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

P.F.P. Ferraz¹*, E.T. Andrade¹, R.B. Vilas Boas¹, T. Yanagi Junior¹, R.R. Andrade², V. Becciolini³ and M. Barbari³

¹Federal University of Lavras, Agricultural Engineering Department, BR37200-000 Lavras, Minas Gerais, Brazil
²Federal University of Goiás, Department of Biosystems Engineering, College of Agronomy, BR74690-900 Goiânia, Brazil
³University of Florence, Department of Agriculture, Food, Environment and Forestry, Via San Bonaventura 13, IT50145 Firenze, Italy
*Correspondence: paricia.ponciano@ufla.br

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 (t_db), dew point temperature (t_dp), 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 (t_cloacal) 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 t_cloacal 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.

Key words:

Study of influence of heat stress on some physiological and productive traits in Holstein-Friesian dairy cows

T. Penev¹*, D. Dimov¹, I. Marinov² and T. Angelova³

¹Trakia University, Faculty of Agriculture, Department of Applied Ecology and Animal Hygiene, BG6000 Stara Zagora, Bulgaria
²Trakia University, Faculty of Agriculture, Department of Animal Husbandry – Ruminants and Dairy Farming, BG6000 Stara Zagora, Bulgaria
³Institute of Agriculture, BG6000 Stara Zagora, Bulgaria
*Correspondence: tonchopenev@abv.bg

Abstract:

The aim of the research was to study the effect of heat stress (HS) on some physiological and productive traits in Holstein-Friesian dairy cows. The study included 22 cows on different parities. In the building where the cows were housed, the temperature-humidity index (THI) was reported at 10:00 and 15:00 h, at the same time the rectal temperature (RT) and respiratory rate (RR) were reported for each of the examined cows. The daily rumen activity was taken from the SCR system by Allflex. The average THI values in May were 71, in June – 75, in July – 74, and in August – 77, from which it follows that in the summer months the cows were in conditions of mild to moderate heat stress throughout the day. The average daily milk yield of the cows increased from May to June and reached 41.44 kg day^-1, then decreased in July and August to 37.2 and 32.48 kg day^-1, respectively. With an increase in the THI values, an increase in the RR and RT was registered, as in THI above 79 the RR was 56.54 per min, and the RT was 39.33 °C. With increasing the THI values, the rumination of the cows decreased from 563 per day at THI < 72 to 542.5 at THI > 79. In cows with high daily milk yield, a higher RT was registered, and in cows with more than 50 kg per day, the RT was 39.09 °С. A more intense rumination was found in cows with higher daily milk yield. In cows with an average daily milk yield of 33.26 kg, an average of 450 ruminations per day were reported, and in those with an average milk yield of up to 42.89 kg – 650 ruminations per day. From the research conducted it was found that the studied physiological traits – rectal temperature, respiration rate and rumination are influenced by HS and the intensity of this effect depend on the daily milk yield of cows and THI levels.

Key words:

dairy cows, heat stress, rectal temperature, respiratory rate, temperature-humidity index