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Articles by B.D. Fairchild
Total Records ( 3 ) for B.D. Fairchild
  V.L. Christensen , M.J. Wineland , I. Yildirum , B.D. Fairchild , D.T. Ort and K.M. Mann
  Avian embryo thyroid responses to incubator temperature and oxygen concentrations during the plateau stage in oxygen consumption were measured. It was hypothesized that turkey embryo thyroid responds in a limited way at this critical time to environmental conditions to modulate basal metabolism. Turkey embryos were exposed to one of four incubator temperatures (36, 37, 38 or 39oC) beginning on the 25th day of incubation at the onset of the plateau, a time when plasma thyroxine (T4) and triiodothyronine (T3) concentrations normally increase. Blood was collected and thyroid hormone concentrations were measured at pipping (27th day) and hatching (28th day). Elevated temperatures depressed T3 and T4 concentrations and increased the T3 to T4 ratios. In a second experiment four oxygen concentrations (17, 19, 21 or 23% oxygen) were provided to the embryos using identical procedures. The 21% treatment significantly reduced T3 and T4 at pipping compared to all other treatments, but 23% oxygen increased plasma T3 and the T3 to T4 ratio compared to all other treatments. The 17% oxygen treatment elevated T3 compared to all other treatments. At hatching, 23% oxygen elevated T3 and T3 to T4 ratios compared to all other treatments. When temperature and oxygen treatments were applied together in a factorial arrangement, temperature and oxygen affected T3 and T4 hormone concentrations independently but did not interact. Therefore, we conclude that temperature and oxygen are independent stimuli of the avian embryonic thyroid gland during the plateau stage, and that incubator temperature and oxygen concentrations can modulate development of turkey embryos by changing plasma T3 and T4 concentrations.
  M.W. Wineland , V.L. Christensen , I. Yildrum , B.D. Fairchild , K.M. Mann and D.T. Ort
  Incubator temperature and oxygen concentrations were tested as factors determining the intestinal maturation of two lines of broiler chickens. One line was a Low G line selected because its eggs display low eggshell conductance. The second line was a High G line that grew at a reduced rate and its eggs show high eggshell conductance values. All eggs were incubated normally until the 18th day of development or the beginning of the plateau stage in oxygen consumption. At that time the eggs were divided randomly and placed into experimental cabinets operating at 36, 37 38 or 39oC in experiment 1 or with 17, 19, 21 or 23% oxygen in experiment 2. In experiment 3, the best and worst conditions observed in experiments 1 and 2 were combined in a factorial arrangement. Body weight and intestinal maturation were measured by assaying for maltase and alkaline phosphatase activities in intestinal tissues. Increasing temperatures suppressed intestinal maturation whereas increasing oxygen concentrations enhanced intestinal maturation. When examined together in a factorial arrangement, it was clear that the effects of temperature and oxygen on the embryos were independent because they did not interact. The effects of temperature and oxygen were greater on Low G broiler embryos than they were on High G type embryos. It is concluded that incubator temperatures greater than 37oC, and oxygen concentrations less than 21% are detrimental to intestinal maturation in broiler chicks.
  M.J. Wineland , V.L. Christensen , I. Yildrum , B.D. Fairchild , D.T. Ort and K.M. Mann
  We hypothesize that temperature and oxygen in conjunction with genetic lines of broilers regulate embryo thyroid function. Thyroid response of broiler embryos of the two lines was measured at different incubator temperature and oxygen concentrations at the plateau stage in oxygen consumption (days 17 to 20 of embryo development). Each of the lines showed different eggshell conductance (G) values. Eggs of the same weight from the lines of broilers were incubated identically until the 17th day of development. On the 17th day (plateau stage in oxygen consumption), eggs were randomly distributed by line into four incubators operating at 36, 37, 38 or 39oC in trial 1 or at 17, 19, 21 or 23% oxygen in trial 2. At external pipping (the end of the plateau stage in oxygen consumption) as well as at hatching ten embryos or chicks per treatment were sampled for blood plasma. Plasma was analyzed for thyroxine and triiodothyronine concentrations. In trial 3, temperature line of broiler and oxygen treatments were arranged factorially. Increasing temperatures suppressed hormone concentrations in embryos, and the suppression was greater with low G. Increasing oxygen increased hormone concentrations in low G embryos to a greater degree than high G. It can be concluded that incubation temperature suppresses plasma thyroid hormone concentrations in low G lines whereas oxygen increases it.
 
 
 
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