Environmental complexity and group size: Immediate effects on use of space by domestic fowl

Environmental complexity: A buffer against stress in the domestic chick

Birds kept in commercial production systems can be exposed to multiple stressors from early life and this alters the development of different morphological, immunological and behavioural indicators. We explore the hypothesis that provision of a complex environment during early life, better prepares birds to cope with stressful events as well as buffers them against future unpredictable stressful episodes. In this study, 96 one day old pullets were randomly distributed in eight pens (12 birds/pen). Half of the chicks (N = 48) were assigned to a Complex Environment (CENV: with perches, a dark brooder etc.) the others to a Simple Environment (SENV: without enrichment features). Half of the birds from each of these treatments were assigned to a No Stress (NSTR, 33°C) or to an acute Cold Stress (CSTR, 18–20°C) treatment during six hours on their second day of life. At four weeks of age, chicks with these four different backgrounds were exposed to an Intermittent Stressful Challenges Protocol (ISCP). In an immunological test indicative of pro-inflammatory status Phytohemagglutinin-P (PHA-P), the response of CSTR birds was ameliorated by rearing chicks in a CENV as they had a similar response to NSTR chicks and a significantly better pro-inflammatory response than those CSTR birds reared in a SENV (five days after the CSTR treatment was applied). A similar better response when coping with new challenges (the ISCP) was observed in birds reared in a CENV compared to those from a SENV. Birds reared in the CENV had a lower heterophil/lymphocyte ratio after the ISCP than birds reared in SENV, independently of whether or not they had been exposed to CSTR early in life. No effects of stress on general behaviour were detected, however, the provision of a CENV increased resting behaviour, which may have favoured stress recover. Additionally, we found that exposure to cold stress at an early age might have rendered birds more vulnerable to future stressful events. CSTR birds had lower humoral immune responses (sheep red blood cells induced antibodies) after the ISCP and started using elevated structures in the CENV later compared to their NSTR conspecifics. Our study reflects the importance of the early provision of a CENV in commercial conditions to reduce negative stress-related effects. Within the context of the theory of adaptive plasticity, our results suggest that the early experience of the birds had long lasting effects on the modulation of their phenotypes.

Use of space and its impact on the welfare of laying hens in a commercial free-range system

The aim of this study was to explore the factors influencing patterns of space use of commercial free-range laying hens and their relation to welfare indicators. Three free-range laying hen flocks were studied during one production cycle by collecting spatial locations on 150 individually tagged hens per flock. At the end of production, welfare and morphometric measures were collected. The results indicated that use of the outdoor area was lower during midday (P < 0.05), but remained stable across age periods (P > 0.05). Tagged hens were classified according to their use of the outdoor area (heavy, medium, light, or never) per age period. A total of 49.5% were never observed using the outdoor area, which was higher than any other category (P < 0.05). In addition, the early experience of the hens using the outdoor area during the first 16 wk (20 to 36 wk) determined the level of use of the outdoor area at later ages (P < 0.05). Most use of space parameters did not vary according to age period (P > 0.05); only activity center indoors increased (P < 0.05), while mean distance from the hen house tended to increase (P = 0.053). However, birds with a higher frequency of use of the outdoor area had larger home ranges and activity centers (r = 0.956, r = 0.964 P < 0.05, respectively) and showed lower plumage damage (r = -0.337, P < 0.05) and a lower incidence of footpad dermatitis (r = -0.307, P < 0.05). On the contrary, birds showing higher total walked distance indoors showed a higher incidence of footpad dermatitis (r = 0.329, P < 0.01). We conclude that there exist individual differences in the use of the outdoor area, with early experience (20 to 36 weeks) during the production period being the most relevant factor affecting outdoor area use. Birds visiting the outdoor area more frequently also used larger areas. In addition, individual patterns of space use had some relevance on the incidence on foot pad dermatitis and plumage condition.

Floor space covered by broiler chickens kept at stocking densities according to Council Directive 2007/43/EC

It is controversially discussed whether the stocking densities set by the EU Directive 2007/43/EC allow a species-appropriate housing of broiler chickens. To calculate the exact area broilers occupy due to their physical size and shape, planimetric measurements using a colour-contrast method were carried out. In total, 1949 photographs of standing and 1482 of squatting chickens, taken from a top view, were analysed. A computer program counted the pixels representing the previously weighed animal in the photograph and calculated the animal area. The average area covered by chickens with 400 g live weight was 116.64±13.12 cm(2) in a standing and 138.61±12.92 cm(2) in a squatting position. These areas increased linearly as a function of live weight to 452.57±58.89 cm(2) (R(2)=0.90 standing) and 513.54±42.70 cm(2) (R(2)=0.82 squatting) at the end of the study (3200 g live weight). Squatting chickens occupied more space compared with a standing position in most of the tested weight classes (P<0.05). Depending on target weights, stocking densities and body positions, broilers occupied 48.5-77.7 per cent of 1 m(2) Thus, from a physical point of view, simultaneous resting is possible at any stocking density provided by the EU Directive and at common target weights.

Density-Dependent Spacing Behaviour and Activity Budget in Pregnant, Domestic Goats (Capra hircus)

Very little is known about the spacing behaviour in social groups of domestic goats (Capra hircus) in the farm environment. In this experiment, we studied interindividual distances, movement patterns and activity budgets in pregnant goats housed at three different densities. Norwegian dairy goats were kept in stable social groups of six animals throughout pregnancy at 1, 2 or 3 m² per individual and their spacing behaviours (i.e. distance travelled, nearest and furthest neighbour distance) and activity budgets (e.g. resting, feeding, social activities) were monitored. Observations were made in the first, second and last thirds of pregnancy in the mornings, at noon and in the afternoons of each of these phases (4.5 hours per observation period). The findings show that goats held at animal densities of 2 and 3 m² moved longer distances when they had more space per animal and kept larger nearest and furthest neighbour distances when compared to the 1 m² per animal density. Less feeding activity was observed at the high animal density compared to the medium and low density treatments. The phase of gestation also had an impact on almost all behavioural variables. Closer to parturition, animals moved further distances and the increase in nearest and furthest neighbour distance was more pronounced at the lower animal densities. During the last period of gestation, goats spent less time feeding and more on resting, social behaviours and engaging in other various activities. Our data suggest that more space per goat is needed for goats closer to parturition than in the early gestation phase. We concluded that in goats spacing behaviour is density-dependent and changes with stages of pregnancy and activities. Finally, the lower density allowed animals to express individual preferences regarding spacing behaviour which is important in ensuring good welfare in a farming situation.

A medium density genetic map and QTL for behavioral and production traits in Japanese quail

BACKGROUND

Behavioral traits such as sociability, emotional reactivity and aggressiveness are major factors in animal adaptation to breeding conditions. In order to investigate the genetic control of these traits as well as their relationships with production traits, a study was undertaken on a large second generation cross (F2) between two lines of Japanese Quail divergently selected on their social reinstatement behavior. All the birds were measured for several social behaviors (social reinstatement, response to social isolation, sexual motivation, aggression), behaviors measuring the emotional reactivity of the birds (reaction to an unknown object, tonic immobility reaction), and production traits (body weight and egg production).

RESULTS

We report the results of the first genome-wide QTL detection based on a medium density SNP panel obtained from whole genome sequencing of a pool of individuals from each divergent line. A genetic map was constructed using 2145 markers among which 1479 could be positioned on 28 different linkage groups. The sex-averaged linkage map spanned a total of 3057 cM with an average marker spacing of 2.1 cM. With the exception of a few regions, the marker order was the same in Japanese Quail and the chicken, which confirmed a well conserved synteny between the two species. The linkage analyses performed using QTLMAP software revealed a total of 45 QTLs related either to behavioral (23) or production (22) traits. The most numerous QTLs (15) concerned social motivation traits. Interestingly, our results pinpointed putative pleiotropic regions which controlled emotional reactivity and body-weight of birds (on CJA5 and CJA8) or their social motivation and the onset of egg laying (on CJA19).

CONCLUSION

This study identified several QTL regions for social and emotional behaviors in the Quail. Further research will be needed to refine the QTL and confirm or refute the role of candidate genes, which were suggested by bioinformatics analysis. It can be hoped that the identification of genes and polymorphisms related to behavioral traits in the quail will have further applications for other poultry species (especially the chicken) and will contribute to solving animal welfare issues in poultry production.

Short- and long-term movement patterns in complex confined environments in broiler chickens: the effects of distribution of cover panels and food resources

In captivity, the positioning of structural enrichment and food resources influences behavior and space use. The aim of this experiment was to examine the influence of cover panels and the positioning of food resources on the movement and space use of domestic fowl (Gallus gallus domesticus). Eight groups of 45 male chickens were used for this study. Each group was temporarily divided into 2 groups of 20 birds; each group was used to investigate the influence of cover panels and the effects of food resources. In the cover panel treatments, 20 birds were placed in the 10-m(2) testing enclosures that contained one 2-m cover panel in the center, four 0.5-m panels in a zigzag fashion, or had no panels (controls). In the food resource treatments, the position of the feed trays varied, with 1 feed tray in the center; 2 feed trays, one at each edge; or 4 feed trays, one at each corner of the enclosure. Locations of focal birds were collected through instantaneous scan sampling that was recorded as X,Y coordinates. From these X,Y coordinates, we calculated net and total distance moved, mean and maximum step lengths, and angular dispersion of the path of movement. To calculate long-term space use, 3 replications for each of 3 cover panel and food resource treatments were placed in nine 10-m(2) enclosures for 1 wk. Locations of focal birds in each group were collected by ad libitum scan sampling and data were used to calculate core areas by kernel estimates. Mixed model ANOVA was used to determine the effects of the distribution of cover panels and positioning of food resources on movement parameters during the study period, whereas 1-way ANOVA was used for core areas. Surprisingly, our analyses showed that long-term and short-term movement was not affected by changing the location of cover panels or food resources. Only net distance seemed to be affected to a certain degree by the presence of the cover and the distinctive availability of food resources.

Separating the impact of group size, density, and enclosure size on broiler movement and space use at a decreasing perimeter to area ratio

The goal of this study was to determine the impact of enclosure size on space use and movement patterns of domestic fowl (Gallus gallus domesticus), independent of group size and density. Research designed to estimate the effects of group size, density, or enclosure size involves inherent confounding between factors, clouding their individual effects. This experimental design enabled us to conduct multiple contrasts in order to tease apart the specific impacts. Treatments consisted of five combinations of three square enclosures: small (S; 1.5m(2)), medium (M; 3.0m(2)), and large (L; 4.5m(2)), and three group sizes of 10, 20, and 30 birds. We made comparisons while holding group size constant, holding density constant, and the third while maintaining a constant enclosure size. Nearest neighbor distances increased with enclosure size but appeared to be constrained by density. Net displacement and minimum convex polygons increased with enclosure size regardless of group size or density. We found no evidence of social restriction on space use. Results indicate that broilers adapted their use of space and movement patterns to the size of the enclosures, spreading out and utilizing a greater amount of space when it was available.

Space use according to the distribution of resources and level of competition

The manner in which an animal moves throughout and utilizes the space available to it depends on the dispersal, availability, and level of competition for resources the animal requires for its biological functioning. We tested groups of broilers (Gallus gallus domesticus) in 3 experimental group sizes of 5, 10, and 20 individuals per group under 3 resource distribution patterns. Groups were tested with access to 1 large single feeder, 2 medium-sized feeders, or 4 small feeders. In all arrangements the total amount of food available per bird remained constant. During the first phase groups had free access to all available feeders, and in the second phase access at each feeder was restricted to a single bird. Space use, measured by calculating core areas and interindividual distances between group members, increased as group size grew larger and as feeders became more widely distributed. Not all group sizes responded equally to the resource distribution patterns. Space use patterns for the smaller group sizes were more strongly affected by resource distribution patterns than the larger group sizes. When access to the feeders was restricted, consumption, aggression, and space use increased. Broilers adjusted their space use and aggressive behavior according to the level of competition, dictated not only by group size but also resource distribution and accessibility.

ANÁLISE DE CORRELAÇÃO ENTRE COMPORTAMENTOS DE MATRIZES PESADAS E VARIÁVEIS AMBIENTAIS

Entender o comportamento das aves vem ganhando maior importância na exploração avícola moderna, pois expressa as complexas interações sociais e ambientais das aves. Isso ocorre por causa do modo complexo de como ambiente afeta o desempenho zootécnico das aves e, portanto, a análise do comportamento pode prever maior eficiência e precisão no controle do ambiente de criação. Além disso, também motivando esses estudos, destaca-se o impacto gerado pelas garantias de bem-estar nos alojamentos de animais que o consumidor europeu tem exigido. Com o objetivo de contribuir com os estudos de bem-estar de matrizes pesadas baseados em observações comportamentais, este trabalho avalia a dependência das variáveis comportamentais e ambientais de matrizes pesadas, utilizando para isso o coeficiente de correlação linear de Pearson. O trabalho foi desenvolvido com dados coletados em ambiente controlado, utilizando três linhagens de matrizes pesadas, submetidas a três condições controladas de temperatura e com o monitoramento da concentração do gás amônia. Foram observadas correlações lineares positivas e negativas entre as variáveis comportamentais e ambientais de matrizes pesadas, utilizando para isso o coeficiente de correlação linear de Pearson. O trabalho foi desenvolvido com dados coletados em ambiente controlado, utilizando três linhagens de matrizes pesadas, submetidas a três condições controladas de temperatura e com o monitoramento da concentração do gás amônia. Foram observadas correlações lineares positivas e negativas entre as variáveis comportamentais e ambientais, podendo contribuir para futuros estudos de modelos estatísticos de estimativa do bem-estar.