Brent Jones from Southwest Ontario Veterinary Services, Understanding The Negative Effects Of Ammonia On Health

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It    is    well    understood    that    gaseous ammonia   is  harmful  to  pig  health  and productivity.     Exactly     how     ammonia causes    these    harmful    effects    is    not understood  as  well.  Researchers  used  24  separate controlled  atmospheric  chambers  to  house    total  of 120   Duroc×Landrace×Yorkshire   pigs.   The   pigs were  continuously  exposed  to  gaseous  ammonia  at 0,5,  10,  15,  20,  and  25  ppm  for  4  weeks.  High-throughput  genetic  sequencing  was  used  to  perform 16S  rRNA  gene  analysis  in  nasal  swabs  samples from 72 pigs (n = 12). The results of the  nasal  microbiota analysis  showed that    an    increase    in    ammonia    concentration, especially at 20 and 25 ppm, decreased the diversity and    relative    abundance    of    nasal    microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria,   and   Chloroflexi   were   the   most abundant microbial families. Pseudomonas, Lactobacillus,  Prevotella,  and  Bacteroides     were significantly  decreased  at  25  ppm,  while  Moraxella and Streptococcus were increased at 25 ppm.  An   increase   in   ammonia   levels,   especially   an ammonia  level  of  25  ppm,  caused  respiratory  tract injury  while  simultaneously  decreasing  respiratory immunity    and    growth    performance.

Ammonia treatments at 0–10 ppm resulted in a relatively intact tracheal  mucous  membrane  structure. In  the  15–20 ppm ammonia environment, the cilia of the tracheal mucosa    were    moderately deteriorated. In    the presence  of  25  ppm  ammonia,  the  structure  of  the tracheal  mucosal  layer  was  severely  deformed,  and the columnar cilia of the pseudostratified layer were also largely absent.

The following changes were noted at different levels of ammonia in the air:

>  10  ppm  increased  blood  ammonia  and  urea nitrogen concentrations and decreased the antioxidant ability of pigs.

> 15 ppm affected the expression of genes related to the integrity of the trachea structure (wind pipe)

>  20  ppm   r educed   the   levels   of   antibodies (immunoglobulins)   in  the  mucosal   lining  of  pig trachea .

> 25 ppm significantly damaged tracheal mucosa  cilium (hairs) and decreased growth performance. A large  number  of  inflammatory  cells  were  found  in the alveolar cavity, and severe reddening of the lung tissue

Take Home Message

Controlling ammonia  levels  in the pig barn  is an important  part of  a  disease  control  plan  for  both multi-systemic  diseases  (eg  Glassers)  as  well  as respiratory diseases (PRDC).

Increased  ammonia  concentration  can  alter  the microbiota  of  the  nasal  passage  and  make  pigs more susceptible to disease in multiple ways.

These  researchers  suggest  a  target  for  ammonia of  20  ppm  but  their  research  seems  to  confirm that  it  is  wise  to  keep  ammonia  levels  under  10 ppm.

Submitted by Brent Jones, DVM

Ref:  Wang  T,  He  Q,  Yao  W,  Shao  Y,  Li  J,  Huang  F.   The Variation of  Nasal  Microbiota  Caused  by  Low  Levels  of  Gaseous Ammonia Exposure in  Growing  Pigs.    Front Microbiol. 2019 May  16;10:1083. doi: 10.3389/fmicb.2019.01083. eCollection 2019

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