Making the most of genetic potential

Beneath the surface
with David Law
Forward Farming

Imagine buying a Maserati to be told you’re only permitted to drive it at 50km/hr. Bit of a waste of potential, don’t you think?

The same goes for dairy cows. Many are not performing to their true genetic potential because farmers are choosing a higher stocking rate, leaving cows underfed and underperforming.

Farmers spend a lot of time and money choosing the best genetics with which to breed their cows, but there is no emphasis on getting a return on that investment.

With artificial breeding, most cows have the potential to do high production – approximately 1kgMS per 1kg liveweight.

However, what varies is the ‘opportunity’ to express that genetic potential in milk production – is the herd being fed enough to perform at its potential? Or has the farmer tipped the balance between stocking rate and feed availability?

In a calendar year, a cow generally only needs eight weeks – or 56 days – dry to prepare herself for the next season. That leaves 44 weeks – or 308 days – in which to maximise her genetic potential.

Lactation days

So how do you work out the current number of lactation days of your herd? Look at the time between your median calving date and dry-off date, and you will get a general estimate of total number of lactation days.

If your herd’s average lactation length is 235 days, you’re experiencing a dramatically shortened season and individual cows are not milking to their full genetic potential. To see maximum genetic potential, you need to be able to feed cows comfortably to a 270-300-day lactation.

This is where stocking rate comes in. A 500-cow herd with average of 235 days lactation equals a total of 117,500 lactation days across the herd.

Increasing lactation length by just one month, to 265 days, means you can lower your stocking rate to 443 cows without losing any lactation days. This is 117,500 divided by 265 equals 443 cows.

Those extra 57 cows would have required 12kgDM/cow/day as maintenance, a total of 684kgDM/day. Over a year, that’s 249,660kgDM, costing roughly $80,000 at .32c/kg.

Instead, that 684kgDM/day, divided by the lesser stocking rate of 443 cows, is 1.54kgDM/day extra feed available to the herd.

That extra feed goes a long way toward cows expressing their genetic performance potential.

Smaller herd

At 1kgMS per 1kg liveweight, an average mixed breed cow can comfortably produce 450kgMS if it is fully fed on a mixed ration diet. With a herd of 443 cows, that’s 199,350kgMS.

However, a herd of 500 cows may only produce 340kgMS due to being underfed – that’s 170,000kgMS.

In comparison, it’s easy to see that in most cases it is far better to fully feed a smaller herd, allowing them to perform closer to their genetic potential, than to have a higher stocking rate and be unable to fully feed them.

Underfed cows not only experience lower production but calve at a lower condition score. Heading into the peak profit window of July-December, low condition score cows don’t have the reserve condition to pull themselves through the increased demand.

They are also under more pressure during mating, resulting in higher empty rates. All these flow-on effects cost the farmer money.

Every farm has a different system: some farmers carry young stock, or winter all or a percentage of cows on-farm, requiring a build-up of feed on-farm; others winter cows off-farm, allowing pasture recovery during winter months.

Comparing your farm system to others does not accurately determine whether your business is profitable or sustainable – but by designing Key Performance Indicators for your own farm system, you can decide what a profitable system is, and how you will measure that.

Feeding too many cows

Many farmers are simply feeding too many cows. Getting your stocking rate and lactation length right is the most efficient way of operating a profitable business. If you feel you need to increase lactation length by dropping your cow numbers, the best cows to drop are your last calvers.

For more information on balancing stocking rate and lactation length, please contact me for advice. David Law is the director of Forward Farming Biological Consultancy.


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