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Öğe Incubator environment interacts with genetic line of broiler at the plateau stage to affect embryo plasma thyroxine and triiodothyronine concentrations(2006) Wineland M.J.; Christensen V.L.; Yildrum I.; Fairchild B.D.; Ort D.T.; Mann K.M.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 39°C 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. © Asian Network for Scientific Information, 2006.Öğe Incubator Temperature and Oxygen Concentration at the Plateau Stage Affects Intestinal Maturation of Turkey Embryos(Asian Network for Scientific Information, 2004) Christensen V.L.; Wineland M.J.; Yıldırum I.; Ort D.T.; Mann K.M.The plateau stage in oxygen consumption of turkey embryos occurs at 25 and 26 days of incubation when many embryos die. The plateau stage creates hypoxia, hypercapnia and presents a paradox for growth and embryo metabolism. Prior to the plateau, vital tissues accumulate glycogen to ensure embryonic survival through anaerobic metabolism during the plateau. Intestinal maturation at the plateau demands great amounts of energy. Therefore, the objective of the study was to define the temperature and oxygen concentrations at the plateau that affect intestinal maturation. Three experiments were conducted to test incubator conditions during the plateau stage and their affect on intestinal maturation. In Experiment 1, turkey embryos at the plateau stage were exposed to 36, 37, 38 or 39°C. In Experiment 2, embryos at the plateau stage were exposed to 17, 19, 21 or 23% oxygen concentrations, and in Experiment 3, the extreme levels of temperature and oxygen treatments were combined to test interaction effects on intestinal maturation. Elevating temperature depressed intestinal weight but not length. The elevated temperature also depressed intestinal maltase and alkaline phosphatase activities indicating inhibited function. Increasing oxygen had little effect on intestinal weight or length, but hypoxia increased maltase and decreased alkaline phosphatase activities in hatchlings. When examined in a factorial arrangement, temperature and oxygen displayed independent effects on growth and function and did not interact. Thus, incubator temperature greater than 37°C and oxygen concentrations less than 19% during the plateau stage delay intestinal maturation.Öğe Incubator temperature and oxygen concentration at the plateau stage in oxygen consumption affects intestinal maturation of broiler chicks(2006) Wineland M.W.; Christensen V.L.; Yildrum I.; Fairchild B.D.; Mann K.M.; Ort D.T.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 39°C 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 37°C, and oxygen concentrations less than 21% are detrimental to intestinal maturation in broiler chicks. © Asian Network for Scientific Information, 2006.
