Over winter, growth rates were above average, and wet weather and snowfall affected pasture utilisation in many South Island areas. This can make it difficult to achieve optimum pasture residuals in the first grazing rotation post-calving.
Achieving grazing residuals is crucial for future pasture quality and growth. If post-grazing residuals are above target, i.e. 1500 to 1600 kilograms of dry matter (kg DM) or 3.5 centimetres (cm), residual material will decay in the base of the sward. This will affect pasture growth and quality as well as utilisation, which has a knock-on effect on milk production in future rotations.
1. Have confidence in the Spring Rotation Planner (SRP)
Grazing pressure will increase as more cows calve and enter the milking herd. There’s a risk that target residuals won’t be met due to continued high growth. Remember to remove supplementary feed to maximise pasture utilisation. Check out dairynz.co.nz/srp
2. Be prepared to tidy up paddocks in the next round
If post-grazing residuals of 1500 to 1600kg DM/ha are not met due to wet weather, record and prioritise these paddocks with harder grazing or topping in the next round to limit negative effects for the rest of the season.
3. Bring cows home early
If you can, consider bringing cows home early from winter grazing (but bear in mind any risks of a deficit if future growth slows).
4. Use dry cows to graze the highest-cover paddocks
This will maximise the quality of intake for the milking herd. Careful allocation will prevent overfeeding of dry cows on longer covers, particularly if they’re above body condition score (BCS) targets.
5. Delay and/or reduce nitrogen use
If nitrogen is applied when there’s already surplus pasture, the surplus will increase. This will lower pasture quality and increase costs associated with managing the surplus, e.g. making silage. Use a feed wedge to forecast potential deficits and delay nitrogen use for then.
6. Drop out some area for silage
Shortening the grazing rotation will ensure post-grazing residuals are being reached, although early spring silage may be lower quality due to a high moisture content and fermentation difficulties. Also, if too much area is dropped out in early spring when growth rates can be variable, it may create a feed deficit.
Managing spring surpluses – online info
- Download DairyNZ’s Spring Survival Guide at dairynz.co.nz/spring
- Check out Farmfact 1-38 Surplus management and DairyNZ’s Technical Series September 2016 at dairynz.co.nz/late-spring
- Get involved in the spring surplus conversations on Facebook pages for the Lincoln University Demonstration Farm (LUDF) and Southern Dairy Hub (SDH):
This article was originally published in the South Island edition of Inside Dairy September 2019
