Case for supplements
Many Waikato dairy farmers want to know why they need to feed supplements, when in the past grass was enough. Waikato FarmWise consultant Bridget Ray addresses this.
Often on a farm the discussion: ‘‘What is going on? We used t o do i t j ust on grass, we never had to buy supplements,’’ comes up.
Probably the biggest cont ri buting f actor as t o why now, grass alone i s not enough, is that for the past t hree years we have had seasons with poor growing conditions. Put simply, we are not growing grass as we used to.
Although it is hard to put an exact figure on how much less grass we are growing there are some reports that we are producing between two and four tonnes a hect are a year l ess i n some areas in the Waikato.
There are a number of reasons why t his is happening.
Obviously, l ack of rain means less growth but it is also the three hard seasons in a row, having an accumulative effect.
Farmers looking at their pasture sward will, I am sure, notice a change in composition. The death of desirable pasture species has left gaps for weeds and undesirable grasses such as poa to come into swards.
With long dry spells the nitrogen cycle slows or stops altogether making less nitrogen available f or plant growth. Stressed plants are more prone to insect damage.
DairyNZ f i gures show a 450kg cow producing 350kg of milk solids (MS), eating 11 mega joules of metabolisable energy (MJME) feed, being milked f or 250 days and using 80 per cent of pasture grown needs 5.1 t onne of f eed annually.
A 500kg cow doing 400kgMS needs 5.8 tonne.
A dairy f arm stocked at three cows/ ha would, therefore need to grow 15.3 tonne grass/ha to meet feed demands for a grass only, fully fed cow.
This raises the question, ‘ ‘ how many people have grown t his much on t heir f arms in t he l ast t hree years?’’
Probably not very many in the Waikato. What can be done? Farmers have t hree options:
1) Accept less production per cow and maintain stocking rate.
2) Decrease the stocking rate but maintain cow production.
3) Buy in supplement. It is important to note the scenario, grass growth drops by 1 tonne a hectare, a year.
To maintain t he same stocking rate and accept a drop in per cow production farmers can expect a drop in kgMS/ ha by about 10 per cent. On a 300 cow f arm doing 1000kg MS/ha, milk production would drop to 900kg MS/ha. All other costs would stay similar so at a payout of $6/kg MS loss in income would be $600/ha.
If there is less feed available on farm, in order to meet cow body condition score and pasture cover t argets cows would have t o be dried off earlier t han before. If t his was not done, production and mating perf ormance t he f ollowing season would be compromised.
The other option to feed the cows at the same levels with less grass grown is to decrease the stocking rate.
Farmers would need t o drop stocking rates about 7 per cent to achieve this.
On the average farm, as described above, this means dropping the stocking rate from 3 cows/ha to 2.8 cows/ ha. The cost is about 60kg MS/ ha or at a $ 6 payout $360/ha.