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)

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)

Effect of high incubation temperature on the blood parameters of layer chicks

Adequate environmental temperature control is essential for incubation efficiency. Layer breeder eggs (n=360) were weighed and distributed in a completely randomized experimental design with two treatments, consisting of two incubation temperatures (T1=37.5 °C, control; and T2=39.0 °C, hot), with two incubators per temperature, and 90 eggs per incubator, totaling 360 eggs. Hatchability, embryo mortality, and chick cloacal and body surface temperatures were not affected by incubation temperature. Eggs incubated at the hot temperature presented greater egg mass loss and higher eggshell conductance than those incubated at the control temperature. Layer chicks derived from eggs incubated at control temperature showed greater absolute weight, yolk-free egg mass, and heavier hearts than those from eggs submitted to heat stress during incubation. The control group presented lower base excess and ionized calcium blood levels. Incubating eggs at temperatures higher than those recommended compromises body and heart development of layer chicks and negatively affects blood ionized calcium availability, and therefore, bone mineralization during embryo development. Efficient temperature control during the incubation of fertile eggs is essential to obtain good quality layer chicks.

Effect of high incubation temperature on the blood parameters of layer chicks

Adequate environmental temperature control is essential for incubation efficiency. Layer breeder eggs (n=360) were weighed and distributed in a completely randomized experimental design with two treatments, consisting of two incubation temperatures (T1=37.5 °C, control; and T2=39.0 °C, hot), with two incubators per temperature, and 90 eggs per incubator, totaling 360 eggs. Hatchability, embryo mortality, and chick cloacal and body surface temperatures were not affected by incubation temperature. Eggs incubated at the hot temperature presented greater egg mass loss and higher eggshell conductance than those incubated at the control temperature. Layer chicks derived from eggs incubated at control temperature showed greater absolute weight, yolk-free egg mass, and heavier hearts than those from eggs submitted to heat stress during incubation. The control group presented lower base excess and ionized calcium blood levels. Incubating eggs at temperatures higher than those recommended compromises body and heart development of layer chicks and negatively affects blood ionized calcium availability, and therefore, bone mineralization during embryo development. Efficient temperature control during the incubation of fertile eggs is essential to obtain good quality layer chicks.(AU)

Crude protein and metabolizable energy levels for layers reared in hot climates

The objective of the present study was to evaluate the effects of different dietary crude protein (CP) and metabolizable energy (ME) levels on the performance, internal and external egg quality, and cloacal temperature of commercial layers reared in hot climate. In this trial, 100 commercial Hy-Line W-36 layers between 20 and 32 weeks of age were distributed according to a completely randomized experimental design with a 2 x 2 factorial arrangement, consisting of two CP levels (15 e 18%) and two ME contents (2700 and 3100 kcal/kg) with five replicates per treatment and 10 birds per replicate. Performance (feed intake, egg production, egg mass, and feed conversion ratio), internal (Haugh units and albumen and yolk percentage) and external (eggshell % and thickness) egg quality parameters were evaluated. Cloacal temperature was measured in two birds per replicate at 8:00 h and 13:00 h. The diet containing 2700 kcal ME/kg promoted the best performance, whereas the worse performance observed in birds fed the diet with 3100 ME/kg was partially recovered when the diet contained 18% CP. Haugh units worsened as dietary CP level increased. The other external and internal egg quality parameters were not affected by dietary CP or ME levels. The cloacal temperature of birds fed 15% CP was lower in the morning and higher in the afternoon relative to those fed 18% CP, which temperature did not change during the day. It was concluded that dietary CP and ME levels influenced the performance and the body temperature of commercial layers.(AU)