The purpose of this study was to design and test five SNP markers in an inbred chicken cross between Red Junglefowl and domestic White Leghorn of the 8th generation. The markers lie in a region affecting the tonic immobility behaviour which differs significantly between the two species. The markers could be identified by usage of PCR and pyrosequencing. The data obtained were further used in a small scale quantitative trait locus (QTL) analysis. QTL analysis is a statistical method to link phenotypic traits to genotypic data. Four out of five markers could be genotypes and thereby, made it possible to proceed with the QTL analysis. The results showed that there is no QTL associated with the markers identified. The two flanking markers were closest to a significant difference between genotypes and it is therefore a possibility that a QTL lies close further down or up the searched region. From the line map it is indicated that there is little recombination in the marker region.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第20025号 / 情博第620号 / 新制||情||108(附属図書館) / 33121 / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 守屋 和幸, 教授 松田 哲也, 教授 廣岡 博之 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DGAM

In layer hen commercial production systems, chicks are not raised by hens and do therefore not receive any maternal care. In the wild, after hatching, chicks undergo filial imprinting where they create a social bond with a stimulus in their surrounding environment, usually the mother hen. Filial imprinting behaviors remain in chicks until adulthood. This bond and maternal care influence the emotional development of chicks. Here, I aimed to investigate short- and long-term effects of filial imprinting on a model hen, on the emotional state of White Leghorn chicks, hatched at Linköping University. To measure optimism, pessimism, and fear, a judgment bias test (JBT), an open field test (OFT), and a novel object test (NOT), was performed and replicated. Before the tests, half of the chicks were imprinted on a model hen, while the other half was not given such a model to imprint on. All chicks were weighed during the entire project. The hypotheses were that the imprinted chicks would be more optimistic in the JBT, show less fearful behavior in the OFT and NOT, and weigh more compared to the non-imprinted chicks. If these results would be found, imprinting could potentially be used to reduce stress in commercially hatched chicks, and thus improve their welfare. The results were inconsistent with all three hypotheses. This indicates that imprinting on a model hen, did not have a positive impact on the chicks’ emotional state. Further studies need to be performed to find methods to improve commercially hatched chicks’ emotional welfare.

The effects of domestication on animals’ behaviors and morphology are well known and documented. Changes due to domestication include higher sociability, decreased fearfulness, and increased boldness. These changes have been documented in the chicken breed known as White Leghorn (Gallus gallus domesticus), which is a domesticated relative to the Red Junglefowl (Gallus gallus). Though domestication have altered the chicken’s behavior, its effect on the cognitive learning capabilities of the chicken is still unclear, which is the focus of the study. Two tests were conducted in this study: associative learning and spatial learning. The fowls natural desire to remain close to other fowl was used as the main motivation for completing the tests. The associative learning test was performed by testing the two breeds of associating an item with finding their way to their flock. The spatial learning test was performed by measuring the time needed for an individual to return to their flock from behind an obstacle. For the associative learning test, a significant difference between the cognitive learning capability of the two breeds could be found for part 2 (tests 11-20), as well between part 1 and part 2 within the breed White Leghorn. Between the sexes no significant difference could be seen, but within the females, a significant difference was detected between part 1 and part 2. For the spatial learning test, no significant difference could be found between the two breeds nor the sexes. No correlation could be found between associative- and spatial learning test on an individual level. Due to few significant results, further studies should be conducted to confirm the effects of domestication on learning.

Egg-laying hens coming from commercial hatchery go through hatchery procedures considered as stressful and engaging prolonged stress response in adult chickens. The aim of our study was to evaluate the impact of commercial hatching procedure on the affective state of chicks, on their short- and long-term memory and on their need for social reinstatement. To assess the affective state of the chicks we used a cognitive bias protocol integrating the ecological response of a chick to the picture of another chick, to an owl and to an ambiguous cue mixing features of both the chickand the owl pictures. Short-term memory was evaluated by using a delayed matching-to-sample experiment (with 10, 30,60 and 120 s delays), with conspecifics as sample stimuli. We assessed long-term memory with an arena containing multiple doors leading to conspecifics, in which a chick had to remember which door was open after a delay of one hour or three hours. Finally, we observed the need for social reinstatement through a sociality test arena allowing a chick to be more or less close to conspecifics. We found that chicks coming from commercial hatchery were in a depressive affective state compare to control group. Those chicks also showed higher need for social reinstatement and loss weight. No differences were found regarding short- and long-time working memory between the two groups, but the methods used during these experiments will be discussed. Studying how commercial procedures impact the cognition and more specifically the emotions and state of mind of chickens, is a necessary step forward into the understanding of farm animals’ welfare.