18 September 1998

Cheap milk from autumn grass makes good sense

AUTUMN grass is a quality milking feed, high in both ME and protein, writes BGS grazing consultant Paul Bird.

Producers focused throughout the grazing season on milk from grass have another three months at least of producing cheap milk with minimal, if any, concentrates and no silage.

Where cows have been grazing laxly, and there is a build up of rotting material in the sward base, milk potential off grass will now begin to drop rapidly along with grass quality. Grass will have low metaboliseable energy and crude protein levels. On these farms winter kill – which generally occurs in patches, with green grass in-between – will be a concern unless action is taken now.

Graze grass more tightly to remove these rotting areas of grass. Where you are not prepared to do this mowing will be necessary.

Those extending grazing well into November should be on the second last grazing rotation, grazing about one-fortieth of the farm each day. On a 100-cow, 40ha (100 acre) farm this equates to 1ha (2.5 acres) every 24 hours. Where grass cover in this 1ha is at least 3000kg DM/ha, or 12cm or longer, there should be enough grass to supply 14-16kg DM a cow a day.

When grass growth is dropping, apply 50-60kg/ha (40-48 units/acre) of nitrogen. The aim should be to have a high grass cover in early to mid-October of 2300-2900kg DM/ha that can be eaten by cows in the final grazing rotation. The area allocated each day for this final rotation should be only one-fiftieth to one-sixtieth of the farm, or on the 40ha (100 acre) farm, about 0.7-0.8ha (2 acres) a day.

From October onwards, apply light rates of urea; 25kg/ha of nitrogen (20 units/acre) until soil temperature is below 6-7C (38-40F). This will encourage growth and maintain grass quality through winter.

In autumn-calving herds, grass demand will be less in September and October as there will be dry cows as well as an increasing number of milkers. Extra N in September and October may not be necessary to boost grass growth.

Starting block calving in August is too early to get the most from grazing. Cows require a reasonably consistent diet three to four weeks before mating. Calving on August 1 means mating starts on October 23. Grazing in October becomes more risky.

Where autumn herds could start calving in mid- to late-September, milking cows could get a large part of their diet from grazing in October and early November, and could then be brought in onto a consistent winter diet before mating begins.

Most producers who say that poaching is a problem in late autumn and early spring have poor access to fields and non- existent track systems, so poaching is inevitable.

But extended grazing is working, and improving profits on many farms. I suggest the sceptics visit farms that are doing it and find out how. &#42

EXTENDED GRAZING

&#8226 Plan for grazing

&#8226 Graze tightly

&#8226 Tracks essential

&#8226 Calving date?