Pasture has the potential to provide
1. The horses nutrition
2. A Safe exercise area
Potentials rarely achieved, often neglected
All information given here is believed to be correct but the author cannot be responsible for any consequences of it's use.
by Denis Lindsell
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The preservation of grass material by acidification. The principal is the same as pickling onions
in vinegar except that in this case the acid is produced by bacteria. The cut material is compressed to squeeze
out as much air as possible then sealed. As the plant material is still alive, respiration is continuing and the
oxygen present is used creating the required anearobic conditions. Fermentation results in the production of lactic
acid from sugars by anaerobic bacteria - Lactobaccilli, Streptococci, Pediococci, to produce the required pH of
around 4.0 when the DM is 20%. A higher pH is acceptable for higher dry matter.
It is interesting to note that the majority of bacteria on plants are aerobes - they are normally in aerobic conditions of course. Very few lactoccilli are found on crops, and those will be low down on decaying leaves. Natural inoculation comes from equipment.
It is necessary to produce anaerobic conditions as quickly as possible by-
Clostridia - anaerobic gram +ve baccilli (rod shaped bacteria), spore forming, usually motile. This group of bacteria
includes those that cause botulism. Though classed as anaerobes (live in an atmosphere devoid of oxygen, some will
tollerate low lovels of oxygen.
These are harmful to cattle and especially harmful to horses.
Clostridia are not naturally present on the grass crop but are common in the soil and in animal faeces. Therefore control of cutting height and hygiene are vital. Clostridia will not be active if the pH is sufficiently low (sufficiently acid). If clostridia become active, they will break down lactic acid to form butyric acid. Butyric acid is a weaker acid than lactic acid, therefore this will cause the pH to rise, resulting in more clostridia becoming active and the problem accelerates.
Clostridia will also produce ammonia, and possibly acetic acid, resulting in a foul smell (acetic acid being the acid present in vinegar). Therefore beware of any silage that does not have the normal attractive smell.
Air leaks will allow aerobic organisms (including moulds) to become active, causing a breakdown of nutrients and
the production of mould spores that may cause respiratory problems.
The liquid that may seep from a silage clamp, especially if the moisture content of the plant material is high,
has a very high BOD (biological oxygen demand) - 200 times that of raw sewerage.