GOOD SPRING GRAZING
Preparing for an early turnout in spring starts
this month, maintains Livestock Improvement Consulting officer
John Simmonds, a New Zealander who has been running grass discussion groups in the UK under
the auspices of the British Grassland Society.
Here he details how to maximise use of grass.
WHICH answer will describe early spring grazing of grass on your farm in 1998? Will it be something that will happen depending on how good the spring is, or will grass be created, however bad the spring?
It should be the latter answer, because good grazing is created by management of pasture supply. And the critical factor determining early spring grass, despite the weather, is the date of the last grazing in winter, even in the UK.
Management during the autumn/winter is the key difference between NZ and UK grazing systems.
In NZ every effort is made to accumulate grass ahead of the cows, the aim being that grass grows grass. Grazing extends for longer into winter, and starts earlier in the spring.
In the UK winter is often described as the time when there is no grass to feed cows. But in NZ districts with even the coldest of winter climates, farmer experience is that the length of winter has been reduced by at least one month, simply by attention to autumn grazing and accumulation of quality grass supplies.
When challenged if this is a management option here, UK dairy farmers answer:
• Autumn grass does not supporthigh yields in fresh calvers.
• Pastures suffer winter kill.
• Sheep-keep is important income.
• Wet soils cannot be grazed with cows.
Are these valid reasons for not using autumn/winter grass for cows, or simply excuses to cover other inadequacies?
Autumn grazing and high yielding cows
When autumn grazing is on short length grass, typical of a set stocking regime, its no wonder cows will not milk on it. Dont blame the quality – its quantity.
High yielding cows require high intakes. This means the pasture must be at least 15cm (6in) high, and NZ experience suggests grazing intervals of at least 40 days in autumn are needed to achieve grass of this height.
From late September, effort must focus on reducing the grazing area per day, slowing the rotation, and generally pushing grass ahead of the cows. Give the grass more time to get to the ideal grazing height because radiation from daylight hours and temperature is declining. Remember – grass grows grass.
In spring, when grass grows rapidly there is probably little difference between rotational and set stocked grazing systems. But when conditions are slowing growth, such as late in autumn and early in spring, rotational grazing will always carry more grass in a grazable state ahead of the cows.
Grass for grazing cows in say late November, would previously be grazed in late September, fertilised and kept free of any other stock for 40 days. Another way we describe this is to offer no more than one fortieth of the total grazing area each day to the stock.
When there is insufficient grass on this area for the cows, then offer buffer feeds. High yielders are certain to require other inputs, but pasture could still provide at least half their diet, provided it is managed correctly.
Winter kill of pasture and sheep-keep
In the 60s, UK research showed that winter kill was a real factor, but present day pasture varieties have better winter tolerance. So does winter kill present the same threat? It is agreed that the residual, or grass left behind from cow grazings in autumn must be cleaned off. Pasture winter kill will be worse on any old, ungrazed spots. High yielding, high intake cows feeding 40-day old pasture in autumn will leave a higher residual of grass, which will thus require manicuring. Dry cows and youngstock can be used but sheep are the most common manicurer of autumn pasture residues.
But are these sheep eating the last of last years grass, or the first of next years grass? Income gained from sheep could be increasing the volumes of silage and cake required to keep the milking cows indoors in March/April.
If they have to be used, the timing of sheep grazing has a marked effect on grass available in early spring. Successful early spring grass grazers in the UK emphasise that sheep must be grazed early in the winter only. At a Cumbria Grasslands meeting the conclusion was "none later than New Years Day". Spring grazing was available from mid March on these farms, at least one month earlier than those where sheep keep remained on the farm until into February.
Where dairying is on very heavy soil types, farmers claim that using grass is more of a limitation than actually growing it. In difficult times such as late autumn and early spring, increased grass use is evident on farms with good access tracks, water troughs, and internal fencing. Mud is reduced by fewer stock movements over the same area. Also ensure:
• Track access to all grazed fields,
• Water troughs sited out into the field, away from the gateway. Putting them under fencelines between fields, is one way of economising, but the ideal position is probably in the centre of the field, with 360-degree access.
• Several gateways into a field, so several days of grazing do not cover the same tender area of ground. Ideally, make cows enter the field at the furthest point from the parlour, and exit from the nearest point.
Rules are made to be broken
While the principle is each day "always graze your longest grass first", be prepared to vary this according to individual paddocks weaknesses.
For example, if a farm has two out of 12 grazing fields where the cows must go through a paddock to get to a paddock – this is not direct access. Whenever the weather is dry, graze these fields, even if the grass is only 15 days old, and the desired interval is 40. Equally so, save the handy fields with best access for when conditions are bad.n
Inset: New Zealand consultant John Simmonds… Good grazing is created by management of pasture supply.