In spite of the extreme thinness of the avian pulmonary blood-gas barrier (PBGB), it is remarkably strong. To understand the basis of the remarkable strength of the avian PBGB, network of collagen connective tissue that form the lung’s parabronchial fibrous framework and type-IV collagen, a principal component of the basement membrane was investigated in the BGB and in the epithelial-epithelial contacts between the air capillaries in the domestic fowl, Gallus gallus variant domesticus. Techniques of discriminatory staining, selective alkali digestion, vascular casting followed by alkali digestion and immunoelectron microscopy were used. Abundant collagen fibers of the interparabronchial septa, which form part of the tunica adventitia of the interparbronchial vessels, firmly interconnect adjacent parabronchi directly and indirectly (via intraparabronchial vessels). Peripherally, the intraparabronchial artery, with its tunic of collagen fibers, enters and penetrates the exchange tissue mantle. The collagen fibers around the vessel decrease in quantity as it divides into blood capillaries. From the luminal side, the projection of the parabronchial lumen into the exchange tissue mantle as the atria, the infundibulae and the air capillaries, in this order, carry collagen covering which reduces in quantity with each division. The three-dimensional interactions between blood capillaries from the peripheral part and air capillaries from the central lumen allow contact formation between blood capillaries, air capillaries and between air- and blood capillaries. Collagen fiber continuum starting from the interparabronchial septa runs through the exchange tissue by following the three contacts sites and terminates at the parabronchial lumen. At the periphery, the collagen fibers constitute a conspicuous bundle. Within the exchange tissue mantle, the collagen forms diffuse complex interconnections of thin fibers. Towards the parabronchial lumen and within interatrial septa, the thinner collagen fibers of the exchange tissue mantle aggregate to form thick bundles which bind to the connective tissues surrounding the parabronchial muscles. Based on the structural arrangements and function of the smooth muscle, the collagen- and the elastic tissue fibers, and structures like the interparabronchial septa and their associated blood vessels, it was envisaged that: dynamic- tension and compressive forces exist in a parabronchus to form a tensegrity (tension integrity) system. The tensegrity arrangement imparts rigidity to a parabronchus while strengthening the air and the blood capillaries. Mechanical interdependence between parabronchi and between air- and blood capillaries allows efficient transmission and redistribution of tension. The tortuous course of the collagen fiber continuum that follows the three-dimensional intertwining of the gas exchange units- from septa to the lumen- ensures that tension does not travel a straight course and as such, any extrinsic or intrinsic force applied to the structure is transmitted away from the point of origin. Graded exercise intensities and perfusion at different pressures on the integrity of the BGB were used to determine the condition under which the blood-gas barrier in the avian lungs fails. Number of red blood cells and protein concentration in the harvested lung lavage fluid were estimated in the exercised chickens. For histological analysis, numbers of epithelial-epithelial (E-E) breaks and blood-gas barrier (BGB) breaks were counted in each of the four vascular regions of the lung in both the exercised and the perfused lungs. Post exercise blood lactate analysis showed a 4-fold increase between rest and maximal exercise (2.95 m/s) while the numbers of red blood cells and protein concentration increased steadily with increasing exercise intensity, however, the degree of increments appeared to decrease at higher workloads. The two kinds of breaks occurred at all levels of exercise and in the resting birds but at any exercise intensity, there were more E-E breaks than BGB breaks. The numbers of breaks increased with increasing exercise intensity and the difference between the two types of breaks decreased with increasing exercise intensity. In resting birds, there were no breaks in the area of the lung supplied by the cranial branch of the PA. In the exercised birds, differences in number of blood-gas barrier breaks among the four vascular territories only occurred at 0.66 m/s where the lowest and highest counts occurred in the cranial- and caudomedial regions respectively, whereas at all other levels of exercise, the numbers of breaks were comparable. Presence of red blood cells in the lungs of resting birds indicated that failure of the blood-gas barrier might be a common but inconsequential event in the avian lung. A positive linear relationship exists between the perfusion pressure and the numbers of both E-E and blood-gas barrier breaks. At all perfusion pressures, there are more E-E breaks than BGB breaks. The difference between the two types of breaks decreased with increasing pressure. At any perfusion pressure, more breaks occurred in the regions supplied by the accessory- and caudomedial branches of the PA than in the regions supplied by the cranial- and the caudomedial ones. This could be because the pressures in the two blood vessels may be higher since the caudomedial branch is the most direct continuation of the PA while the accessory branch is the narrowest and the first to originate from the PA. Because of the extreme thinness of the blood-gas barrier and unavoidable puncturing of air sac when the thorax is accessed to cannulate the pulmonary vessels, the exact pressure at which the BGB fails could not be ascertained since both types of failure occurred at all perfusion pressures. However, separation of the epithelial-epithelial contacts, caused by distension of the blood capillaries, started appearing at the perfusion pressure of 2.89kPa. This may represent the pressure at which the blood-gas barrier starts to fail.

The process of domestication of the chicken had knowingly and unknowingly employed genetics to achieve human perceived changes in economic traits such as growth and egg production. These changes sometimes resulted in negative side effects, such as a physiological delay in sexual maturity observed in a line of White Plymouth Rock chickens selected for low body weight. These chickens plateaued after about 30 generations of selection possibly due to a conflict between survival/reproduction and the selection for slow growth. Yet, the even smaller red junglefowl seem to be free of such physiological barriers. Here, data are presented for reproductive, growth, and behavioral traits for the Richardson strain of red junglefowl, a line of White Plymouth Rock chickens that has undergone 57 generations of selection for 8-week body weight and their F1 and F2 reciprocal crosses. While exploring the physical and genetic differences between domestic chickens, as well as the genetic basis for the striking differences in growth patterns between the two lines, observed was plasticity and considerable residual genetic variation which likely facilitated the adaptability of the chicken to a broad range of husbandry practices. Differences in growth patterns implied additive and non- additive genetic variation and modifications in resource allocation strategies during domestication. / PHD / The use of intensive genetic selection and heterosis in breeding programs since the end of World War II has contributed to poultry industry achievements of high economic production. This has come about through increased feed efficiency, greater processing yield, shorter generation intervals, and improvements in growth rates of commercial populations. However, with these improvements there has been a 50% decrease in genetic diversity in commercial pure lines in comparison to their ancestors. This change has been attributed to the limited number of commercial primary breeders and increased inbreeding. Animals in populations that have been through intense selection for high and efficient production may be more at risk for physiological, and immunological issues. This dissertation addresses the relationship between the junglefowl and the domestic chicken with regard to these issues through a three-generation quantitative and molecular analysis.

Personality has been reported in a large variety of animal species, but it is not obvious why animals have personality. Variation in physiological traits, such as growth rate, should theoretically affect variation in behaviours and thus can explain why we observe variation in personalities. Growth rate is, theoretically, positively correlated with active personality types. Empirical studies have reported this pattern in different fish species, but there are not yet many studies on endothermic animals. I have therefore scored behaviours of 100 red junglefowl (Gallus gallus) chicks in four personality assays; novel arena, novel object, tonic immobility, and a proactive-reactive test, together with recording variation in growth rate of these individuals. The chicks individual growth rate (% day-1) were calculated and the relationship between personality and growth rate investigated. There was significant difference in growth rate between the sexes, where males grew faster than females, detected already at one week of age. However, no significant correlations between behavioural traits and growth rate were observed, indicating that personality seem to be independent of growth rate. Further studies should therefore investigate the generality of this finding, and alternative underlying mechanisms for variation in personality should be explored.

Social support is thought to give animals benefits from social partners, such as improved coping with challenges. The aim of this study was to investigate differences in social support in the red junglefowl (RJF) and a domestic layer strain, the White Leghorn (WL). A runway test consisting of two compartments with unfamiliar and familiar stimulus animals was used to measure social motivation before and after a stressful experience. Total number of test animals was 56 divided into four groups; male and female WL as well as male and female RJF. Results showed that females preferred to stay close to familiar conspecifics after stress treatment. Before stress treatment there was little difference between either sex of WL while RJF males and females chose different zones. Females preferred familiar conspecifics, indicating that they rely more on familiar social stimuli for social support. Males of the two breeds behaved differently towards stimulus animals. WL males showed aggression towards familiar stimulus animals while RJF males directed aggression towards unfamiliar stimulus animals. Indication of sexual behavioural dimorphism was supported while further research is needed in domestication effects on social support in chickens.

When animals are stressed they use a trait called social support to alleviate their stress responses. With domestication many traits from the ancestor red junglefowl have changed in the domesticated breed white leghorn. White leghorns are bred to be able to live in large groups where it becomes hard to recognize every chicken. They are therefore not as dependent of familiar stimuli birds for social support as red junglefowl. Our hypotheses were that red jungle males would be more interested in unfamiliar stimuli birds than white leghorn male before stress due to their territoriality. We tested total 56 chickens in an open field test. The test arena was divided in three zones and the time the focal birds spent in each zone was recorded. The focal bird was recorded in 300 seconds before being stressed by being suspended in a net and then recorded again in 300 seconds. The results showed that social support and social behaviour differs between females and males for both breeds. No significant differences were found between the breeds. There was a tendency for significant of breed (P=0.08) effects in the central zone unstressed. The two interactions before stressed between breed and sex, central zone (P<0.01) and unfamiliar zone (P<0.01) had significant effects. We observed fights between white leghorn males and familiar stimuli. Waltzing did also occur in red jungle males in front of unfamiliar. In conclusion, numeric differences can be seen but not large enough to be significant and our hypotheses are not confirmed.

Domestication in chickens has made feed-restriction a necessity if broiler breeder hens should reach sexual maturity and be fertile. This is claimed to cause chronic hunger. To measure hunger the gene expression of the appetite regulators agouti-related peptide (AgRP), pro-opiomelanocortin (POMC), neuropeptide Y (NPY) and adenosine monophosphate-activated protein kinase (AMPK) of the melanocortin system was quantified with qPCR. This was done in feed-restricted Red Junglefowl and compared with the gene expression of two strains of feed-restricted broilers, Ross 308 and Rowan Ranger, to detect possible effects on domestication on appetite regulation. POMC-expression was upregulated 2-fold in the feed-restricted Red Junglefowl. POMC-expression was downregulated by half in the feed-restricted Ross 308. AgRP/NPY-expression was upregulated 4-fold in feed-restricted Rowan Rangers. A comparison between the control groups (ad libitum fed) of the breeds showed that the NPY-expression was lower in Ross 308 and Rowan Ranger compared with the ancestor. Results show no difference in body weight of ad libitum fed and feed-restricted Red Junglefowl. Conclusions were that the feed-restricted Red Junglefowl was not properly restricted in food supply since no difference in body weight between the treatment groups was detected. The upregulation of POMC in the feed-restricted Red Junglefowl could be stress-linked influenced by the feeding type (scattering of food in litter). No conclusions of the impact of domestication on chicken’s appetite could be drawn. Domestication has probably had its impact by altering other signaling pathways of the melanocortin system than in the arcuate nucleus.

The study of the formation of new cardiac muscle cells during postnatal development is a relatively new field. During fetal development, new cells are formed as the heart grows. However, the proliferative ability of postnatal cardiomyocytes is still debated. While several studies have been made on mammals, less is known about the chicken cardiac cells and their postnatal proliferation. As almost all previous studies have used microscopy-based cell counting methods, there has been some limitations on accuracy and amounts of cells that could be counted. The aim of this study is to develop a method for using flow cytometry to analyze proliferative ability of chicken cardiomyocytes and to investigate if any postnatal proliferation exists. For this study, 4 weeks old Red Junglefowl (Gallus gallus) chickens were used for isolating cardiomyocytes. In addition, 19 days old Red Junglefowl embryos were used to asses if a longer incubation time would yield a higher number of proliferative cells. Cells were stained using a commercial EdU imaging kit and analyzed using flow cytometry and imaging flow cytometry. The produced results could not be used for determining the proliferative ability of the cardiomyocytes, but provides crucial information for possible method improvements. In conclusion, this study has laid important groundwork for future studies on the proliferative ability of chicken cardiomyocytes.

<p>The aim of this thesis was to study chickens of an F7 intercross between red junglefowl and White Leghorn layers in five behavioural tests to see if there were any correlations between traits in the intercross. 80 animals were used (40 males, 40 females); they were tested in a tonic immobility test, an open field, a fear of human test, an aggression test and lastly a sociality test. The results indicate a pair of correlations between the different variables; chickens with long tonic immobility duration were less aggressive, and chickens with a high fear of humans were more social towards other chickens, which could suggest a correlation between fear and social behaviour/aggression. The results from this study also support previous studies showing that one QTL controls chickens’ behaviour in the tonic immobility test based on the correlations found between the variables in the tonic immobility test. Differences between the genders were found in variables that correlated with each other; this could lead to a speculative suggestion that those behaviours are affected by genes on the X-chromosome. There was also a significant relationship between the weight of the male chickens and their behaviour in the open field test and in the fear of human test, in which the heavier males were less fearful than the lighter ones.</p>

<p>Domestication is a process in which animals become adapted to a life among humans by means of selection. A reduced fear of humans is probably one of the first aims of selection, intentionally or unintentionally. Animals that have undergone the process of domestication have a different appearance than animals in the wild (domestic phenotype) and behave in a different way towards humans. In this study I have looked at foraging and explorative behaviours in an unselected parental generation of red junglefowl and their offspring. The parental generation were bred in three lines, a high line, with birds displaying a strong fear of humans, an intermediate line, birds showing a modest fear, and one low line, with birds performing a more tame behaviour towards humans. I presented the birds with three different feeding alternatives, familiar chicken food, meal worms camouflaged with wood shavings and just wood shavings. I counted number of pecks in the different food options, number of changes between sites and how many sites a bird visited. The results show that females of both generations were more explorative than males, by pecking more in cups of meal worms hidden in wood shavings whereas the males pecked more in cups containing chicken food. Females also moved around more in the arena. Results from the first selected generation show significant differences between the selection lines among the females, with females from the high and low groups being the most explorative.</p>

<p>Historically during domestication of animals, tameness towards humans was likely the most desired trait and therefore bred on. The red junglefowl (Gallus gallus) is the wild progenitor of all domestic chicken breeds and earlier studies present clear morphological, physiological and behavioural differences between domesticated breeds and the non-domesticated red junglefowl. These changes may be the result of altered gene expression - pleiotropy or linked genes. The aim of this thesis was to evaluate (1) effects of tameness selection on social behaviour towards conspecifics and (2) social behaviour differences between the sexes. Two generations of red junglefowl, P0 and its offspring F1, were studied. Both generations were divided into three selection lines (tame, intermediate or fearful), depending on their results in a fear of humans test.  A novel type of social reinstatement test was set up, containing a non-social area without stimulus, and a social area containing a mirror serving as stimulus animals. The social and aggressive behaviours performed towards the mirror were recorded, so was the time spent in the social versus non-social part. An undisturbed behaviour test was performed, as well as a standardized social reinstatement test. The P0-females performed significantly more social behaviour (p=0.008) at 26 weeks than males in the mirror test, and females also displayed significantly more social (p=0.04) and agonistic behaviour (p<0.001) than males in the undisturbed behaviour test. The social reinstatement test displayed a significant effect between the selection lines with regards to sociality. This suggests that there are immediate selection responses in early domestication.</p>