Efeito da manipulação térmica durante a incubação sobre as variáveis hematológicas, bioquímica sérica e morfometria da bolsa cloacal de codornas japonesas submetidas ao estresse crônico por calor / Effect of thermal manipulation during incubation on the hematological variables, serum biochemistry and morphometry of cloacal bursa of Japanese quails submitted to chronic heat stress

Objetivou-se avaliar os efeitos da manipulação da temperatura de incubação sobre a resposta imune de codornas desafiadas termicamente após eclosão. Para isso, foram utilizados 540 ovos, distribuídos em três incubadoras, com temperatura de 37,8°C e umidade de 60%. A partir do sexto dia de incubação até a eclosão, as temperaturas foram ajustadas em 37,8°C (padrão), 38,5°C (intermediária) e 39,5°C (alta). Após a eclosão as codornas foram pesadas e distribuídas, em delineamento inteiramente ao acaso, com três temperaturas de incubação (37,8, 38,5 e 39,5°C) e duas temperaturas de ambiente (estresse e termoneutro). Aos 10, 20, 30 e 40 dias, quatro codornas por tratamento foram eutanasiadas para coleta da bolsa cloacal, do fígado e do coração, para se determinar o peso absoluto (g), o peso relativo (%) e a área dos folículos bursais. Sangue foi coletado para realização do hemograma, do leucograma e da bioquímica sérica. Os dados foram analisados e as diferenças entre as médias foram determinadas pelo teste de Tukey a 5%. O estresse térmico por calor, a partir dos 20 dias, promove redução no peso absoluto do fígado, do coração, da bolsa cloacal e na área dos folículos bursais, além de heterofilia, linfopenia e aumento da relação heterófilo/linfócito. Em conclusão, o estresse térmico por calor após 10 dias de idade pode causar imunossupressão.(AU)

The objective of this study was to evaluate the effects of manipulation of the incubation temperature on the immune response of quails challenged thermally after hatching. For this, 540 eggs were distributed in three incubators, with temperature of 37.8°C and 60% humidity. From the 6th day of incubation to hatching the temperatures were adjusted to 37.8°C (standard), 38.5°C (intermediate) and 39.5°C (high). After hatching the quails were weighed and distributed in a completely randomized design with three incubation temperatures (37.8, 38.5 and 39.5°C) and two ambient temperatures (stress and thermoneutral). At 10, 20, 30 and 40 days four quail per treatment were euthanized to collect the cloacal burse, liver and heart to determine the absolute weight (g), relative weight (%) and area of the bursal follicles. Blood was sampled for determination of hemogram, leukogram and serum biochemistry. The data were analyzed and the differences between the means were determined by the Tukey test at 5%. Heat stress from 20 days onwards promotes a reduction in the absolute weight of the liver, heart, cloacal sac and in the area of the follicles. In addition, there was heterofilia, lymphopenia and increased heterophile/lymphocyte ratio. In conclusion, heat stress after 10 days of age can cause immunosuppression.(AU)

Photoperiodism in Japanese quail (Coturnix coturnix japonica) with special reference to relative refractoriness.

Cloacal gland (an androgen dependent sex accessory) of Japanese quail exhibits full breeding condition as long as these were maintained under long days (LD 16:8). When shifted to short daylength (LD 6:18), scotosensitivity (cloacal gland regression) was observed up to 5 weeks, followed by scotorefractoriness (cloacal gland development). There was a regression in cloacal gland volume of the birds when shifted to intermediate daylength (LD 13.5:10.5 and 13:11) after 12 weeks of exposure to long days (relative refractoriness) but no regression when shifted to relatively short days (< 14 hr) after 3 weeks of exposure to long daylength. Birds maintained under constant short photoperiod (LD 6:18) exhibited cyclicity. Shift experiments (quail reared and maintained under continuous light; LL, were shifted to LD 16:8, 13:11 and 8:16, similarly quail maintained under LD 16:8 were shifted to rest three photoperiods and so on) made to compare the cloacal gland responses indicated that if the difference between two photoperiods (previous and shifted one) was more the percentage of difference in cloacal gland response was also high. Short daylength (LD 8:16) was always gonadoinhibitory for the quail previously exposed to any daylength (13L, 16L or 24L) and 16L and 24L were always stimulatory for the quail previously exposed to other daylength (8L, 13L, 16L). But, when the birds were shifted to 13L, photoresponses cannot be generalized and it depends on the photoperiod to which quail were exposed previously (i.e. photoperiodic history).