Dangers of manure gases
The three main gases released during slurry mixing are ammonia, hydrogen sulphide and carbon dioxide. All three are highly soluble and can be released into the barn during rapid agitation while pumping manure storage pits.
Studies from Ontario suggest hydrogen sulphide, which has a rotten egg odor, is the most likely cause of accidents.
Manure gas dangers can be reduced by the following management measures:
- Use pit exhaust fans that work, that are the proper size and in the proper location. They draw the air from above the slats to below the slats and ventilate the free space above the slurry. Remote warning devices should be installed to warn of fan failure.
- During slurry mixing, operate only the pit exhaust fans, not the barn exhaust fans. The latter tend to draw manure gas above the slats. This is especially critical if pit fans fail and barn exhaust fans are still on or during the winter when air intakes in the barn are adjusted for winter ventilation rates.
- Avoid splashing and free-falling slurry. Allow adequate free space, minimum 30 cm (one foot), for the pit exhaust fans to be effective.
- A submerged recirculation pipe nozzle releases less gas and odorous compounds into the air than an exposed nozzle with splashing slurry in the free space. It also reduces odor when slurry is pumped from the barn to an outdoor open-top storage tank or to tankers.
- Agitating and mixing slurry by blowing air into the bottom of the pit is not recommended. It results in the rapid release of hydrogen sulphide at lethal levels.
- Custom manure-spreading operators must never start pumping and agitating manure on their own. – Manitoba Swine Update
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
“New” dairy nutrients?
Work on nutrients necessary for milk production continues with the focus now on trace minerals and vitamins. Choline, chromium and folic acid are three such nutrients which have been reported.
- Choline is a vitamin involved in many functions including nerve transmission, cell membrane structure and lipid (fat) transport. Dietary choline is extensively degraded in the rumen. The development of a protected choline may benefit the dairy cow. Because of its function in fat synthesis and transport, choline may have a role in decreasing fatty livers and ketosis.
Supplemental choline may also improve milk production due to its sparing effect on dietary methionine. Methionine is an essential amino acid for milk production and is used for choline synthesis. Studies in which choline has been supplemented either by infusion directly into the abomasum or in a rumen protected form have resulted in milk production responses of zero to seven pounds per day. Choline intakes of 30 to 50 grams per cow per day appear to be optimal.
- Research into the use of chromium in beef, swine and dairy diets looks promising. Chromium is a trace mineral and its main role appears to be in the immune system. Inorganic chromium is very poorly absorbed so research has centred around the use of chelated chromium. Sickness due to shipping fever has been shown to be greatly reduced.
The effects of supplemental chromium on dairy cows is more preliminary. Increases in antibody concentration have been shown, which is associated with greater resistance to disease. Evidence also suggests improved milk production with no accompanying decrease in body weight or reproductive efficiency when first-calf heifers were fed diets supplemented with chromium.
Supplemental chromium sources are not registered for use in feed.
- Folic acid is a B vitamin generally considered to be synthesized in adequate amounts in the rumen. Research has shown serum levels of folic acid decrease by 40 percent from two months postpartum to parturition indicating that rumen synthesis may be inadequate during this time. In humans, fetal storage of folic acid is known to increase during the last part of gestation.
In research at Agriculture Canada in Lennoxville, Que., cows were injected weekly with zero or 160 mg of folic acid from 45 days after breeding to six weeks after calving. Supplementary folic acid tended to increase milk production and milk protein during the last half of lactation in multiparous cows. This period corresponds to gestation and the increased demands of fetal growth. No effects on cows or calf growth up to 10 weeks of age were noted.
– Animal Nutrition Update
