June 2017 Monthly Management
12-Hour Grazing Blocks, Fertilizer Second Cut Silage, Slurry Gas Monitor, Weed Control in Reseeds
Getting Away from a 12 Hour Block
The use of 12-hour grazing blocks is very common and will be required in situations where feed is scarce, grazing conditions are poor or when you may have to graze high covers. Where feed is scarce or growth rates are low, supplementary feed in the form of concentrate or silage will need to be fed in order to maintain or increase the rotation.
In periods of good growth and good grazing conditions, it is worth considering if using 12 hour blocks is necessary.
Many find using 12 hour grazing paddocks easy to manage however it may have some disadvantages. If grass is not being measured and enough is not being allocated grass intakes will be reduced. Getting cows to graze down every 12 hours puts pressure on the cow as there has to be some element of hunger to get her to graze down. This will impact on all important production parameters including milk solids and fertility.
If you look at one weeks grazing, that is 14 grazing allocations - ask yourself how many times was grass over allocated - the answer is often never or very few, this will result in cows been under fed on many grazings.
By extending the block to 36 hours we are asking the cow to graze hard 4 times every 6 days rather than graze hard 12 times over the same period.
Benefits of larger grazing blocks;
There will be a positive effect on feed intake by not limiting the amount of grass a cow will eat. Higher intakes will help milk yields and milk solids.
The other benefit of allocating a larger grazing blocks is that it will become more obvious if you are under allocating grass, for example the cows may have grazed most of the grass of a 36 hour allocation after only 24 hours. This could potentially lead to a grass shortage and reduced rotation length.
Larger blocks will reduce competition for feed space. In smaller allocations timid cows and first calvers are often bullied by dominant cows, leading to these cows being underfed most often. The highest performing cows in the herd will also get a better opportunity to maximize their intakes in order to cover their higher output.
Larger blocks will reduce workload for the farmer by taking away the need of putting up and taking down strip wires every grazing.
Fig1 : 36 hour vs 12 hour grazing block
In times when both grazing conditions and growth rates are good then the use of 24, 36 or 48 hour grazing should be considered where possible. Asking the herd to clean out a paddock once in every 3 or 4 grazings to avoid wasting grass will ensure cows are fully fed as much as possible and allow the herd to produce to their full potential.
Fertilizer Second Cut Silage
Second cut silage will require approximately 100Kg N/ha (80 units/acre) with high perennial ryegrass content swards (recently reseeded ground) requiring higher levels of nitrogen compared to older swards. Make allowances for any organic manures used i.e. slurry farm yard manure, etc. This should also have an impact on the level of phosphorous and potassium needed.
Apply fertiliser promptly after the first cut and evenly as possible. Be mindful of over-fertilising silage ground as excess nitrogen (N) and potassium (K) will have a negative effect on both crop preservation and animal performance. Too much nitrogen in grass at cutting reduces grass sugar levels & increases buffering capacity. To reduce this risk, allow enough time for any N applied to be taken up by the crop before deciding cut . Approximately 2 units of N per day are used up by the crop in good growing conditions.
In relation to potassium requirements, fertiliser needs to be applied per the soil index reading. Sufficient time must be given to low index soils that need extra K fertiliser allow for time crop uptake. Excess potash that is carried in with the crop will lead to a range of problems at the feed-out stage next winter. These include milk fever, Hypomagnesaemia and other metabolic disorders through depressed magnesium absorption in the rumen.
Slurry Gas Monitor - 10% off
When the crust of slurry is broken, a number of gases are released – hydrogen sulphide, ammonia and methane. Hydrogen sulphide poses the greatest danger as it is poisonous to humans and animals. It is fatal in a matter of seconds as one breath is enough to kill. Hydrogen sulphide is heavier than air and is prevalent at ground level and in confined areas, particularly on calm days when slurry is being agitated.
This poisonous gas has an unpleasant odour at very low concentration levels but as concentration levels increase, i.e. at agitation time or disturbance of the slurry crust, it has no odour at all. This is where the greatest danger is.
To minimize the risk of hydrogen sulphide gas, ensure the following:
• Remove all livestock and control pets;
• Open all doors and control access;
• Ventilate, stay away for 30 minutes during agitation;
• Work upwind at all times;
• Do not enter tanks even when empty
Weed Control in Reseeds
The best time to control weeds in reseeds is at the 4-leaf stage in weed seedlings. At this stage, grass seeds are tillering and weeds are established enough to ensure successful weed control. Many reseeds are at this stage now and if weather conditions allow, weed control should be carried out.
By using a recommended post emergence spray, seedling weeds can be destroyed before they have time to develop and establish root stocks. Established weeds can seriously reduce the yield potential and performance of the reseeded sward by competing with grass for nutrients and space. The post emergence spray should be applied approximately four to six weeks after establishment just before the first grazing takes place. Most perennial and annual weed seedlings can be controlled by a broad-spectrum herbicide such as High Load Mircam or Pastor Trio. Clover-safe herbicides like clovermax need to be used in reseeds where clover is present, bear mind that this does not cover chickweed Triad is a clover-safe chickweed control option and can be used in conjunction with clovermax.
The Driangh Grassland Weed Control Guide gives a full list of recommended herbicides in reseeds, including rates and target weeds controlled.
10% off Slurry Gas Monitors until 15th of July 2017