Autumn a season of change for grassland management

WITH autumn fast approaching, the focus of grassland management on dairy farms should be shifting slightly.

Throughout the summer the target should have been to graze covers of between 1,300 to 1,500 kg of dry matter (DM) per hectare, in order to balance feeding of dairy cows, and ensuring cows graze out to four centimetres to maintain pasture quality.

It is important to walk the farm once a week to keep abreast of how the farm is growing.

Autumn is a hugely important time of year for grassland management, as it determines the amount of grass available for grazing the following spring. Once the last of second cut silages are tidied, the entire farm will become available for grazing.

Reseeded swards will be coming back into the rotation over the next six to eight weeks also. The objective for grassland management should be to ensure that the highest cover on the farm will be around mid-September. This will guarantee that sufficient grass will be on the farm for October and possibly November, depending on soil type, location of farm, stocking, and other variables.

Cover per cow will be the main figure to consider. At a stocking rate of 2.5 cows to the hectare, a cover of 200kg DM per cow with a rotation length of 25 days is ideal.

At this stocking rate, and a demand of 18kg of DM per cow, the demand is 45kg of DM per hectare per day. But in the Kerry/Limerick region last week growth rates of up to 70kg per hectare per day were still being experienced, so surpluses are occurring on many farms.

These need to be dealt with sooner rather than later by taking the high covers for big-bale silage, as recovery will be less on these swards as we move closer to September.

Also, these heavy covers will become excessively high and will be very difficult to graze out during September.

By September 1, the rotation length should be increased to 30 days, and the cover per cow to 300 kg DM. From mid-September to the start of October, the cover per cow should be 400kg DM, and rotation length should be around 40 days to cater for lower growth rates.

Where there is sufficient grass supply, as is the case on most farms at the moment, there will be little benefit from supplementation with concentrates, particularly when you take current milk prices into consideration. However, farms with high stocking rates may need to introduce concentrates in order to extend the rotation length.

Your local Teagasc dairy advisor can help you with your autumn grassland management decisions.