The influence of providing perches and string on activity levels, fearfulness and leg health in commercial broiler chickens

The aim of this study was to assess the effect of providing environmental enrichment in the form of perches and string on the behaviour and welfare of commercial broiler chickens. Houses containing ~23 000 broiler chickens were assigned to one of four treatments in a 2×2 factorial design. Treatments involved two levels of access to perches (P) (present (24/house) ‘+P’ or absent ‘−P’) and two levels of access to string (S) (present (24/house) ‘+S’ or absent ‘−S’). All houses contained windows, and 30 straw bales were provided from day 10 of the rearing cycle. Treatments were applied in one of four houses on a single farm, and were replicated over four production cycles. Behaviour and leg health were observed in weeks 3 to 5 of the rearing cycle. Production performance and environmental parameters were also measured. There was an interaction between perches and age in the percentage of birds observed lying, with higher percentages of birds observed lying in the +P treatment than in the −P treatment during weeks 4 and 5. There was also a significant interaction between string and age in the percentage of birds observed in locomotion, with higher percentages observed in locomotion in the −S treatment than in the +S treatment during weeks 4 and 5. There was also an interaction between string and age in average gait scores, with lower gait scores in the +S treatment than in the −S treatment during weeks 3 and 5 but not within week 4. Daytime observations showed that perches and strings were used frequently, with one bout of perching occurring approximately every 80 s/perch, and one bout of pecking at string occurring every 78 s/string on average. There was a significant effect of age on use of perches (P<0.001) and string (P<0.001), with perching peaking during week 5 and string pecking peaking during week 3. We conclude that commercial broilers in windowed houses with access to straw bales display an interest in additional enrichment stimuli in the form of perches and string, and therefore that these stimuli have the potential to improve welfare. In addition, provision of string as a pecking device appeared to positively influence walking ability. However, this effect was numerically small, was only shown in certain weeks and was not reflected in the other leg health measure (latency to lie). The results also showed an apparent negative effect of string and perches on the activity levels of birds (recorded away from the immediate vicinity of these enrichments) towards the end of the production cycle. These results emphasise the need for further research into optimum design and layout of enrichment stimuli for modern broilers in windowed houses to ensure that their provision leads to clear welfare benefits

State and parameter estimation of physics-based lithium-ion battery models

This thesis investigates novel algorithms for enabling the use of first-principle electrochemical models for battery monitoring and control in advanced battery management systems (BMSs). Specifically, the fast solution and state estimation of a high-fidelity spatially resolved thermal-electrochemical lithium-ion battery model commonly referred to as the pseudo two-dimensional (P2D) model are investigated. The partial-differential algebraic equations (PDAEs) constituting the model are spatially discretised using Chebyshev orthogonal collocation enabling fast and accurate simulations up to high C-rates. This implementation of the P2D model is then used in combination with an extended Kalman filter (EKF) algorithm modified for differential-algebraic equations (DAEs) to estimate the states of the model, e.g. lithium concentrations, overpotential. The state estimation algorithm is able to rapidly recover the model states from current, voltage and temperature measurements. Results show that the error on the state estimate falls below 1% in less than 200s despite a 30% error on battery initial state-of-charge (SoC) and additive measurement noise with 10mV and 0.5°C standard deviations. The parameter accuracy of such first-principle models is of utmost importance for the trustworthy estimation of internal battery electrochemical states. Therefore, the identifiability of the simpler single particle (SP) electrochemical model is investigated both in principle and in practice. Grouping parameters and partially non-dimensionalising the SP model equations in order to understand the maximum expected degrees of freedom in the problem reveals that there are only six unique parameters in the SP model. The structural identifiability is then examined by asking whether the transfer function of the linearised SP model is unique. It is found that the model is unique provided that the electrode open circuit voltage curves have a non-zero gradient, the parameters are ordered, and that the behaviour of the kinetics of each electrode is lumped together into a single parameter which is the charge transfer resistance. The practical estimation of the SP model parameters from frequency-domain experimental data obtained by electrochemical impedance spectroscopy (EIS) is then investigated and shows that estimation at a single SoC is insufficient to obtain satisfactory results and EIS data at multiple SoCs must be combined

Evaluation of a dustbathing substrate and straw bales as environmental enrichments in commercial broiler housing

The use of straw bales as an environmental enrichment is common for broiler chickens in enriched housing systems, however relatively little information exists about their effectiveness in improving welfare. There has also been no widespread introduction of a dustbathing material for broilers. The main aim of this trial was to evaluate the use of a dustbathing substrate (in the form of oat hulls), both as an alternative to straw bales and as a supplementary enrichment. Over four replicates, four commercial houses, each containing approximately 22,000 broilers, were assigned to one of four treatments over the 6-week production cycle: (1) straw bales (B; one per 155 m2), (2) oat hulls as a dustbathing substrate (OH; provided in 1 m diameter steel rings, one per 155 m2), (3) both oat hulls and straw bales (OH + B), and (4) a control treatment with no environmental enrichment (C). Observations of broiler behaviour and leg health were taken weekly, and performance data was collected for each cycle. Broilers housed in the OH and OH + B treatments had better gait scores in week 6 than those housed in the C treatment (P &lt; 0.05), which suggests that the provision of oat hulls improved bird leg health. However, there was no associated increase in activity levels in unenriched areas of the houses. Conversely, more locomotion (P &lt; 0.001), less sitting inactive (P &lt; 0.001) and less sitting pecking (P &lt; 0.001) were observed in the C treatment than in unenriched areas of B, OH and OH + B treatments. More birds were recorded around the bales compared to the oat hulls (P &lt; 0.001), however birds performed significantly more foraging (P = 0.019) and dustbathing (P = 0.045) in oat hulls than around straw bales. Although oat hulls appear to be more suitable for stimulating active behaviours than straw bales, the high level of resting recorded around the bales suggests they may have a positive function as protective cover. The presence of an additional type of enrichment in the house did not affect the number of birds, or the type of behaviours performed in close proximity to either straw bales or oat hulls (P &gt; 0.05). Treatment did not have a significant effect on pododermatitis levels or slaughter weight, on mortality rates, or on litter quality or atmospheric ammonia levels (P &gt; 0.05). Overall, our results suggest that the oat hulls substrate was a successful enrichment in terms of promoting dustbathing and foraging, and improving bird leg health. The straw bales also appeared attractive to the birds, however, which suggests that a dustbathing substrate should be a supplementary enrichment.</p

Synthèse et caractérisation optique de nanoparticules d’or couplées avec un matériau thermochrome dopé au tungstène.

Les nanoparticules d’or sous irradiation lumineuse sont le siège du phénomène de résonance de plasmon de surface localisé (LSPR) et peuvent agir comme sources thermiques locales en convertissant l’énergie lumineuse absorbée en chaleur. Les matériaux thermochromes présentent une transition de phase d’un état isolant vers un état métallique à une température de transition TIMT. Dans le cas du dioxyde de vanadium, la valeur de la TIMT est de 68°C. Ce changement de phase est accompagné par une variation importante de la transmission, en particulier dans le domaine de l’infrarouge et par celle de la résistivité électrique. En couplant des nanoparticules d’or avec un matériau thermochrome, il est alors possible de concevoir des dispositifs contrôlables optiquement. Cependant, pour faciliter le développement d’applications à base de VO₂ et de nano-objets plasmoniques, il faudrait induire la transition de phase à une température inférieure à 68°C. Ceci est rendu possible grâce au dopage du VO₂. Le tungstène est considéré comme un des dopants métalliques les plus efficaces. En effet, il permet d’abaisser la température de transition de l’ordre de 24°C/at.%. Dans ce travail, plusieurs configurations de couplage entre les nanoparticules d’or et le dioxyde de vanadium dopé au tungstène sont explorées pour la première fois et les résultats sont comparés au matériau non dopé. La synthèse des couches minces de VO₂ et de VO₂ dopé au tungstène est réalisée par ablation laser pulsée en configuration « faisceaux croisés » pour obtenir une couche d’excellente qualité. La fabrication des différents réseaux d’or fait appel à différentes techniques de nanofabrication à savoir, la lithographie par faisceau d’électron, la gravure par plasma et l’évaporation. Par la suite, ces différents réseaux ont été caractérisés optiquement soit la détermination de la variation de leur absorbance en fonction de la longueur d’onde. Ces réseaux consistent, en particulier, de plots d’or de 50 nm à 200 nm, distancés de 250 nm et déposés sur ou incorporés dans des couches minces d’oxyde de vanadium dopé. Ces mesures optiques confirment la modulation de la LSPR selon les différentes configurations de couplage. Elles permettent aussi de mettre en évidence l’efficacité du dopage pour atteindre des températures de transition proches de la température ambiante. Gold nanoparticles under light irradiation are the seat of the localized surface plasmon resonance (LSPR) phenomenon and can act as local heat sources by converting absorbed light energy into heat. Thermochromic materials exhibit a phase transition from an insulating state to a metallic state at a transition temperature TIMT. In the case of vanadium dioxide, the value of TIMT is 68°C. This phase change is accompanied by an important variation of the transmission, in particular in the infrared range, and by that of the electrical resistivity. By coupling gold nanoparticles with a thermochromic material, it is then possible to design optically controllable devices. However, to facilitate the development of applications based on VO₂ and plasmonic nano-objects, it would be necessary to induce the phase transition at a temperature below 68°C. This is made possible by doping the VO₂. Tungsten is considered as one of the most efficient metallic dopants. Indeed, it allows lowering the transition temperature of about 24°C/at.%. In this work, several coupling configurations between gold nanoparticles and tungsten doped vanadium dioxide are explored for the first time and the results are compared to the undoped material. The synthesis of VO₂ and tungsten doped VO₂ thin films is performed by pulsed laser ablation in a "crossed beam" configuration to obtain a layer of excellent quality. The fabrication of the different gold gratings uses different nanofabrication techniques such as electron beam lithography, plasma etching and evaporation. Thereafter, these various networks were optically characterized by determining the variation of their absorbance according to the wavelength. These gratings consist, in particular, of gold dots of 50 nm to 200 nm, spaced 250 nm apart and deposited on or incorporated in thin layers of doped vanadium oxide. These optical measure ments confirm the modulation of the LSPR according to the different coupling configurations. They also allow highlighting the efficiency of the doping to reach transition temperatures close to room temperature

Effect of Sand and Wood-Shavings Bedding on the Behavior of Broiler Chickens

The purpose of this study was to determine the effect of 2 different bedding types, sand and wood shavings, on the behavior of broiler chickens. In experiment 1, 6 pens were divided down the center and bedded half with sand and half with wood shavings. Male broilers (10/pen) were observed by scan sampling at 5- or 12-min intervals throughout the 6-wk growth period during the morning (between 0800 to 0900 h), afternoon (1200 to 1500 h), and night (2300 to 0600 h). There was a significant behavior x substrate x week interaction during the day (P \u3c 0.0001) and at night (P \u3c 0.0002). Drinking, dustbathing, preening, and sitting increased in frequency on the sand side but decreased on the wood shavings side during the day, as did resting at night. In general, broilers performed a greater proportion of their total behavioral time budget on the sand (P \u3c 0.0001) as they aged. Broilers used the divider between the 2 bedding types to perch; perching behavior peaked during wk 4. In experiment 2, male broilers were housed in 8 pens (50 birds/pen) bedded only in sand or wood shavings. Bedding type had no effect on behavioral time budgets (P = 0.8946), although there were age-related changes in behavior on both bedding types. These results indicate that when given a choice, broilers increasingly performed many of their behaviors on sand, but if only one bedding type was provided they performed those behaviors with similar frequency on sand or wood shavings

Energy allocation and behaviour in the growing broiler chicken

Broiler chickens are increasingly at the forefront of global meat production but the consequences of fast growth and selection for an increase in body mass on bird health are an ongoing concern for industry and consumers. To better understand the implications of selection we evaluated energetics and behaviour over the 6-week hatch-to-slaughter developmental period in a commercial broiler. The effect of posture on resting metabolic rate becomes increasingly significant as broilers grow, as standing became more energetically expensive than sitting. The proportion of overall metabolic rate accounted for by locomotor behaviour decreased over development, corresponding to declining activity levels, mean and peak walking speeds. These data are consistent with the inference that broilers allocate energy to activity within a constrained metabolic budget and that there is a reducing metabolic scope for exercise throughout their development. Comparison with similarly sized galliforms reveals that locomotion is relatively energetically expensive in broilers

Selecting appropriate bedding to reduce locomotion problems in broilers

Two experiments were carried out at the Poultry Sector of the School of Agrarian Sciences of the Federal University of Grande Dourados to evaluate the incidence of leg problems in broilers reared on two distinct types of bedding material: rice husks or wood shavings, both new and reused. In both trials, a randomized experimental design was applied in factorial arrangement (2 x 2 x 2) using two genetic strains (Cobb® or Ross®); two sexes (male or female), and two litter materials (rice husks or wood shavings). In each trial 1080 one day pullets were reared equally divided in the treatments. The birds were placed in 4.5 m² boxes at a density of 10 birds m-2. All birds were fed diets with equal nutritional density, and water was offered ad libitum. Feeds were divided in three phases: starter diet (1 - 21 days), grower diet (22 - 35 days), and finisher diet (36 - 45 days). On day 45, fifty birds were randomly selected in each experiment to evaluate flock leg problems. The following parameters were analyzed: gait score, incidence of valgus and varus disorder, footpad dermatitis, femoral degeneration, tibial dyschondroplasia, and spondylolisthesis. Ambient temperature during rearing and litter caking and moisture content were recorded in four boxes per treatment. The analytical hierarchy process was used to organize the data into specific criteria. Several criteria, related to the attributes that were determinant according to the statistical analysis, were chosen in order to provide the best input to the process. Results indicated that new wood-shavings bedding was the most appropriate bedding to prevent locomotion problems, followed by new rice husks, reused wood shavings, and reused rice husks. However, when leg problems were associated to sex and genetic strain, male Ross birds strain presented less problems when reared on new rice husks, followed by new wood shaving