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The first objective of this work was to compare and contrast different methodologies for genetic analysis. As the range of all possible models can be very large in practice, it is advisable to have a preliminary idea of the covariance structure of the data, and a non-parametric approach based on the variogram was proposed. It is especially adapted for exploratory analysis when a large number of observations is available per subject over time and was applied to the analysis of daily records for milk production in dairy cattle. Model comparisons in the univariate case showed that character processes were generally better able to fit the covariance structure than random regression with fewer parameters. However, CP models do not allow a straightforward extension to the multivariate case. Further research showed that structured antedependence models offer similar advantages to character processes compared to random regression while allowing an extension to multi-trait analyses. SAD models were even able to capture the highly non-stationary correlation pattern in the application to lactation curve analysis. For genetic evaluation of dairy cattle, longitudinal models can easily provide estimation of individual cumulative milk productions as well as genetic values at 305 days. However, these predictions do not take into account the drying-off process and can be highly overestimated for short lactations. A methodology to correct them was suggested. All these analyses were performed in the case of normally distributed longitudinal data. An extension to the genetic analysis of non-normally repeated measures was considered. Estimation procedure becomes much more complicated and requires the use of Markov Chain Monte Carlo methods. In this study antedependence models appeared to be the most appropriate for genetic analysis of longitudinal data.

The principal objective of this thesis is to investigate factors relevant to locomotion in the domestic fowl. Experiments concentrated on the influence of environmental (rearing condition, resource distribution, space, and restraint), social (presence and familiarity of companions), and genetic (age and breed factors). A familiar bird, an unknown bird, and an empty cage were used to investigate the effect of familiarity and companionship on birds' locomotion. It was found that isolation may cause a fear reaction, isolated birds were more nervous and less active, and remained motionless for a longer period of time, they performed more behaviour patterns with social content such as preening and foraging. Familiarity between birds increased locomotion: birds walked more and were less aggressive when the companion birds were familiar. The presence of companions and familiarity with flock mates may produce a situation where birds feel more secure and relaxed to explore. Familiarity and companionship of another bird had no effect on inter-individual distance. When broilers, layers and a dual-purpose breed (Taiwan Country chickens) were compared, laying hens were the most nervous and active breed, while the broilers were the least active. The meat type broiler breed ground-pecked less, but still grew fastest. Broilers fed efficiently without spending much time on foraging activity such as ground-pecking/scratching. This suggests that genetic selection has changed behaviour repertories, even those essential for survival. Age had little influence on locomotion. The findings show that in domestic fowls locomotion is motivated, and its expression influenced by a wide range of factors, and there are possible implications for welfare: the present battery cage system may not be appropriate for such motivation to be expressed. The design of housing system should take into account the layout of the equipment, and resources should be carefully distributed to prevent intense competition between birds.

The aims of this project were i) to take measures of behaviour in cattle that could be demonstrated to be reliable indicators of temperament traits, and ii) to look for areas of the genome harbouring genes involved in these traits. Behavioural tests were carried out on a large number of animals from a Charolais x Holstein cross-bred herd. Four different tests were examined for their potential to measure different temperament traits: a Flight-from-Feeder Test (FF), a Social Separation Test (SS), a Novel Object Test (NO) and a Handling Test (HA). The results of the tests were assessed using two criteria: inter-animal variability and intra-animal repeatability. The FF, SS and HA Tests showed high values in these two criteria. Experiments were then carried out to validate these three tests, by examining whether relationships were seen between responses from different test situations that were though to measure the same traits. Full validation of the three tests was not achieved. Experiments were also carried out to investigate how stable the behaviour measurements remained with increasing age. Results of SS and HA Tests carried out at four months of age were compared with those from the same tests repeated on the animals at 12 months of age. A relationship was found between SS measures from the two ages. Results from behavioural tests carried out on heifers at 10 months of age were compared with behaviour scored in the dairy parlour at 30 months. The measurements at the younger age were not predictive of adult behaviour in the diary. In order to localise areas of the genome involved in the behavioural traits, preliminary Quantitative Trait Loci (QTL) analysis was carried out on four chromosomes. Associations between behavioural phenotypes from the FF and SS Tests and the inheritance of DNA markers were examined for a large number of animals. The possible effects of environmental factors on the test results were examined prior to the analysis. Four putative QTL locations were identified.

The objective of this thesis was to investigate the longitudinal aspect of the genetics of egg laying in two heavy female turkeys and explore whether considering time features of laying may improve selection efficiency. The dataset consisted of records from two commercial lines, although only one had longitudinal data. The genetic correlation between body weight and total egg number was estimated to be -0.7±0.1 and -0.5±0.1 in the two lines studied. Both estimates were highly negative and larger in magnitude than in traditional and lighter lines, suggesting that the continuous selection for growth hinders genetic progress for egg production. Heritability estimates for body weight were high (around 0.4), while being lower for total egg number (around 0.2 for egg records on which Box-Cox transformation has been applied to reduce their deviation from normality). Since heavier birds tended to lay fewer eggs within a specific period, this implied reduced rates of lay. In order to explore this consequence of the selection for antagonistic traits, a time-to-event trait was formulated that corresponded to the days required for a hen to lay 82 eggs (the average egg production in the dataset). It was shown that the Weibull distribution could satisfactorily serves the baseline function under a survival analysis context. So, a frailty model was constructed to perform a genetic analysis of the time trait and it was found that its heritability estimate was between that for the transformed and untransformed total egg number. Random regression (RR) models were also considered for the longitudinal analysis of egg production. The detailed covariance structure obtained on a longitudinal basis can be used to target more effectively the selection pressure on the most informative stages of laying and thus, to maximise the output of breeding programmes.

This work represents a study of aspects of passive immunityand the method of its transmission to the Dewly born foal. All the foals examined were agammaglobulinaemicat birth. Traces of antitoxin, too low to be of any protective value, were present in foals born to hyper immune dams. The foals rapidly acquired passive y globulbin by absorption of colostral proteins from the small intestine. The antibody levels attained were somewhatlower than those of the dams' serum at parturition. The passive y globulin and anti toxin declined steadily after 24 hours and br three weeks at age their levels bad been halved. The duration of demonstreble passive immunity did not extend for more than four months of life. The development of active immunity began within the first month of life. Autogenous y globulin was detected after two weeks in the colostrum deprived foals. In foals which received colostrum, y globulin levels approaohing those for adult horses were detected by about four months of age. The mechanism of absorption of colostral proteins was by uptake into the epithelial cells of the small intestine and transfer via the lacteals to the systemic oirculation. The intestine was apparently non-selective in its absorption of maoromolecules. The efficiency of absorption three hours after birth of labelled PVP, a synthetic polymer of similar molecular size to y globulin, was shown to be 22% of the total dose. There followed a linear decline in efficiency of absorption with age to the lowest recorded levels at 20 hours. By 24 hours of life the intestinal epithelium was no longer permeable to marker antibody. Examination of the colostral proteins after absorption revealed that the high molecular weight component, y globulin, was retained in the foal's circulation, but that the smaller size milk proteins were excreted in the urine. This neonatal proteinuria persisted only during the period of intestinal absorption.

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