Avaliação da temperatura, umidade e vacinação in ovo

ABSTRACT
Incubation is fundamental to expansion and maintenance of quail production. This
research aimed to study factors that influence on performance of Japanese quail
incubation: temperature, humidity and in ovo vaccination. Three experiments were
carried out. The first verified the effects of temperatures on hatchability, hatch weight,
hatch time and embryo mortality. 800 eggs were divided into eight experimental groups
incubated at different temperatures (34, 35, 36, 37, 38, 39, 40 and 41ºC). The other
incubation conditions were identical for all groups, 60±5% of relative humidity and egg
turning every two hours until transference. The second experiment aimed to verify the
effect of relative humidity during incubation of Japanese quail eggs on hatchability, egg
weight loss, hatch weight, and embryo mortality. 300 eggs were divided into three
experimental groups: low humidity (36.05%), intermediate (52.25%) and high
(76.50%). The other incubation conditions were identical for all groups, 37.5°C of
temperature and egg turning every 30 minutes until transference. The third experiment
aimed to evaluate the effects of in ovo vaccination procedures on incubation of Japanese
quail eggs. The experiment was carried out in a factorial design (4x4) with 17
experimental treatments (4 injection days x 4 injection protocols, plus 1 control group).
The injections were tested at four incubation days: at 0, 5, 10 or 15. At each day, the
eggs were submitted to four distinct injection procedures: saline injection with or
without egg sealing and Newcastle disease (ND) vaccine plus saline or industrial
diluent, both without sealing. The eggs were incubated at 37.5º C and 60% RH. All eggs
and hatched quails were weighted. Unhatched eggs were opened to classify embryo
mortality. Hatched quail were bled to evaluate antibody response. The results showed
that hatchability was higher for eggs incubated at 37 and 38ºC, 76.67 and 80.76%,
respectively. Eggs incubated at 34ºC did not hatch and at 35 and 41ºC showed very poor
hatchability. The other temperatures had hatch rates from 50.33 to 57.73%. There were
higher hatch weights in eggs incubated at 38-41°C compared to those at 35-37°C. The
higher temperature became the smaller hatch time was. This relation was observed until
39°C. Embryos seemed to be resistant to embryo death in high temperatures until 40°C
at the early period of incubation, however the same was not observed at the later stages
when high temperatures (39-41°C) promoted elevated levels of embryo mortality. It was
verified that Japanese quail eggs incubated at the lower humidity presented the highest
level of hatchability (79%) compared to intermediate and high humidities. Egg weight
loss was respectively 11.96%, 8.94%, and 4.89% for low, intermediate and high
humidity groups. Furthermore, the weight at hatch was influenced by the different
humidities. The injection process itself (saline with/without sealing) was not harmful for
eggs at 10 and 15 days of incubation for Japanese quail eggs, however in ovo
vaccination with live ND vaccine (HB1 strain) is not recommended to fertile quail eggs
at any incubation periods due to high levels of embryo mortality and poor post-hatch
antibody titers.
Key words: temperature, humidity, in ovo vaccination, Japanese quail, eggs
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