مختصر البحث:
Vaccination is an important tool in
poultry health, but is itself a stressor often resulting
in a reduction in feed intake, body weight gain, and nutrient
digestibility. In other species, vaccination is associated
with an immediate acute-phase r…
Vaccination is an important tool in
poultry health, but is itself a stressor often resulting
in a reduction in feed intake, body weight gain, and nutrient
digestibility. In other species, vaccination is associated
with an immediate acute-phase response. As
an important immune parameter, the circulating heterophil/
lymphocyte (H/L) ratio is a well-recognized parameter
of stress in poultry. In this study, the effects
of a routinely used commercial poultry vaccine on the
acute phase response (APR) and H/L ratios in specific
pathogen-free (SPF) layer chicks was examined
to determine if post vaccination (PV) stress and an
APR occur. A combined Newcastle disease and infectious
bronchitis vaccine (Nobalis Ma5+Clone 30) was
administered to SPF chicks by the intraocular route
at age 7 d. Acute phase proteins (APP), alpha-1 acid
glycoprotein (AGP) and serum amyloid A (SAA) were
measured by enzyme-linked immunosorbent assays at
d 0 (pre-vaccination) and d 0.5, 1, 2, 3, 4, 5, 6, and 21
PV. Stress was determined in the chicks by measurement
of the H/L ratio. The immune response to the
vaccine was estimated by measurement of the antibody
(IgY) response to the vaccine at d 21.
The antibody titer was significantly (P < 0.05) higher
in the vaccinated group at 21 d PV, confirming stimulation
of the immune system. The H/L ratio was also
significantly higher in the vaccinated group at 1 to
2 d (P < 0.01) and at 3 d (P < 0.05) PV. The concentration
of SAA increased by 2.8-fold, from 63.7 μg/mL
in controls to 181 μg/mL in the vaccinated group,
(P < 0.05) at 1 d PV. AGP increased 1.6-fold at 2 d
PV, (from 0.75 g/mL in the control group to 1.24 g/mL
in the vaccinated group, P < 0.05).
In conclusion an immediate but mild APR occurred
in the chicks following intraocular vaccination, whereas
the stress response as measured by H/L ratio seemed
to be more specific and sensitive. Measurement of these
biomarkers of the host response could be a tool in vaccine
development.
