3 August 2001

Additional grazing for cows with catch crops

By Richard Allison

SOWING catch crops to follow whole-crop or cereals can provide up to 15 weeks additional autumn dairy cow grazing to eke out scarce winter forages and reduce concentrate and use.

However, adequate soil moisture at sowing is essential for good establishment, says Kingshay Farming Trusts James Hague. "Currently, soil in some areas of the UK is too dry for establishing cat`ch crops."

Check for moisture in the top 5cm (2in) of soil, when none is found, germination will be poor. Cereals are a poor indicator of soil moisture status for subsequent crops as their roots extend more than 1m (3.3ft) deep. However, applying dirty water from slurry lagoons may increase soil moisture to help germination.

"When soil moisture is adequate, using a drill will ensure seeds are in contact with soil. Alternatively, seed can be broadcast and followed by Cambridge rollers or light discing."

Once the crop has grown, early planning is crucial. Wetter fields should be grazed first, leaving dryer areas for grazing when conditions become wetter. It is also important to ensure fields have good access tracks to minimise risks of lameness, he advises.

To ensure continuous grazing, Mr Hague recommends staggering sowing dates by three weeks. Dry matter yields of 3t DM/ha (1.2t DM/acre) are easily achieved eight weeks after sowing.

Mr Hague also advises sowing kale or stubble turnips near an area of fallback grazing. This prevents cows from consuming too much of the highly palatable crops which can lead to milk taints. Aim for cow intakes of up to 4kg DM/day, any higher is unrealistic considering the low dry matter content of these crops.

Another option is to let cows out for a limited period to graze the crop when housed during autumn. But care is needed to balance the whole ration including the catch crop, particularly fibre supply, he adds.

Cows yield well when fed kale and turnips because it offers a balance of protein and metabolisable energy, better than many compounds. Mr Hague explains that concentrates can be reduced by 2kg/cow when feeding kale without compromising milk output.

Mark Osman, herd manager for the 300ha (750-acre) Berks farm owned by Zeneca, sows half of his stubble turnips in late July and the remainder four weeks later. "This ensures a split growth pattern to balance growth, so stretching out autumn grazing to 10 weeks," he adds.

Both stubble turnips and Italian ryegrass are essential catch crops within Mr Osmans winter feeding strategy. "Stocking rates are tight at 2.7cows/ha and catch crops are ideal for providing additional feed from land for maize."

"Italian ryegrass is sown after wheat in early September. It provides a quick bite for cows in autumn, three weeks early grazing in February and a first cut of grass silage."

Ryegrass is then ploughed before sowing maize for silage. Using a ryegrass catch crop also boosts maize field yields by 2t/ha (0.8t/acre), making it an effective system, explains Mr Osman.

Stubble turnips usually follow whole-crop wheat, before going into maize the next May. The mixture consists of 40% rape and 60% turnips, and is used to over-winter 90 dry cows on 16ha (40 acres). Dry cows are also fed straw, to appetite, in ring feeders and dry cow rolls to provide minerals and vitamins.

Mr Osman believes this system saves 0.5t/cow of straw bedding as a result of reducing the winter housing period by 10 weeks. "This is good news with the recent hike in straw prices." &#42