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Pre-slaughter conditions, animal stress and welfare: current status and possible future research
- E. M. C. Terlouw, C. Arnould, B. Auperin, C. Berri, E. Le Bihan-Duval, V. Deiss, F. Lefèvre, B. J. Lensink, L. Mounier
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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.
Molecular characterization of prolactin receptor in tilapia
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- By P. Prunet, O. Sandra, B. Auperin
- Edited by S. J. Ennion, University of London, G. Goldspink, University of London
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- Book:
- Gene Expression and Manipulation in Aquatic Organisms
- Published online:
- 04 August 2010
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- 20 June 1996, pp 201-212
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Summary
Introduction
Prolactin (PRL) is a polypeptide hormone, which in all vertebrates except Cyclostoms is synthesized in the adenohypophysis (Schriebman, 1986). PRL belongs to a family of structurally and functionally related hormones which include growth hormone, placenta lactogen, proliferin in mammals and somatolactin in fish. Based on amino acid sequence homologies, it has been reported that these proteins have arisen by duplication of an ancestral gene (Bewley & Li, 1971; Takayama et al., 1991). Although in man, rat and turkey, PRL is the product of a single gene, the hormone occurs in multiple molecular forms, cleaved, phosphorylated or glycosylated whose discrete functions remain a matter of debate (Lewis et al., 1984; Clapp et al., 1989; Brooks et al., 1990). Among teleost fish, PRL was isolated in the tilapia species Oreochromis mossambicus (Specker et al., 1985), salmonids (Idler, Shamsuzzaman & Burton, 1978; Kawauchi et al., 1983; Prunet & Houdebine, 1984; Anderson, Skibeli & Kautvik, 1989), carp (Yasuda et al., 1987) and eel (Suzuki et al., 1991). Amino acid sequence identity between fish and mammalian PRLs is only 20–30% whereas it increases to 60–80% between fish PRLs. The major difference between fish and mammalian PRLs is the absence of one disulfide loop in the N-terminal region. Nucleotide and polypeptide sequences analysis of these fish PRLs revealed the existence of two distinct, albeit similar, genes in some species. This is the case for salmon or carp (Yasuda, Itoh & Kawauchi, 1986, 1987).
In tilapia species, Oreochromis mossambicus and O. niloticus, a somewhat different situation was described, and two much less similar PRL molecules were characterized (Specker et al., 1985; Yamaguchi et al., 1988; Rentier-Delrue et al., 1989).