This study compares various morphometric features of two strains of broilers, selected and ‘relaxed’ (ie random-bred), raised under two feeding regimes, ad-libitum-fed and restricted-fed. We consider the possible consequences of the different body shapes on the musculoskeletal system. The ad-libitum-fed selected birds reached heavier bodyweights at younger ages, had wider girths, and developed large amounts of breast muscle which probably displaced their centre of gravity cranially. At cull weight, they had shorter legs than birds in the other groups and greater thigh-muscle masses; therefore, greater forces would have to be exerted by shorter lever arms in order to move the body. The tarsometatarsi were broader, providing increased resistance to greater loads, but the bones had a lower calcium and phosphorus content, which would theoretically make them weaker. Many of these morphological changes are likely to have detrimental effects on the musculoskeletal system and therefore compromise the walking ability and welfare of the birds.

This study tests the hypothesis that growth rate and bodyweight affect walking ability in broilers by comparing objective measurements of the spatial and temporal gait parameters of several groups of birds. Two strains of birds were used (relaxed and selected), raised on two feeding regimes (ad-libitum and restricted), and culled at the same final bodyweight (commercial cull weight of 2.4 kg). The ad-libitum-fed selected birds walked more slowly, with lower cadences, and took shorter steps. The steps were wider, and the toes were pointed outwards, resulting in a wider walking base. They kept their feet in contact with the ground for longer periods, having longer percentage stance times, shorter percentage swing times and increased double-contact times compared to the relaxed birds. These changes serve to increase stability during walking and are a likely consequence of the morphological changes in the selected broiler — in particular, the rapid growth of breast muscle moving the centre of gravity forward, and the relatively short legs compared to their bodyweight (see Corr et al, pp 145-157, this issue). This altered gait would be very inefficient and would rapidly tire the birds, and could help to explain the low level of activity seen in the modern broiler.

Cats living long-term (over one month) in shelters were assessed for behavioural indicators of stress, using a stress scoring method in combination with behavioural observation. It is hypothesised that because of the inappropriate social grouping of unrelated adult cats and group instability, communal housing creates more stress than discrete-unit housing. Seventy-two cats were observed: 36 were housed communally with unfamiliar conspecifics, and 36 were housed in discrete units, either alone or with other previously familiar conspecifics. The mean stress score was greater in communal housing than in discrete-unit housing. Stress scores range from 1 to 7, with 1 indicating no stress experienced, and 7 indicating extreme stress. Individual scores showed that cats in discrete units, in comparison to those in communal housing, gained a significantly higher percentage of observations in the score 2 category, indicating that no stress was being experienced. Cats in communal housing gained a significantly higher percentage in the score 4 category (stressed). Score 5 was found exclusively in communal housing, but only in 2% of instances. Extreme stress was not found in cats housed under either condition. Cats in the different types of housing differed in their frequencies of hiding, play, sleeping/resting in close contact with one another, and agonistic behaviour. There was no difference between housing types in frequency of eating, drinking, grooming, and toilet use. In this study, cats housed communally experienced moderately higher levels of stress than cats housed in discrete units. Further research is recommended to determine the effect on stress levels of longer shelter residence time and of changes in group size and/or density.

In this study, we analysed the effects of social and human contact on calves ‘ behaviour and stress responses. We also measured the effect of this contact on calves ‘ reactions to novel conspecifics and novel humans. Sixty-four calves were housed either alone or in pairs and received either minimal human contact or ‘additional’ human contact (stroking and talking). At six, 10 and 14 weeks of age, the behaviour of the calves was recorded in their home pens. Calves were then tested in an unfamiliar arena either alone, with an unfamiliar calf, or with an unfamiliar man, and in a Y-maze with one arm leading to a calf and the other to a man. An adrenocorticotrophic hormone (ACTH) challenge was performed in order to assess chronic stress responses. Compared with individually housed calves, pair-housed calves were more active and made fewer contacts with their neighbours when in their home pens; they were also less active in the arena, spent more time near the calf in the Y-maze, and had lower Cortisol responses to ACTH. Calves that had received additional human contact interacted more with the man in the arena and had lower mean heart rates than those that had received minimal contact. This study confirmed that calves feel a need for social contacts and that pair-housing can lower the stress felt by calves separated from their conspecifics. Additional contact from stockpersons increases calves ‘ likelihood of approaching humans but cannot compensate for their lack of social partners. Hence, when calves are separated, the duration of the separation should be limited, and visual and physical contact with other calves should be provided.

A Delphi technique was used to gather the opinions of animal welfare experts on the most appropriate measures for welfare assessment of farm animals. The experts were asked to consider measures that were directed towards the animal (animal-based), rather than measurement of their environment. This systematic approach was designed to achieve a degree of consensus of opinion between a large number of experts. Two rounds of postal questionnaires were targeted at people with expertise in one or more of the species of interest. The respondents suggested measures based upon observations of health status, behaviour, and examination of records. These measures reflect the animal's welfare state — in other words, how the animal is coping within the environment and husbandry system in which it lives. The measures for cattle, pigs and laying hens were categorised into 22, 23 and 28 aspects, respectively, with the highest ranking of importance being given to observation of lameness in dairy cattle and pigs and to observation of feather condition in laying hens. This Delphi study was the basis for the development of a series of protocols to assess the welfare state of dairy cattle, pigs and laying hens.

The welfare of transgenic animals is often not considered prior to their generation. However, we demonstrate here how a welfare risk assessment can be carried out before transgenic animals are created. We describe a risk assessment identifying potential welfare problems in transgenic pigs generated for future xeno-donation of organs. This assessment is based on currently available information concerning transgenic animal models in which one or more transgenes relevant to future xeno-donation have been inserted. The welfare risk assessment reveals that future xeno-donor pigs may have an increased tendency toward septicaemias, reduced fertility and/or impaired vision. The transgenic animal models used in generating hypotheses about the welfare of xeno-donor pigs can also assist in the testing of these hypotheses. To ensure high levels of welfare of transgenic animals, analogous risk assessments can be used to identify potential welfare problems during the early stages of the generation of new transgenic animals. Such assessments may form part of the basis on which licenses to generate new transgenic animals are granted to research groups.

Forty-eight Large White x Landrace multiparous sows were mixed into twelve groups of four animals after their piglets were weaned. These groups were defined as static, with no animals being added to or removed from the groups after their formation. Aggressive and submissive behaviours were recorded continuously for 9 h after the sows were mixed, and the sows were assigned high or low social status on the basis of their relative aggressiveness and success in aggressive interactions. After five weeks, each static group was mixed into a dynamic group of 40 ±2 sows for an 11-week period. Three static groups (ie 12 animals) at a time were added to the dynamic group at three-week intervals; the same number of animals was removed at these time-points in order to maintain the group number at 40 ± 2. Injury levels increased significantly with the transition from static groups to the dynamic group (P < 0.001). Sows with low social status had lower bodyweights (P < 0.001) and higher injury levels one week after mixing into static and dynamic groups (P < 0.01). Social status did not significantly affect salivary Cortisol levels. Sows with low social status were positioned lower in the feed order, determined using an electronic feeder (P < 0.001), and tended to be displaced from the feeder queue more often (P < 0.1) in the dynamic group. Sows with low social status were also displaced from the drinker more often than highranking sows in the dynamic group (P < 0.01). This may have led to the greater frequency of drinking behaviour shown by low-ranking sows (P < 0.05). Sows with low social status were observed less often in the kennel areas than were the high-ranking sows in the dynamic group (P < 0.05), suggesting that they were denied access to the prime lying areas. The results suggest that the welfare of sows is negatively affected by low social status in both small static and large dynamic groups.

In Callitrichid primates, offspring remain in their natal group beyond the age of sexual maturity, increasing the group's inclusive fitness by cooperatively rearing their siblings. Contraception of the dominant female in these groups may alter the associated costs and benefits of this cooperative rearing in such a way that offspring themselves attempt to breed when a period longer than the normal inter-birth interval of one year has elapsed. Contraception of the dominant female may also induce changes in socio-sexual interactions between group members, which can lead to increased aggression after a short period. In this study, we investigated the occurrence of aggression in 16 captive groups of golden-headed lion tamarins (Leontopithecus chrysomelas) under three conditions: 1) no contraception used; 2) contraception used and offspring younger than one year present within the group; and 3) contraception used and all offspring in the group older than one year. We found that the probability of aggression occurring in the groups was best predicted by logistic regression models containing the factors ‘group size ‘ and ‘overall proportion of males ‘ or ‘number of sons ‘. Aggression was more likely in larger groups with a high proportion of males or a large number of sons. This effect was significantly stronger for groups in which all offspring were older than one year. Absence of dispersal opportunities and differences in male and female reproductive strategies may explain the observed patterns. The increased instability of large non-breeding groups presents a problem when using long-term contraceptive methods and should be taken into account when making decisions on the most suitable population-control procedures.

The visual system of domestic poultry evolved in natural light environments, which differ in many respects from the artificial light provided in poultry houses. Current lighting systems are designed mainly around human vision and poultry production, ignoring the requirements of poultry vision and the functional development of visual abilities during rearing. A poor correlation between the light provided and that required for effective vision may influence visually mediated behaviours such as feeding and social interaction, leading to distress and poor welfare. To understand fully the impact of the light environment on the behaviour and welfare of domestic poultry we need (i) to measure the physical properties of the light environment in a standard and relevant manner; (ii) to identify the limits of visual abilities in various light environments; (iii) to determine how light environments during rearing may disrupt the functional development of vision; and (iv) to resolve how visual abilities and lighting interact to affect visually mediated behaviour. Some conclusions can be drawn about the impact of current lighting regimes on bird welfare but there remains a pressing need to resolve various issues in this interaction. We propose, first, that dark periods should have a minimum duration of six hours; second, that bright light should be used in cases where pecking damage and cannibalism do not pose a problem; and third, that it is unlikely that the 100 Hz flicker associated with fluorescent light can be perceived by poultry. With less certainty, we can suggest that ultraviolet-supplemented lighting may have some welfare benefits, and that very dim lighting may adversely affect ocular development. We can only speculate on other issues, such as preferences and motivations for different coloured lighting or the ways in which lighting affects recognition of conspecifics. Several organisations and authorities have issued guidelines for poultry house lighting that strive to safeguard welfare and that are consistent with our current, but limited, understanding. One omission is a standard system for measuring light levels in poultry houses. Illumination with natural daylight would be an ideal solution to many lighting problems. Although some systems require artificial lighting for production purposes, we argue that it may be possible to rear birds humanely in artificial environments that contain some features of natural light. These features should be those for which poultry show some motivation, or whose exclusion would damage visual development.