Browsing by Subject "hybrid striped bass"
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Item Evaluation of various dietary supplements and strategies to enhance growth and disease management of hybrid striped bass Morone chrysops x M. saxatilis(Texas A&M University, 2006-04-12) Li, PengThe US hybrid striped bass (Morone chrysops x M. saxatilis) industry has been negatively impacted by infectious diseases because there are very few approved drugs and vaccines. Therefore, a series of experiments was conducted to explore the potential use of various dietary supplements including autolyzed brewers yeast, the commercial prebiotic GroBiotic?, oligonucleotides and levamisole for improvement of hybrid striped bass growth, immunity and resistance to disease caused by various pathogenic bacteria. In two trials with brewers yeast, fish fed diets supplemented with yeast at 2% generally showed enhanced weight gain and feed efficiency compared with those fed a basal diet. Brewers yeast also positively influenced resistance to S. iniae infection. In addition, results of immune response assays demonstrated that brewers yeast can be administered for relatively long periods without causing immunosuppression. GroBiotic? (Grobiotic) also resulted in significantly enhanced weight gain, innate immune responses and resistance of juvenile hybrid striped bass to S. iniae infection. An additional experiment with sub-adult fish showed significantly reduced mortality of fish fed a diet supplemented with GroBiotic? at 2% when subjected to an in-situ Mycobacterium marinum challenge. This is the first report of positive effects from dietary prebiotics for fish health management, although many fundamental questions should be pursued further. Dietary supplementation of a commercial oligonucleotide product (Ascogen P?) at 0.5% of the diet was shown to enhance resistance of hybrid striped bass against S. iniae infection and increased their neutrophil oxidative radical production. However, the effect on growth was marginal. Dietary levamisole supplementation at a low level (100 mg/kg) enhanced the growth and feed efficiency of juvenile hybrid striped bass. However, an elevated dosage (1000 mg/kg diet) strongly suppressed growth, feed intake and feed efficiency. Hypothesized beneficial influences, including antibody production and resistance to S. iniae and A. hydrophila were not substantiated. Although dietary levamisole increased fish macrophage respiratory burst, an in vitro study failed to show a direct effect on cultured macrophages. This suite of studies demonstrated the potential use of some dietary supplements to enhance hybrid striped bass production. Thus, immunonutrition represents a valuable strategy to apply in aquaculture.Item Evaluation of Whole and Lipid-Extracted Algae Meals (LEA) in the Diet of Juvenile Red Drum (Sciaenops ocellatus) and Digestibility of LEA by Red Drum and Hybrid Striped Bass (Morone chrysops x Morone saxatilis)(2013-04-02) Patterson, Donovan AaronAs aquaculture continues to expand, protein sources have become more costly and less available. Simultaneously, lipid-extracted algal meals (LEA) (co-products of bio-diesel production) are becoming increasingly available as alternative sources of energy are investigated. By integrating LEA into aquaculture diets, feed prices could be lowered and bio-diesel production would have an additional revenue stream. Three feeding trials each of 7 weeks duration were conducted to evaluate five different algal meals as partial replacements for fishmeal and soy protein concentrate in diets for juvenile red drum (Sciaenops ocellatus). Apparent digestibility coefficients (ADCs) for CP and energy in various LEAs also were determined with red drum and hybrid striped bass (HSB). In the first trial, whole algae meal and LEA derived from Navicula sp. replaced 5 or 10% of the crude protein (CP) in the reference diet. Weight gain, feed efficiency (FE), hepatosomatic index (HSI), as well as protein and energy retention were not significantly (P>0.05) affected by the dietary treatments. Algal inclusion significantly affected the ADCs of the various dietary treatments for dry matter, CP, and energy. The inclusion of ash in the form of diatomaceous earth improved digestibility of protein as well as weight gain, survival and FE. A second feeding trial evaluated LEA derived from Chlorella sp. processed at high temperatures, replacing 5, 10, 20, and 25% of the CP in the reference diet. Weight gain, FE, survival, and protein efficiency ratio (PER) were significantly reduced at substitution levels of 20 and 25%. The third feeding trial evaluated LEA derived from Nanochloropsis salina, replacing 5, 7.5, 10, and 15% of the CP in the reference diet. Weight gain, FE, survival, and PER were significantly affected by some dietary treatments, with the 15% substitution levels causing significant reductions in performance. Intraperitoneal fat ratio and whole-body lipids were significantly lower in the fish fed the 15% substitution diet. Based on the results of these experiments, replacement of up to 10% of CP from fishmeal and soy protein concentrate with LEA was possible without causing substantial reductions in fish performance, and the whole algae product provided a more nutritious product. Red drum and HSB showed similar responses in their ability to digest CP and energy from the various algal products, although ADCs varied greatly among the different products and processing methods.Item Quantitative genetics of growth, carcass-quality traits, and disease resistance in hybrid striped bass (Morone chrysops [female] x Morone saxatilis [male])(2009-05-15) Wang, XiaoxueA 10 x 10 factorial mating design and a ?common-garden? rearing approach were employed to examine genetic effects and heritability of growth, carcass-quality traits, and disease resistance, important production traits in the aquaculture of hybrid striped bass (? white bass, Morone chrysops, crossed with ?striped bass, Morone saxatilis). Genotypes at four to ten nuclear-encoded microsatellites were used for parentage assignment and a general, linear-mixed model and a Restricted Maximum Likelihood (REML) algorithm were used to estimate variance components associated with dam, sire, and dam x sire interaction effects. Dam and sire effect on juvenile growth (weight, length and growth rates) were significant, whereas dam by sire interaction effect was not. Estimates of broad-sense heritability for growth, based on family means (h2 f), in dams ranged from 0.60 ? 0.20 to 0.82 ? 0.10 and in sires ranged from 0.43 ? 0.20 to 0.75 ? 0.18. High correlations were found between growth rates measured at two time intervals. Estimates of general combining ability for growth rates differed significantly among dams and among sires, whereas estimates of specific combining ability for each dam ? sire combination did not differ significantly from zero. These results suggest that additive-effect genes contributed to the differences in juvenile growth. Dam and sire effect on fillet weight were significant; dam effect on liver weight and sire effect on total viscera weight were also significant. Dam and sire effect on hepatosomatic index and viscerasomatic index were significant, as was dam and sire interaction effect on viscerasomatic index. Phenotypic and genetics correlations between body weight and carcass-quality traits were high (0.85 - 1.00). Phenotypic correlations between body weight and standardized carcass-quality traits were positive but low, ranging from 0.07 to 0.19. Resistance to S. iniae was assessed in a challenge experiment, using the 10 dam x 10 sire factorial mating design. A significant effect of sire on resistance to S. iniae was found, and offspring from one sire had a 2.4 times higher probability of dying than offspring from the ?average? sire. Genetic effects on the immune-response parameters and on stress-response parameters assessed were non-significant.