Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Assessing keel bone damage in laying hens by palpation : effects of assessor experience on accuracy, inter-rater agreement and intra-rater consistency
Buijs, S. ; Heerkens, J.L.T. ; Ampe, B. ; Delezie, E. ; Rodenburg, T.B. ; Tuyttens, F.A.M. - \ 2019
Poultry Science 98 (2019)2. - ISSN 0032-5791 - p. 514 - 521.
accuracy - deviation - fracture - keel bone - palpation

Accurate assessment is essential when evaluating keel bone damage. Palpation is commonly used to assess keel bone damage in living hens. However, there is little information on the accuracy of assessment of deviations and fractures on different parts of the keel, and on the consistency within, and agreement between, assessors. Crucially, although the importance of experience is commonly emphasized, knowledge on its effect is scarce. Ten assessors with or without prior experience palpated the same 50 75-wk-old hens for deviations, medial fractures, and caudal fractures (scored as present/absent). Accuracy, sensitivity, specificity, precision, and negative predictive value were determined by comparing palpation scores to post-dissection assessment, and then compared between experienced and inexperienced assessors. To determine the effect of the experience gained during the experiment, hens were subsequently re-assessed. Consistency within, and agreement between, assessors were also determined. Assessors with prior experience were more accurate (proportion of accurately assessed deviations: experienced 0.83 vs. inexperienced 0.79±0.01, P = 0.04; medial fractures: 0.82 vs. 0.68±0.03 in session 1 only, P = 0.04; caudal fractures: 0.41 vs. 0.29±0.03, P = 0.03), and inexperienced assessors classified medial fractures more accurately in session 2 (session 1: 0.68 vs. session 2: 0.77±0.04, P = 0.04). However, effect sizes were small for deviations and even experienced assessors lacked accuracy when assessing caudal fractures. Unexpectedly, deviations tended to be assessed more accurately in session 1 than in session 2, regardless of assessor status (1: 0.83 vs. 2: 0.79±0.01, P = 0.06), suggesting that prolonged assessment contributes to errors. Prior experience decreased specificity and precision of fracture assessment (more unfractured keels were classified as fractured) even though overall accuracy was greater. Intra-rater consistency was fair to good (0.55 to 0.67) for deviations and medial fractures, but poor to fair (0.36 to 0.44) for caudal fractures, and unaffected by prior experience (P = 0.49 to 0.89). In conclusion, experience improves accuracy to a limited extent but does not guarantee high accuracy for all types of damage. Future research should determine if other training methods (e.g., comparison to post-dissection scores or to radiographs) improve accuracy.

Interactions between broiler chickens, soil parameters and short rotation coppice willow in a free-range system
Stadig, Lisanne M. ; Tuyttens, Frank A.M. ; Rodenburg, T.B. ; Vandecasteele, Bart ; Ampe, Bart ; Reubens, Bert - \ 2019
Agroecology and Sustainable Food Systems 43 (2019)9. - ISSN 2168-3565 - p. 1009 - 1030.
agroforestry - biomass - carbon storage - nitrogen loss - poultry - Willow

Planting short rotation coppice willows (SRCW) in chickens’ free-range areas could have several advantages for the chickens, environment and farmer. Our aim was to test the effects of combining SRCW and chickens on free-range use, soil conditions and SRCW growth. A free-range chicken area was partially planted with a grass/clover mixture, and partially with SRCW. Chickens preferred to range in SRCW compared to grassland. No effects of periodical chicken presence on SRCW growth were observed. Total mineral N (Nmin) was affected by interactions between vegetation type, location, and soil depth; it was generally higher in SRCW than in grassland and in areas close to the chicken houses. Nmin did not appear to accumulate in the soil over the years, but there were strong indications for higher risk of N leaching to deeper soil layers and possibly to groundwater close to the houses and in SRCW. SRCW was beneficial for the chickens, but the combination needs to be studied further with a focus on strategies for preventing nutrient leaching to groundwater.

Wormbelasting van de uitloop
Niekerk, T.G.C.M. van; Bestman, Monique ; Rodenburg, T.B. ; Haas, E.N. de; Tuyttens, F. - \ 2018
De Pluimveehouderij (2018). - ISSN 0166-8250 - p. 22 - 23.
Aanvullend op het Welfare Quality-protocol voor leghennen zijn modules ontwikkeld om de snavelpunten en de borstbenen nauwkeuriger te monitoren. Deze modules zijn uitgetest op acht commerciële legbedrijven. Er kwamen een aantal interessante verbanden te voorschijn.
Opportunities for short rotation coppice production on free-range chicken farms in Flanders : Farmers' perceptions and cost-benefit analysis
Stadig, Lisanne M. ; Tuyttens, Frank A.M. ; Rodenburg, T.B. ; Verdonckt, Pieter ; Wauters, Erwin ; Borremans, Lieve ; Reubens, Bert - \ 2018
Renewable Agriculture and Food Systems (2018). - ISSN 1742-1705 - 10 p.
Economic analysis - farmer opinion - net present value - poultry - willow - wood chips

This paper focuses on systems producing short rotation coppice willows (SRCW) in chickens' free-range areas. We aim to map chicken farmers' motivation to implement SRCW, and to assess the economic viability of these systems. Semi-structured interviews were conducted with 18 free-range chicken farmers. Farmers agreed that chickens would prefer SRCW over grassland, which could benefit chicken welfare. They expected establishing an SRCW system would be labor intensive, and doubted if it would be a profitable investment. Some concerns of farmers might be taken away by exchanging information with farmers with SRCW experience. A partial budget analysis was performed to calculate the net present value (NPV) of six different scenarios, differing in the type of chickens, in whether the produced biomass was sold or valorized on-farm and in harvest pattern, all over a 23-yr period. The NPV was positive but low for all scenarios. A sensitivity analysis showed that changes in biomass yield, wood chip price, a price premium for poultry products and current fuel price were most likely to influence the NPV. A risk analysis revealed that NPVs were positive in the majority of the modeled cases. Scenarios in which biomass was used for on-farm heat production showed the highest risk of a negative NPV. A price premium for poultry products may be most effective at increasing profitability, but may only be feasible for farms selling directly to consumers. Establishing a solid market for biomass energy, including guaranteed demand and availability of appropriate machinery for cultivation, may mitigate farmers' concerns.

Long-term impact of zinc supplementation in sows : Impact on zinc status biomarkers and performance
Riet, Miriam M.J. Van; Bos, Emilie Julie ; Ampe, Bart ; Bikker, Paul ; Vanhauteghem, Donna ; Bockstaele, Filip Van; Cornillie, Pieter ; Broeck, Wim Van Den; Laing, Gijs Du; Maes, Dominiek ; Tuyttens, Frank A.M. ; Janssens, Geert P.J. ; Millet, Sam - \ 2018
Journal of Swine Health and Production 26 (2018)2. - ISSN 1537-209X - p. 79 - 94.
Dietary zinc concentration - Performance - Rubber top layer flooring - Swine - Zinc status biomarkers
Objectives: To evaluate the long-term impact of zinc (Zn) supplementation on performance and Zn status biomarkers in sows and on whether this possible impact depends on housing conditions. Materials and methods: Six groups of sows were allotted to group housing on two different floor types during gestation. Within each group, sows were randomly allocated to one of three diets varying in the amount of Zn supplemented (0, 50, or 100 mg added Zn per kg diet; 50% ZnO: 50% organic Zn) to a basal diet containing 46.6 and 128.9 mg Zn per kg during gestation and lactation, respectively. Blood was collected at days 0, 50, 108, and 143 of every cycle and analyzed for plasma Zn and copper and serum metallothionein (MT) concentrations. After slaughter, mineral concentrations of metacarpals, liver, and abaxial horn wall were determined. Results: Dietary Zn supplementation beyond basal dietary Zn concentrations did not influence serum MT concentrations (P = .77) and Zn concentrations in blood plasma (P = .13), liver (P = .54), bone (P = .26), and horn wall (P = .39). The 100-mg Zn per kg supplemented sows had lower bodyweight, body condition score, and backfat thickness (P < .001). The lack of impact of Zn supplementation may have been (partly) attributed to the unexpected high supply of Zn through premix in the lactation diet. Implications: Under these study conditions, commercially grown sows might not need Zn supplementation during gestation when their basal diet contains Zn with phytase.
Long-term impact of zinc supplementation in sows : Impact on claw quality
Riet, Miriam M.J. Van; Bos, Emilie Julie ; Ampe, Bart ; Bikker, Paul ; Vanhauteghem, Donna ; Bockstaele, Filip Van; Cornillie, Pieter ; Broeck, Wim Van Den; Laing, Gijs Du; Maes, Dominiek ; Tuyttens, Frank A.M. ; Janssens, Geert P.J. ; Millet, Sam - \ 2018
Journal of Swine Health and Production 26 (2018)1. - ISSN 1537-209X - p. 10 - 24.
Claw conformation - Claw lesion - Dietary zinc concentration - Rubber top layer - Swine
Objectives: To evaluate the long-term impact of zinc (Zn) supplementation on claw lesions, claw conformation, and histological and mechanical claw characteristics of sows housed in groups on rubber top layer or concrete floors during gestation. Materials and methods: Six groups of 21 ± 4 sows were allotted to group housing on different floor types for 80 days during gestation. Within each group, sows were randomly allocated to one of three diets supplementing a basal diet (46.6 and 128.9 mg Zn per kg during gestation and lactation, respectively) with 0, 50, or 100 mg Zn per kg. Claw lesion scoring, claw conformation, and horn growth and wear measurements were performed at days 50 and 140 of every cycle. Histological and mechanical characteristics were evaluated on claw samples of 36 sows after slaughter. Results: Dietary Zn supplementation affected heel horn erosion score (P = .01): sows supplemented with100 mg Zn per kg diet had better scores. Distances between dermal papillae of the sagittal heel horn were larger (P = .004). Heel height was lower for sows supplemented with 0 and 100 mg Zn per kg than for 50 mg per kg (P = .01). Horn growth and wear were lower for sows housed on rubber at day 50 (P < .001, both variables), but not at day 140. Dermal papillae distance was shorter for sows on rubber (P = .04). Implications: Unlike floor type and phase within the reproductive cycle, and under the conditions of this study, dietary zinc supplementation minimally influences claw quality.
An automated positioning system for monitoring chickens' location : Accuracy and registration success in a free-range area
Stadig, Lisanne M. ; Ampe, Bart ; Rodenburg, Bas ; Reubens, Bert ; Maselyne, Jarissa ; Zhuang, Shaojie ; Criel, Johan ; Tuyttens, Frank A.M. - \ 2018
Applied Animal Behaviour Science 201 (2018). - ISSN 0168-1591 - p. 31 - 39.
Accuracy - Outdoor - Poultry - Signal reception - Ultra-wideband - Vegetation
Free-range use in chickens is often suboptimal, and the full potential of outdoor access for chicken welfare may not be achieved. Many studies use visual observations of free-range use, imposing several limitations. An automated system capable of continuously monitoring the location of multiple individual birds over a long time period has the potential to increase the amount and accuracy of the gathered data. Therefore, the aim of this study was to test a newly developed Ultra-Wideband system for monitoring the position of chickens with free-range access. This system consists of active tags (attached to the chickens) that send signals to anchors positioned at fixed locations in the field; the tags' position can be calculated using the time of arrival of their signal. The effects of vegetation type, precipitation, tags being mounted on a chicken, tag height, angle and orientation, coverage by A-frames or mobile chicken houses, and proximity of other tags on accuracy of the registered positions (distance between the registered and the true position of the tag) and on registration success (percentage of registrations where a position could be calculated) were assessed. Overall, the median error was 0.29 m, which was below the aim of 0.5 m, and the mean percentage of successful registered positions was 68%. None of the variables had a clear effect on the accuracy of the positions. Errors were generally larger in certain areas of the experimental field, which may be due to the asymmetrical setup of the anchors. The percentage of successful registrations was negatively affected by shelter type, with lower percentages in dense vegetation (short rotation coppice willows; SRCW) than on grassland, possibly due to malfunctioning of two anchors close to the SRCW plots. Rain and placing the tags underneath a wooden A-frame, but not placing them in a mobile house, resulted in a lower percentage of successful registrations. The tag being mounted on a chicken, height and angle of the tag and proximity of other tags had no negative effect on the percentage of successful registrations. Placing more (functioning) anchors may contribute to better accuracy and registration success. Alternatively, the bias resulting from the variables that had a negative effect on registration success could be corrected for when using the system in its current setup. Overall, this system shows great promise for monitoring chickens' free-range use.
Effects of dark brooders and overhangs on free-range use and behaviour of slow-growing broilers
Stadig, L.M. ; Rodenburg, T.B. ; Reubens, B. ; Ampe, B. ; Tuyttens, F.A.M. - \ 2018
Animal 12 (2018)8. - ISSN 1751-7311 - p. 1621 - 1630.
dark brooder - fearfulness - outdoor - shelter - short rotation coppice
Broiler chickens often make limited use of the free-range area. Range use is influenced by type of shelter available. Range use may possibly be improved by a more gradual transition from the house to the range and by using dark brooders (secluded warm, dark areas in the home pen) that mimic aspects of a broody hen and possibly reduce fearfulness. The aim of this study was to assess effects of dark brooders on fearfulness, free-range use and behaviour later in life. Another aim was to test the chickens’ preference for shelter type and the effects of overhangs outside of the pop holes to provide a gradual transition to the range. Three production rounds, each with 440 Sasso broiler chickens (110/group), were completed. Chicks were housed indoors from days 0 to 25; per round, two groups had access to a dark brooder, whereas the other two groups had conventional IR lamps. Fearfulness was assessed by the open field (OF) and tonic immobility (TI) tests on days 22 to 24 on 25 chicks/group per round. Birds were then moved to four mobile houses from which they could access both grassland with artificial shelter (AS) and short rotation coppice (SRC). Two of the houses had overhangs extending from the pop holes; these were switched between the four houses weekly. Free-range use and behaviour were observed three times daily from Monday to Friday. Dark brooders did not affect results from the OF or TI test, except for jumps in the OF test which tended to occur less often in brooded chicks. Neither dark brooders (34.9% without v. 31.7% with brooder) nor overhangs (32.5% without v. 34.1% with overhangs) influenced the percentage of chickens outside. Chickens showed a clear preference for SRC, range use increased over time in SRC, and more birds ranged farther from the house in SRC. Behaviours of chickens observed outside were mainly influenced by shelter type, age of the birds and distance from the house. Locomotion tended to occur more in the presence of overhangs. Overall, these results could not confirm the hypothesis that dark brooders would decrease fearfulness and thereby increase free-range use. Overhangs also did not improve free-range use, and neither brooders nor overhangs had considerable impact on behaviour of chickens outside. Chickens clearly preferred dense natural vegetation over AS and ranged farther in it, indicating that this type of shelter is more suitable for slow-growing free-range broilers.
Consumer acceptance of minced meat patties from boars in four European countries
Aluwé, M. ; Aaslyng, M. ; Backus, G. ; Bonneau, M. ; Chevillon, P. ; Haugen, J.E. ; Meier-Dinkel, L. ; Mörlein, D. ; Oliver, M.A. ; Snoek, H.M. ; Tuyttens, F.A.M. ; Font-i-Furnols, M. - \ 2018
Meat Science 137 (2018). - ISSN 0309-1740 - p. 235 - 243.
Androstenone - Boar taint - Castration - European consumers - Skatole - Thresholds
A consumer study was performed in four EU countries to further clarify the acceptability of meat with boar taint. In Denmark, France, Italy and Poland, a total of 476 female consumers evaluated 8 meat patties from boars with varying levels of skatole (0.10–0.40 μg/g fat tissue) and androstenone (0.47–2.00 μg/g fat tissue), in a pair-wise comparison with patties from castrates. Boar meat patties were always less preferred than the castrate meat patties, regardless of the level of androstenone and skatole. Acceptability of the boar meat patties decreased with increasing skatole level. In samples with low skatole levels, higher levels of androstenone also reduced acceptability among androstenone sensitive consumers. No clear threshold levels for androstenone and skatole could be identified. Maps presenting the reduction in preference due to increasing levels of skatole and androstenone, and corrected for the general acceptance of the meat product were developed, taking into account androstenone sensitivity. Further work is needed, covering the whole range of androstenone and skatole levels found in entire male pigs and for a wider set of meat products.
An automated positioning system for monitoring chickens' location: Effects of wearing a backpack on behaviour, leg health and production
Stadig, Lisanne M. ; Rodenburg, T.B. ; Ampe, Bart ; Reubens, Bert ; Tuyttens, Frank A.M. - \ 2018
Applied Animal Behaviour Science 198 (2018). - ISSN 0168-1591 - p. 83 - 88.
Body weight - Broiler chicken - Habituation - Position monitoring - Ultra-Wideband - Welfare

Automated tracking of the location of individual chickens is becoming more common in behavioural research. This technology has several advantages including gathering large amounts of data and monitoring of individual animals as opposed to flocks. To ensure the quality of the research the transmitters or tags attached to the bird as part of the automated positioning system should not have any effect on bird behaviour, welfare and production. Tag-related effects may lead to unreliable results which cannot be extrapolated to untagged birds. Therefore, we tested the effects of wearing a backpack containing a tag as part of an ultra-wideband system for automated position monitoring. The chickens' behaviour, leg health, cleanliness and body weight gain were studied. Sixty slow-growing broiler chickens (Sasso XL451) were housed in groups of 10 birds. Per pen, five birds were fitted with a 36-g tag (TAG) in a backpack from day 35-70 and the other five were identified using colour markings (CON). Behavioural observations from video recordings of TAG and CON chickens were performed twice daily (15-min periods) every other day. Birds were weighed on day 35 and 70, and on day 70 foot pad and hock dermatitis, gait, and cleanliness were scored. TAG birds walked less than CON birds in week 6, but this difference was absent from week 7 onwards. CON birds pecked more at TAG birds than other TAG birds did in week 6, probably due to the novelty of the tags, whereas the TAG birds could investigate their own tag instead of pecking at other birds' tags. No significant differences were observed for scores for foot pad and hock dermatitis, gait and cleanliness scores or weight gain between TAG and CON birds. These results indicate that the backpacks with tags had only minor, non-persistent effects on slow-growing broiler chickens' behaviour. The effects of colour-marking on behaviours observed in this study are likely to be small. The results indicate that the tags can be used for further studies in which these behaviours, welfare measures and production parameters play an important role.

Effect of free-range access, shelter type and weather conditions on free-range use and welfare of slow-growing broiler chickens
Stadig, Lisanne M. ; Rodenburg, Bas ; Ampe, Bart ; Reubens, Bert ; Tuyttens, Frank A.M. - \ 2017
Applied Animal Behaviour Science 192 (2017). - ISSN 0168-1591 - p. 15 - 23.
Free-range access for broiler chickens can benefit animal welfare because the birds have access to a more natural environment and more opportunities to perform natural behaviours than in indoor systems. Also, they have more space and more environmental enrichment, which could lead to better leg health and decreased fearfulness. In practice, however, use of the free-range area is often low. Lack of shelter likely plays an important role in this, as do weather conditions. In this study during 2 production rounds of slow-growing broiler chickens, 200 chickens were housed indoors (IN), 200 were provided with free-range access to grassland with artificial shelter (AS), and 200 were provided with free-range access to an area with short rotation coppice (SRC) from 4 until 10 weeks of age. Free-range use was monitored using photographs and live observations. Weather conditions and free-range use were monitored throughout the outdoor period. Tonic immobility (TI) as fearfulness assessment was done at the beginning (round 2 only) and the end of both production rounds; leg health and tibia bone health were assessed at the end of the production rounds. Mean percentage of birds using the free-range area was higher in SRC than in AS groups (42.8% vs. 35.1%; F1,7 = 1180.00, P < 0.001). The mean percentage of animals located further than 5 m from the house was 10.6 ± 1.1% of the chickens that were outside in the SRC groups vs. 4.1 ± 0.8% in the AS groups (F1,7 = 24.03, P = 0.002). The interactions of shelter type with rainfall (F2,5578 = 70.59, P < 0.001), increasing radiation (F2,5578 = 300.93, P < 0.001) and increasing wind speed (F2,5578 = 14.77, P < 0.001) showed that these factors were related with fewer chickens being outside; and that these effects were more pronounced in SRC than in AS chickens. An increasing temperature was related with more free-range use (F1,5578 = 32.24, P < 0.001). A shorter TI duration in week 3 (at group level) was associated with more chickens further than 5 m from the house (F1,250 = 13.79, P < 0.001). The percentage of animals needing more than one induction to induce TI in week 10 was higher for chickens from SRC (29.7%) than from IN groups (4.8%; t102 = −2.61, P = 0.028) but not AS (14.8%). Hock dermatitis occurred less in AS (7.6%) than in IN (40.1%; t222 = 3.15, P = 0.005) but not SRC (13.7%). These findings indicate that presence of SRC was most effective in encouraging chickens to use the free-range area, but that free-range access was only moderately related to better leg health and fearfulness (at group level).
Effects of shelter type, early environmental enrichment and weather conditions on free-range behaviour of slow-growing broiler chickens
Stadig, L.M. ; Rodenburg, T.B. ; Ampe, B. ; Reubens, B. ; Tuyttens, F.A.M. - \ 2017
Animal 11 (2017)6. - ISSN 1751-7311 - p. 1046 - 1053.
artificial shelter - fearfulness - free range - poultry - short rotation coppice

Free-range use by broiler chickens is often limited, whereas better use of the free-range area could benefit animal welfare. Use of free-range areas could be stimulated by more appropriate shelter or environmental enrichment (by decreasing birds’ fearfulness). This study aimed to assess the effects of shelter type, early environmental enrichment and weather conditions on free-range use. Three production rounds with 440 slow-growing broiler chickens (Sasso T451) were carried out. Birds were housed indoors in four groups (two with males, two with females) from days 0 to 25, during which two of the groups received environmental enrichment. At day 23 birds’ fearfulness was assessed with a tonic immobility (TI) test (n=100). At day 25 all birds were moved (in mixed-sex groups) to mobile houses, and provided with free-range access from day 28 onwards. Each group could access a range consisting for 50% of grassland with 21 artificial shelters (ASs, wooden A-frames) and for 50% of short rotation coppice (SRC) with willow (dense vegetation). Free-range use was recorded by live observations at 0900, 1300 and 1700 h for 15 to 21 days between days 28 and 63. For each bird observed outside the shelter type (AS or SRC), distance from the house (0 to 2, 2 to 5, >5 m) and its behaviour (only rounds 2 and 3) were recorded. Weather conditions were recorded by four weather stations. On average, 27.1% of the birds were observed outside at any given moment of observation. Early environmental enrichment did not decrease fearfulness as measured by the TI test. It only had a minor effect on the percentage of birds outside (0.4% more birds outside). At all distances from the house, SRC was preferred over AS. In AS, areas closer to the house were preferred over farther ones, in SRC this was less pronounced. Free-range use increased with age and temperature and decreased with wind speed. In AS, rainfall and decreasing solar radiation were related to finding more birds outside, whereas the opposite was true in SRC. Behaviour of the birds depended on shelter type, distance from the house, early environmental enrichment, time of day and age. Chickens ranged more and farther in SRC, possibly because this provided a greater sense of safety because of the amount of cover and/or better protection against adverse weather conditions. These results indicate that SRC with willow is a more appropriate shelter for slow-growing broiler chickens than A-frames.

Effects of free-range access on production parameters and meat quality, composition and taste in slow-growing broiler chickens
Stadig, Lisanne M. ; Rodenburg, Bas ; Reubens, Bert ; Aerts, Johan ; Duquenne, Barbara ; Tuyttens, Frank A.M. - \ 2016
Poultry Science 95 (2016)12. - ISSN 0032-5791 - p. 2971 - 2978.
Body weight - fatty acid profile - meat color - short rotation coppice - taste

Demand for meat from free-range broiler chickens is increasing in several countries. Consumers are motivated by better animal welfare and other product attributes such as quality and taste. However, scientific literature is not unanimous about whether free-range access influences quality, composition, and taste of the meat. Because chickens normally do not use free-range areas optimally, it is possible that provision of more suitable shelter will lead to more pronounced differences between chickens raised indoors and outdoors. In this study, an experiment with 2 production rounds of 600 slow-growing broilers each was performed. In each round, 200 chickens were raised indoors (IN), 200 had free-range access to grassland with artificial shelter (AS), and 200 had free-range access to short-rotation coppice with willow (SRC). Free-range use, feed intake, and growth were monitored, and after slaughter (d72) meat quality, composition, and taste were assessed. Free-range use was higher in SRC than in AS chickens (42.8 vs. 35.1%, P < 0.001). IN chickens were heavier at d70 than AS and SRC chickens (2.79 vs. 2.66 and 2.68 kg, P = 0.005). However, feed intake and conversion did not differ. Breast meat of chickens with free-range access was darker (P = 0.021) and yellower (P = 0.001) than that of IN chickens. Ultimate pH was lower (5.73 vs. 5.79; P = 0.006) and drip loss higher (1.29 vs. 1.09%; P = 0.05) in IN versus AS chickens. The percentage of polyunsaturated fatty acids was higher in AS than in IN meat (35.84 vs. 34.59%; P = 0.021). The taste panel judged breast meat of SRC chickens to be more tender (P = 0.003) and less fibrous (P = 0.013) compared to that of AS and IN chickens, and juicier compared to the IN chickens (P = 0.017). Overall, free-range access negatively affected slaughter weight, but positively affected meat quality, taste, and composition. Only a few differences between AS and SRC were found, possibly due to limited differences in free-range use.

Free-range use and behavior of slow-growing broiler chickens: effects of shelter type, enrichment, age and weather conditions
Stadig, L.M. ; Rodenburg, T.B. ; Ampe, B. ; Reubens, B. ; Tuyttens, F.A.M. - \ 2016
In: Proceedings of the 50th congress of the International Society for Applied Ethology. - Wageningen : Wageningen Academic Publishers - ISBN 9789086862870 - p. 279 - 279.
Increased free-range use by slow-growing broiler chickens could benet their welfare. €is study aimed to assess the e�ects of enrichment early in life, shelter type (articial or natural), weather conditions and age on broilers’ free-range use. €ree production rounds (R) were performed, with 440 Sasso chickens each. Birds were housed indoors in 4 groups of 110 animals from d0-25, during which 2 groups per round received environmental enrichment (hay bales, strings, grain, mealworms). At d25, birds were moved to 4 mobile houses on a 1 ha eld. From d28-70, birds had access to both grassland with articial shelter (A-frames; AS) and short rotation coppice (SRC). SRC consisted of densely planted willows (15,000 trees/ha). Free-range use was observed 3 times daily on 15, 21 and 18 days in R1, R2, and R3, respectively. €e number of animals outside, their location (AS; SRC) and distance from the house (0-2 m; 2-5 m; >5 m) were recorded. In R2 and R3, behavior of the outside chickens was also recorded. Weather conditions were recorded every 15 min. Data were analyzed using a GLM Poisson regression model, with a rst-order autoregressive covariance-structure to correct for multiple observations over time within the same house. For multiple comparisons, p-values were corrected using the Tukey-Kramer method. On average, 26% of the birds were outside. Early-life enrichment tended to have a small positive e�ect on free-range use (0.4% more birds outside; P=0.052). At all distances, more birds were in SRC compared to AS (all P<0.001). In AS more birds were at 0-2 m than at 2-5 m or 5 m from the house (all P<0.005). In SRC more birds were at 0-2 m and 2-5 m than at >5 m from the house (all P<0.001). Freerange use increased with age, particularly in areas further from the house (P<0.001). In AS, rainfall and low solar radiation were related to more birds outside, while the opposite was true in SRC (P<0.001). Fewer birds were outside with increasing wind speed (both AS and SRC; P=0.049). A higher percentage of chickens was observed to forage in AS compared to SRC (50 vs 28%; P<0.001). €e opposite was true for standing (6 vs 9%; P<0.001) and sitting, but for the latter the di�erence tended to decrease with distance from the house (P=0.065). We conclude that: (1) early-life enrichment had no profound e�ect on free-range use in broilers; (2) SRC was preferred over AS, suggesting this shelter was more suitable and attractive; and (3) behavior was related to shelter type.
Use of an Ultra-Wideband system to monitor chickens' position in a free-range area
Stadig, Lisanne ; Ampe, Bart ; Criel, Johan ; Maselyne, Jarissa ; Rodenburg, T.B. ; Reubens, Bert ; Tuyttens, Frank A.M. - \ 2016
In: Proceedings of the Benelux ISAE Conference 2016 Berlicum, The Netherlands : International Society for Applied Ethology (ISAE) - ISBN 9789462573949 - p. 24 - 24.
Ramps and hybrid effects on keel bone and foot pad disorders in modified aviaries for laying hens
Heerkens, J.L.T. ; Delezie, E. ; Ampe, B. ; Rodenburg, T.B. ; Tuyttens, F.A.M. - \ 2016
Poultry Science 95 (2016)11. - ISSN 0032-5791 - p. 2479 - 2488.
aviary - foot health - keel bone - laying hens

Non-cage systems provide laying hens with considerable space allowance, perches and access to litter, thereby offering opportunities for natural species-specific behaviors. Conversely, these typical characteristics of non-cage systems also increase the risk of keel bone and foot pad disorders. The aim of this study was twofold: 1) to investigate if providing ramps between perches (housing factor) reduces keel bone and foot pad disorders and 2) to test for genetic predisposition by comparing 2 different layer hybrids. In a 2 × 2 design, 16 pens were equipped either with or without ramps between perches and nest boxes (8 pens/treatment), and housed with either 25 ISA Brown or Dekalb White birds per pen (in total 200 birds/hybrid). Keel bone injuries and foot health were repeatedly measured via palpation and visual assessment between 17 and 52 wk of age and daily egg production was recorded. The relationships between the dependent response variables (keel bone and footpad disorders, egg production) and independent factors (age, ramps, hybrid) were analyzed using generalized linear mixed models and corrected for repeated measures. Ramps reduced keel bone fractures (F1,950 = 45.80, P <0.001), foot pad hyperkeratosis (F1,889 = 10.40, P = 0.001), foot pad dermatitis (F1,792 = 20.48, P <0.001) and bumble foot (F1,395 = 8.52, P <0.001) compared to pens without ramps. ISA Brown birds sustained more keel bone fractures (F1,950 = 33.26, P <0.001), had more foot pad hyperkeratosis (F1,889 = 44.69, P <0.001) and laid more floor eggs (F1,1883 = 438.80, P <0.001), but had fewer keel bone deviations (F1,1473 = 6.73, P <0.001), fewer cases of foot pad dermatitis (F1,792 = 19.84, P <0.001) and no bumble foot as compared to Dekalb White birds. Age, housing and hybrid showed several interaction effects. Providing ramps proved to be very effective in both reducing keel bone and foot pad problems in non-cage systems. Keel bone and foot pad disorders are related to genetic predisposition. These results indicate that adaptation of the housing systems and hybrid selection may be effective measures in improving laying hen welfare.

Risk factors associated with keel bone and foot pad disorders in laying hens housed in aviary systems
Heerkens, J.L.T. ; Delezie, E. ; Rodenburg, T.B. ; Kempen, I. ; Zoons, J. ; Ampe, B. ; Tuyttens, F.A.M. - \ 2016
Poultry Science 95 (2016)3. - ISSN 0032-5791 - p. 482 - 488.
aviary - foot health - housing system - keel bone

Aviary systems for laying hens offer space and opportunities to perform natural behaviors. However, hen welfare can be impaired due to increased risk for keel bone and foot pad disorders in those systems. This cross-sectional study (N = 47 flocks) aimed to assess prevalences of keel bone and foot pad disorders in laying hens housed in aviaries in Belgium to identify risk factors for these disorders and their relation to egg production. Information on housing characteristics and egg production were obtained through questionnaire-based interviews, farm records, and measurements in the henhouse. Keel bone (wounds, hematomas, fractures, deviations) and foot pad disorders (dermatitis, hyperkeratosis) were assessed in 50 randomly selected 60-week-old laying hens per flock. A linear model with stepwise selection procedure was used to investigate associations between risk factors, production parameters, and the keel bone and foot pad disorders. The flock mean prevalences were: hematomas 41.2%, wounds 17.6%, fractures 82.5%, deviations 58.9%, hyperkeratosis 42.0%, dermatitis 27.6%, and bumble foot 1.2%. Identified risk factors for keel bone disorders were aviary type (row vs. portal), tier flooring material (wire mesh vs. plastic slats), corridor width, nest box perch, and hybrid. Identified risk factors for foot pad disorders were aviary type (row vs. portal), free-range, and hybrid. Percentage of second-quality eggs was negatively associated with keel bone deviations (P = 0.029) at the flock level. Keel bone and foot pad disorders were alarmingly high in aviary housing. The identification of various risk factors suggests improvements to aviary systems may lead to better welfare of laying hens.

Simplifying the Welfare Quality® assessment protocol for broiler chicken welfare
Jong, I.C. de; Hindle, V.A. ; Butterworth, A. ; Engel, B. ; Ferrari, P. ; Gunnink, H. ; Perez Moya, T. ; Tuyttens, F.A.M. ; Reenen, C.G. van - \ 2016
Animal 10 (2016)1. - ISSN 1751-7311 - p. 117 - 127.
animal welfare, - broilers, - animal-based assessment protocols, - simplification
Welfare Quality® (WQ) assessment protocols place the emphasis on animal-based measures as an indicator for animal welfare. Stakeholders, however, emphasize that a reduction in the time taken to complete the protocol is essential to improve practical applicability. We studied the potential for reduction in time to complete the WQ broiler assessment protocol and present some modifications to the protocol correcting a few errors in the original calculations. Data was used from 180 flocks assessed on-farm and 150 flocks assessed at the slaughter plant. Correlations between variables were calculated, and where correlation was moderate, meaningful and promising (in terms of time reduction), simplification was considered using one variable predicted from another variable. Correlation analysis revealed a promising correlation between severe hock burn and gait scores on-farm. Therefore, prediction of gait scores using hock burn scores was studied further as a possible simplification strategy (strategy 1). Measurements of footpad dermatitis, hock burn, cleanliness and gait score on-farm correlated moderately to highly with slaughter plant measurements of footpad dermatitis and/or hock burn, supporting substitution of on-farm measurements with slaughter plant data. A simplification analysis was performed using footpad dermatitis, hock burn, cleanliness and gait scores measured on-farm predicted from slaughter plant measurements of footpad dermatitis and hock burn (strategy 2). Simplification strategies were compared with the full assessment protocol. Close agreement was found between the full protocol and both simplification strategies although large confidence intervals were found for specificity of the simplified models. It is concluded that the proposed simplification strategies are encouraging; strategy 1 can reduce the time to complete the on-farm assessment by ~1 h (25% to 33% reduction) and strategy 2 can reduce on-farm assessment time by ~2 h (50% to 67% reduction). Both simplification strategies should, however, be validated further, and tested on farms with a wide distribution across the different welfare categories of WQ.
Suggestions for modifications of the WQ broiler chicken welfare assessment protocol
Jong, I.C. de; Butterworth, A. ; Tuyttens, F.A.M. ; Buijs, S. - \ 2015
Effect of outdoor access and shelter type on broiler behaviour, welfare, and performance
Stadig, L. ; Rodenburg, T.B. ; Ampe, B. ; Reubens, B. ; Tuyttens, F. - \ 2015
In: Proceedings of the 49th Congress of the International Society for Applied Ethology. - Wageningen Academic Publishers - p. 72 - 72.
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