Leg disorders in broilers are a major economic and welfare problem. The aetiology of many disorders is complex but includes genetics, growth rate (due to feed restriction or lighting regime), feed conversion efficiency and body conformation, exercise, circadian rhythms, nutrition and stocking density. These categories are not mutually exclusive as one aetiological factor may affect another. Many studies of leg disorders fail to identify the specific pathological condition underlying the observed lameness. However, disorders may be classified according to underlying pathology as infectious, developmental and degenerative. This classification is difficult because these categories are not mutually exclusive. Infectious conditions include bacterial chondronecrosis with osteomyelitis (BCO or femoral head necrosis, FHN), tenosynovitis and arthritis, infectious stunting syndrome (ISS) and viral induced neoplasia. Developmental conditions include varus valgus disease (VVD), rotated tibia, tibial dyschondroplasia (TD), rickets, chondrodystrophy and spondylolisthesis. Degenerative disorders include osteochondrosis (often TD), epiphyseolosis (often classified as FHN), degenerative joint disease (DJD), spontaneous rupture of the gastrocnemius tendon and contact dermatitis. BCO, TD, dermatitis and VVD are the most common disorders. Outbreaks of leg disorders are often site / context specific. The welfare of broilers with leg disorders may be impaired due to pain from the condition, an inability to walk leading to frustration and associated problems of being unable to feed and drink due to immobility (which may result in starvation). In assessing welfare, the individual broiler must be considered irrespective of the frequency of occurrence of the disorder. Most studies of welfare in relation to leg disorders have used a subjective gait scoring method (0 is normal walking and 5 is unable to walk). Gait scoring is a practical method for assessing broiler lameness in the field. The method provides a useful tool to employ in the field without recourse to pathological investigation and, while the method conflates conformity with pathology, it is a helpful and constructive additional method to assist in welfare studies. For birds with scores greater than 3, lameness may be viewed as severe enough to potentially impair welfare. It is difficult to assess all disorders in relation to frequency of occurrence and their impact on welfare due lack of evidence. BCO (or FHN and BCN) is the most common disorder and is often severe in form. TD (incl. epiphyseolysis) and rickets is common, often sub-clinical but when severe is a considerable impact on welfare. Contact dermatitis may be common under certain conditions and causes poor welfare when severe. Gastrocnemius tendon slippage, tenosynovitis, DJD and spondylolisthesis are not so common but are likely to cause poor welfare when they occur (i.e. pain and prevention of certain behaviours). VVD and rotated tibia can be common but tend not to be directly painful unless another condition is pre...

Two experiments investigated the welfare of pigs during transport. In experiment 1, 12 groups offour 90-kg pigs were transported to slaughter in a commercial livestock lorry for 1·5 h. Half the animals were transported in their social groups (unmixed condition) and half were transported with groups of previously unfamiliar pigs mixed together (mixed condition). Behaviour was recorded, a general activity index scored and saliva samples taken at different stages of the journey for analysis ofcortisol. Pigs spent most of their time standing in both conditions. The journey was very rough (as revealed by characterization with an accelerometer) and in the unmixed condition the pigs appeared to stand to reduce travel sickness. In contrast, in the mixed condition, this preference for standing seemed to be due to fighting which stressed and exhausted the animals (the general activity index was three times the unmixed condition). Levels of salivary cortisol were higher in the mixed condition at the beginning, middle and end of the journey. In experiment 2, six 35-kg pigs, prepared in advance with jugular vein catheters, were loaded onto a commercial livestock lorry (09.30 h) where they were individually penned. The vehicle remained stationary with the engine off and blood samples were taken at 30-min intervals during the next 8 h (control). Two days later this procedure was repeated while the vehicle was driven for 8 h (on main roads and motorways). Plasma concentrations of cortisol and beta-endorphin increased markedly in both conditions immediately after loading. Cortisol levels were greater (relative to control) at the beginning, in the middle and at the end of the journey. Concentrations of beta-endorphin did not differ between control and experimental conditions except during the final 180 min of the journey when the control levels were higher.

Two experiments were made to investigate the effects of road transport on stress hormone responses in pigs. In experiment 1, seven 40-kg pigs, prepared with jugular catheters, were loaded onto a livestock lorry and transported over a 2-day period on routes characterized, by means of an accelerometer, as rough or smooth. Two 100-min journeys, one rough and one smooth, separated by a 100-min rest period, were conducted each day. The experimenters travelled with the animals and blood samples were taken for hormone analysis from each pig at 20-min intervals. On the 3rd day, samples were collected from the pigs when housed in their home pen (control). Plasma concentrations of cortisol increased after loading, remained higher for longer on rough compared with smooth journeys and were higher during both journeys on day 1 compared with day 2. Concentrations of beta-endorphin increased after loading on day 1 but neither beta-endorphin nor lysine vasopressin showed clear changes in secretion pattern during rough or smooth journeys. On day 3 (control), mean concentrations of all three hormones were significantly lower than on days 1 and 2, indicating that the responses observed were not due to a diurnal rhythm. In experiment 2, six 35-kg catheterized pigs were loaded on a lorry (09.30 h) that remained stationary while blood samples were taken at 30-min intervals during the next 8 h (control). Two days later, this procedure was repeated with the vehicle in motion for 8 h. Plasma concentrations of lysine vasopressin during driving increased between 2 and 4·5 h which coincided with behavioural observations indicating that the pigs were travel sick.

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