Physiological and behavioural parameters of broiler chicks grown under different heating systems

Abstract

This study aimed to compare the internal environment, physiological variables, and behavioural responses of chicks under two different heating systems. The experiment was performed in two commercial broiler houses located in Brazil, where 28,000 male Cobb chicks were housed during the first three weeks of life. One of the broiler houses was heated by an industrial indirect-fired biomass furnace (S1). In addition, another heating system consisting of two furnaces for indirect heating of the air using biomass (wood) as fuel, built by hand with bricks, mud, and dung on an iron structure (S2), was tested. Measurements of the dry bulb temperature (tdb), dew point temperature (tdp), and relative air humidity (RH) were performed. Subsequently, the temperature-humidity index (THI) was calculated. In addition, the physiological variables of the respiratory rate (RR) and cloacal temperature (tcloacal) were measured three times a day (8:00 am, 2:00 pm, and 6:00 pm) in four chicks. The behaviours were grouped by dendrograms, in which the similarity of these data was qualified. During the second and third weeks of life, the THI values were below the recommended range. The RR and tcloacal data were below the recommended comfort values, which may be an indicator that the chicks were subjected to cold conditions. Regarding their behaviour, the chicks exhibited calm, feeding, and sleepy behaviours most of the time. Problems in the heating system inside the broiler house could be observed, possibly affecting the chicks’ thermal comfort and welfare, which consequently can result in productive and economic losses.