Keel bone damage (KBD) in laying hens is an important welfare problem in both conventional and organic egg production systems. We aimed to identify possible risk factors for KBD in organic hens by analysing cross-sectional data of 107 flocks assessed in eight European countries. Due to partly missing data, the final multiple regression model was based on data from 50 flocks. Keel bone damage included fractures and/or deviations, and was recorded, alongside with other animal based measures, by palpation and visual inspection of at least 50 randomly collected hens per flock between 52 and 73 weeks of age. Management and housing data were obtained by interviews, inspection and by feed analysis. Keel bone damage flock prevalences ranged from 3% to 88%. Compiled on the basis of literature and practical experience, 26 potential associative factors of KBD went into an univariable selection by Spearman correlation analysis or Mann–Whitney U test (with P<0.1 level). The resulting nine factors were presented to stepwise forward linear regression modelling. Aviary v. floor systems, absence of natural daylight in the hen house, a higher proportion of underweight birds, as well as a higher laying performance were found to be significantly associated with a higher percentage of hens with KBD. The final model explained 32% of the variation in KBD between farms. The moderate explanatory value of the model underlines the multifactorial nature of KBD. Based on the results increased attention should be paid to an adequate housing design and lighting that allows the birds easy orientation and safe manoeuvring in the system. Furthermore, feeding management should aim at sufficient bird live weights that fulfil breeder weight standards. In order to achieve a better understanding of the relationships between laying performance, feed management and KBD further investigations are needed.
Feather pecking (FP) in laying hens is an important animal welfare problem in practice, despite extensive research and increasing sources of advice for farmers. We aimed to give an overview over results from experimental and epidemiological studies. We included noncage systems, covering the rearing and laying phase. The investigated factors were categorised into those with either good, contentious or no evidence regarding preventive effects on FP. Moreover, we wanted to know to what extent recommendations for farmers are based on this scientific evidence. We extracted 62 potential preventive factors from 88 experimental and 21 epidemiological studies. 17 factors during rearing, and 32 factors during the laying phase significantly affected the risk to develop FP or plumage damage (PD). Factors were counted as significant if other studies found no or at most one opposite result. Seven factors during rearing and 16 factors during laying were confirmed by more than one study, with no or at most one opposite result. Provision of dry litter on the floor and sufficiently high perches during rearing and laying or a high use of the free range area during the laying phase were among these influencing factors. In the reviewed 15 practice recommendations, almost all of these factors have been taken up, although no recommendation comprises all factors and most miss more than the half of them. This leaves ample room for improvement of the recommendations. On the other hand, they altogether recommend 15 contentious as well as eight non-significant or 12 not yet investigated factors for which further scientific investigation is necessary. Keywords: Laying hens; Feather pecking; Plumage damage; Recommendations 'damaging feather pecking' or 'plumage damage' were included. In addition, reference lists of retrieved papers were searched for further studies. Recommendations were sought using the internet search engine 'Google' with the keywords 'laying hens' and 'feather pecking' which were used in combination with 'recommendations', 'management guidelines' or 'references'. Also, the German keywords 'Federpicken' and 'Legehennenhaltung' were applied in combination with 'Empfehlungen', 'Prävention', 'Managementempfehlungen', or 'Haltungsempfehlungen'. Selection criteria for the recommendations were that they must be freely available, that they covered rearing, placement or the laying period and that they are related to non-cage systems.
In the European research project HealthyHens, welfare indicators as well as husbandry and management conditions were recorded in 107 organic laying hen farms in eight countries. Farms were visited at peak and end of lay. Egg production was on average comparable to breeder specifications. A mean mortality of 5.7% and mean prevalences of footpad lesions of 30.5%, keel bone damage of 44.5%, 57.3% of flocks with on average >200 Ascarid eggs per gram faeces and 28.2% of flocks with >100 mites/trap were recorded. A large variation between flocks indicated options for improvement. Based on the results, the following measures can be recommended: (i) decreasing mite and worm infestation and (ii) providing an attractive covered veranda, because of their association with decreased mortality; (iii) maximising access to the free range, because of its relation to decreased A. galli infection and less injurious pecking; (iv) feeding sufficient protein levels and (v) providing adequate litter as preventive measure against feather pecking and cannibalism; (vi) ensuring that the birds have sufficient weight and (vii) preventing accidents by adequate hen house facilities and light conditions to reduce keel bone damage. These primarily management-based measures have the potential to improve bird welfare both in terms of behavioural and health aspects.
Keel bone damage (KBD) can be found in all commercial laying hen flocks with a wide range of 23% to 69% of hens/flock found to be affected in this study. As KBD may be linked with chronic pain and a decrease in mobility, it is a serious welfare problem. An automatic assessment system at the slaughter line could support the detection of KBD and would have the advantage of being standardized and fast scoring including high sample sizes. A 2MP stereo camera combined with an IDS imaging color camera was used for the automatic assessment. A trained human assessor visually scored KBD in defeathered hens during the slaughter process and compared results with further human assessors and automatic recording. In a first step, an algorithm was developed on the basis of assessments of keel status of 2287 hens of different genetics with varying degrees of KBD. In two optimization steps, performance data were calculated, and flock prevalences were determined, which were compared between the assessor and the automatic system. The proposed technique finally reached a sensitivity of 0.95, specificity of 0.77, accuracy of 0.86 and precision of 0.81. In the last optimization step, the automatic system scored on average about 10.5% points lower KBD prevalences than the human assessor. However, a proposed change of scoring system (setting the limit for KBD at 0.5 cm deviation from the straight line) would lower this deviation. We conclude that the developed automatic scoring technique is a reliable and potentially valuable tool for the assessment of KBD.
Laying hens often suffer from keel bone damage (KBD) that includes pathologies with different etiologies, like diverse forms of fractures and deviations. Since KBD is a problem in all countries and housing systems, methods for the assessment of deviations are urgently needed. Comparisons between genetic lines and between studies are important to detect underlying mechanisms. Field researchers often use palpation as a low-cost and feasible technique for the assessment of KBD. In contrast to palpation, radiography is effective and highly precise at least in detecting keel bone fractures. The aim of this study was to: i) develop a scoring system to assess keel bone deviations from radiographs, ii) to assess inter- and intra-observer reliability of this scoring system, and iii) to investigate whether fractures and deviations of the keel are correlated. In total, 192 hens were used for the investigation. Digital radiographs were taken and evaluated for all hens after slaughter. We developed a tagged visual analog scale with two extreme images as anchors and four intermediate tags, resulting in six images representing the range from “no deviation” to “highly deviated” on a 10 cm line. Eleven participants scored 50 radiographs of keels with varying degree of severity, whereas five images were scored twice to assess intra-observer reliability. Intraclass correlation coefficient for inter-observer reliability was 0.979 with a confidence interval of 0.968 < ICC < 0.987 (F49,268 = 54.2, p < 0.0001). Intraclass correlation coefficient for intra-observer reliability was 0.831 with a confidence interval of 0.727 < ICC < 0.898 (F54,55 = 10.8, p < 0.0001). Individual intra-observer reliability ranged from 0.6 to 0.949. The Spearman correlation showed a strong positive correlation of fractures and deviations (sroh= 0.803, p < 0.001). The tagged visual analog scale could be a reliable instrument for the scoring of keel bone deviations. Our results support the assumption that the majority of highly deviated keels suffer from fractures as well. Further research is needed to investigate the correlation of palpation scores with the evaluation on radiographs.
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