With first cut beckoning at Waterside Farm, Perthshire, Sophie Vance Kinnear has battled through a challenging spring managing a newly-established dairy herd
With first cut beckoning at Waterside Farm, Dunblane, Perthshire, Sophie Vance Kinnear has battled through a challenging spring managing a newly-established dairy herd on an unfamiliar paddock grazing system where maintaining cow body condition has been a priority.
Miss Vance Kinnear says: “Grass growth has been low due to the cold weather. It only just reached 59kg dry matter [DM] per hectare per day in mid-May. There is quite a bit of variation across the two-hectare paddocks set up to provide a day’s grazing allocation for the 152 cows.”
Having served many herd members in late autumn, the cows’ body condition has held up well with the switch to grazing – a welcome surprise given the diversity in genetics and range of outlets from which the recently established herd was sourced, she says.
Current fresh grass analyses taken for DairyCo’s Forage for Knowledge project suggests a crude protein level of 24.3 per cent, 12.3 ME and DM of 17.5 per cent. Supplemented with 1kg concentrate/cow fed in the parlour, the herd’s average milk yield is now 20 litres/cow/day. Mineral licks and salt have been set out for different ages of stock to avoid deficiencies as the cold weather remains.
She says: “It has been a steep learning curve assessing the individual paddocks, as some lie cold and others, wet. To avoid cutting up the leys – most of which have been reseeded in the past five years by owners Robin and Barbara Young – cows have been taken off leaving residuals of 1,600kg DM/ha, although the original target was 1,500kg DM/ha.
“Robin has been applying 36kg N/ha in the form of urea behind each paddock grazing, using a GPS-guided fertiliser spreader for accuracy,” she adds.
The unit relies heavily on silage as a main winter feed and the 900 tonne clamp is completely empty. Contractors are set up to come in late May but slow growth may see this put back to early June. Miss Vance Kinnear says: “We expect to take out 80 acres of first cut, including 20 acres reseeded last September with late heading perennials, clover and rye-grass. To reduce risk of spoilage, all silage will be treated with an additive.
“My plan is to go over the aftermaths with a top dressing of 22:4:14 fertiliser at 200kg/acre plus 7kg/acre of sulphur. Hopefully weed burdens will be low as all leys were sprayed earlier this spring to tackle docks. I intend to keep going around with the quad bike spraying persistent patches.”
Surplus grass is being cut to be conserved as bales for use later in the grazing season if grass growth stalls. This will avoid a need to open the silage clamp unnecessarily early.
She says: “We aim to calve a block in September. Low yielders or those with poor milk constituent were put to a British Blue and milkier cows to a Friesian – both by AI – last autumn as we got to know the new herd. Limousin and Angus sweeper bulls then ran behind.
Fertiliser application is top priority following first cut, however, it is important to take stock of the crop requirements and on-farm nutrient stores to keep costs low, says DairyCo research and development manager, Dr Debbie McConnell.
She says: “Nitrogen application for second cut should take account of increased mineralisation of N from the soil and lower grass growth rates at this time of year. As a result, 35 per cent of the annual N requirements should be supplied ahead of second cut, usually 80–100kg N/ha. However, grass N requirements vary with soil type, climate, grass species, clover content, organic manure input and soil mineralisation so it is important to calculate fertiliser requirements using chapter eight in RB209, specific to individual farms.
“With atmospheric sulphur deposition levels falling by 94 per cent over the last three decades, sulphur application is necessary, especially at second and third cuts and on sandy soils. Atmospheric deposition now accounts for less than 10 per cent of crop requirement, hence an application of 40kg of sulphate is required at each cut to prevent sulphur deficiencies.”
Slurry can be a cost-effective source of nutrients after first cut. A typical 30cu.m application of dairy cow slurry will supply 75 per cent of the 25kg/ha requirement of phosphate and the total requirement for potash on Index 2 soils. A 30cu.m/ha application will also supply 25kg of available N, depending on spreading conditions and technique, and 20kg of sulphate. This equates to a financial value of £108/ha (£44/acre).
Dr McConnell says: “At this time of year there is also a strong economic incentive to use low emission spreading techniques, such as trailing shoes or injectors. Losses of ammonia to the atmosphere can be as much as £16/ha when using an injector compared with a splashplate.
“This also widens the spreading window available. Research has shown slurry can be spread up to 28 days after first cut with a trailing shoe or dribble bar, without a detrimental impact on yield or quality. This window is more restricted with a shallow injector as the cutting tines may damage the sward after a few weeks. Nonetheless, it is important to separate slurry application and fertiliser applications by at least three to four days to avoid any loss of nitrogen through the interaction of fertiliser N with moisture in slurry.”