Feeding cows: Get a calculator
Imagine for a moment that you change careers and purchase three lactating cows and a disused rugby field for them. You will be in line with most Kiwi dairy farmers, running a stocking rate of three cows per hectare.
Of course, you are a pasturebased farmer and feed your cows 100 per cent grass.
To ensure your cows are well fed, you will give each cow 150 square metres of grass per day. A rugby field is 77m wide. Each day you will set up a portable electric fence running from one sideline to the other – essentially giving the cows a block of grass 77m by 6m.
Your cows will start in your own in-goal area and will move
on to a new block of grass in 6m increments. After 22 days you will reach the opposition in-goal area.
At which point you will simply take your three cows back to your own in-goal area and do the whole thing again.
Luckily the grass has been growing over those 22 days and there is plenty of new grass available.
At this point, you will be feeling quite good about your change in career – despite having to milk three cows on Christmas Day and staggering out of bed at noon on New Year’s Day to three cows wondering why you are five hours late.
That is, until the grass stops growing. At this point, you will realise why the central point of conversation at any rural gathering is any factor or thing, that may in any way affect the growth of pasture.
In mid-May when your three cows have reached the opposition end-goal area once again, you will look back across the halfway line, past your 22 and into your end-goal and realise there is no new grass for your cows to eat.
The economics are now somewhat different. You now need to feed your three cows for 90 days with no grass growth.
Farmers measure feed in kilograms of dry matter per hectare. Dry matter is the content of feed with all the water removed.
During the spring, summer and autumn your three cows have frolicked in a spacious 150sqm of pasture measuring 2500kg dm/ha. If you were to carry on with the same feeding system you would require another four rugby fields of grass to keep your cows fed for the next 90 days.
You could decide to buy in some other feeds and only feed 50 per cent of your cow’s diet in grass. In this case, each cow would get 75sqm and you would need only two extra rugby fields.
Another option is to find a rugby field with very long grass of 3500kg dm/ha. In this case, you will need only one extra rugby field to see you through the winter and each cow will have 37.5sqm per day.
Why not just do away with grass altogether and feed a cereal crop like oats. A good oat crop will yield 6000kg dm/ha and the cows will require just one-third of a rugby field and each cow will have 42sqm per day.
What if you could find an even higher-yielding crop?
A fodder beet crop will yield 20,000kg dm/ha. Now we’re talking. All you need now is 10 per cent of a rugby field of fodder beet to feed your three cows for 90 days.
You simply plant the opposition end-goal area in fodder beet and there is no need to buy or find more land at all. This is great in every way. On those frosty winter days, the cows quickly eat their daily ration and spend the day laying in the sun.
But it is a different story when it rains, as it tends to do in the winter. During the summer months, your cows have enjoyed 150sqm of pasture. Now each cow only requires 4sqm of fodder beet to receive 50 per cent of their diet. But your 450kg cows quickly turn the wet soil in that 4sqm into mud which doesn’t make for good drone footage.
But you have options, you could build a feed barn. But your bank manager frowns at a cost of $2900 per cow. Banks don’t want to lend to rugby field farmers at the moment.
You could build a concrete feed pad. After your cows have eaten their fodder beet you can put the cows on to the concrete for the rest of the day munching on silage. But the cost of $425 per cow plus the extra labour to move the cows on and off the crop every day is still an additional cost.
You look at the many other options for managing your winter feeding.
Whichever way you look at it you realise the costs of feeding your three cows for the 90 days over winter is going to increase.
You start to wonder if you paid too much for that rugby field.