How a pasture is grazed and managed over winter will determine how quickly it responds to the increase in day length and temperature observed in the spring. We have collated some tips below to help make sure your pasture is ready to respond at maximum capacity.
Grazing residual and recovery
Grazing residual – what is left behind by the animal, is key in how quickly that plant will recover. Over grazing of pastures and leaving short residual (2cm or 700kgDM) means that the plant takes longer to recover leaf area or in worst cases dies back. Table 1 below shows the pastures ability to regrow after grazing. Ideally at least 1000 kgDM/ha or 3cm residual should be left to ensure pasture regrowth is not reduced.
Table 1. Grazing residual knock on effects
|Residual in cm||Residual feed on offer||Expected regrowth
|Regrowth feed on offer|
|2cm||700 kgDM/ha||2 cm||1200 kgDM/ha|
|4cm||1200 kgDM/ha||3cm||1700 kgDM/ha|
|6cm||1600 kgDM/ha||4cm||2200 kgDM/ha|
Leaf emergence rates and optimum maturity stages
Figure 1. Ryegrass leaf to feed ratio
Figure 1 shows the pasture mass that can be expected at each of the leaf stages of a ryegrass plant and similar can be said of any of the perennial species (i.e. most of the mass comes with the emergence of the later leaves). Perennial plants should be grazed at different leaf stages – Ryegrass 2-3 leaves, Phalaris 4 leaf stage and cocksfoot 4-5 leaf stage.
Adverse grazing pressure (i.e. grazing residual too low or grazing before optimum leaf stage) slows down the overall plant growth, decreases the plants carbohydrate storage reserves and results in smaller root systems, or root system dieback which leads to decreased plant persistence and opportunities for weed invasion.
Leaf emergence can easily be calculated using the following equation:
Note: don’t take measurements from pasture clumps, you must be able to identify a ‘remnant’ or eaten leaf.
Planning a rotation
Rotational grazing during winter requires longer rest periods because leaf emergence is reduced. When developing a rotation you need:
In winter when leaf appearance rate is slow to maintain your rotation length, you will need to supplement the animals with conserved or brought in feeds to ensure that residuals are maintained. To do this you will need to perform a feed budget. Use this calculation guide to help calculate how long your paddocks will last.
When livestock demand is higher than grass growth you can consider using the following to boost grass production.
For further information on spring pasture management register for Agriculture Victoria’s Beef Sheep Networks upcoming webinar titled Focus on – Spring pastures. Featuring Fiona Baker, Beef Extension Officer. Fiona will cover topics such as How much nutrients will I lose conserving fodder? Tillering why is it crucial? Grazing management for spring and Spring trigger points for decisions on Autumn pasture renovation. The webinar will take place on Thursday 17 September at 12.30pm – 1.30pm. View this link to register.
Nitrogen from the legume content of pasture swards may not be adequate to boost winter growth rates. Use Nitrogen to boost plant response, which will result in increased Dry Matter yields and keep plants at optimum nutrient availability for an extended period. The optimal temperature for the use of urea in winter is 8-10⁰C. Response rates in winter vary between 5-10kgDM/kg. N response is dependent on water or nutrient (phosphorus, Potassium or Sulphur) limitations.
The use of Gibberellic acid (GA) can be an economic method to increase winter pasture reserves when the soil temperature is above 5⁰C (9am and 10 cm depth). At temperatures above 15⁰C the plant can produce enough GA and no additional response will be gained. By using GA you can expect in most species a 150-500kgDM/ha response when used to the manufacturers label. This can give crucial pasture growth to avoid over grazing. Read more information on the use of Gibberellic acid
On most farms pasture growth will generally exceed animal requirements in early to mid-September, but ensure you only ‘lock up’ a genuine surplus. If locking up early, ensure that you conserve at the appropriate time (prior to ear emergence approx. 11MJME/kgDM) to ensure nutritive quality remains high. It is not recommended with pasture silage to go for ‘quantity over quality’, you can achieve similar mass yield cutting early and grazing the regrowth.
For more information on fodder conservation register for Agriculture Victoria’s Beef Sheep Networks upcoming webinar titled Focus on – Fodder conservation. This webinar features Michele Jolliffe, Dairy Extension Officer and Claire Waterman, Farm Business Economist. This one hour webinar on Thursday 3 September will cover; How do I determine how much of my farm to cut? When to cut? Making quality silage and hay and the costs involved in conserving fodder. View this link to register.
Various Management Options for winter
- Supplementary feeding of silage/hay/grain
- Containment feeding areas and sacrifice paddocks
One way to overcome the winter feed gap (between livestock requirements and pasture growth) is to provide another source of feed, reducing the demand on the pasture and allowing the current grazing program to stay the same.
To find out more on winter feeding and livestock health join Agriculture Victoria’s Beef Sheep Networks webinar titled Focus on – Livestock health and nutrition. This webinar features Dr. Jeff Cave, District Veterinary Officer and Nick Linden Sheep Industry Development Officer and will be held on Thursday 13 August. It will be held from 12.30pm – 1.30pm and will cover topics such as Livestock nutrition – the importance of fibre, winter feed budgeting, trace mineral deficiencies and livestock health issues to watch out for. View this link to register.
Containment areas/sacrifice paddocks
Often, cattle can be fed supplement in containment areas, minimising the area that is damaged by overgrazing. The extra organic matter that is left in the paddock then puts the paddock in a good position for any planned pasture renovations or improvements with extra nutrients.
If feed demand is matched to pasture growth (the perfect farming system) then supplemental feeding isn’t needed. However matching demand to growth is hard in some systems. Having your farming enterprise geared to sell excess stock (e.g. weaners) when you can see that the feed on hand will run out soon.
Another management option is to take on agistment to manage your excess feed, and then it can slowly be removed during the slower growing periods.
For more information on grazing management watch Agriculture Victoria’s grazing management webinar