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AA amyloidosis (AAA) is a disease known as amyloid arthropathy in chicken, which represents substantial economic losses, in addition to welfare concerns. Enterococcus faecalis (E. faecalis) is the major pathogen found in field outbreaks of amyloid arthropathy and its specific association with this disease has been extensively confirmed. The following review discusses the sequence types of E. faecalis associated with AAA that have been identified and characterised both poultry and humans and provide different hypotheses and theories about pathogenesis and transmission of this disease. This article covers the pathology both in field and induced cases of avian amyloidosis and concludes with approaches for a possible treatment, needs for further research and future perspectives. This paper is a consolidation of current knowledge on AAA in chickens which has been obtained over the last twenty years. [ABSTRACT FROM PUBLISHER]

Egg quality traits are of utmost importance in layer breeding programs due to their effect on profitability in the egg production industry and on the production of quality chicks. Therefore, the aim of this study was to analyze and estimate genetic parameters of different quality traits: egg weight, breaking strength, dynamic stiffness (Kdyn), egg shape index, eggshell thickness, and albumen height. Eggs were obtained from 4 pure lines of birds. Two different tests were performed: a white breeding program, with eggs from a male and female line of a white egg layer program that were analyzed at 67 to 70 wk of age, and a brown breeding program, with eggs from a male and female line of a brown egg layer program that were analyzed at 32 to 36 wk of age. In general, heritabilities were moderate to high for all traits (h2 = 0.23 to 0.71). A high genetic correlation was estimated in both tests between breaking strength and Kdyn (rg = +0.40 to +0.61). Shell thickness was also positively correlated with breaking strength (rg = +0.50 to +0.63) and Kdyn (rg = +0.28 to +0.69). These moderate relationships demonstrate that the strength of an egg not only relies on the shell thickness but also on the quality and uniformity of eggshell construction. Dynamic stiffness might be preferred for breeding purposes due to its lower negative genetic correlation with egg weight and its higher heritability (h2 = 0.35 to 0.70) compared with breaking strength (h2 = 0.23 to 0.35). Breaking strength and Kdyn were positively correlated with shape index, which confirms that round eggs will show higher shell stability. Therefore, it is necessary to monitor egg shape to maintain an optimal form. [ABSTRACT FROM AUTHOR]

With the Weihenstephan funnel nest box, 12 laying hen flocks were tested for their individual lay-ing performance, egg quality, and nesting behavior in a noncage environment. During the whole observation pe-riod of 8 yr, a transponder-based data recording system was continuously improved and resulted in a recording accuracy of 97%. At peak production, heritabilities for the number of eggs laid are in some flocks higher than expected. With improved data accuracy, heritability estimates on individual egg weights are more stable. Heritabilities for nesting behavior traits range between a low to moderate level, providing very useful infor-mation for laying hen selection to help improve traits that cannot be recorded in cages. Over the years, the benefits of the Weihenstephan funnel nest box for lay-ing hen breeders have grown. This is due to higher data recording accuracies and extended testing capacities, which result in more reliable genetic parameters. [ABSTRACT FROM AUTHOR]

Selection to reduce susceptibility to Enterococcus faecalis infection in laying hens may contribute to the prevention of amyloid arthropathy since it is mainly induced by this bacterium. Therefore, the aim of the present study was to investigate the possibility to select more laying hens that are resistant against E. faecalis infection through the embryo lethality assay (ELA), which is proposed as an alternative model to replace the adult avian challenge assay. Ten-day-old embryos of 500 Lohmann Brown layers were inoculated into the allantoic cavity with an infectious dose of 2.5 colony-forming units (cfu)/mL of the avian E. faecalis strain K923/96 in 3 ELAs. The embryonic mortality rate (EMR) was determined by candling the eggs daily over a period of 4 d. The average EMR estimated during the 3 ELAs was 50% and the highest EMR occurred 3 to 4 d post inoculation. The estimated heritability for embryonic survivability to the infection was h2 = 0.12–0.14, calculated with the logistic and probit link function, respectively, indicating that the selection of more laying hens that are resistant to E. faecalis infection is feasible. A highly negative genetic correlation was estimated between embryonic survivability and laying performance at the peak of lay (rg = –0.22) and at the end of the production (rg = –0.65), as well as with breaking strength (rg = –0.30 to –0.37). A positive correlation was found between egg weight and the embryonic survivability (rg = +0.16), and no genetic correlation was found with body weight and dynamic stiffness. Therefore, although it was demonstrated that it is possible to breed for E. faecalis resistance, special care should be taken to monitor and to take all traits and their genetic correlations into account in order to achieve a balanced genetic progress. Besides, the ELA does not require that the hens are exposed to pathogens thereby saving labor and cost. Therefore, it could be feasible that ELA be implemented in selection programs. [ABSTRACT FROM AUTHOR]