A wet autumn has brought a premature end to the grazing season, and on most livestock farms, cattle were house earlier than planned.
With early housing, there is a strong possibility cattle will spend six to seven months indoors before returning to grass next April, putting severe pressure on fodder reserves. Silage quality will also be an issue in second and third cuts, following the wet summer.
Therefore, it is important that farmers establish how much silage is currently on farm and whether there is a deficit or surplus in place.
If there is a fodder deficit, the earlier this is identified, the better, as there will be more options for stretching silage reserves.
A fodder budget is relatively straight forward, with online calculators making the task simple to complete, such as this one.
Alternatively, the pen and paper method will do. Start by counting up how many bales are on farm, plus the volume of pit silage.
When measuring the pit, stepping out the length and width is handier than using a tape, and shouldn’t be that far off in terms of accuracy. Measure in metres.
Take an average height of the clamp, allowing for the ramp at the pit face and the rear wall. Multiply the height, length and width to give cubic metres (m3).
To convert to tonnes of freshweight silage, multiply by 0.68 for forage at 25% dry matter, or 0.6 for silage at 30% dry matter. Most first cuts made in dry conditions during May and June should be in the region of 28% to 30% dry matter.
Second and third cuts are likely to be wetter and closer to 25%.
If water can be squeezed from silage by hand, dry matter will be closer to 20%, so multiply by 0.7 to get the tonnage in a clamp.
For bales, most modern machines will produce a bale weighing 800kg to 900kg. Multiplying the number of bales by an average weight of 850kg will give an indication of tonnage.
The next step is working out fodder demand, based on how many stock will be fed silage over winter and for how long.
A dry suckler cow will eat 30kg to 35kg/day, or 1t/month. Lactating cows will consume around 45kg to 50kg/day, or between 1.3t and 1.5t/month.
Weanlings eating 20kg to 25kg/day will consume around 0.75t/month, with finishing cattle on 0.75t to 1t/month depending on meal levels.
Dairy cows are likely to consume 1.5t/month of grass silage, with ewes eating around 0.2t/month for lowland types. Hill ewes will consume around 0.15t.
Deficit or surplus
Once demand is calculated, subtract from the tonnage of silage on farm. A negative figure means a fodder deficit is likely and vice versa. Repeat the exercise again at the start of January.
As an example of a fodder budget, take a farmer wintering 30 spring-calving cows from October to mid-April. Cows are dry from October to early March, when calving starts.
Six yearling heifers are retained for replacements, one stock bull and 15 light weanlings to be sold in April are also wintered.
Assuming cows eat 1t/month from housing to 1 March, then 1.5t/month after calving until turnout in mid-April, cows will consume around 7t to 8t/head.
Taking a higher figure around 8.5t/cow allows for waste forage, therefore cows require 255t of silage.
The six heifers and weanlings average 0.75t/month and the bull eats 1t/month. Allowing 10% for waste forage, it brings total livestock demand to 365t. The clamp measures 9m wide, 21m long and 2m high, giving 378 cubic metres (m3).
First cut was made in dry conditions and assumed to be 30% dry matter, giving 227t of silage.
An additional 140 bales of silage were made mid-summer, which, at 850kg/bale, gives another 119t of silage and a total of 346t of forage.
This leaves the farm facing a potential fodder deficit of 19t.
Feeding an additional 1kg/head of meal to weanlings could save 5kg/day of silage and improve weight gain, potentially saving 13.5t of silage over winter.
The additional meal should leave weanlings in a saleable condition, allowing animals to be sold in early March, rather than April – further saving on silage.
Assuming dry cows are in good body condition, animals could have forage intakes restricted by 10% up to Christmas, stretching silage reserves.
Dry conditions in May and June should result in few issues with first cut silage this winter. But the delayed harvesting of second and third cuts will pose problems. Below are some queries relating to low dry matter forages posed by farmers.
1. My second cut was delayed until September. How long after ensiling is it safe to feed silage?
Generally speaking, it will take three to four weeks for silage to ferment into a stable feed. If silage was ensiled wet, allow five weeks for fermentation.
Therefore, on farms where silage was harvested in late August and early September, these forages should be safe to feed out from early to mid-October.
2. Should I feed straw with a late season cut of wet silage?
Wet, late cuts of silage will be low in feed value. Intakes will also be lower.
That means cattle will struggle to physically eat enough silage to maintain weight gain or milk production.
Mixing with straw can help make the feed more palatable, but will do little to increase feed value, as straw is low in energy and protein.
Straw will also increase fibre intake, slowing down the rate of digestion and will keep animals fuller for longer. As such, daily intakes won’t alter that much.
Straw quality is also extremely variable this year. Do not feed straw with mould to cattle, particularly pregnant cows. What straw will do is stretch out reserves of silage where supplies are limited.
3. Should I feed more meal with wet silage?
With lactating cows and finishing cattle, feeding a wet, low-energy silage will reduce performance and body condition, as well as increase metabolic issues in freshly calved cows.
Feeding an extra 1kg to 2kg/head of concentrates may be needed to supplement diets.
Get silage analysed to properly formulate a balanced winter diet for high-performing animals.
4. I’ve limited fodder, can I restrict silage?
If feed value is ok, restricting silage for dry suckler cows in good condition can work. Avoid thin cows and restricting closer to calving. Start restricting after weaning and limit to six to eight weeks.
With cows in milk and finishing cattle, increase meal levels to stretch silage, rather than restrict intakes.
Only restrict silage if all cows can access the feed barrier simultaneously. Otherwise, bully cows will eat to appetite, leaving shy cows underfed and prone to metabolic problems.
5. How can I stop the pit face from spoilage?
Wet silages generally experience poor fermentation due to low sugars. The end result will be higher levels of butyric acid production, rather than lactic acid.
This results in higher pH and ammonia levels. Such forage will have a rancid smell and a tendency to turn dark in colour when fed out and mould can be found on the pit face if not kept fresh.
To keep the pit face fresh, cut shallower blocks with the shear grab. That should help move across the feed face faster, reducing the amount of waste silage accumulating.
Molasses will improve the palatability and energy intake where cattle are offered with low dry matter silages.