Ammonia (NH3) in Norwegian dairy herds

Lars Erik RuudAssociate professor

lars.erik.ruud@inn.no

NHH

H

• Dairy• Advisory service

Ammonia – NH3

• A poisonous gas with distinct and unpleasant odour• Has local effects on mucosal surfaces

– Associated with respiratory problems in animals and humans• Negative environmental effects; acidifying, eutrophying

and is a source of the greenhouse gas N2O

• Density is approx. 59% of atmospheric air

NH3

ppm Symptoms7-10 Negative effects of long term exposure5-15 Odour threshold humans20 Irritation of eyes in broiler30 Irritation of eyes and respiratory tract in animals and humans50 Reduced production/ yield, watery eyes70 Fast reduction of growth and very poor feed utilization100 Increased respiratory rate, edema of the lungs5000 Lethal in minutes

Several studies shows negative effects:

Occupational exposure limit (N): 15 ppm (8h/day) Regulations on keeping cattle: 10 ppm

[Gustavsson, 1988]

What is the source of NH3?

Emmission

Production

The source of NH3?

During degradationof proteins and nucleic acids nitrogenous waste is formed

AmmoniaUreaUric acid

[Mod. after Gustavsson, 1988]

The source of NH3?

Stable atmosphere(emmission)

Litter/ manure(production)

During degradationof proteins and nucleic acids nitrogenous wastesare formed

AmmoniaUreaUric acid

NH4+

AmmoniumNH3

Ammonia

pH –increase

pH –decrease

GaseousNH3

[Mod. after Gustavsson, 1988]NH3 -concentration

in the stable atmosphere

Ventilation

NH3- consentration varies with• pH in manure (animal species, feeding etc.)• N-surplus in manure (feeding)• Air temperature and relative humidity• Dry matter in manure• C/N – ratio in bedding material• Soiled area (m2 wet by urine)• Ventilation

• => Housing design («technical sorroundings»)

Objective• To measure NH3-concentration in Norwegian

dairy herds• Investigate associations between housing

design and NH3-consentration

Method• Mean for recorded value

measured central on feed bunk, activity area and resting place= NH3-consentration

• «Barn design», cleanliness, feeding and more was recordedduring one winter-time visit(minimum ventilation rate)

t-test/ ANOVA was used to evaluatedifferences between different design etc

[Micro IV, GfG instruments]

Material• 62 herds from the central east Mjøs-region (n=31),

Nordland (n=6) or north-west Norway (coast) and Sør-Trøndelag (n=25)

• Visited once by a trained technician from Tine or a technician from HINN during the winter 2012 – 2013

• 109 ± 59,8 animals; 49 ± 21,6 lactating dairy cows• 2002 [1975 – 2012]; 87 % loose housing (free stalls)• One herd was excluded because of extreme values due

to aeration of NH3-treated straw inside of the barn60°N

70°N

Results (n = 61 herds)

• Mean NH3-concentration: 4,5 ppm [0 – 20,2 ppm]

Regulation on keeping cattle; 90 % <10 ppm

Occupational limit; 98 % <15 ppm

Occupational limit (<2002 -> 2024); 2 % >15 ppm

«Negative» results (no associations)• Feeding (composition of the meny)

– TMR/PMR vs roughage & concentrate fed separately• Herd size• Housing system (loose housing vs tie stalls)• Flooring (slatted floor vs solid floor)• Open vs closed connection between manure storage and the animal

room (traditionally manure are stored in cellar)• Sloped alley floor vs flat floor• Animal crowding/ m2 and m3

• Type of ventilation system; natural, guided natural or mechanical• Location of ventilation fan; cellar, wall or pipe

«Positive» results (significant association)• Fully insulated > non-insulated and low-insulated

buildings• System for urine drainage < without• RH% + indoor temperature < 90

– capacity/ adjustment of the ventilation system• CO2 (capacity/ adjustment of the ventilation system)• Low indoor temperature < high indoor temperature• Clean stalls < dirty stalls (cleanliness and management)

Tendencies (p = 0,06-0,10)

• Compost bed < other housing systems• Natural ventilation < mechanical ventilation

Discussion• Lower concentration than expected (feared)

Hygiene=> the main source for NH3-formation is removed

Urine drainage=> a source for NH3-formation is removed

Compost bed=> manure is absobed, pH, C/N-ratio

RH% + ind. temp (90-rule) => Ventilation capacity/ adjustment = Increased air exchange

Uninsulated => NH3 is evacuated through roofopenings because NH3 has lower density comparedto atmospherical air

• No effect of fan in cellar or open connectionon on NH3-concentration – …because density of NH3 is < density of atm. air

• Confirmed by the lower NH3 concentrations when naturally ventilated (openridge)

• NB! Other gases have other effects, e.g. H2S (hydrogen sulfide) that has a higher density than atm.air– «Manure gases» ≠ NH3

– Different gases has to be handled independently

• The housing design may influence on NH3 concentrations, however also cleaning routines (management) has positive effects

Conclusion• Uninsulated/ low insulation• Natural ventilation• High ventilation rate (>90)• Cleanliness routines

• Urine draining systems• Reccomended ventilation rates

for fully insulated barns

Important to achieve low concentrations

Worth further investigation

Thank you for your attention!

Cow cleanliness

Stall cleanliness• 1 - Clean• 2 - Some dirt• 3 - Dirty• 4 - Very dirty

Mechanical scraper on slatted floor

…may be automatic as well !