Dairying Notes May 2007
Grazing Management
Excellent grazing conditions in early April allowed turn out 1-3 weeks earlier than usual. Although swards have been well grazed on the first rotation, you need to manage swards carefully next month to ensure high quality re-growths for the rest of the season.
Areas for attention during May
- Turn cows unto swards with a cover of 3300-3500 KG DM/ha (15 cms tall) and graze down to 1600-1800 KG DM/ha (6 to 7 cms tall).
- Walk grazing twice per week for early identification of a grass surplus.
- Check AgriSearch Grasscheck grass growth figures in agricultural press or on the internet. If cows graze swards with covers over 4000 kgs DM/ha, the sward to graze in 10 days time has already a cover of 3000 KG DM/ha.and with Grasscheck predicting growth rates of 80-90 KG DM/day grazing will further get ahead of the herd. Cut surplus grass immediately for silage.
- Towards the end of the month start topping swards if required.
Feeding concentrates at grass
In ideal grazing conditions like those of recent weeks, grazed grass can sustain cows yielding 25 to 27 litres per cow per day during May. Cows yielding above this require concentrates. Suggested feeding levels for cows grazing good quality grass in May are:
Table 1. Supplementary concentrate levels for high yielding cows.
| Milk yield (litres/ cow/ day) | 25 | 35 | 40 |
|---|---|---|---|
| Grass DM intake (KG/ cow/ day) | 18 | 16 | 14 |
| Concentrate (KG/ cow/ day) | 0 | 4 | 8 |
In poorer conditions,concentrate levels should be increased by 2 to 3 KG. Make allowance for the lower appetite of first calvers by feeding concentrates for production above 21 to 22 litres.
Buffer feeding
You may be considering buffer feeding grass silage or an alternative forage to maintain forage intakes. Best responses to buffer feeding are obtained where grass supplies are restricted or grass intakes are reduced due to adverse grazing conditions. In situations where grass is readily available or poor quality silage is buffer fed, milk yields can be reduced.
Silage – when to cut
Grass maturity at cutting has the greatest influence on silage quality. For a target ‘D’ value of 70, you should cut at the first sign of ear emergence. For each week’s delay in cutting an extra 2.2 KG of concentrates/cow/day would be required to maintain the same milk yield.
The warm dry weather this April could influence when you should take first cut silage. Early heading grass varieties have matured rapidly and will head earlier than normal - some County Down producers may already have completed first cut. If this fine weather continues, mid and late heading varieties may have to be cut earlier than usual. Check the weekly Agrisearch Grasscheck report for up-dates on grass maturity during May.
Fertiliser application on many farms was delayed by the wet conditions in March. Where normal nitrogen application rates have been used, analysing a grass sample to check nitrate levels before cutting would be advisable. If nitrate levels are high cutting may have to be delayed unless a good wilt (greater than 25 percent DM) can be achieved.
Wilting
The positive impact of feeding high dry matter silage on cow intake and performance was evident on many units last winter - hopefully the weather will again favour wilting. To achieve a target dry matter of 25 percent consider
- A crop cut at 20 percent DM will reach target in 24 hours if left in single swathes in dry weather.
- In ideal wilting weather a crop will reach target within 8 hours if spread out
- Even in good wilting conditions, crops cut damp will need to be spread if the target DM is to be achieved within 24 hours.
- Avoid overwilting which can produce unstable silage. If ensiling is delayed, rowing up swathes reduces wilting rate.