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Hypoxia tolerances in nitrogen dilution chamber of chickens at sea level and high altitudes, discussing role of hematocrit and heart mass

INTRODUCTION CALCULATIONS of surface area of irregularly or asymmetrically shaped objects may involve complex measuring methods or mathematical computations. In those structures exhibiting symmetry, the procedure may be less complicated; for example, the total surface of a parallelepiped is equal to the summation of the areas of its sides. On the other hand, the surface area of objects has been reckoned using adhesive tape, weights of peelings, or by considering the surface as a function of the two-thirds power of the weight (Mueller and Scott, 1940). The surface area of avian eggs has been estimated in similar ways (Dunn and Schneider, 1923; Murray, 1925; Marshall and Cruickshank, 1938; and Romanoff and Romanoff, 1949), but the most useful and accurate methods have been based on the volume (Romanoff and Romanoff, 1949). However, if the object forms a surface of revolution, like an egg shell, it is possible to perform these measurements utilizing . . .

INTRODUCTION IT IS well known among those who examine egg contents that the blastoderm is found on the upper surface of the yolk—and more-or-less independently of the position of the egg’s major axis with respect to gravity. This characteristic location results from density gradients in the yolk and a general association of the blastoderm and the pole of minimum density. However, in a series of experiments on the effect of mechanical forces on embryo development (Besch, 1964; Besch et al., 1965), it was observed that the pole of minimum density did not coincide with the blastoderm position on the surface of the yolk. The present study was undertaken to determine these positional differences of the yolk and the influence of various factors on them. METHOD The egg used in these experiments were from Single Comb White Leghorns (Gallus domesticus), usually abbreviated S.C.W.L., and from Japanese quail (Coturnix japonica). After …

Differential effects of chronic exposure to increased acceleration on antagonistic skeletal muscle pairs in chickens

The hen's egg is a convenient and suitable model for biological systems in which mass is asymmetrically distributed. Under the influence of an acceleration field (such as provided by gravity on earth), such systems will become oriented, and this may have biological significance. However, depending upon the viscous and elastic properties of the system, some minimal force, i.e. a threshold, will be necessary for movement in the system. This threshold, and the restraining properties of the yolk-albumen boundary, have been evaluated for the hen's egg and are reported herein.

IT IS perhaps paradoxical that the quality of the non-edible portion of an egg is a primary factor in the production of market eggs. However, the importance of shell strength is indicated by its frequent study. In a recent review of the subject (Tyler, 1961), 16 methods of shell strength determination were reported. Subsequently different methods have been reported by Rehkugler (1962) and Frank et al. (1964). In general, quantitative studies of shell strength have been made by either static loading of eggs, or impacting some moving object against them. None of these methods simulate the more frequent conditions of shell failure—dynamic situations involving impact deceleration of the egg. Dynamic testing of egg shell strength requires large and complex machines—drop testers—which are not ordinarily available to those interested in shell quality. However, impact deceleration can be simulated by increasing the hydrostatic pressure of the egg contents. A…

Since 1953 a Phytotron Committee at Davis has been concerned with various means of controlling the environment of plants. A glass block-roofed phytotron unit which combined the best features of the greenhouse (sunlight) and the conventional growth chamber (insulation) was built and tested as a possible research tool. The present study reports details of the phytotron unit’s construction, operation, and maintenance; energy exchanges and operating costs; efficiency of the glass blocks as a light-transmitting medium; and preliminary experiments with plants. Incandescent lighting was investigated. Other devices, including reflectors and rotation of a room to face the sun, were studied. Some of the detailed information gathered during the course of this study has been omitted from this publication. The information is available, however, on microfilm for anyone having need for further details. Directions for obtaining a microfilm of this supplementary material will be found on the inside back cover.