Three solutions to grass shortage

Many New Zealand dairy farmers want to know why they need to feed supplements, when in the past grass was enough. In this article, Waikato FarmWise consultant Bridget Ray addresses this question.
Bridget Ray says she often hears the on-farm discussion: "What is going on? We used to do it just on grass, we never had to buy supplements."
In many areas of the country, Bridget says, the biggest contributing factor as to why grass alone is not enough, is probably, "that for the past three years we have had seasons with poor growing conditions - put simply, we are not growing grass like 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 per hectare per year less in some regions."
Bridget says she believes there are a number of reasons why this is happening.
"Obviously lack of rain means less growth, but it is also the three hard seasons in a row, having a cumulative effect.
"Farmers looking at their pastures will notice a change in composition. The death of desirable pasture species has left gaps for weeds and undesirable grasses such as poa to come in."
Bridget says with long dry spells the nitrogen (N) cycle slows down or stops altogether making less N available for plant growth.
She said stressed plants are more prone to insect damage.
"According to DairyNZ figures a 450kg cow producing 350kg of milk solids (MS), eating 11 mega joules of metabolisable energy (MJME) feed, being milked for 250 days and utilising 80 per cent of pasture grown needs 5.1 tonne of feed annually. A 500kg cow doing 400kg MS needs 5.8 tonne.
"A dairy farm stocked at three cows/ha would need to grow 15.3 tonne grass/ha to meet feed demands for a grass only, fully-fed cow."
She says this raises the question how many people have grown this much on their farms in the last three years?
What can be done?
Bridget says farmers have three options:
1) Accept less production per cow and maintain stocking rate.
2) Decrease the stocking rate but maintain per cow production.
3) Buy in supplement
Grass growth drops by 1 tonne per hectare, per year, which means, says Bridget, if farmers were to maintain the same stocking rate they would expect to see a drop in per cow production by approximately 10 per cent.
"For example, on a 300 cow farm 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."
She says if there is less feed available on farm, farmers would need to dry off earlier than before in order to meet cow body condition score and pasture cover targets.
"If this is not done, production and mating performance the following season will be compromised.
"Another option in order to feed the cows at the same levels with less grass grown is to decrease the stocking rate."
Farmers would need to drop stocking rates by about 7 per cent to achieve this, says Bridget.
"On the average farm, as described above, this means dropping the stocking rate from 3 cows/ha to 2.8 cows/ha. The cost of this is about 60kg MS/ha or at a $6 payout, $360/ha.
"By dropping cow numbers farmers will also drop their variable cow costs by approximately $400 per cow. By dropping the stocking rate by 0.2 of a cow, costs saved would be $80/ha."
She says a third option with a drop in grass growth, is to fill the deficit with supplement.
"This means production per cow and stocking rate stay the same, so income stays the same, but feed costs have increased.
"To make buying in supplements to fill the deficit a more profitable option than dropping stocking rate, the cost of buying and feeding out would have to be less than the loss in production."