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The influence of microbial phytase on growth performance, availability of macro and trace minerals, apparent ileal digestibility (AID) and apparent "fecal" digestibility (AFD) of amino acids (AA) and CP were investigated. The optimum level of dietary Ca and P for the maximum efficacy of supplemental phytase in broiler chickens was also studied. Phytase supplementation (600 U/kg) to a low P diet increased $(P 0.05)$ on feed efficiency in broiler chickens at 21 d. The efficacy of phytase, particularly in stimulating growth, was higher in male than female chickens. The relative retention of Ca, P, Cu, Zn and N increased by addition of phytase to a low P diet but phytase had no effect $(P >0.05)$ on the retention of Mg, Mn and Fe. Phytase supplementation increased $(P 0.05)$ on plasma Zn, Cu, and Mg. Phytase increased $(P 0.05)$ on mineral proportions in the tibia ash; however, it increased $(P 0.05)$ on AID of any of the AA in male chickens. Addition of phytase did not have any effect $(P > 0.05)$ on AFD of any of the AA in male chickens but increased $(P 0.05)$ on either AID or AFD of CP and AA at 21-d. In summary, phytase supplementation increased the growth performance, availability of P, Ca, Cu, Zn and N, plasma P, and tibia ash and reduced plasma Ca; it also increased the AID and AFD of most of the AA, particularly in female chickens at 28-d. The efficacy of microbial phytase was high when dietary P and Ca levels were low.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 22, 2009) Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Food Science, Nutrition and Health Promotion. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains v, 56 p. Vita. Includes abstract. Includes bibliographical references (p. 34-37).

Summer brooding often requires some form of air modification in addition to maximizing ventilation rate to prevent animal heat stress and possible death due to hyperthermia. A rockbed thermal storage module was designed and constructed to provide sensibly cooled air for a broiler space under summer brooding conditions. A mathematical model of rockbed thermal storage module was developed to predict performance of the prototype module. Experiments to evaluate the rockbed module under different weather conditions and operating schedules were conducted. The results were presented and compared with the mathematical simulation. A microprocessor control system was designed and assembled to control the ventilation air that would enter a broiler house during warm weather periods. The system was capable of taking temperature samples from thermocouples and then operate a damper arrangement which determined the mixture of outdoor and sensibly cooled air from rockbed thermal storage module. The cost and feasibility of utilizing a rockbed thermal storage module and a microprocessor control ventilation system were discussed. / Graduation date: 1989

Radioreceptor binding studies were carried out in broiler chickens in order to characterize adrenergic receptors on their abdominal fat adipocytes. The radioligands ($ sp3$H) DHA and ($ sp3$H) YOH were used to identify $ beta$- and $ alpha sb2$-adrenoceptors respectively. The determination of receptor criteria indicated that the optimal protein concentration for the simultaneous binding of both receptor types was between 0.35 and 1.0 mg/ml. Pharmacological specificity for both $ beta$- and $ alpha sb2$-adrenoceptors was demonstrated using receptor specific antagonists and an agonist. Saturation isotherms indicated that ($ sp3$H) DHA and ($ sp3$H) YOH labelled with high affinity, a homogenous population of non interacting $ beta$- and $ alpha sb2$-binding sites respectively. Scatchard analysis of the saturation data for ($ sp3$H) DHA revealed a Kd value of 8.1 nM and a Bmax value of 420 fmol/mg protein, while ($ sp3$H) YOH binding had a Kd value of 7.0 nM and a Bmax value of 68 fmol/mg protein. The variation in $ beta$- and $ alpha sb2$-adrenoceptor binding parameters was then investigated on the abdominal fat pad adipocytes of male and female broiler chickens at 4, 6 and 9 weeks of age. Scatchard analysis of the binding data for $ beta$-adrenoceptors indicated that Bmax values were greater in male and female broilers at 9 weeks of age (p $<$ 0.05) and that overall Bmax values were greater in females than in males (p $<$ 0.05). Scatchard analysis of $ alpha sb2$-adrenoceptor binding revealed that in females Bmax values remained constant but differed at all ages in males. The $ beta$-adrenoceptor Bmax values were always significantly greater (p $<$ 0.05) than the corresponding $ alpha sb2$-adrenoceptor Bmax values. / These results established for the first time the existence of adrenergic receptors on broiler chicken adipocytes using a radioreceptor binding assay. Although the physiological implication of these receptors is not known, it is a critical step toward the understanding of the influence of the adrenergic system on adipose tissue metabolism in avian species.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 107-127)

Thesis (M.Sc.(Agric.)) -- University of Pretoria, 2008. / Abstract in English. Includes bibliographical references.