In recent times, fermented and ensiled forages and grains have become very popular feedstuffs in a cow's diet.
Good fermentation and ensiling would enable dairy farms to preserve forages that cannot be dried properly for baling.
When that happens, it would decay before it could be fed out.
Fermentation and ensiling also makes it possible for a consistent supply for fiber, protein and energy for dairy herds throughout the year.
The main goal of fermentation is to preserve as much organic matter as possible to be stored and used as future feed for the herd.
Factors affecting fermentation:
There are many factors affecting fermentation and ensiling process.
One such factor is the moisture at the time of harvesting, chop length, silo packing speed an silage pack density.
Another important factor is how well the bunk is covered for storage, thus keeping out air and moisture.
How well the face of a pole of silage is managed will also influence the quality of silage after it has been ensiled.
Poor fermentation will cause excessive effluent runoff, loss of nutrients and the production of spoiled silage not fit for feeding.
Types of forage:
Grasses, legumes and small grain forages such as barley, oats and hybrids such as triticale are regularly harvested and stored as ensiled feeds.
The most popular forage to be ensiled is corn due to its superior harvested tonnage and calories to the acre. Corn also provides significant levels of nutrition from both starch and cellulose.
However, due to its size and structure, the corn plant cannot be mowed, dried, cured and baled like you do with alfalfa or pasture grasses. It must be chopped into smaller pieces, packed and stored in airtight silos or bunkers.
Grasses and legumes, with their smaller stem sizes can be wilted, crushed and packed and made into high quality silage.
The fermentation process will start immediately after harvesting which is what turns forages into "silage".
Fermentation and ensilng of forages involve two steps: 1) removal of air while the forage is being packed 2) final production of lactic acid which lowers the pH and stabilizes the organic matters.
The key to make sure the silage is in good condition is to minimise air exposure during feedout.
Air is the main culprit of the fermentation process and stability of silage.
Hence, rapidly squeezing air out of the packing process is important in keeping aerobic microbial activity to the minimum.
The quicker air is used up in a pile, the sooner the anaerobic process of fermentation can start.
Formation of lactic acid is the wanted end product of fermentation in a pile of silage.
The pH level of silages is crucial as well. The more rapidly the lactic acid stage can begin, the quicker the silage can completely ferment and stabilse.
The final pH of ensiled forage will depend on the type of forage as well as condition at the time of ensiling. Hay crops made into haylage will reach have a pH of around 4.5 while corn silage will be around 4.0.
Proper fermentation will also depend on the moisture level of the forage at the time of packing.
Moisture level must be kept low or else other types of fermentation aids will be produced during silage.
Regardless of types of forage, harvesting or chopping at moisture levels above 75% will cause undesirable fermentation.
Removing silage from a pile and storing it temporarily at other place is also discouraged as there will be secondary fermentation and oxidation due to exposure to air.
Corn silage is most popular due to its uniformity and predictability in growing and harvesting an the presence of high levels of carbohydrates that will stimulate the fermentation process and provide metabolisable energy to the cow.
Recommended moisture level of a corn corp at harvesting is around 30 - 35%. Anything above that will cause problems.
Ensiling forages represents a decent amount of investment for dairy farms.
It is crucial to have proper forage management as poorly fermented silages will cause a lot of trouble as the cost of feeding cows amounts to more than half of the total operating cost.
It is also recommended to add bacterial inoculants on all forages to increase lactic acid production in a pile of forage which will ultimately preserve and recover more organic matter, which will in turn increase profitability of the dairy farmer.