DAERA Management Notes: Dairying

Slurry spreading using the trailing shoe system for second cut silage
Slurry spreading using the trailing shoe system for second cut silage

Slurry and fertiliser for second cut silage

The online CAFRE Crop Nutrient Calculator is useful for working out slurry and fertiliser requirements for second cut silage. At soil index 2 for phosphate and index 1 for potassium (potash), typical indexes of fields with a history of being cut for silage, slurry has the potential to provide some of the nitrogen and potash and all of the phosphate.

An application of 22 cubic metres of dairy cow slurry per hectare (2,000 gallons per acre) and 375 kg (three bags per acre) of a 22:0:10 type fertiliser can meet second cut requirements at these indexes. At a practical level evenly spread slurry improves silage fermentation and minimises sward damage.

Growing a low potash (K) silage for dry cows

There are health and performance advantages to producing silage specifically for dry cows. Aim for a low K grass at cutting as high K silages are associated with metabolic disorders and subsequent poor milk yields in early lactation cows.

Fields previously cut for silage should not receive slurry again. An application of 315 kg per hectare (two and a half bags per acre) of CAN fertiliser (27:0:0) is enough to grow a low K silage for dry cows. Bale silage is suitable for feeding to dry cows. Leave cutting until early August as stem development coincides with a fall in the grass K levels. To avoid mould growth or mycotoxins the harvested grass dry matter should not rise above 35% before baling. It takes seven hectares to produce enough bales to feed 100 cows in the last four weeks of the dry period. Store the bales separately and use only for dry cow feeding.

Condition scoring late lactation cows

Cows calved last autumn are over 200 days in milk and should be condition scored any time now. Aim to have them at condition score 2.75 at calving. These cows should be about condition score 2.5 at the moment. Assess fat cover over the loin, pelvis and tail area:

Loin - there should be a slight depression along the cow’s top line and her loin. The shelf at the end of her transverse processes and flank should be filling.

Pelvis - there should be a good cover of tissue developing on the plates.

Tail area - there should be a good cover of tissue over the pin bones and the cavity at the tail head should be filling.

If you have cows that have not yet reached this stage and are well past 200 days in milk increase their dry matter intake. Try feeding some rolled cereal.

Water for cows at grass

Water for cows at grass is extremely important with 100 cows drinking 6,500 litres daily. On hot days (temperatures above 20oC) this figure can double. Troughs should be large enough so that 10% of the herd can drink at any one time with 30-50% water intake occurring within one hour of milking. Troughs in the centre of paddocks with fast flow valves and large bore pipes ensure cows have easy access to water. Clean troughs regularly as cows are very sensitive to smell and will not drink dirty water.

June jobs checklist

l Ensure good grazing management by grazing swards down to 1,600 kg dry matter per hectare to maintain sward quality.

l Think about dry cow winter diets now so that low potash silage can be made.

l Top grazing swards containing dead grass or seed heads to maintain sward quality.

l Calibrate parlour and out of parlour feeders to ensure accurate feeding.

l Carry out spraying if conditions are suitable and docks/weeds are at the right stage for control. If spraying docks in silage fields generally allow an interval of at least 21 days between spraying and harvest. Always read the label on the product used.