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The objective was to study the enzymatic production of triiodothyronine (T₃) in the intestine of chickens during perinatal intestinal maturation in two lines of chickens selected for high (HW) or low (LW) body weight at eight weeks of age. Valid assay conditions (proportionality of enzyme activity with enzyme concentration and assay time) were established and the intestinal 5'-deiodinase (5'D) activity was characterized for comparison with other tissues. The characterization studies showed that intestinal 5'D is like the Type I 5'D in liver of birds and mammals previously studied. Specific activity of adult intestinal 5'D is significantly higher in the HW than in the LW line. In both lines intestinal 5'D increases significantly between embryos that have not pipped into the air cell (NP) and embryos that have pipped into the air cell (AC) and 5'D activity peaks in embryos that have pipped through the shell (TS). In contrast to the line differences in adults, LW embryos have much higher 5'D specific activity than HW embryos until 1d posthatch. Plasma thyroxine (T₄) and T₃ also increased between consecutive stages and peaked in embryos pipped through the shell, then decreased abruptly at 1d posthatch. Both plasma hormones were higher at each perinatal stage in the LW line than in the HW line and the LW line hatched earlier than HW. Intestinal alkaline phosphatase (a marker of differentiation) showed a significant increase in activity at each of the stages of development in both lines. Alkaline phosphatase activity was significantly higher in the LW line than the HW line at the NP, AC and TS stages but not at 1d posthatch. Previous work in other laboratories indicates that T₃ plays a role in triggering intestinal differentiation and maturation of intestinal function for posthatching life. The results of this study indicate that T₃ for this signal originates at least partially from 5'deiodination of T₄ within the intestinal tissues as well as from T₃ available in the plasma. / Master of Science

Call number: LD2668 .T4 1978 A23 / Master of Science

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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Kwan Suet-ming. / Bibliography: leaves 75-94 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (M.Sc. (Animal Production)) -- University of Limpopo, 2014 / Two experiments were conducted to determine the effects of supplementing diets with effective microorganisms on intake, growth and carcass characteristics of Ross 308 broiler chickens. The first experiment determined the effect of supplementing diets with effective microorganisms on performance of unsexed Ross 308 broiler chickens aged one to three weeks. Two hundred unsexed day-old chicks were randomly assigned to five treatments with four replications, each replication having ten birds. A complete randomized design was used. The chickens were fed a grower diet supplemented with 0 (EM0), 30 (EM30), 50 (EM50), 70 (EM70) or 100 (EM100) ml of effective microorganisms per litre of water. Effective microorganism supplementation did not improve (P>0.05) diet and metabolisable energy intakes of the chickens. Effective microorganism supplementation reduced (P<0.05) growth rate and live weight of the chickens. Poorer (P<0.05) feed conversion ratios were observed in chickens supplemented with effective microorganisms. However, effective microorganism supplementation improved (P<0.05) crude protein retention of the chickens. Supplementation with effective microorganisms reduced (P<0.05) mortality rate of the chickens from 10 to 0 %. The second experiment determined the effect of supplementing diets with effective microorganisms on performance of male Ross 308 broiler chickens aged 22 to 42 days. The chickens were randomly allocated to five treatments with four replications, each replication having 10 birds. The chickens aged 21 days, weighing 474 ± 2g, were allocated to the treatments in a complete randomized design. The chickens were fed a grower diet supplemented with 0 (EMM0), 30 (EMM30), 50 (EMM50, 70 (EMM70) or 100 (EMM100) ml of effective microorganisms per litre of water. Effective microorganism supplementation did not improve (P>0.05) intake, DM digestibility, metabolisable energy, feed conversion ratio, fat pad weight and meat sensory attributes of the chickens. Effective microorganism supplementation reduced (P<0.05) growth rate, live weight and carcass weight of the chickens. However, effective microorganism supplementation improved (P<0.05) crude protein retention and crude protein content of meat of the chickens. Supplementation with effective microorganisms reduced (P<0.05) mortality of the chickens from 5 to 0 %. v It is concluded that effective microorganism supplementation to the diets of Ross 308 broiler chickens reduced growth rate and live weight of the chickens. However, effective microorganism supplementation improved crude protein retention and crude protein content of the meat of broiler chickens. Supplementation with effective microorganisms reduced mortality of the chickens to zero.

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