Abstract:
Salinity intrusion into the freshwater system due to climate change and anthropogenic activities is
a growing global concern, which has made humans and domesticated animals more susceptible to
diseases, resulting in less productivity. However, the effects of salinity on domesticated and wild
birds, especially in terms of production and immunity, have not been fully elucidated yet.
Therefore, this study was designed to examine the effects of salinity on the production and immunity
of birds and the mechanisms by which immunity is compromised. Broiler chicks were
subjected to different concentrations of salty water (control = normal water, treatment = 5 g/L,
treatment = 10 g/L, and treatment = 15 g/L). The collected blood and organs from different
groups of broilers were biochemically and histopathologically examined. Birds in salt-treated
groups consumed significantly less feed than the control group, while the feed conversion ratio
(FCR) was significantly higher. Body weight gain was significantly lower in salt-treated groups
compared to control. Serum analysis revealed a lower systemic antibody titer in the salt-treated
groups compared to the control. Primary lymphoid organs (thymus and bursa of Fabricius) were
reduced in size in the salt-treated group due to cellular migration and depletion from these organs.
Importantly,
most
of
the
parenchyma
of
lymphoid
organs
was
replaced
with
fibrotic
tissue.
Gut
microbes,
Escherichia
coli
(E.
coli)
and
Salmonella
spp.,
from
salt-treated
groups,
showed
less
viability
but
developed
antibiotic
resistance.
Levels
of
salinity
were
significantly
and
negatively
correlated
with feed intake, body weight gain, antibody titer, lymphoid organ size, and viable
count of gut microbes, while FCR, fibrosis of lymphoid organs, and antibiotic resistance were
significant positively correlated. In conclusion, increased salinity is a possible threat to food security and safety as it decreases body weight gain, reduces immunity, and influences the
development of multi-drug resistance in gut microbes.
