| An automatic hypoxic simulation incubator was developed. Then eggs of Tibetan (T), Tibetan reared at Beijing (TB), Dwarf Recessive White (D), Shouguang (S), Tibetan×Dwarf Recessive White (TD), Tibetan × Shouguang (TS), Miniature Laying (M), Miniature Laying reared at Tibet (MT), Tibetan × Miniature Laying (TM), and White Laghorn (W) were incubated at Beijing (lowland), Linzhi (altitude of 2900 m) and Lhasa (altitude of 3650 m) of Tibet, and with normobaric hypoxic simulation at lowland, and with adding oxygen at highland. The hatchability and water loss were measured, and the distributions of embryonic death were analyzed with a multiphasic model, to study the mechanism of adaptability during incubation and key factors that influenced hatchability of eggs at high altitude. In order to understand the physiological mechanism of adaptation to highland and techniques of hybridization in Tibetan chicken, five groups of chicken, T, D, S, TD and TS, were fed at Beijing and Linzhi, and the vital organs, blood physiology, blood gas, LA, LDH, SDH, NO and NOS were measured at the age of one day, 2 weeks, 6 weeks and 10 weeks. The growths of weight and shank were analyzed with curve equations. The carcass performances and meat quality were conducted at the age of 70 days and 90 days. The results showed as follow:(1) The inflow of N2 was control automatically by information of O2 concentration, so the incubator was stable and convenient to simulate hypoxic condition. The incubator was refitted simply, and then it could be used to incubation adding oxygen at highland.(2) Tibetan chicken adapted to hatching at high altitude with lower water loss and metabolism during incubation, and the hatchabilities at Beijing, Linzhi and Lhasa were 87.4%, 79.51% and 30.70% respectively, and the values at high altitude were higher than that of lowland chickens. Heterosises of TD and TM in hatchability at high altitudes were better. The results of inter-groups and intra-group correlation between hatchability and water loss indicated that the embryonic vitality at highland was the most impartment for hatching at altitude of 2900 m. The multiphasic model that was developed in this paper was fitted to describe the distribution of embryonic death at high altitude, and to assess influences of environment and breed.(3) Normobaric hypoxia decreased the hatchability of lowland chickens at sea level, and hypobaric normoxia increased the hatchability at high altitude. The results indicated sufficiently that hypoxia was important reason that resulted in embroyonic death, and the embryo at early phase of incubation was the most sensitive to hypoxia.(4) In Tibetan chicken, the heart and lung were bigger, and the right heart index was in normal scope. Increased the efficiency of O2 transportation with higher RBC and MCHC, and lower Hct, MCV and MCH, the T have adapted to hypoxic condition. The blood contents of T were low, and the values at highland and lowland were similar, but the blood content of other groups at high altitude decreased significantly comparing with that at lowland, which was contributed by depressed plasma content. With lower venous pH, and higher venous PCO2, and lower venous and arterial PO2 in high altitude, the T wasbetter to unload O2 to tissues by blood, and had greater tension of driving O2 to enter into blood in lung, which was favorable for transporting O2 efficiently. The LA and LDH activity of heart muscle were low, and SDH activity was high, so its heart muscle cells depended on fewer anaerobic metabolisms, and could utilize O2 efficiently. The higher NOS activity in lung of T indicated that T was resistive to highland pulmonary hypertension and right ventricle hypertrophy.(5) Richards model was superior for fitting the growth courses of chickens at lowland and highland. The parameters fitted with Richards indicated that T showed lower final weight and initial specific growth rate, and higher inflection point time. The hybridation of TD had greater heterosis in final weight, inflection point weight, initial spec...
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