Mississippi State University - Catfish Nutrition Lab
Mississippi State University - Catfish Nutrition Lab
Dr. Fernando Yamamoto
1,2Jing Huang, 3Heather Jordan, 4Caitlin E. Older, 1,5Matt J. Griffin, 2Peter J. Allen, 1,2David J. Wise, 1Penelope M. Goodman, 1J. Grant Reifers, and 1,2Fernando Y. Yamamoto
1Thad Cochran National Warmwater Aquaculture Center, Mississippi Agriculture and Forestry; Experiment Station, Mississippi State University, Stoneville, MS 38776; 2Department of Wildlife, Fisheries, and Aquaculture, College of Forest Resources, Mississippi State University, Starkville, MS 39762; 3Department of Biology, Mississippi State University, Starkville, MS 39762; 4Warmwater Aquaculture Research Unit, Agricultural Research Service, Department of Agriculture, Stoneville, MS, 39762; 5Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, MS, 38776
Probiotics aid in driving multiple physiological reactions, including altering the intestinal architecture and immunity. Data have shown the benefits of dietary probiotics in aiding psychological disorders. In fish, some probiotics have presented beneficial effects on regulating stress responses. In the present study, a novel autochthonous probiotic, Lactococcus lactis MA5, previously isolated from hybrid catfish (Ictalurus punctatus × I. furcatus), was tested as a dietary supplement to improve stress regulation of hybrid catfish subjected to acute hypoxia conditions. In total, 450 hybrid catfish juveniles (~16.4 g) were equally distributed into 18 tanks operating as a flow-through system. During the feeding trial, each tank was assigned an experimental diet (Control, 104, and 106 CFU/g of lyophilized MA5) in a completely randomized block design (n=6), using rations corresponding to 3-4% of the biomass for 56 days. Tank biomass was recorded bi-weekly during the feeding trial and feeding rations were adjusted accordingly. Fish receiving diets supplemented with 106 CFU/g MA5 presented a significantly higher average body weight since week six, and the thermal unit growth coefficient significantly increased after fish received the probiotic supplemented diet. After the feeding trial, fish were subjected to acute hypoxia challenge (stress gave under 1.8-2.0 mg/mL dissolved oxygen environment for two hours with 10 fish in 22.5L aquarium tank) and blood parameters including hematocrit, hemoglobin, red blood cell count (RBC), and total protein levels were evaluated. Fish fed the dietary probiotic presented higher hemoglobin and RBC after hypoxia conditions, when compared to the fish under normoxia conditions (control group). Overall, fish receiving probiotic diet for 56 days had improved growth performance and were better able to with cope hypoxic stress.
1,2Crystal L. Conde, 1,3Vitor F. Silva, 1Ana Beatriz de S. Farias, 1,4Thiago M. Santana, 1Penelope M. Goodman, 1J. Grant Reifers,5 Caitlin E. Older, 2Peter J. Allen, and 1,2Fernando Y. Yamamoto.
1Thad Cochran National Warmwater Aquaculture Center, Delta Research and Extension Center, Mississippi State University (MSU), Stoneville, MS, 38776; 2Department of Wildlife, Fisheries, and Aquaculture, MSU, MS, 39762; 3AQUOS- Aquatic Organisms Health Laboratory, Department of Aquaculture, Federal University of Santa Catarina; 4Graduate Program of Animal Science and Fisheries, Federal University of Amazonas, Manaus, AM, Brazil; 5Warmwater Aquaculture Research Unit, Agricultural Research Service, U.S. Department of Agriculture, 141 Experiment Station Rd., Stoneville, MS, 38776, USA.
Soy lecithin (SOL) has been shown to improve the ability of farmed fish to cope with stress. The objectives of this study were to determine the optimal SOL inclusion level for channel catfish juveniles in a dose-response experiment, and assess if SOL can improve the physiological responses of the fish after an air exposure stress challenge. Experimental treatments were formulated using plant-based ingredients, and SOL was included at 0, 0.5, 1.0, 1.5, and 2% in expense of soybean oil. The 750 channel catfish juveniles (~4.4g) were equally distributed in 25 tanks (n=5; 30 fish/tank) operating as a recirculating aquaculture system and fed for 70 days. At the end of the feeding trial, production performance, blood samples, digesta, and condition indices were computed. The catfish fed the diet containing 1.5% SOL presented higher weight gain and better feed efficiency when compared to the control group. Four days after the feeding trial, the remaining fish were exposed to an acute air stress challenge for 2 minutes. Blood samples were collected after 0, 0.5, 1, 2, and 6 hours. A higher hematocrit was observed for fish fed with 2% SOL when compared to the 1.0% SOL group. No significant differences were observed for hemoglobin and erythrocyte count. No statistical differences were observed for the whole-body proximate analysis; however, the protein conversion efficiency was significantly higher in 0.5% SOL (38.45 ± 2.26). Intestinal microbiota presented significant differences only for alpha diversity (Pielou’s evenness index; p=0.046). The sampling after the air exposure challenge demonstrated statistical differences among all treatments for hematological parameters. The analyses of stress markers are ongoing. The preliminary results of this study indicate that the supplementation of 1.5% SOL can enhance the growth performance of channel catfish juveniles.
Cristian C. Suarez1,2, Heather R. Jordan3, Caitlin E. Older4, Matt J. Griffin1,5, Esteban Soto6, Fernando Y. Yamamoto1,2
1Thad Cochran National Warmwater Aquaculture Center, Delta Research and Extension Center, Mississippi State University (MSU); 2Department of Wildlife, Fisheries, and Aquaculture, MSU; 3Department of Biology, MSU; 4Warmwater Aquaculture Research Unit, Agricultural Research Service, U.S. Department of Agriculture; 5Department of Pathobiology and Population Medicine, College of Veterinary Medicine, MSU; 6Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis
The aquaculture industry urgently requires alternative therapeutic agents that can effectively manage bacterial diseases without contributing to the growing problem of antibiotic resistance. Plant-based compounds have been traditionally used and scientifically validated as nutraceuticals, immunostimulants, or antibacterial agents in numerous in vivo and in vitro experiments. Despite this, there remains a significant gap in understanding how these phytochemicals can impact the bacterial metabolic pathways during infections in fish. With this in mind, the objective of this research was to evaluate the potential suppressive effects of the phytocompounds Citral, Carvacrol, and Thymol on pathogenic bacteria in fish. These substances were subjected to testing against a range of bacterial strains, including Aeromonas hydrophila (ML09-119 and S14-452), S. ictaluri (CNA2848), Streptococcus agalactiae (RUSVM-CV), Edwardsiella ictaluri (S97-773), E. piscicida (S11-285), S. iniae (LSU 01-105, LSU 10-070, LSU 94-034, LSU 96-525, LSU 94-0.36), and S. dysgalactiae subsp. equisimilis (STC3), to determine their inhibitory capabilities. The antagonistic effects of selected phytochemicals were tested against bacterial pathogens using disk diffusion assays at a concentration of 50 mg/ml and broth microdilution assays at 1.56 mg/ml to evaluate their antibacterial efficacy. Additionally, the ability of these compounds to prevent bacterial biofilm formation was tested using gentian violet staining. Hemolytic activity was confirmed using 5% sheep blood agar–Brain Heart Infusion plates and inhibition of hemolysis was determined by evaluating serial dilutions of the phytocompound since 195 μg/ml after 24 hours of incubation. The disk diffusion method indicated that carvacrol and thymol markedly suppressed the growth of all bacterial strains tested. These findings were corroborated by broth microdilution assays, which helped establish the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for the pathogens. In biofilm inhibition assays, sub-MIC levels of the compounds significantly hindered the adhesion of bacteria to polystyrene surfaces. The three phytocompounds significantly inhibited the hemolytic activity of A. hydrophila and S. iniae. The findings indicate that incorporating these nutraceutical phytocompounds into the culture media, even at concentrations below the determined minimum inhibitory concentration (MIC), can significantly impact the normal metabolism of an array of fish pathogens. These preliminary results set the foundation for further studies investigating the viability of these botanical extracts as a prophylactic treatment or even as substitutes for traditional antibiotics in the management of bacterial diseases in fish.