Dairy notes July 2008
The exceptionally dry conditions over most of the past two months have created severe forage problems particularly in the east of Northern Ireland. This has led to:
- Tight grazing supplies
- Low fodder stocks
- Burnt out swards
Grazing Management
Despite recent rain, Grass Check has predicted that grass growth rates to the beginning of July will remain low (leass than 35 KG dry matter per ha per day) - a result of cloudy conditions, lower temperatures and the severe soil moisture deficit. Grazing supplies are going to be tight for some time. If you haven’t already started buffer feeding silage, you will probably have to start to prevent cow yields dropping too rapidly, the normal decline is usually under 2.5 percent per week.
Practical considerations for buffer feeding include:
- The buffer silage should be of high quality to so that the animal feed requirement can be met without having to offer excessive levels of concentrates. Big bale silage made during early May when there was excess grass on grazing swards will fill the role well.
- Ensure there is adequate feed space so that all cows have access to the silage at the same time. If housing facilities don’t suit, consider setting up temporary troughs in an empty silo or yard where slurry can be contained and scraped to a nearby tank. Cows could be held for two to three hours after milking before returning to the field. Alternatively feed trailers could be placed in the field the cows are grazing or in a sacrifice paddock.
- Silage will spoil rapidly when fed out in warm weather. Feed passage/trailers should be cleaned out daily to prevent excessive wastage.
- The objective of the buffer feeding will be to supplement scarce grass. Monitor grass growth and cut back buffer levels as grass supplies increase, your silage supplies may already be tight for this winter.
Fodder Stocks
There is a potential fodder short fall on many farms for this winter because first cut yields were lower than normal as crops were cut early to ensure high quality and poor re-growth on swards closed for second cut. Scarce grazing supplies also mean that cows having to be buffer fed silage or swards originally closed for silage being grazed. To ensure fodder stocks are adequate for this winter, action needs to be taken now :
- Rather than finishing beef cattle and cull cows sell early to release land for third cut silage.
- If you have cereal crops, consider ensiling some of these. A good crop of winter wheat could produce 11 tonnes dry matter per ha of whole-crop for feeding, it could take three to four hectares of third cut grass to produce the same amount of feed.
- Despite the slow growth of second cut crops, these will mostly be cut this month, so there is time to plan a third cut. What area will you need to cut? Measure up silage stocks as soon as second cut is complete (allow for normal settling) to see what forage is in store. Estimate a potential yield for any whole-crop wheat or forage maize still to be ensiled. Compare the total forage available with likely winter demand
Table 1: Conversion factors to convert grass silage volume to tonnes of silage
Silage dry matter content % |
Conversion- Tonnes of silage/ cubic metre |
|---|---|
| 20 | Multiply by 0.77 |
| 25 | Multiply by 0.68 |
| 30 | Multiply by 0.60 |
Worked example - Silo measures 28 metres long x 10 metres wide x 2.7 metres deep = 756 cubic metres. To calculate the fresh weight of a 25 percent DM silage available in this volume multiply the 756 cubic metres by 0.68 = 514 tonnes of fresh silage.
Table 2: Estimated monthly feed requirement of stock (assuming silage is 25 percent dry matter)
| Silage (tonnes/month) | |
|---|---|
| Dairy cow in milk | 1.4 |
| 250-250 kg heifer | 0.6 |
| 350-400 kg heifer | 0.9 |
