Maximising the amount of grass cows harvest themselves is a balance between making sure there is enough to eat, and maintaining the quality needed to support target milk production. Piers Badnell of DairyCo (pictured) dispenses best advice

Achieving this requires an understanding of how ryegrass grows. At any one time, a plant only has three living leaves; as a new leaf emerges, the oldest leaf dies back and rots, wasting potential feed.

When a plant has been eaten, sugars stored in the base of the plant powers the production of the first new leaf. This then provides the energy needed to grow the next two leaves. Hard grazing that takes out this first leaf will delay recovery and reduce overall productivity.

To maximise grass availability, cows should be turned into a pasture that has between 2.5 and three leaves, and taken out once the sward has been eaten down to a height of 5cm, preferably within 12, or at most, 24 hours.

How quickly leaves grow depends on temperature - in winter it may take 30 days to grow one; in May and June, just six. This is why the grazing rotation varies during the year - in winter as much as 90 days; in spring as little as 18.

The best way to manage these fluctuations in growth is by using a plate meter, which works out how much grass is available per hectare at any one point in time.

Cows should enter a paddock when there is 2800kg/ha DM and exit when they have eaten it down to 1500kg/ha DM. Letting cows into a paddock with more than 3000kg/ha DM results in wastage and poor use. Worse still, it reduces the quality of subsequent grazings.

Like conserved forage fed in winter, grazed grass should form the basis of the cows' summer diet. Only supplement with silage or concentrates when there is not enough grass to provide sufficient nutrients for maintenance and target milk yields.

How does silage fit into a grazing system?

For many producers in Britain, out-wintering dairy cows is not viable, so even systems that set out to maximise grazed grass need to make some conserved forage.

Silage is expensive to make so aim to make the best quality feed possible to ensure a good return on investment.

To maximise grassland use, grazing and forage conservation should be integrated. Identify fields for silage from any expected surpluses in the grazing rotation. Close up any grazing areas already at 3000kg/ha DM and not due to be eaten in the next few days. Be flexible in deciding which fields to cut - each year may differ slightly due to the weather.

What can you do to encourage cows to graze more?

Offering high-quality grass and making it easy for the cows to access it will maximise intakes.

Palatability is key - some grass varieties are more palatable than others as are young, leafy swards compared to more mature stalky pasture.

Avoid having dead and dying grass or muck and slurry in the base of the sward, as this will put animals off eating right down.

Access to and from the fields is important. Infrastructure such as free-draining tracks that allow swift, easy return to the paddock after milking will maximise time spent grazing. Drainage needs to be good to prevent mud baths. Consider having "in and out" gateways to reduce poaching in wet weather. Cows should not have to walk more than 250m to the nearest water trough.

Make sure electric fencing is working so the cows stay put, and do not move onto pastures that are not ready to be eaten yet.

When should you re-seed?

The ideal grazing sward consists of 70% perennial ryegrass (PRG) and 30% white clover. Once ryegrass levels fall below 50%, consider re-seeding.

The key questions are: Are you losing out from the genetic gains in yield and feeding attributes of newer varieties, and will the cost of re-seeding be paid back by the consequent gain in production and quality?

Monitor field yields throughout the season. Even a rough-and-ready reckoner, such as the number of cow grazings/ha, will allow a comparison between fields and previous years if recorded annually.

When soil tests reveal P and K levels are sufficient and compaction is not a problem, underperforming fields may warrant a re-seed. The Recommended Grass and Clover List details the most productive varieties.

How do you reduce the risk of compaction?

Compaction is unavoidable when you have 600+kg animals walking to, from and across paddocks every day, but the extent of any damage to the soil below will vary.

Compacted soils, where air pockets are squeezed and water cannot freely drain, create anaerobic conditions in which grass cannot grow. Overall yield and quality will be severely compromised.

Dig a hole to find out if there is a problem. Compaction caused by grazing is usually just below the surface, and will be most marked at gateways and around water troughs. Relieve the pressure by slit aerating in the spring (or autumn) when soil conditions allow.

How can you get the best start?

Grass starts growing at 5C, and above this growth accelerates. Monitor the rise using a cheap meat thermometer pushed into the soil, and use the information to plan first fertiliser applications.

There is no point spending money on nitrogen fertiliser when the extra grass that grows is not eaten by the cows. So use fertiliser as a tool to grow grass when needed. Use DEFRA booklet RB209 to derive a base nitrogen plan and measure grass growth to refine it.

Walk the pastures regularly to see how well or badly they have come through winter. Send any over-wintered sheep away once they have cleared out the old mature grass from autumn, or they will start eating grass the cows should be having in their first grazing.

Try to turn cows out earlier than usual - even two weeks can make significant savings. The cost of housing, excluding feed, ranges from 55p a day to £1.74 a day, so getting 100 cows out a fortnight earlier can save between £770 and £2436. Remember, shorter housing periods means less grass is needed for silage.

Start grazing with the low and mid-yielders - getting them to eat 5kg DM a day. This will take them three to four hours. Make sure they have not filled up on a TMR breakfast before going out, and allocate a small area so that grazing pressure is tight and they leave very little. This will ensure the quality of the grass the next time it is grazed - probably by higher-yielding cows - will be very high.

At turnout, the paddocks should ideally be at different stages of growth, so that when cows have finished grazing one (down to 1500kg/ha DM), the next is at the perfect stage (2800kg/ha DM) for them. Thus a constant supply of high-quality grass is put in front of the cows each day. Creating paddocks at different stages of growth is known as having a "feed wedge".

Fields shut up first in the autumn will have more cover in early spring and should be grazed first. If no wedge has been created, start grazing fields at around 2200kg/ha DM - below the optimum for grazing, but as grass continues growing in other paddocks, entry covers will gradually increase to the desired 2800kg/ha DM. This will establish a more ideal "wedge" for grazing the second time around.