Managing autumn grass on dairy farms

THERE are two main objectives in autumn grassland management on dairy farms – firstly to maintain the level of grass in the cows’ diets as against more expensive concentrate use and secondly to finish the grazing season with adequate grass cover in order to have sufficient grass for sustainable early turnout of the cows next spring.

Grassland budgeting and measurement is essential to achieve these two aims. During August/September and early October period it is important to measure grass supply weekly so that you know how much grass you have and how much you need to have.

As all the grass platform is available one should target a rotation length to 35 days by mid –September. If farm cover is below target at any stage, take quick action to bring it back on course, such as introducing a higher level of concentrate or removing surplus stock.

Start to close paddocks from the 10th October onwards (1-2 weeks earlier in wet areas). Aim to have 60% farm closed by the end of the first week of November (again, 1-2 weeks earlier in wet areas).

The paddocks grazed by this date will have an opportunity to grow grass before growth rates decline in November. The grass that will be grazed in the spring is this grass that is grown in the autumn.

Closing paddock covers should average 550600kg DM/ha with covers ranging from 900kg DM/ha for the first paddock closed to 200kg DM/ ha for the last paddock closed. It is important to graze down paddocks well - to a residual of 4 – 4.5 cm to stimulate growth throughout the late autumn and winter (if conditions allow) and avoid the carryover of dead material over the winter and into the following spring.

Demand is under the farmers control, however growth is mostly dependant on weather conditions.

The use of strip wires can become essential to allocate milking cows the correct amount of grass and also minimising damage to paddocks in unfavourable ground conditions.

Use wet weather grazing techniques if ground conditions deteriorate (e.g. on-off grazing, strip wires). During the last rotation, focus on grazing residual heights if you want to have top quality swards for your milking herd next spring. Feed supplements if there is insufficient grass in the daily allocation.

Avoid the temptation to re-graze fields that have been closed as spring grass availability will be reduced. 1 kg DM of Spring grass is worth in the region of €0.16/kg DM while in the Summer 1 kg DM of grass is worth €0.04/kg DM – so the economics favour spring grass and it should be prioritised for this reason. Be flexible – an autumn budget is a target for grass supply relative to growth and demand.