The pig appeasing pheromone (PAP) applied in spray has shown to be effective in reducing the frequency of aggression and the stress response of young and adult pigs under experimental conditions. This preliminary experiment investigates the effect of the PAP in a slow releasing block on the behaviour and skin lesions of weaners after mixing on a commercial farm. Two identical rooms containing six replicates per treatment of a commercial weaner building were used. There were two treatments (PAP block and Control) and each room contained one treatment. In the PAP treatment, the day before weaning and after washing and disinfection, two PAP blocks (1 block / 20 m2) were placed hanging on top of the pens. Six hours after mixing, there was a significant effect of the PAP block treatment on the occurrence of social negative behaviour (PAP mean; median [95 % CI] for median = 3.6; 2.7 [1.5-5.4] % vs. Control 8.3; 8.7 [6.1-11.3] % P = 0.003, social positive behaviour (PAP 5.5; 5.1 [4.5-6.8] % vs. Control 1.4; 1.3 [0-2.8] % P = 0.02), feeding (PAP 9.1; 7.4 [5.5-16.5] % vs. Control 1.6; 0.0 [0-6.1] % P = 0.02, drinking (PAP 3.1; 2.9 [2.5-3.9] % vs. Control 0.8; 0.5 [0-1.7] % P = 0.04) as well as on the sitting position (PAP 1.2; 0.9 [0-2.4] % vs. Control 4.1; 4.2 [2.1-6.0] % P = 0.02). Except for social positive behaviour (PAP 5.6; 6.0 [3.9-7.5] % vs. Control 2.9; 2.8 [1.6-4.2] % P = 0.02) those differences were not significant 24 h post-mixing anymore. The prevalence of wounded animals was not significantly different between treatments. The PAP in block form may be a promising tool to reduce food neophobia and aggression after mixing. Still, further research is needed to increase the effect of the PAP block over time under commercial farming conditions.

The screening of putative semiochemicals involved in the interaction between Lepeophtheirus salmonis copepodid and the Atlantic salmon could be used to develop methods to prevent infestation. A bioassay was designed to evaluate the attractiveness of Atlantic salmon for L. salmonis copepodids by counting the number of hooked parasites. A salmon was bathed in a tank with 60 copepodids during 45 min. The salmon was humanely killed and its body was scrubbed above a plastic bag. The content of the bag was filtered to count the number of hooked parasites. This procedure was tested at different water temperatures and for different body mass. The temperature significantly influenced the number of hooked copepodids (p < .05). Smolts presented significantly more hooked copepodids at a higher water temperature (24.6 at 13.8°C) compared to smolts at a lower temperature (18.6 at 6.1°C; p = .011). No correlation was found between the body mass and the number of hooked parasites (p = .65). This bioassay was used to successfully measure the attractiveness of Atlantic salmon for L. salmonis copepodids, making it an interesting tool to screen putative semiochemicals designed to prevent the infestation.

Stress is an important cause of illness and mortality in chick production. Stressors such as manipulation, absence of maternal care, transport, and housing can lead to welfare issues, immunodepression, and decreased productivity. The mother hen uropygial secretion analogue ( MHUSA ), a synthetic analog of a maternal semiochemical secretion, has been proven to protect chicks and broilers against stress, significantly reducing the heterophil-to-lymphocyte ratio. The aim of the present study was to test the effects of the MHUSA on chicks' stress when single-sprayed on their fluff at the age of 1 d. Two-hundred eighty ROSS 308 chicks were included in the study. At day 1, each chick received a spray of 200 μL of a 2% MHUSA aqueous solution (140 chicks) or the same amount of the excipient (control group, 140 chicks), and then chicks were housed in 2 separate rooms. To assess the persistence of the MHUSA after this single application, fluff was sampled from 10 chicks every day for 7 d and at day 13 and 19, weighed, placed in dichloromethane, and analyzed by gas chromatography. Blood smears and the bursa of Fabricius were collected every 3 d from 10 chicks of each group for 36 d to assess the heterophil-to-lymphocyte ratio and the bursa weight–to–BW ratio, respectively. Gas chromatography analysis showed that the MHUSA was present on chick fluff until day 5. The statistical analysis revealed that the heterophil-to-lymphocyte ratio was lower in the MHUSA group at day 4, 7, and 9 ( P < 0.0001 for day 4 and 7; P = 0.0377 for day 9). The bursa weight–to–BW ratio was significantly higher in the MHUSA group than in the control group from day 4 until day 29. These results confirm the beneficial effects of the MHUSA on chicks' adaptation to the new environment and on bursa of Fabricius development, suggesting its potential role in improving chicks' immune response.

sons no inondaient pins hare de coloration, ni de la chair, ni des \ i sec reel qu'ils auraient pu être sans inconvénient livrés à la consommation. Ce laps de temps de 8 jouis ne serait peut-être pas toujours suffisant et la prudence recommandeiait de la prolonger un peu pour armer à la certitude que les poissons sont complètement déeoloiés.

No abstract