No abstract

The present paper describes the main procedures used to slaughter fowl, pigs, calves and adult cattle, sheep, and farmed fish, starting on the farm and ending with the death of the animal at the abattoir. It reviews the currently known causes of stress, indicated by behavioural and physiological measurements on the animal level, and by post-mortem muscle metabolism. During the pre-slaughter period, psychological stress is due to changes of environment, social disturbances and handling, and physical stress is due to food deprivation, climatic conditions, fatigue, and sometimes pain. The exact causes of stress depend, however, on the characteristics of each species, including the rearing system. For fowl, bird catching and crating, duration and climatic conditions of transport and of lairage and shackling are the main known pre-slaughter stress factors. For pigs, stress is caused by fighting during mixing of pens, loading and unloading conditions, and introduction in the restrainer. Handling and novelty of the situation contribute to the stress reactions. For veal calves and adult cattle, disruption of the social group, handling, loading and sometimes unloading conditions, fatigue, novelty of the situation and for calves mixing with unfamiliar animals are known stress factors. Gathering and yarding of extensively reared lambs and sheep causes stress, particularly when shepherd dogs are used. Subsequent transport may induce fatigue, especially if sheep are commercialised through auctions or markets. In farmed fish, stress is predominantly related to environmental aspects such as temperature, oxygen, cleanliness of the water and, to a certain extent, stocking density and removal of the fish from the water. If transport and lairage conditions are good and their durations not too long, they may allow pigs, calves and adult cattle, sheep, and fish to rest. For certain species, it was shown that genetic origin and earlier experience influence reactions to the slaughter procedure. Stunning techniques used depend on the species. Pigs and fowl are mostly electrically or gas-stunned, while most adult cattle are stunned with a captive bolt pistol. Calves and sheep may be electrically stunned or with a captive bolt pistol. Various stunning methods exist for the different farmed fish species. Potential causes of stress associated with the different stunning procedures are discussed. The paper addresses further consequences for meat quality and possible itineraries for future research. For all species, and most urgently for fish, more knowledge is needed on stunning and killing techniques, including gas-stunning techniques, to protect welfare.

No abstract

No abstract

The effect of stocking density on feed intake, feed utilization and feeding behaviour was studied in groups of rainbow trout submitted to different levels of food accessibility. In the first experiment, 18 groups of 100, 300 or 500 fish (initial individual weight 26 + 0.5 g) were held in 1 m 3 tanks where they were fed: in excess using belt feeders; or by means of self-feeders with a fixed reward level (4 g per trigger actuation); or a reward level proportional to fish density (2 g/100 fish/trigger actuation). Final biomass after 125 days was c. 25, 70 and 100 kg/m 3 in groups of 100, 300 and 500 fish respectively. Growth and feed intake was affected by fish density, feeding technique and reward level. However, feed efficiency, body composition, as well as nutrient retention and loss were unaffected by the treatment. In the self-fed groups, daily pattern of feeding activity was affected by fish density when the reward level was fixed but not when the reward level was proportional to fish density. In a second experiment, groups of 100 or 500 fish (same initial individual weight) had access to one or three self-feeders. Access to multiple self-feeders had no positive effect on any of the studied parameters. The fish used only one of the three feeders at a time, and the three feeders where not used equally. We conclude that feed intake but not feed utilization was impaired by increased density, indicating that density in itself is not stressful to the fish. Food accessibility is the main factor responsible for the observed density ± related decrease in growth.