be greater under a higher stocking rate and not less.

Research results from New Zealand indicate an increase in pasture grown of 1t DM/ha for every extra cow/ha increase in stocking rate. In addition, research results and on-farm results indicate an increase in pasture utilised of 2t/ha for every extra cow/ha increase in stocking rate.

From a tenant farmer/share milker point of view, where their equity is in their cows, what would be the optimum stocking rate? Should they be aiming to stock according to fodder grown on farm and matching the two? Or, how far over that line before buying in feed from outside dare they go?

The optimum stocking rate from a cash return perspective is the same as for owner operators. However, there are equity gains to having a marginally higher stocking rate, because of the extra calves born.

For the first and second part of the John Roche Q&A session visit the DairyCo website.