Influence of light-dark schedules and stocking density on behaviour, risk of leg problems and occurrence of chronic fear in broilers.

1. The aims of this study were to determine (1) the effect of light-dark schedules on the walking ability, the risk of tibial dyschondroplasia (TD) as well as the duration of tonic immobility (TI) reactions in commercial broiler flocks and (2) the effect of a daily dark period and reduced density on the behaviour of broiler chickens. 2. Experiment 1. Group 1 had a 2 to 8 h daily dark period from 2 to 26 d of age (light-dark programme A) at a stocking density of 28.4 chicks/m2. Group 2 had 8 h of darkness daily from 2 to 38 d of age (light-dark programme B) at 24 chicks/m2. The control group had 24 h continuous light at 28.4 chicks/m2. 3. Experiment 2. Behaviour was studied with and without a daily 8 h dark period and at high (30 chicks/m2) and low (18 chicks/m2) stocking densities. 4. Programme B reduced the prevalence of impaired walking ability, corresponding to gait score > 2, when compared with controls. The effect on walking ability corresponding to gait score > 0 approached significance. 5. Both light-dark programmes reduced the occurrence of TD. Programme B (combined with reduced stocking density), however, had the greater effect. 6. Both light-dark programmes reduced the duration of TI, compared with controls (mean = 426 s) Programme B resulted in a larger reduction (alpha = -156.9 s) than programme A (alpha = -117.0). 7. The proportions of chicks drinking, eating, pecking, scratching, standing and performing vertical wing-shakes increased--both when the 8 h dark period and the reduced stocking density were applied separately and in combination (experiment 2). 8. For all behaviours, except standing, the effect of the dark period was largest in broilers kept at the high stocking density (d 40).

Influence of zinc bacitracin, light regimen and dustbathing on the health and welfare of broiler chickens.

1. The influence of zinc bacitracin, an antibiotic growth promoter, and the combined influence of two environmental factors (8 h of darkness and access to sand) on health and welfare variables were studied in 96 broiler chickens (kept as pairs). 2. Chickens fed with zinc bacitracin (ZB) had a higher frequency of tibial dyschondroplasia (TD) and a higher frequency of dustbathing than chickens fed without zinc bacitracin. 3. When 42 d old, chickens exposed to 8 h of darkness and access to sand were heavier than chickens reared under continuous light and with no access to sand. 4. Fluctuating asymmetry was higher in the 'light/no sand' groups than in the 'night/sand + ZB' group. 5. There was a negative correlation between tonic immobility and weight and a positive correlation between weight and TD.

Development of dustbathing behavior sequences in the domestic fowl: the significance of functional experience.

The development of the sequential structure of dustbathing bouts was studied in domestic egg-layer chicks from hatching until 23 days of age using a first order Markov chain model analysis. Chicks were reared either with access to sand ("sand chicks ") or on a wire floor ( "wire chicks"). All chicks in both groups developed a basic structure of the elements pecking, bill raking, ground scratching, vertical wingshaking, head rubbing, and side rubbing. Nonetheless, there was more cohesion in the bouts of sand chicks than in those of wire chicks: wire chicks had more pauses in their bouts and performed more elements while standing; also, allopecking (feather-pecking) and preening were incorporated into their bouts. We conclude that the basic structure of dustbathing bouts develops even in the absence of functional experience with feedback from sand. However, absence of normal feedback can lead to problems consisting of interruptions and feather-directed behavior.

Relationships between leg disorders and changes in the behaviour of broiler chickens.

The relationships between the severity of lameness, the presence of tibial dyschondroplasia, and the frequency of dustbathing behaviour and duration of tonic immobility were studied in 96 broiler chicks kept from day-old in groups of four in wire-floored cages. Dustbathing was observed when the birds were given access for one hour to a tray containing sand or straw. The duration of tonic immobility and the severity of lameness were scored during weeks 3, 4, 5 and 6. After slaughter at 41 or 45 days of age the birds were examined for tibial dyschondroplasia; 34 birds were classified as having tibial dyschondroplasia and 54 had detectable lameness problems. Birds with tibial dyschondroplasia had a higher lameness score (P < 0.001), dustbathed on fewer days (P < 0.0001), and had longer periods of tonic immobility (P < 0.03) at six weeks than birds which did not have the condition. However, almost all the chicks, including those with tibial dyschondroplasia dustbathed on day 27 after they had not been given access to the tray for three days, significantly more than on days when they had not been deprived of the tray (P < 0.0001). Furthermore, lame birds and birds with tibial dyschondroplasia also dustbathed less with age. Studies of the vertical wing-shaking element of dustbathing confirmed that tibial dyschondroplasia reduced dustbathing (P < 0.05) and also showed that during the one-hour tests, sand resulted in more dustbathing than straw (P < 0.01).

Development of social behaviour in four litters of dogs (Canis familiaris).

The development of social behaviour in 4 litters of dogs was observed without interfering with the puppies from birth to 8 weeks of age. Direct and continuous observation was combined with video recording. Three of the litters were observed during one session of 2 h once a week, and the fourth litter during one session of 40 min twice a week. Social interactions were divided into 1) investigation of litter mates (licking, sniffing or investigating orally), 2) social play, 3) and interactions in which agonistic elements (dominance postures, threats, bites or submission) were displayed. The different forms of social interactions appeared for the first time when the puppies were between 14 and 21 days of age. Social investigation appeared first and was followed by play and agonistic interactions. From week 5, differences between the puppies in the tendency to initiate social play and agonistic interactions emerged. Generally, within the litters individual differences were consistent over weeks 6-8 (positive correlations between weeks), whereas the tendency in the puppies during these weeks were negatively correlated with those of week 3 (play) or weeks 3 and 4 (agonistic interactions), indicating a rebound effect for both play and agonistic behaviour. No significant correlations, however, were found for social investigation. More often than expected males played or engaged in agonistic with other males, whereas these behaviours occurred less often than expected between females. Both males and females, however, preferred male partners for agonistic interactions. No sex differences were found in the direction of social investigation. Agonistic behaviour was often responded to by play and play was often responded to by agonistic behaviour, and the results indicated that before 8 weeks of age differences in social behaviour between the puppies were already established.

Development of a new production system for weaned and growing pigs.

The design of modem housing systems for farm animals calls for cooperation between scientists within different disciplines. This article describes the design of a new production system for weaned and growing pigs, as well as the analyses and working processes behind its development. The aim of the study was to develop an economically competitive system that also provided better welfare for the animals and a healthier environment for the workers. Analyses were carried out with emphasis on behavioral needs and building design and economy. The resulting system, the "safari system," consists of a number of straw flow pens of increasing size. Pigs are moved to larger and larger pens each week until slaughter. The main advantage is that pigs are not mixed during the growth period and that they are given more space, especially toward the end of the growth period when their space demand is high. Furthermore, the provision of straw for comfort and exploration and of wallow basins for cooling in the pens for the larger pigs were considered significant welfare improvements. An analysis revealed that the safari system would be economically competitive in comparison to traditional intensive systems.

The stress of not being able to perform dustbathing in laying hens.

The stress of not being able to perform dustbathing was studied in small groups of laying hens. The birds were reared and kept for 2.5 years in cages with either sand ("sand birds") or wire floors ("wire birds"), and subsequently deprived of sand (sand birds) or given access to sand (wire birds). Before this change, wire birds had a higher incidence of unilateral wing/leg stretching and stereotypic pecking compared to sand birds; however, there was no difference in corticosterone concentrations. Deprivation of sand in the sand birds resulted in a total absence of dustbathing and in a significant increase in corticosterone concentrations. Although the wire birds dustbathed on the wire before the change of floors, there was a significant increase in the incidence of dustbathing after sand was provided, but no changes in the concentrations of corticosterone. Threats and allopecks decreased in the wire birds after access to sand, whereas no changes were found in the sand birds. Stereotypic pecks on feathers were absent in the sand birds, but were frequent in most of the wire birds both before and after they were given sand. Also, in the wire birds, all feather pecking (stereotypic and nonstereotypic) was positively correlated with the concentration of corticosterone, and this kind of pecking may, thus, be an expression of stress in laying hens. We conclude that the nonperformance of dustbathing behavior is associated with the experience of stress.

Developmental stability in relation to population density and breed of chickens Gallus gallus.

Bilaterally symmetrical morphological characters with fluctuating asymmetry usually have small, random deviations from symmetry that reflect the ability of individuals to cope with genetic and environmental stress. A comparison of the level of fluctuating asymmetry in two fast-growing breeds (ScanBrid, Ross 208) with that of a slow-growing breed (La Belle Rouge) and wild jungle fowl from India revealed a positive relationship between growth rate and asymmetry. Fast-growing chickens kept at three densities (20, 24, and 28 chickens per square meter) revealed a positive association between fluctuating asymmetry and density. Large individuals generally had higher levels of fluctuating asymmetry than small individuals. Tonic immobility, which is often used as a measure of fearfulness, was weakly positively associated with the degree of fluctuating asymmetry (P < .05). Measures of fluctuating asymmetry may provide information on levels of stress experienced by domesticated animals.