Epsilon Archive for Student Projects

Abstract

Uppskattningsvis transporteras 171 miljoner grisar inom EU varje år, varav ca 3,5
miljoner i Sverige. Grisarna kommer, under hela förloppet från förflyttningen från box i
stallet till bedövningen i slakteriet, att utsättas för stressande moment. Orsakerna är
bland annat omgrupperingar, nya miljöer, vibrationer i bilen samt, speciellt under
sommaren, värmestress.
Temperaturen i djurtransportbilen är en nyckelfaktor som dessutom kan förstärka
effekten av andra stressorer. Lastning i höga temperaturer ökar risken för värmestress.
Värmestress innebär att djuren får allt svårare att avge sin värme. Även den relativa
luftfuktigheten har betydelse, framförallt vid temperaturer över 30°C.
Det är ventilationen i transportbilen som ska transportera bort värme och fukt från
bilen. Utetemperaturen, luftflödet per gris och antal lastade djur per ytenhet påverkar
temperaturen i djurutrymmet. Ventilationen spelar även stor roll för luftrörelserna i
djurutrymmet.
Det finns två typer av ventilationssystem för djurtransporter; naturlig och mekanisk.
Det är den naturliga ventilationen som är vanligast. Den naturliga ventilationen drivs av
temperaturskillnader mellan inne- och uteluft, vind och fordonets hastighet. Den
varierar därmed stort och är främst beroende av fordonets hastighet. Den viktigaste
faktorn för hur naturlig ventilation fungerar i bilen är storlek på och placering av
ventilationsöppningarna.
Mekaniska fläktar kan monteras på bilen för att ge en garanterad ventilation under
stillestånd. Fläktarna kan även användas under hela transporten för att ge en jämn
ventilation i hela djurutrymmet.
Denna studie syftar till att öka kunskapen om hur den termiska miljön i olika delar
av djurutrymmena ("skåpet") på lastbilen utvecklas vid normala transporter mellan
gårdar och slakteri. Studien innefattar en jämförelse mellan naturlig ventilation och
mekaniska ventilation. En djurtransportbil, med 7 tilluftsfläktar (total kapacitet 8 100
m3/tim) placerade på vänster sidas ventilationsöppningar, försågs med mätinstrument
för att registrera klimatet på olika platser i skåpet. Temperatur, luftfuktighet, koldioxid
och solinstrålning registrerades var 30:e sekund. Klimatet i bilen studerades vid tio olika
transporttillfällen sommaren 2004 i nordvästra Skåne. Transporterna var normala
transporter med hämtning från gårdar till slakteri. Fem mätningar gjordes när mekanisk
ventilation användes, fem med enbart naturlig ventilation. Klimatutveckling
registrerades under lastning, stillestånd, körning och urlastning.
Resultaten visar att vid lastning ger mekanisk ventilation en långsammare
temperaturökning jämfört med naturlig ventilation, 0,10°C/minut, respektive
0,21°C/min. Vid längre lastningstider ger mekanisk ventilationen med tiden en sänkning
av temperaturökningen, vilket inte skedde med naturlig ventilation. Detta visar
betydelsen av hur lång tid lastningen tar. Mekanisk ventilation bidrar till att förbättra
klimatet i lastbilen framförallt vid längre stillestånd.
Vid lastningen var det betydligt varmare, 3,4°C, i de två främre facken än i de
övriga, vare sig naturlig eller mekanisk ventilation användes. Vid längre stillestånd med
naturlig ventilation ökade skillnaderna ytterligare, medan de vid mekanisk ventilation
istället minskade. Här syns således effekten av en mer långsam ökning av temperaturen
vid mekanisk ventilation.
Luftfuktigheten - när bilen var fullastad vid stillestånd - var vid naturlig ventilation,
i genomsnitt 97 %. Vid mekanisk ventilation låg motsvarande medelvärde på 82 %.
Detta visar att fläktarna hjälper till att transportera bort fukt från bilen.
Koldioxidkoncentrationen steg snabbt vid lastning, både med naturlig och
mekaniska ventilation. Men vid mekanisk ventilation antog koldioxiden ett stabilt värde
på 2000 ppm. Vid naturlig ventilation fortsatte koldioxidkoncentrationen att öka upp till
8000 ppm som var mätinstrumentets övre begränsning. Under körning var
koldioxidkoncentrationen 600-700 ppm både vid mekanisk och naturlig ventilation,
vilket vittnar om ett bra luftflöde.
Luftrörelserna kartlades både vid stillastående och körning. Vid stillastående bil och
mekanisk ventilation, konstaterades att de mekaniska tilluftsfläktarna verkligen satte
"snurr på luften". Vissa mindre utrymmen i skåpet hamnade dock i lä och kunde inte
nås av tilluftströmmen. Under körning har fläktarna begränsad betydelse.
Lufthastigheterna i djurutrymmet var 2 – 3 m/s både vid mekanisk och naturlig
ventilation. Däremot var luftrörelserna olika. Fläktarna gör det möjligt att garantera ett
visst luftflöde vid låga körhastigheter.
En nackdel med den mekaniska ventilationen, när den är påslagen, är den relativt
höga bullernivån i djurutrymmet, 75-81 dB(A). Den ökar grisarnas motstånd att gå på
bilen. Därmed förlängs lastningstiden.
I studien observerades vid vissa tillfällen mycket långa lastningstider. De grisar som
lastas först blir extra utsatta för såväl värme som social stress. Långa tider på en
stillastående bil ökar längden på slagsmålen. Det ger fler skador på grisarna och
påverkar köttkvaliteten negativt.
Den huvudsakliga slutsatsen från denna studie är att mekanisk ventilation jämfört
med naturlig ventilation ger lägre temperatur och relativ fuktighet samt högre
lufthastigheter kring grisarna. När bilen står stilla minskas därmed risken för
värmestress under varma dagar.
En annan slutsats från detta arbete är att slakteriernas organisation bör vara flexibel
så att djur kan transporteras under natten vid varmt väder. Rutinerna bör förbättras så att
lastningstiderna blir så korta som möjligt. Mer forskning på detta område efterlyses.
Bland annat studier där jämförelser i grisarnas beteende under lastning, stillestånd och
transport med naturlig och mekanisk ventilation genomförs. I framtiden kan sådan
forskning läggas till grund för lagtext om utformning av ventilation och
klimatbestämmelser för djurtransporter.
Det inte finns en enda omfattande åtgärd som kan förbättra djurtransporterna i ett
slag. Däremot är det möjligt att kontinuerligt göra många förbättringar av mindre
omfattning för att transporterna ska bli optimala ur såväl djurskydds- som
produktionsperspektiv.

SUMMARY
Every year an estimated 171 million pigs are transported within the EU, including 3.5
million in Sweden. The entire transport process, from pen to abattoir, puts the pigs
under stress. Stress factors include regrouping, new environments, vibration during
transit, and, particularly during the summer, uncomfortable climate. The greatest stress
is experienced during loading and when the truck is standing still in warm weather. The
ventilation inside is poor and there is little chance for the air to move freely unless the
trailer is fitted with fans.
The temperature can reinforce or mitigate the effects of the other climate factors and
is therefore critical to the pigs' well-being. Loading on very hot days increases the risk
of heat stress, which prevents the animals from cooling themselves down effectively.
Stress also increases the amount of heat emitted by the pigs into their surroundings.
Heat is transferred, by the laws of physics, via conduction, convection, radiation and
evaporation. The first three of these are governed by the temperature differential
between the animal and its immediate environment. The relative humidity of the air is
also significant, especially at temperatures above 30°C. As there is no exact definition
of an upper critical temperature, it is set at the point when the animal has to activate
physiological mechanisms to prevent its body temperature rising.
A free flow of air is needed to remove heat and moisture from within the truck. The
ventilation inside the trailer and the density of the animal cargo affects the ambient
transit temperature and subsequently the quality of the meat. Ventilation is an important
determiner of this temperature, and pursuant to EU recommendations is to have a
capacity of at least 60 m3/hour and 100 kg animal mass. The most important factor
deciding the interior ventilation is the size of the ventilation grills, which should make
up 20 percent of the floor space.
There are two types of ventilation system that can be used for animal transportation:
natural and mechanical, the former being the most common. This system is based on the
temperature difference between the external and internal air, wind speed and, most
crucially, the speed of the vehicle itself. It thus varies considerably. Mechanical fans can
be mounted inside to provide a more even ventilation effect and to guarantee that the
trailer remains ventilated for the entire journey – even when the truck is standing still.
The purpose of the present study is to improve our understanding of the thermal
dynamics at various points within the trailer. The main body of the study comprises a
comparison between natural and mechanical ventilation. A commercial pig truck was
fitted with climate sensors that registered temperature, humidity, carbon dioxide levels
and direct sunlight every 30 seconds between source farm and slaughterhouse. Ten
measurements were made in total, five with mechanical ventilation, five with only
natural ventilation. Interior climate readings were taken during loading, when the truck
was standing still, when the truck was in motion, and during unloading.
One important lesson from this study is the significance of loading times. When the
truck is standing still, the temperature rises in the container, with or without mechanical
ventilation. Although the temperature gradient is shallower and flattens out more quickly when mechanical ventilation is used. This indicates that mechanical ventilation
helps to improve the interior climate, mainly when the truck is standing still.
When the wind was low and natural ventilation used, a temperature rise of 0.21°C
per minute was measured. With mechanical ventilation the rise was only 0.10°C per
minute. No differences in temperature rise could be observed windy days.
A difference in temperature distribution could be seen in the animal compartment. It
was considerably warmer in the front, 3.4°C, during loading. During standing still time,
fully loaded, the temperature difference increased with natural ventilation and decreased
with mechanical. This shows the slower rise in temperature when fans are used.
A difference in humidity could also be detected. In average, when natural ventilation
was used, the relative humidity leveled at 97 %. This should be compared with the level
when mechanical ventilation was used; 82 %. This shows that fans help to remove
moisture from the animal compartment.
The carbon dioxide rose quickly during loading. The level stabilized at 2 000 ppm
when the fans started to work. With natural ventilation, the level kept rising. No
difference in carbon dioxide level (600-700 ppm) could be seen during the
transportation.
Loading times varied considerably during our study, which suggests that effects on
the well-being of the livestock have not been given sufficient attention.
One disadvantage of mechanical ventilation is the noise, which reaches between 75-
81 dB(A). This increases the pigs' resistance to board the truck and thus lengthens
loading times. Animals loaded first then have to stand for long periods of time in the
standing vehicle, aggravating the effects of heat and social stress and escalating the
duration of fights.
The main conclusion of this study is that mechanical ventilation is indeed beneficial
when compared with natural ventilation. It gives lower temperatures, lower humidity
and higher air velocity. Thereby the risk for heat stress during loading is decreased hot
days.
The overall conclusion is that there is no one catch-all solution to improve animal
transportation. Nevertheless, it is important to make many, smaller continual
improvements in order to optimize the process in terms of both animal welfare and meat
production. These two perspectives seldom prove to be mutually exclusive: the humane
handling and transportation of pigs produces greater efficiency in the production chain
and better quality meat. Moreover, the converse also seems to apply: the presence of
many, though not necessarily serious, deficiencies lead to stress, which prolongs the
production chain and impairs the quality of the meat. Prevention is thus just as
important as cure.

Every year an estimated 171 million pigs are transported within the EU, including 3.5
million in Sweden. The entire transport process, from pen to abattoir, puts the pigs
under stress. Stress factors include regrouping, new environments, vibration during
transit, and, particularly during the summer, uncomfortable climate. The greatest stress
is experienced during loading and when the truck is standing still in warm weather. The
ventilation inside is poor and there is little chance for the air to move freely unless the
trailer is fitted with fans.
The temperature can reinforce or mitigate the effects of the other climate factors and
is therefore critical to the pigs’ well-being. Loading on very hot days increases the risk
of heat stress, which prevents the animals from cooling themselves down effectively.
Stress also increases the amount of heat emitted by the pigs into their surroundings.
Heat is transferred, by the laws of physics, via conduction, convection, radiation and
evaporation. The first three of these are governed by the temperature differential
between the animal and its immediate environment. The relative humidity of the air is
also significant, especially at temperatures above 30°C. As there is no exact definition
of an upper critical temperature, it is set at the point when the animal has to activate
physiological mechanisms to prevent its body temperature rising.
A free flow of air is needed to remove heat and moisture from within the truck. The
ventilation inside the trailer and the density of the animal cargo affects the ambient
transit temperature and subsequently the quality of the meat. Ventilation is an important
determiner of this temperature, and pursuant to EU recommendations is to have a
capacity of at least 60 m3
/hour and 100 kg animal mass. The most important factor
deciding the interior ventilation is the size of the ventilation grills, which should make
up 20 percent of the floor space.
There are two types of ventilation system that can be used for animal transportation:
natural and mechanical, the former being the most common. This system is based on the
temperature difference between the external and internal air, wind speed and, most
crucially, the speed of the vehicle itself. It thus varies considerably. Mechanical fans can
be mounted inside to provide a more even ventilation effect and to guarantee that the
trailer remains ventilated for the entire journey – even when the truck is standing still.
The purpose of the present study is to improve our understanding of the thermal
dynamics at various points within the trailer. The main body of the study comprises a
comparison between natural and mechanical ventilation. A commercial pig truck was
fitted with climate sensors that registered temperature, humidity, carbon dioxide levels
and direct sunlight every 30 seconds between source farm and slaughterhouse. Ten
measurements were made in total, five with mechanical ventilation, five with only
natural ventilation. Interior climate readings were taken during loading, when the truck
was standing still, when the truck was in motion, and during unloading.
One important lesson from this study is the significance of loading times. When the
truck is standing still, the temperature rises in the container, with or without mechanical
ventilation. Although the temperature gradient is shallower and flattens out more
10
quickly when mechanical ventilation is used. This indicates that mechanical ventilation
helps to improve the interior climate, mainly when the truck is standing still.
When the wind was low and natural ventilation used, a temperature rise of 0.21°C
per minute was measured. With mechanical ventilation the rise was only 0.10°C per
minute. No differences in temperature rise could be observed windy days.
A difference in temperature distribution could be seen in the animal compartment. It
was considerably warmer in the front, 3.4°C, during loading. During standing still time,
fully loaded, the temperature difference increased with natural ventilation and decreased
with mechanical. This shows the slower rise in temperature when fans are used.
A difference in humidity could also be detected. In average, when natural ventilation
was used, the relative humidity leveled at 97 %. This should be compared with the level
when mechanical ventilation was used; 82 %. This shows that fans help to remove
moisture from the animal compartment.
The carbon dioxide rose quickly during loading. The level stabilized at 2 000 ppm
when the fans started to work. With natural ventilation, the level kept rising. No
difference in carbon dioxide level (600-700 ppm) could be seen during the
transportation.
Loading times varied considerably during our study, which suggests that effects on
the well-being of the livestock have not been given sufficient attention.
One disadvantage of mechanical ventilation is the noise, which reaches between 75-
81 dB(A). This increases the pigs’ resistance to board the truck and thus lengthens
loading times. Animals loaded first then have to stand for long periods of time in the
standing vehicle, aggravating the effects of heat and social stress and escalating the
duration of fights.
The main conclusion of this study is that mechanical ventilation is indeed beneficial
when compared with natural ventilation. It gives lower temperatures, lower humidity
and higher air velocity. Thereby the risk for heat stress during loading is decreased hot
days.
The overall conclusion is that there is no one catch-all solution to improve animal
transportation. Nevertheless, it is important to make many, smaller continual
improvements in order to optimize the process in terms of both animal welfare and meat
production. These two perspectives seldom prove to be mutually exclusive: the humane
handling and transportation of pigs produces greater efficiency in the production chain
and better quality meat. Moreover, the converse also seems to apply: the presence of
many, though not necessarily serious, deficiencies lead to stress, which prolongs the
production chain and impairs the quality of the meat. Prevention is thus just as
important as cure.