CC BY
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1 -y 'J 'J
Elzbieta Bombik , Antoni Bombik , Katarzyna Rymuza , Krystyna Tyszuk
1 Department of Reproduction and Animal Hygiene,
2 Department of Agricultural Experimentation,
University of Podlasie, Siedlce, Poland
RELATION BETWEEN AIR VELOCITY AND COOLING POWER IN PIGGERIES AND EXTERNAL CLIMATE
The work contains comparisons of selected microclimate parameters in five piggeries over a autumn and winter period. Moreover, the relation between the external climate and air velocity and cooling power in these buildings was determined.
Key words: piggery, air velocity, cooling power, external climate
Introduction. The main factors influencing environmental conditions inside and outside livestock buildings include concentration and type of livestock production, system of rearing animals (e.g. with bedding, without bedding), manure management (farmyard manure, slurry) and microclimate inside animal housing facilities which is influenced by both technical and technological factors.
Microclimatic conditions in buildings where pigs are raised physically, chemically and biologically influence their health and performance (Fraqueza et al., 1998). The physical environmental conditions include lighting, temperature, humidity, air velocity, cooling power, atmospheric pressure and dust levels (Traczykowski, 2008).
Air velocity in livestock buildings is associated with an impact of winds on the building, ventilation and heating systems, rate of tractor entries as well as animal movement. It is recommended that the air velocity in piggeries should not exceed 0.2 m-s-1 in winter and 0.5 m-s-1 in summer. The cooling power of the air is an indicator of a combined influence of temperature, humidity and air velocity. Cooling power is a bio-meteorological measure of heat loss by the body of an animals under certain microclimatic conditions dependent on radiation, convection, conduction and evaporation (Kosla, 2001). According to Dobrzanski and Kolacz (1996) as well as Kosla (2001), the optimum cooling in a piggery should range between 25 and 29 mW-cm-2.
A livestock building should be designed in the way to create optimum conditions for animal rearing and assure that the internal climate changes do not exceed limits for the microclimate inside the building (Bombik and Kolbuszewski, 1995).
The aim of the work was to compare microclimates in selected piggeries over the autumn and winter period, as well as determine the degree of relationship between the external microclimate and air physical parameters (air velocity and cooling power) in the buildings.
© Elzbieta Bombik, Antoni Bombik, Katarzyna Rymuza, Krystyna Tyszuk, 2009
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The work is a continuation of the previous paper by Bombik et al. (2008).
Materials and methods. Studies were conducted in five piggeries (A, B, C, D, E) in the Mazovia region. The piggeries were characterized by similar technical and technological solutions and similar stocking rate. They were specialist, detached relatively and new buildings as they had been under use for 7 to ten to 10 years. Bricks and hollow tiles were used for their construction, the walls were plastered on both sides, the ceiling was concrete with a functional attic. The animals were kept on shallow bedding, the sewage system was in a good working condition. Ventilation facilities were based on air ducts blowing off the air whereas fresh air entered the buildings through slightly open doors and windows. One-pane glass windows with wooden frames were situated in longer walls. Depending on the building, the ratio of window pane area and floor area ranged from 1:20 to 1:30.
Measurements of physical air parameters, that is air velocity and cooling power, were recorded over a autumn and winter period according to the methodology developed by Janowski (1979) and Dobrzanski and Kolacz (1996). Air velocity and cooling power were measured by the Hill katathermometer, three times daily (in the morning, at noon and in the evening) for 14 days in autumn and winter. The measurements were taken at the height of porker backs at three places situated diagonally across the room (one in the centre, the second and the third at shorter walls). The same measurements were taken over the same time period for the external climate.
The results obtained were statistically analysed based on the work by Oktaba (1980), and Tr^towski and Wojcik (1991). The arithmetic mean (x) and coefficient of variation (V%) were calculated for the parameters describing external conditions (air velocity and cooling power) over both seasons: autumn and winter. The parameter values were also subjected to one-way analysis of variance in order to compare means for those parameters over both seasons. The same procedure, that is calculation of arithmetic mean (x) and coefficient of variation (V%), was used to describe microclimatic conditions inside the buildings. Moreover, a two-way analysis of va-riance, including an interaction effect, was attempted to examine significance of an impact of seasons and buildings on air velocity and cooling power. Tukey's test was used to determine significant differences between means for the parameters describing internal and external conditions. Also, the relationship between the external climate and the internal air physical parameters studied was determined at the probabi-lity level of 0.05 and 0.01 using the linear correlation coefficient (r) which measures the strength of a linear relationship between two variables.
Results and discussion. The description of the internal climate over the autumn and winter period is included in table 1.
Analysis of variance revealed no significant differences between means of either air velocity in autumn (4.41 m-s-1) and winter (3.00 m-s-1) or cooling power (respectively: 149 and 154 mW-cm-2).
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Table 1
Description of the external climate in autumn and winter in terms of air velocity (m-s-1) and cooling power (mW'cm2)
Seasons Statistical Examined parameters
of the year measures Air velocity Cooling power
Autumn x V% 4.41 a 44.3 149 a 23.6
Winter x 3.00 a 154 a
V% 30.6 13.6
LSDo.O5 insignificant differences insignificant differences
Explanations: means in columns followed by the same letters do not differ significantly (P<0.05)
Coefficients of variation calculated for the external climate indicated that air velocity and cooling power were more diverse in autumn than in winter.
Table 2 contains the description of the microclimate inside the buildings in the autumn and winter.
Table 2
Description of the internal climate in autumn and winter in terms of air velocity (m^s"1) and cooling power (mW'cm2)
Seasons of the year Examined parameters
Buildings Air velocity Cooling power
Autumn 0.130 a 32.0 a
Winter 0.128 a 37.2 b
LSDO.O5 insignificant differences 1.2
A 0.155 c 29.2 a
B 0.155 c 34.4 b
C 0.130 bc 37.2 c
D 0.110 ab 33.8 b
E 0.095 a 38.3 c
LSDo.O5 0.031 2.6
Explanations as in table 1.
Analysis of variance yielded no significant effect of the seasons on air velocity. However, there were found significant differences between mean values of air velocity for the buildings under study. The significantly lowest air velocity was recorded in buildings D and E (respectively 0.110 and 0.095 m-s-1), whereas the highest values were obtained in buildings A and B (0.155 m-s-1). There was found a significant influence of the seasons on cooling power inside the piggeries. The mean cooling power over the autumn period (32.0 mW-cm-2) was significantly lower compared with winter (37.2 mW-cm-2). The significantly lowest cooling power was found in building A (29.2 mW-cm-2) whereas the highest values were measured in buildings C and E (respectively: 37.2 and 38.3 mW-cm"2).
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Table 3 demonstrates an association between air velocity and cooling power in the piggeries in autumn and winter.
The air velocity values inside the buildings over the study seasons fell within a very broad range, which is indicated by mean values for this parameter (from 0.080 in building E in autumn to 0.172 m-s-1 in building A in autumn) as well as coefficients of variation which exceeded 30 or even 50% in winter (respectively in buildings A and E). The coefficients of linear correlation between air velocity in and outside the buildings were insignificant. However, a slight tendency could be observed as the values of the coefficients were positive in all the buildings in the autumn whereas in the winter they were negative.
Table 3
Relationship between air velocity (m^s-1) and cooling power (mW-cm-2) _in piggeries and the external climate in autumn and winter_
Buildings Statistical Air velocity Cooling power
measures Autumn Winter Autumn Winter
x 0.172 0.139 25.6 32.9
A V% 17.1 30.7 9.7 5.4
r 0.244 -0.180 0.322 -0.348
x 0.171 0.139 33.5 35.2
B V% 11.6 15.7 4.7 7.8
r 0.255 -0.042 -0.409 -0.354
x 0.129 0.131 35.3 39.2
C V% 19.8 13.8 9.1 5.0
r 0.046 -0.247 0.116 -0.090
x 0.100 0.120 30.1 37.4
D V% 14.7 21.7 2.1 10.3
r 0.636 -0.317 0.231 0.117
x 0.080 0.110 35.4 41.2
E V% 12.4 55.6 6.0 6.3
r 0.379 -0.016 -0.183 0.413
The average air velocity both in autumn and winter met the optimal standards and did not exceed the zoohygienic standards for porkers (R^czkiewicz and Mar-darowicz, 1984; Dobrzanski and Kolacz, 1996). Due to airtight windows and doors there was no draught in the piggeries under study. Owing to it, the values for air velocity complied with the standards. A similar air velocity value was reported by Iwanczuk et al. (1986).
The average cooling power values over autumn months reached in all the buildings were lower (25.6, 33.5. 35.3, 30.1 and 35.4 mW-cm-2, respectively) than in winter (32.9, 35.2, 39.2, 37.4 and 41.2 mW-cm-2, respectively). There was only slight variation in the cooling power inside the buildings (in both autumn and winter) (values of the coefficient of variation ranged from 2.1 to 10.3%). The correlation
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coefficients calculated were insignificant and revealed no tendency either in autumn nor winter (there were both positive and negative values).
Comparison of the results with zoohygienic standards for porkers (Dobrzanski and Kolacz, 1996; Kosla, 2001) showed that the standards were exceeded in all the examined buildings, particularly in the winter months. Low temperature as well as too high relative air humidity inside the buildings under study contributed to it (Bombik et al., 2008).
Conclusions
1. The average air velocity, both in autumn and winter, fell within the optimum range of zootechnical standards.
2. Optimum zootechnical standards for cooling power inside the buildings were exceeded during the winter months.
3. No significant impact of the external climate on air velocity and cooling power in autumn and winter were found. It indicates that any change in the values of these parameters outside the piggeries was followed by no changes inside the buildings.
References
1. Bombik E., Bombik A., Tyszuk K., 2008: Relation between air thermal and humidity conditions in piggery buildings and external climate. Sci Mess. of Lviv National Univ. of Veterinary Med. and Biotechnologies named after S.Z. Gzhytskyj, 10, 2(37), 4, 258-263.
2. Bombik T., Kolbuszewski T., 1995: Bilans cieplny nieogrzewanych budynkow inwentarskich. WSRP, Siedlce.
3. Dobrzanski Z., Grzegorzak A., Kolacz R., 1981: Wpfyw zroznicowanych warunkow mikroklimatycznych na zdrowotnosc swin utrzymywanych w systemie bateryjnym. Medycyna Wet., 2, 82-84.
4. Dobrzanski Z., Kolacz R., 1996: Przewodnik do cwiczen z zoohigieny. AR, Wroclaw.
5. Fraqueza M.J., Roseiro L.C., Almeida J., Matias E., Santos C., Randall J.M., 1998: Effects of lairage temperature and holding time om pig behaviour and on carcass and meat quality. Appl. Anim. Behav. Sci., 60, 317-330.
6. Iwanczuk K., Palach R., Matynia-Wroblewska J., Wronska J., 1986: Wplyw mikroklimatu chlewni i temperatury legowisk na wyniki tuczu. Prz. Hod., 19, 2728.
7. Janowski T., 1979: Metodyka badan zoohigienicznych. PWN, Warszawa -Krakow.
8. Kosla T., 2001 : Cwiczenia z higieny zwierz^t. SGGW, Warszawa.
9. Oktaba W., 1980: Elementy statystyki matematycznej w doswiadczalnictwie. PWN, Warszawa.
10. R^czkiewicz J., Mardarowicz L., 1984: Bioklimatyczne problemy w chowie swin. Medycyna Wet., 40, 277-279.
11. Traczykowski A., 2008: Mikroklimat w chlewni. Farmer, 11, 5-8.
12. Trçtowski J., Wojcik A.R., 1991: Metodyka doswiadczen rolniczych. WSRP, Siedlce.
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Summary
Studies were conducted in five piggeries characterised by similar technical and technological solutions as well as stocking rate. There were taken measurements of two physical air parameters in autumn and winter, that is air velocity and cooling power both outside and inside the buildings.
The results were analysed by means of basic statistical measures, variance analysis and linear correlation.
It was found that the average air velocity values both in autumn and winter fell within the optimum range of zootechnical standards. The optimum standards of cooling power were exceeded inside the buildings in the winter. No significant impact of internal climate in autumn or winter was found on air velocity and cooling power in all the piggeries under study. It indicates that any change in the values of these parameters outside the piggeries was followed by no changes inside the buildings.
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