Effects of dietary vitamin A supplementation on growth performance, non-specific immune responses, and survival after Ichthyophthirius multifilis challenge in juvenile Largemouth bass (Micropterus salmoides) fed practical animal-based and plant-based diets

• Grant number: 14/19810-5
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: April 01, 2015
• End date: November 30, 2015
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: José Eurico Possebon Cyrino
• Grantee: João Fernando Albers Koch
• Supervisor: Rebecca Thoms Lochmann
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: University of Arkansas at Pine Bluff (UAPB), United States
• Associated to the scholarship: 13/17932-3 - Dietary vitamin A requirement for dourado (Salminus brasiliensis) e pacu (Piaractus mesopotamicus), BP.PD

Abstract

Vitamin A is a generic term for compounds with the qualitative biological properties of retinol. In nature, there are three active forms of vitamin A: alcohol (retinol), aldehyde (retinal) and acid (retinoic acid). Vitamin A is involved in many physiological processes for optimal function of an animal. Cell differentiation (vital for reproduction), function in vision, development of epithelial cells from stem cells (including mucus-producing cells), bone formation, and proper differentiation of immune cells in response to exposure to pathogens or foreign proteins. We will conduct two research trials simultaneously at Aquaculture Research Center, in the fish nutrition laboratory, University of Arkansas at Pine Bluff. Two experimental diets (the control in each study) will be formulated to meet the known nutritional requirements of largemouth bass, but replacing the fish meal and fish oil in diet 1 by vegetable ingredients (diet 2). In study 1 the control diet (un-supplemented with vitamin A) will contain animal and plant ingredients with most of the protein provided by fish meal. Diet 2 will contain just plant ingredients and will also be formulated to meet the known nutrient requirements of largemouth bass. The two experimental diets will be analyzed to determine the nutrient composition. After that, the quantity of vitamin A (retinoids) or provitamins (carotenoids) of this diets will be determined and depending on the results, we will formulate diets with 3-4 supplemental levels to each kind of diet (animal/plant or plant only). The vitamin premix will not contain any forms of vitamin A (retinoids). Feed-trained juvenile largemouth bass will be stocked in 110-l tanks and acclimated to laboratory conditions for 1 week after arrival. Fish will be fed with a commercial diet during acclimation. Five pretrial fish will be frozen at 70 °C for subsequent analysis of proximate composition and liver vitamin A content as described for the diets. After that, 20 fish averaging 5.0 g will be randomly selected and stocked into each of twenty aquaria for each study (4 replicates per diet), which will be randomly assigned to each treatment. Fish will be fed to apparent satiation twice daily (08:30 and 16:30 h) for 10 weeks. Mortality and specific vitamin A-deficiency signs will be documented. Growth performance: weight gain (g), final weight (g), feed intake (g), feed conversion ratio (g:g), specific growth rate, survival and protein efficiency ratio; Hematological assay: red blood cell counts, haemoglobin, haematocrit percentage, total plasma protein, mean corpuscular volume, mean corpuscular hemoglobin concentration, albumin concentration, albumin:globulin ratio; Immunological parameters (Non-specific): Lysozyme, Alternative complement assay, Leukocytes respiratory burst activity; besides a Challenge with Ichthyophthirius multifilis (Ich) will be performed in these trials. Data of each trial will be analyzed by one-way ANOVA (±=0.05) utilizing the MIXED procedure of the Statistical Analysis System (SAS) to determine if there is significant differences between dietary treatments. If significance is detected the data will be further analyzed by a regression method which is more suitable to determine the best response. (AU)