Effets de l’inuline et des fructooligosaccharides sur la réponse au stress chronique chez les juvéniles de sandre (Sander lucioperca)

The goal of this study is to evaluate the effect of the inulin and fructooligosaccharides on growth and response to chronic stress of pikeperch juveniles (Sander lucioperca). Four treatments of two rates (10 and 20 g/kg of food) of these two feed additives were tested in three replicates using experimental feed granules on fishes of medium initial weight of 14,6 ± 0,4 g by and comparing them to two control groups (stress and no stress controls). For all treatments, the feed is composed of animal and vegetal meal having protein and fat contents of respectively 40,1 and 12,0%. As the goal was to evaluate if administration a prebiotic could limit the effects of chronic stress, the first stress was applied at day 7, and every week thereafter up to day 36, a total of five manipulations of pond drying. After 36 days of feeding, growth and physiological parameters were assessed. Comparatively to control fish, pond drying stress had no significant effect on fish growth rate. However, significant differences were observed at additive rate of 20 gr per kg the food (20 gr/kg) in treatment IN2 with values of GP (%) and SGR (%/day) that were higher than in others treatments. The level of cortisol was also higher of the stressed controls when compared to all other group, even those fed with prebiotics. Prebiotics had however significantly limited the increase in cortisol indicating their positive effect on stress response. From the results, other studies should test additional rates of probiotics to determine the optimal rate of prebiotics in the feed of pikeperch juveniles to limit the effects of stress. Keywords: Sander lucioperca, inulin, fructooligosaccharide, exondation stress, cortisol, glucoseL’objectif de cette étude est d’évaluer l’effet de l’inuline et des fructooligosaccharides sur le taux de croissance et la réponse au stress chronique chez les juvéniles du sandre (Sander lucioperca). Ainsi, quatre traitements constitués de deux doses (10 et 20 g/kg d’aliment) de ces deux additifs alimentaires ont été testés en triplicat via des granulés expérimentaux sur des poissons de poids moyen initial 14,6 ± 0,04 g en comparaison à deux groupes témoins (témoin stressé et témoin non stressé). Pour tous les traitements, l’aliment est constitué de farines animales et végétales avec des teneurs en protéines brutes et lipides respectivement de 40,1 et 12,0%. Étant donné que l’objectif est d’évaluer si l’administration de prébiotiques pouvait limiter les effets de la réponse au stress chronique, le premier stress a été appliqué à J7, puis par la suite une fois par semaine jusqu’à J36, soit au total 5 manipulations d’exondation. Après 36 jours de nourrissage, les paramètres de croissance et physiologiques ont été déterminés. Comparativement aux poissons témoins, le stress d’exondation n’a pas eu d’effet significatif sur la vitesse de croissance. Cependant, des différences significatives ont été observées à partir de 20 g/kg d’aliment au niveau du traitement à l’IN2 avec des valeurs de GP (%) et SGR (%/j) plus élevées que les autres traitements. Quant aux paramètres physiologiques, le niveau de cortisol était plus élevé chez les témoins stressés comparativement à tous les autres groupes, mêmes ceux nourris aux prébiotiques. Cependant, les prébiotiques ont significativement limité l’augmentation du cortisol indiquant une influence positive des prébiotiques sur la réponse au stress. Au vue de ces résultats, il serait souhaitable par les études supplémentaires de tester d’autres doses afin de déterminer le taux d’incorporation optimal de prébiotiques dans l’alimentation des juvéniles de sandre pour mieux limiter les effets de stress. Mots clés: Sander lucioperca, inuline, fructooligosaccharides, stress d’exondation, cortisol, glucos

Shannon Snow, soprano; Paul Feaver, tenor; Leslee Heys, piano; Katie Fang, piano

Shannon Snow, soprano; Paul Feaver, tenor; Leslee Heys, piano; Katie Fang, pianoShannon Snow et al: presented in partial fulfilment of the requirements for Music 440B. -- Katie Fang: presented in partial fulfilment of the requirements for Music 345B

Які соціально-економічні наслідки матиме скасування мораторію на продаж земель сільськогосподарського призначення в Україні?

This study investigated the long-term effects of total and partial replacement of dietary fish meal (FM) by a mixture of agricultural products on sperm quality of African catfish Clarias gariepinus. Four isonitrogenous and isoenergetic diets were formulated containing graded levels of either 50% FM and maize meal (diet 1); 25% FM mixed with crude sunflower oil cake (SFOC) and bean meal (BM) (diet 2); 12.5% FM mixed with sunflower oil cake, BM and ground nut oil cake (GOC) (diet 3) and 0% FM mixed with de-hulled sunflower oil cake (SFOCD), BM and ground nut oil cake (diet 4). Gonadosomatic index (GSI), sperm quality, plasma sex steroids (11-keto testosterone [11-KT]; testosterone [T]; estradiol-17beta [E2]) were evaluated on 10 to 24 fish fed on each diet. Sperm quality was assessed using computer-assisted sperm analysis (CASA). Total replacement of fish meal by plant products markedly increased sperm volume, spermatocrit, spermatozoa integrity, and sperm motility. Fish fed diet 3 (12.5% fish meal) provided intermediate results on sperm quality whereas the lowest values were obtained in fish fed diets 1 and 2. In fish fed 0% fish meal (diet 4), androgen levels were higher and estrogen levels were lower than in fish fed fish meal diets. Based on dietary lipid and fatty acid analyses, these results suggest a positive impact of short chain n-6 fatty acids on androgen synthesis and sperm quality. In conclusion, a combination of ground nut oil cake, bean meal and sunflower oil cake (preferably when the sunflower is dehulled) in African catfish diet improves the sperm quality

Efficiency of fatty acid-enriched dipteran-based meal on husbandry, digestive activity and immunological responses of Nile tilapia Oreochromis niloticus juveniles

peer reviewedThis study aimed to compare the enrichment capacity of polyunsaturated fatty acids (PUFA) and the long chain polyunsaturated fatty acids (LC-PUFA) of two dipteran species, Hermetia illucens - black soldier fly (BSF) - and a blowfly, Chrysomya putoria (CP), and to test its influence on growth, digestive activities and immune responses of Nile tilapia. Two types of enriched insect larval meal were produced using larvae cultured either on vegetable substrates (VGS) to formulate two diets rich in linolenic acid (ALA) (BSF/VGD and CP/VGD), or on fish offal substrates (FOS), in order to produce two diets rich in ALA and eicosapentaenoic acid (EPA) (BSF/FOD) or in ALA + EPA and docosahexaenoic acid (DHA) (CP/FOD). These four insect-based diets containing only palm oil as a lipid source were compared to a control diet based on fish meal (FM) and fish oil (FO). After 60 days of feeding, ALA or DHA muscle content of fish fed BSF/VGD or CP/FOD diet was comparable to that of the FMFO diet, and all insect diets increased the EPA muscle levels, except for a reduction by the BSF/VGD one. The CP/FOD diet induced similar fish growth, feed efficiency and protein efficiency ratio compared to the control FMFO diet, while a decrease was observed in fish fed other insect diets. Only BSF/VGD led to a decrease in protein and lipid digestibility. CP or BSF larval meal significantly increased alkaline phosphatase activity regardless of fatty acid (FA) enrichment. The expression level of fads2, fads6 and elovl5 was significantly higher in fish fed the BSF/VGD diet compared to fish fed the FMFO diet. FA-enriched insect diets increased some immune variables such as lysozyme, peroxidase and ACH50 values of fish fed CP/FOD, CP/VGD or BSF/VGD diets. Moreover, the expression level of β-defensin-1 and mhcII genes were significantly higher in fish fed the BSF/FOD diet than the FMFO diet. Also, the expression of the pro-inflammatory gene il-1-β was significantly higher in fish fed FMFO diet than in those fed CP/FOD diet, but comparable to fish fed all other diets. No significant effects were observed for the other tested genes. The results showed a better efficiency in LC-PUFA enrichment of the CP larvae compared to BSF ones, resulting in a higher stimulation of the fish nutrient utilization processes and therefore, a higher growth capacity. Nonetheless, all dipteran larval meal stimulated the immune status whatever the insect species or dietary essential fatty acids