Corn Silage: Harvest, Storage and Its Effect on Milk and Fattening
By Saleh Kamal Al-Saleh, dairy farm and cheese factory owner, founder of Lebnara · Last updated:
Corn silage is the cheapest source of energy in a cattle ration, if it is harvested on time and stored tightly. Most of its losses do not happen in the field but in the pit: air gets in, the silage rots, and loses a large part of its value.
When to harvest corn for silage?
The right time is when the dry matter of the whole plant reaches 30 – 35%. The practical sign is the milk line on the kernel: break an ear of corn, and when the line between the hard part and the milky part reaches half or two thirds of the kernel, harvest.
- Early harvest (high moisture): a very acidic silage that leaks liquid, with less energy.
- Late harvest (dry): hard to pack so air stays in and it moulds, and hard kernels pass through undigested.
Chopping, packing and covering
- Chop length 1 to 2 cm, preferably with a machine that cracks the kernels so they are digested.
- Fill the pit in as few days as possible.
- Pack in layers 15 to 20 cm thick, with the tractor passing repeatedly. The target is at least 700 kg of fresh silage per cubic metre.
- Cover immediately with thick plastic made for silage, with tyres or sandbags over the whole surface, and seal the edges well.
- Wait at least 3 weeks before opening, preferably two months, because starch digestibility improves with time.
- For small farms: silage bags (50 to 100 kg) are a practical option, opening one bag every day or two so air loss is small.
How to tell good silage
Mouldy silage is never fed to cows: mycotoxins cause abortion and falling milk, and pass into the milk itself.
| Sign | Good silage | Spoiled silage |
|---|---|---|
| Colour | Yellowish green or light brown | Dark brown or black, or white and blue patches |
| Smell | A pleasant sour smell like light vinegar | Rancid, ammonia or mould |
| Texture | Firm, with no liquid running out | Slimy, or dry and clumped |
| Acidity (pH) | 3.7 – 4.2 | Above 4.5 |
Managing the pit face
Once the pit is opened, air enters from the face. Remove at least a 15 to 30 cm layer from it daily, more in summer, and keep the face level without loosening it. If the pit is wider than your daily consumption you will lose silage to rot, so design its width by the number of animals.
The effect on dairy cows
- Energy and yield: good corn silage has 28 to 35% starch in dry matter, and supports milk yield at lower cost than grain.
- Amount: 15 to 25 kg fresh per milking cow per day, depending on her yield and the rest of the ration.
- Protein: corn silage is low in protein (7 to 8%), so it needs a protein source such as soybean or alfalfa.
- Milk fat: stays good as long as fibre is sufficient. Too much silage and concentrate together causes rumen acidosis and fat falls.
Special importance for cheese factories
Poor silage ruins cheese. Badly fermented silage carries Clostridium spores that pass from the cow's manure into the milk during milking. These spores resist pasteurisation and cause late blowing in aged cheeses: cracks, holes and a foul smell weeks after making.
If your milk goes to a cheese factory, silage quality and udder cleanliness before milking are a priority.
The effect on beef calves
Corn silage lowers fattening cost because it replaces part of the grain and roughage. The usual amount is 8 to 15 kg fresh a day depending on calf weight, with concentrate completing the protein, reduced in the finishing phase in favour of concentrate.
In Lebnara you record silage stock and the amount issued daily, so you know well before the pit runs out when you need to secure a replacement.
Frequently asked questions
- How many days until corn silage is ready?
- At least 3 weeks, preferably two months.
- How many kilos of silage do I give a milking cow?
- Between 15 and 25 kg a day, with a protein source and roughage.
- How long does corn silage last in the pit?
- A year or more if it stays tightly covered with no air getting in.
- Can corn silage be given to young calves?
- After 4 months of age and in a small amount.
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