Dairy management: grass growth slowing

Average grass growth rates are beginning to slide. Grass was growing at a rate of 80 to 90kg/day up to last week, but growth rates of 60 to 70kg/day are more common now.

Is this the effects of a mini drought? I don’t think so. Rainfall levels for the year to date are normal for most weather stations across the country.

Yes, May has been an exceptionally dry month so far but I don’t think a soil moisture deficit is the main cause.

What most farmers need now is a bit of softness in the weather. An easing of the drying north easterly winds and a return to more Atlantic weather patterns would probably see another spurt in growth.

For the moment, there’s no need to panic as this weather pattern is expected later this week. However, the amount of rain it brings with it is hard to know. Certainly, 20 or 30mm of rain would not go astray on most farms.

Even with lower growth rates there is still more than enough grass on most farms so extra supplement is not required in most cases, unless stocking rate is very high with a lot of ground out for reseeding or long term silage.

Because growth rates have slowed, you should aim to reduce demand by bringing land back into the rotation. Cut any paddocks that were earmarked for silage as soon as possible, at least before the weather changes on Thursday.

It’s a good idea to walk the farm to measure grass before cutting these paddocks. If average farm cover has gone low, some of this grass may have to be grazed by the cows.

For me, a low average farm cover is one where average farm cover per livestock unit is less than 135kg/cow and growth rate is less than demand. I’d be more comfortable at a farm cover of 160kg/cow at this stage.

If tight for grass an opportunity to graze a paddock that was earmarked for silage might be worth taking, only if it’s not gone too strong.

Some farmers will take a light grazing and leave a high residual – basically grazing the leaf and leaving the stem. Others will pre-mow and get the cows to eat it all.

Both methods will affect production if the sward is too strong. This can be mitigated against by grazing these covers by day and grazing ‘normal’ covers by night.

Utilisation of grass is generally good and cows are content so there’s no need to panic regarding grass growth. As they say in New Zealand; “panic slowly”.

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