Browsing by Subject "Besatzdichte"

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Impact of housing environment and rearing condition on the immune system and welfare of laying hens
(2021) Hofmann, Tanja Melanie; Stefanski, Volker
In recent years, consumers’ interest in modern farm animal husbandry and, above all, criticism of intensive production systems that can impair animal welfare, have increased sharply. From hatch, chickens are confronted by a wide range of environmental and social stressors that may confound homeostasis and impair their health and welfare. Not being able to deal with the environment can lead to an activation of the stress system, resulting in a release of neuroendocrine signals like glucocorticoids. These have the potential to modify the immune system and alter species-specific behavior with possible detrimental impacts on animals’ health and welfare. In this context, early-life conditions play a special role as they were shown to have long-term consequences for physiology and behavior in the later life. High stocking densities which activate the hypothalamic-pituitary-adrenal-axis are said to be one of the largest welfare concerns in the poultry industry. Previous research has primarily focused on the effects of stocking density on broilers and adult laying hens, but few studies have focused explicitly on layer pullets, and none of them investigated long-term effects on the immune system. The understanding of short- and long-term consequences of environmental conditions during rearing on the immune system and behavior of layer pullets is essential for shaping an environment that avoids allostatic overload, thus promoting animal health and welfare. This doctoral thesis aimed to identify and evaluate potential immunomodulating factors in the housing environment of chickens. In order to achieve this, it summarizes and reviews important aspects of housing environments for the immune system in chickens. Furthermore, an existing flow cytometric method for the enumeration of leukocytes and discrimination of lymphocyte subsets in blood was adapted to lymphatic tissues. Moreover, short- and longterm consequences of stocking density during rearing on the immune system, stress hormone level and behavior in layer pullets were evaluated. The results are described in detail in three peer-reviewed manuscripts published in international journals. The literature analysis identified several housing conditions as immunomodulating factors. Light management was marked as an effective tool to modulate the immune response in chickens, as long light phases were demonstrated to lower adaptive cellular and humoral immune responses while certain light colors, especially of shorter wavelengths, promote some immune functions. Moreover, particularly high ammonia and hydrogen sulfide concentrations pose a threat to chickens’ health by dampening the adaptive immune response and promoting inflammation. However, the interaction between housing environment and management is complex. Depending on the type of housing form, chickens are confronted with different social and environmental challenges, which in turn can have an impact on the immune and stress system. An understanding of immunosuppressive risk factors is essential for successful poultry management aiming to optimize health, welfare and economic efficiency. To broaden the assessment of immune status for scientific purposes, new staining- and gating strategies for avian lymphatic tissues were adapted to an existing flow cytometric method for blood. The adaptation process showed that the application of already established protocols to other tissues is possible, but has to be examined carefully as tissue-specific effects or cell-preparative procedures might lead to differences in possible combinations of antibody-fluorochrome conjugates. The results of the experimental study within this doctoral thesis demonstrate for the first time that stocking density during rearing has not only short- but also long-term impacts on the immune system in laying hens. Pullets reared at high stocking densities showed stress-related alterations in immune cell numbers and higher incidences of feather pecking that manifest in the laying period. This highlights the significance of early-life conditions for immunocompetence throughout the whole production cycle. Of particular interest is that the number of gamma-delta T cells was lower in the high-density group, which has not been investigated in any stress-related studies with chickens before. The present doctoral thesis provides a significant contribution to the improvement of health and welfare in poultry farming and forms a basis for further research about long-lasting consequences of rearing conditions on the immune system, especially in laying hens.
Das Verhalten von Mastputen bei unterschiedlicher Besatzdichte und Einstreuart
(2013) Günthner, Pia; Bessei, Werner
There exists at present no legal regulation concerning housing and management of commercial turkey production in Europe. The European Commission is working on a directive of keeping fattening turkeys. In Germany is a voluntary agreement of turkey producers, animal protection societies and governmental authorities, which provides standards and minimum requirements for adequate turkey rearing. These standards, however, are still being debated. Especially the stocking density is considered too high. The present study was carried out to provide scientific information on the behaviour of turkeys under different stocking densities, and thus, to support the revision of the voluntary agreement on turkey keeping. The turkeys (B.U.T. Big 6) were kept in an experimental turkey house. The male and female birds were kept in two separate parts of the same building. Each part contained 16 identical pens. The males were raised up to the 21 weeks of age and received a commercial pelleted turkey diet in 7 feeding phases. The females were raised upt to 16 weeks and received 6 feeding phases. Three different stocking densities were testet: low, intermediate and high. The existing recommendations of stocking density for males and females of the voluntary agreement were chosen as intermediate density. All birds were kept on wood shavings as litter from day-old to 5 weeks of age. From the 6th week of age (which correspond to the 3rd feeding phase) onwards chopped straw was spread as required to maintain good litter quality. In one additional treatment wood shavings instead of straw were spread throughout the fattening period. The intermediate stocking density of males and females was used for this treatment. Hence the experimental setup consisted of 4 treatments within both sexes. Direct behavioural observations were carried out by 4 trained observers. The direct observations started with the 2nd feeding phase and continued untill the end of the fattening period. Feeding, drinking, walking, sitting/lying, standing, litter pecking/scratching, dust bathing, preening, feather pecking, wound pecking and aggressive pecking were recorded using time sampling technique. In addition all pens were video-recorded in the weeks before or after the direct observations. The duration of the different behaviours were measured using the video records. Feed consumption, water consumption, body weight development and temperature inside the stables were recorded continuously. The experiment was repeated with a second batch of birds using the same experimental layout and the same criteria as in the first batch. Litter temperature was additionally recorded in the second batch. In the first batch the frequency and duration of sitting/lying was significantly higher at the lower stocking density as compared to the stocking density. This could by explained by physical disturbance of resting birds at the higher stocking density. The higher litter temperature under high stocking density might also have interrupted the sitting phases of the birds. At the lower stocking density there were significantly more preening, feather pecking and a non-significantly higher level of dust bathing than in the higher stocking density. The opposite result has been expected with regard to feather pecking. This supports the result of other publications which reported an interrelationship of comfort behaviours, such as preening and dust bathing, and feather pecking. The effect of stocking density was not significant for all other behaviours. This shows that stocking density in the tested range has little influence on the behaviour growing turkeys. Feed intake growth rate and the water : feed ratio were lower at the lower stocking density. The lower water : feed ratio indicated that the reduction of feed intake and growth rate with increasing stocking density is influenced by higher litter temperature. The turkeys raised on wood shavings from the 3rd feeding phase onwards showed significantly more feeding behaviour than those kept on straw in the first batch, and a similar tendency in the second batch. They also pecked significantly more the feathers of their pen mates in both batches. The higher feeding behaviour of the birds kept on wood shavings coincided with a significantly higher feed intake only in the second batch. All other performance traits did not significantly respond to the different litter types. The higher feeding behaviour and feed intake of turkeys kept on wood shavings was explained by a compensatory activity to litter pecking: straw as litter obviously presents a higher stimulus for exploratory litter pecking than wood shavings. The lower feather pecking activity of the turkeys kept on straw can be explained by the same effect. Feather pecking as substitute of litter pecking has been reported in the literature for turkeys and other poultry species. Sitting/lying behaviour was consistently higher in male than in female birds in both batches. The causes of this effect can be manifold. The higher body weight may reduce the ability of standing and thus increase sitting/lying. The lower group size and lower stocking density in the males may have led to less disturbances and allowed more resting behaviour. Finally the higher litter temperature observed in the female pens may have reduced the time spent sitting/lying in the females. Males showed significantly more litter pecking and scratching in both batches. Preening was higher and feather pecking was lower in males. This effect was significant in at least one batch. The inverse relationships between litter pecking and feather pecking among males and females are consistent with the effect of litter on these behaviours. In conclusion, the effect of stocking density in the range tested in the present experiment was relatively small as compared to other factors, such as age, season, sex and Litter temperature.