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Browsing by Author "Cox, Chasity Marie"

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    The effects of dietary β-glucan supplementation on performance and immune response of broiler chicks during an Eimeria challenge
    Cox, Chasity Marie (Virginia Tech, 2009-12-09)
    Escalating consumer concerns have placed the poultry industry under mounting pressure to reduce the use of chemotherapeutic agents as feed additives. One possible alternative receiving increased attention is the use of immunomodulators such as β-glucan. A pilot study evaluated the effects of a yeast derived β-glucan (Auxoferm YGT) on growth performance and immune response of broiler chickens. Day-old chicks were fed a diet containing 0, 0.02, or 0.1% yeast β-glucan. On days 7 and 14 post-hatch, body weight and relative immune organ weights were measured, peripheral blood was collected to determine heterophil to lymphocyte (H:L) ratios, and small intestinal sections were sampled to evaluate relative gene expression. The addition of β-glucan had no influence on growth. Dietary β-glucan supplementation modulated the expression of interleukin (IL)-8, IL-18, interferon (IFN)-γ and inducible nitric oxide synthase (iNOS) in the small intestine. A subsequent study was conducted to investigate the effects of dietary β-glucan on broiler chick (1440 birds) performance and immune response during a mixed Eimeria infection (day 8 of age). Measurements were taken and samples collected on days 4, 7, 10, 14 and 21 post-hatch. The results from this study show that β-glucan supplementation did not negatively impact performance. The addition of β-glucan to the diet resulted in reduced gross lesion severity and increased H:L ratios. The gene expression results suggest that β-glucans are capable of skewing the host immune response toward aTh1 mediated response and consequently down-regulating the Th2 mediated response.
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    In ovo supplementation of Primalac and the effects on performance and immune response of broilers
    Cox, Chasity Marie (Virginia Tech, 2013-03-22)
    Probiotics are live nonpathogenic microorganisms capable of positively impacting the host by improving the natural gut microbial balance and promoting animal health. In ovo technology represents one means to administer probiotics and promote early colonization of beneficial bacteria for stimulating intestinal and immune system development, and warding off enteric threats. Three studies were conducted to evaluate the effects of in ovo administration of Primalac in broilers. The objective of the first study was to determine the effects of administering probiotics in ovo on hatchability, post-hatch performance and expression of immune-related genes in the ileum and cecal tonsils. On embryonic day 18, 360 eggs were injected with water, 1x105, 1x106, or 1x107 probiotic bacteria. Another 90 eggs remained uninjected as a negative control group. Measurements and tissue samples were taken on day of hatch (DOH) and days (d) 4, 6, 8, 15, and 22. A subsequent study was conducted to evaluate the effects of administering Primalac in ovo and in the diet on broiler chick hatchability, post-hatch performance, immune organ weights and ileal immune-related gene expression. At embryonic day 18, 1977 eggs were either not injected (negative control), dry-punched, or injected with 1x106 or 1x107 probiotic bacteria. Performance parameters were measured on DOH and d4, 6, 8, 14, 19, and 42, while immune organ weights and tissue samples were taken on DOH and d4, 6, 8, 14, and 20. A third study investigated the effects of in ovo administration of Primalac on hatchability, performance, immune organ weights, and lesion scores in broiler chicks exposed to Eimeria sp. At embryonic day 18, 210 eggs were injected with either sterile water or 1x106 probiotic bacteria. On d3 post-hatch, half of the chicks from each treatment group were challenged with a mixed inoculum of Eimeria acervulina, E. maxima, and E. tenella. Measurements and tissue samples were taken on DOH and d3, 9 and 15. The results of these studies suggest that in ovo Primalac supplementation does not negatively impact hatchability, enhances performance, modulates intestinal gene expression, and provides protection against a mixed Eimeria infection.