Effect of thermal environment on body temperature of early-stage laying hens

R.R. Andrade¹, I.F.F. Tinôco¹, C.F. Souza¹, K.P. Oliveira¹, M. Barbari²*, V.M.F. Cruz³, F.J.F. Baptista³, M.O. Vilela¹, L. Conti² and G. Rossi²

¹University of Viçosa, Department of Agricultural Engineering of Federal, Av. Peter Henry Rolfs, s/n Campus University of Viçosa, CEP: BR36570-900, Viçosa, Brazil
²University of Firenze, Department of Agricultural, Food and Forestry Systems – Via San Bonaventura, 13, IT50145 Firenze, Italy
³University of Évora, Instituto de Ciências Agrárias e Ambientais Mediterrânicas (ICAAM), Apartado 94, PT7006-554 Évora, Portugal
*Correspondence: matteo.barbari@unifi.it; rafaella.andrade@ufv.br

Abstract:

The thermal comfort condition of early-stage laying hens can be verified by means of physiological variations. The mean surface temperature and cloacal temperature are important parameters to demonstrate the effect of the thermal environment on the birds. The objective of the present study was to correlate homeostasis and stress with physiological responses (mean surface temperature and cloacal temperature) of lightweight laying hens of the Lohmann LSL Lite line aged from one to forty-two days when submitted to different thermal environments. A total of 864 birds with the same age, origin and uniform body weight were randomly distributed in four climatic chambers. The characterization of the different environments was as follows: thermal comfort temperature (33.0–19.0 °C), two cold stress levels (28.0–17.0 °C and 25.0–17.0 °C) and one level of heat stress (38.0 °C – 22.0 °C). The experiment was performed in a completely randomized design in the subdivided plots scheme, with four treatments in the plots and the evaluations (days) in the subplots. The means were compared using the Tukey test, adopting the 5% probability level. The birds maintained the physiological responses, based on cloacal and surface temperatures, within the normal range for all evaluated treatments during the period between 01 and 42 days of life. The surface temperature of the birds varied as a function of the air temperature of each breeding environment, with lower surface temperatures for mild cold and moderate cold treatments.

Key words:

Evaluation of the surface temperature of laying hens in different thermal environments during the initial stage of age based on thermographic images

R.R. Andrade¹, I.F.F. Tinôco¹, F.C. Baêta¹, M. Barbari²,*, L. Conti², P.R. Cecon¹, M.G.L. Cândido¹, I.T.A. Martins¹ and C.G.S. Teles Junior¹

¹ University of Viçosa, Department of Agricultural Engineering of Federal, Av. Peter Henry Rolfs, s/n Campus University of Viçosa, BR36570-900, Viçosa, Brazil
² University of Firenze, Department of Agricultural, Food and Forestry Systems, Via San Bonaventura, 13, IT50145 Firenze, Italy
*Correspondence: matteo.barbari@unifi.it; rafaella.andrade@ufv.br

Abstract:

The initial stage of laying hens requires important care in relation to the thermal environment, in view of the good development of the birds, the obtaining of good quality pullets and, consequently, the adequate laying rate of adult birds.
The aim of the present study was to study, through thermographic images, the variation of the superficial temperature of laying birds of the Lohmann LSL Lite line, from one to forty-two days of age, submitted to different thermal environments. For this experiment, 864 layer chicks were distributed homogeneously in four climatic chambers. The characterization of the different environments was as follows: thermal comfort conditions (32.8 °C–20.2 °C), two cold stress levels (28.0 °C–17.9 °C and 25.5 °C–17.3 °C) and one level of heat stress (37.4 °C–23.3 °C). The black globe temperature and humidity index (BGHI) was also calculated during the trials. The data were evaluated through the Tukey test, adopting the level of 5% of probability. Via infrared thermography the temperatures of head, body and shank of the laying birds were recorded. The results showed effect (P < 0.05) of the temperature of each environment on the surface temperature of the birds. Along with the rise of the ambient temperature, an increase in the surface
temperature (head and shank) was found.
Under the recommended comfort treatment, the performance of laying birds during the earlystage, related to the superficial temperature of the birds shows the best values with temperature ranges of 32.8 °C–20.2 °C and BGHI values between 82.3 ± 1.3 and 66.4 ± 1.3.

Key words:

environmental conditions, images analysis, infrared thermography, layer chicks, poultry, surface temperature