Browsing by Subject "prebiotics"
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Item Effects of prebiotics on growth performance, nutrient utilization and the gastrointestinal tract microbial community of hybrid striped bass (Morone chrysops x M. saxatilis) and red drum (Sciaenops ocellatus)(2009-05-15) Burr, Gary StephenA series of experiments examined the effects of four potential prebiotics-- GroBiotic?-A (a mixture of partially autolyzed brewers yeast, dairy components and dried fermentation products), mannanoligosaccharide (MOS), galactooligosaccharide (GOS), and inulin/ fructooligosaccharide (FOS)--on the gastrointestinal (GI) tract?s microbial community in hybrid striped bass and red drum. The first in vitro experiment applied denaturing gradient gel electrophoresis (DGGE) to examine responses of red drum GI tract microbiota to anaerobic incubation with brewers yeast, FOS, and GroBiotic?-A. Brewers yeast and GroBiotic?-A produced unique microbial communities compared to that associated with the basal diet. Volatile fatty acid (VFA) profiles did not differ among treatments, with acetate being the major fermentation product. A second in vitro experiment examined effects of GroBiotic?-A, MOS, GOS, and FOS on the GI tract microbiota of hybrid striped bass. None of the prebiotics altered the culturable microbial community, but all tended to lower acetate production and increase butyrate production. A third experiment examined the effects of the four prebiotics fed to juvenile hybrid striped bass for 8 weeks. Growth, feed efficiency ratio (FER) and protein efficiency ratio (PER) were not affected by the different prebiotics, but the GI tract?s microbial community was altered from that associated with the basal diet. The fourth experiment consisted of an 8-week feeding trial and one 6-week feeding trial in which the effects of GroBiotic?-A and FOS on growth performance and microbial community composition were compared for red drum living in independent tanks versus tanks with a shared water system. Neither the intestinal microbial community nor growth performance were significantly altered by the prebiotics in these trials; fish in independent and shared water tanks produced similar results. The final experiment examined the effects of GroBiotic?-A, FOS, MOS and GOS on nutrient and energy digestibility of sub-adult red drum fed diets containing fish meal and soybean meal. The prebiotics generally increased protein, organic matter, and energy digestibility, with the exception of FOS/inulin. Lipid digestibility was decreased by GOS, MOS and FOS. These studies are the first to establish that prebiotics can alter the GI tract microbial community of these fish and influence nutrient digestibility.Item Evaluation of guar meal as a source of prebiotic galactomannans for laying hens(Texas A&M University, 2005-11-01) Zhang, ChengFour experiments were conducted to evaluate guar meal as a source of prebiotic galactomannans for laying hens. In the 1st experiment, late phase laying hens were fed diets with 0, 5, 10% guar meal (GM) for 56 days or 15% GM for 28 days then switched to the 0% GM diet for the final 28 days. In the 2nd experiment, young pullets were fed guar germ (GG) or GM at 0, 2.5 or 5% for 20 weeks. In the 1st and 2nd experiments, egg production and feed consumption were not affected by feeding up to 5% guar by-products whereas feed efficiency was decreased by guar feeding. Feeding of GG or GM did not affect egg weight or shell quality, but decreased the egg yolk color and Haugh units. Guar increased absolute and relative liver weight, but did not affect the weights of the pancreas, spleen, or the incidence of fatty liver or liver hemorrhage. Feeding 10% GM depressed feed consumption and increased body weight loss. Feeding 15% GM severely depressed egg production followed by a recovery of production after returning to 0% GM feeding. In the 3rd and 4th experiments, late phase laying hens were induced to molt by feed withdrawal (FW) or feeding 15 or 20% GM with or without β-mannanase (Hemicell??). All hens except those fed 15% GM with enzyme obtained a complete cessation of lay in 10 days. Compared to FW birds, hens fed GM had lower body weight reduction and mortality, while hens fed 20% GM with enzyme had higher post-molt egg production. Salmonella enteritidis (SE) present in 6 organs (crop, liver, spleen, ovary, oviduct and cecum), and SE in cecal contents were significantly reduced by 20% GM feeding with and without enzyme. The results showed that GG or GM can be safely fed to laying hens up to 5% without adverse effects on performance. An alternative molting method employing 20% GM with or without β-mannanase is preferable to FW because GM feeding results in a complete molt and decreases mortality, as well as enhances the resistance to SE of molted hens.