Tag Archives: heat stress

xxx T. Penev, D. Dimov, I. Marinov and T. Angelova
Study of influence of heat stress on some physiological and productive traits in Holstein-Friesian dairy cows
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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.

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1068–1081 M.O. Vilela, R.S. Gates, S. Zolnier, M. Barbari, C.G.S. Teles Junior, R.R. Andrade, K.S.O. Rocha, I.F.F. Tinôco, C.F. Souza, L. Conti and G. Rossi
Variable velocity system for evaluating effects of air velocity on Japanese quail
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Variable velocity system for evaluating effects of air velocity on Japanese quail

M.O. Vilela¹*, R.S. Gates², S. Zolnier¹, M. Barbari³*, C.G.S. Teles Junior¹, R.R. Andrade¹, K.S.O. Rocha¹, I.F.F. Tinôco¹, C.F. Souza¹, L. Conti³ and G. Rossi³

¹Federal University of Viçosa, Department of Agricultural Engineering, Av. Peter Henry Rolfs, s/n Campus University of Viçosa, BR36570-900 Viçosa, Minas Gerais, Brazil
²Iowa State University, Departments of Agricultural and Biosystems Engineering, and Animal Science, Egg Industry Center, 1202 NSRIC, Ames, IA 50011, USA
³University of Florence, Department of Agriculture, Food, Environment and Forestry,
Via San Bonaventura, 13, IT50145 Firenze, Italy
*Correspondence: monique.vilela@ufv.br; matteo.barbari@unifi.it

Abstract:

This study documents the design and performance of a system to apply different magnitudes of air velocity to Japanese quail, to evaluate the combined effects of velocity, temperature and humidity on bird behaviour, performance and welfare. The system was developed to simulate observed field conditions occurring in regions with high winds where quail are raised in curtain-sided housing. System performance consisted of characterizing air velocity distribution in cages downstream of the air velocity which was directed at the front of the cages. The system consisted of two fans attached to a 25 cm PVC tube, one at each end, with the outlet airflow directed through a continuous slot over the cage front at the feeder. The design and performance of this experimental system was evaluated, with six such systems were built and utilized in research trials. To assess system performance, air velocity was measured at 275 points per cage uniformly arranged along the three dimensions (length, width and height) in eight cages with zero, 1, 2 or 3 m s-1 nominal velocity setpoints. Spatial distribution of velocity was analysed by mapping and from descriptive statistics, with attention to the zone closest to the feeder where birds must go to eat. There was no significant difference (P > 0.05) found in mean paired difference of air speed data measured for pairs of front portion cages with similar velocities. A significant positive correlation was found (P < 0.001) between the measured air velocity at paired points in the cages subjected to the same velocity treatment. A comparison of measured mean air velocity to the nominal setpoint values used for experiments indicated that careful attention to outlet adjustment is important, especially at higher nominal velocity setpoint as 3 (± 0.10) m s-1 which was difficult to achieve with the system. An example of the use of the deployment of the variable velocity system in controlled environment chambers with Japanese quail is provided.

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371–377 M.G.L. Cândido, I.F.F. Tinôco, M. Barbari, L.C.S.R. Freitas, T.C. dos Santos, R.R. Andrade, R.S. Gates, L. Conti and G. Rossi
Effect of environmental temperature during the of brooding period on growing period of pullets viscera and tibia
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Effect of environmental temperature during the of brooding period on growing period of pullets viscera and tibia

M.G.L. Cândido¹*, I.F.F. Tinôco¹, M. Barbari², L.C.S.R. Freitas¹, T.C. dos Santos¹, R.R. Andrade¹, R.S. Gates³, L. Conti² and G. Rossi²

¹Federal University of Viçosa, Department of Agricultural Engineering, Peter Henry Rolfs Ave, s/n, BR 36570-000 Viçosa-MG, Brazil
²University of Firenze, Department of Agricultural, Food, Environmental and Forestry, Via San Bonaventura, 13, IT50145 Firenze, Italy
³University of Illinois, Department of Agricultural and Biological Engineering, 1304 West Pennsylvania Avenue, US61820 Urbana-IL, United States of America
*Correspondence: marciagl.candido@gmail.com

Abstract:

Poultry production in subtropical and tropical regions faces many problems, one of which is the high air temperature causing thermal stress, particularly dangerous in high-producing birds. Thus, the negative effects caused by heat stress (HS) must be managed. The objective of this study was to evaluate the effects of four different levels of HS in viscera and tibia of pullets. A total of 648 chicks (Lohmann LSL Lite) were used in this study in two different phases. The pre-experimental phase (PEP) was from day 1 through 6 weeks of age. The birds were reared with three different environmental temperatures: thermal comfort, hot and cold. The experimental phase (EP) was conducted from the 7th to the 17th week. Pullets from each thermal environment of the PEP were submitted to: 20 °C, 25 °C, 30 °C, 35 °C. At the end of the 17th week of age 120 pullets were euthanatized and the organs, heart, liver, spleen and gizzard were weighed, as also their tibias. Effects of PEP, and its interaction with EP, were not significant (P < 0.05) for viscera and tibia weight. However, a significant increase (P < 0.05) in heart weight with the decrease of the environmental temperature was observed, being the pullets subject to 20 ºC and 25 °C with the heaviest weights. For the liver, pullets subject to the 35 °C had the lowest weight and were different (P < 0.05) from the other three treatments. For gizzard, the difference (P < 0.05) was between the treatments 20 ºC and 35 °C. These results indicate that brooding temperatures tested during the first 6 weeks of life did not affect the viscera and bone weight during the growing phase.

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