Forage Focus: March 2015
Exploring the world of high quality forage production and utilisation with specialist agricultural merchant Morton’s
Preparing for Turnout
Turning stock out to grass early can provide benefits in financial terms, however this is not always achievable due to ground conditions. Work carried out at Hillsborough during the nineties showed that turning cows out for even two hours per day in the spring had benefits in milk and protein yield while reducing silage requirements. A gradual turnout is the best approach as this allows the rumen microbes to adjust to the change in diet.
It is important to choose fields which are free draining, south facing, have good access and have been grazed down in the autumn (but not after early October). Grazing sheep later may seem attractive but this will delay turnout and perhaps even the quantity of forage available. The only advantage to grazing sheep after this point is to clear up any old grass, as this will improve the quality of the forage for the spring. Fields shut up first in autumn should generally be the first fields to graze. Fields closed up at different points in the autumn will enable a grass wedge to be built up the following spring, making it easier to manage with fields being ready for grazing at different times. If too much grass is built up then paddocks or fields should be taken out for silage.
Swards will generally be between 8-10cms when they are ready for grazing by cows or beef animals, and should then be grazed down to 4-5cms. As a rough guide, cows will be able to graze 5kg of dry matter in a three hour period. Stocking rates should be adjusted according to ground conditions; stock levels should be lowered if ground is marginal or if it suits it can be grazed with lighter stock. Swards damaged at this point by overgrazing (below 4cms) or poaching will take longer to recover and overall production will be reduced. Introducing stock gradually over a period of two to three weeks means that if weather conditions do not allow continued grazing, stock could be put back on the winter diet with less disruption.
Once soil temperatures reach 6° C grass will actively grow and by the end of March could be producing up to 30kgs DM/hectare/day. Grass responds best to nitrogen when soil temperatures are at 5°C or above for at least four days: at that point, a top dressing of 40 units per acre will give a good response.
Planning for early turnout should also include selecting the correct species and varieties for extending the grazing season. New grass swards can potentially double the output of old swards which have become infested with weed grasses such as creeping bent, Yorkshire Fog, annual meadow grass and rough stalked meadow grass. In addition to the reduction in yield from these species when compared to perennial ryegrass, there is also a reduction in quality and response to nitrogen. Research at Hurley has shown that after eight years only around 50% of the sown species remains in the sward and after 20 years only 12% remains, so this is useful to bear in mind when considering the need for reseeding. Breeders like IBERS now offer varieties which will give extra production in the spring and the autumn.