A comparison was made of rates of growth and body weights between pre- and post-hatching stages of development of the chicken as affected by strains or strain crosses, egg storage, egg weights, time of hatch, sex and post-hatching nutritional environment. The interrelationships of these factors were also investigated. The results of the investigation indicate that practically all of the variation of six-week body weight in this data was successfully accounted for by the combined effects of six-week growth rate, hatching weight and embryonic growth rate between eight and twelve days. The data also indicate that gains in six-week body weight may be made by selecting for early growth rate without concomitant change in other traits. Hatching time, hatching weight and post-hatching growth appear to be affected by egg storage only if some form of stress is present during incubation. In the absence of stress it appears that a compensatory increase in rate of embryonic growth overcomes the effect of a delayed initiation of growth caused by egg storage. A significant influence of sex on embryo weight in favour of the male embryos was observed. / Land and Food Systems, Faculty of / Graduate

Any mathematical formulation for depicting the growth of organisms must yield an empirical fit that is reasonably good. Its validity is enhanced if the equation yields information of biological interest. This investigation is aimed at applying the Parker-Larkin (1959) growth equation to a number of aquatic organisms to describe the problems encountered in making use of this technique. The data are also analysed by the Von Bertalanffy growth equation to bring out the similarities of the constants of both the equations. The data pertaining to three species of marine fish, brill, halibut and herring, four species of freshwater fish, rainbow trout, cutthroat trout and sturgeon and to a lamelli-branch species scallops, have been analysed. It is pointed out that the exponent of the length-weight relationship should not be taken as 3. It is shown that the length-weight relationship of rainbow trout varies depending on sex, maturity and size. In many species the Parker-Larkin growth equation predicted the lengths at various ages accurately. Von Bertalanffy’s equation progressively overestimated the sizes. In white sturgeon the growth increments decrease at first and then become equal. In such a situation it is suggested that the data be split into two stanzas for analysis since the analysis without splitting underestimates the sizes in the early years and overestimates in the older ages. The anterior radius of the scale grows relatively slower than the length of the fish in herring. The regression equation of the body-scale relationship is used only to obtain the value of the intercept. The back calculation of lengths is made by keeping the intercept constant with variable slopes for the individual fish. The Parker-Larkin equation gave an excellent fit for the data on halibut. This is because the observed values of halibut are actually calculated values from a linear logarithmic regression of weight on age - an algebraic equivalent of the Parker-Larkin equation in which the slope is the reciprocal of (l-x). The range of values of z between 1.0 and 1.5, when the line of best fit on a Walford plot approaches the 45° diagonal, is true for salmonids only and in similar situations for other species a value as high as 3.6 for z is obtained. The variability of z depending on the density of the population and/or availability or non-availability of food material is shown for rainbow trout. This dependence of z on the food available is similar to that of L₀₀ or W₀₀. There is an inverse relationship between L₀₀ and z as that of L₀₀ and Κ. It is tentatively suggested that z might be a parameter of physiological importance in the Parker-Larkin equation. Further work of an experimental nature is suggested to establish the physiological significance of the parameters of the Parker-Larkin equation. / Science, Faculty of / Zoology, Department of / Graduate

A series of 88 fetuses of the Columbian black-tailed deer (Odocoileus hemionus columbianus) was examined and measured. From the data obtained it was possible to reconstruct the probable sequence of changes in morphology and patterns of relative growth that occur during the development of the fetus. A series of stages of development was outlined, based on external morphological characteristics. The auricles of the ears appear to be the fastest-growing structures in relation to body length. The cranial portion of the skull grows in diameter faster than the inter-orbital region. In length, the preorbital and postorbital segments of the skull show similar growth rates. The neck grows in circumference relatively faster than the abdomen. The hind limbs grow faster than the fore limbs. Greater differences in patterns of relative growth were observed between this subspecies and the Northern white-tailed deer (O. virginianus borealis) than between the black-tailed deer and Rocky Mountain mule deer (O. h. hemionus). Some sources of variation were examined, including technical problems, individual differences, differences between the sexes and the relationship between size and form. Not all regions appear to develop at the same rate in different animals Males were found to.be larger than females at the same stage of morphological development. Some body dimensions had a much higher correlation with structural change than did others. / Science, Faculty of / Zoology, Department of / Graduate

A review was made of environmental technology as applied to the engineering and construction of artificial environments for plant physiology research. The results of this study were utilized in the development of an artificial environment which incorporated the nutrient mist technique of growing plants. The quality of the environment in plant growth chambers is partly dependent on the type of control instruments used. Solid state electronic control devices offer many advantages, particularly with respect to accuracy, responsiveness, reliability and remote control. A travelling sensor was developed to detect the environmental conditions within artificial environments by remote control. This sensor greatly increased the rapidity and convenience of measurement with minimum disturbance of the environment. The conditions of light intensity, temperature, wind speed and humidity within a commercial growth chamber, the Percival Model PGC-78, were analysed. The results indicated that the chamber's performance was quite nonuniform for all the variables tested. The manufacturer's specifications for the chamber were considered to be limited in extent and to some degree misleading. The design of the artificial environment system constructed for this project is described. With this system, temperature control of ±½°C was achieved within the plant growth area. In addition, the uniformity of light intensity and air flow in the constructed chambers was superior to the PGC-78. / Land and Food Systems, Faculty of / Graduate

Hereditary multiple exostosis is a generalised, heritable disorder of bone, characterised by the appearance of numerous cartilagecappecl exostoses at the juxta-epiphysial regions of the endochondral skeleton. The condition was apparently known even in Hunter's day and most of its characteristic features were described before the end of the nineteenth century. Nevertheless, the evolution of these curious lesions, their unusual distribution and the associated abnormalities of growth are still incompletely defined and largely unexplained.

One hundred crossbred beef steers were used in two experiments to evaluate effects of growth implants on performance. Steers were implanted either at 3.5 months and weaning (CALF); at weaning (WEAN); or not implanted (NONE). In Experiment 1 implanted steers weighed more at weaning (P = 0.01), and had a higher ADG for the entire trial compared to non-implanted steers (P = 0.03). In Experiment 2, at 80 d post wean, implanted steers outweighed NONE (P = 0.09). Overall ADG (P = 0.01) was greater for cattle that were implanted. In the feedlot the CALF group had the lowest ADG (P = 0.01), and final BW (P = 0.07). At harvest CALF had the highest dressing percentage (P = 0.04), smallest LMA (P = 0.1), and lowest IMF (P = 0.06). Implants can increase productivity in beef cattle however, marketing and management strategy will dictate use.

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No description available.

No description available.

A new approach has been introduced to characterize the epidermal growth factor receptors and their relation to the mechanism of cell growth control using hybrid cells made between human EGF responsive cells and mouse A9 cells incapable of EGF binding. BALBc mice were immunized with human carcinoma A431 cells carrying an extraordinary high number of EGF receptors; antisera were used to identify the human nature of EGF receptors in these hybrid cells. One of the hybrid lines, C2B5, that retains only one human chromosome, an X/7 translocation, and a nearly complete mouse parental genome was used to analyze the relationship of the binding ability and certain post-receptor functions to the cellular mitogenic response. It was shown that the ability to bind, internalize and degrade the ligand and/or its receptor is not sufficient for cells to respond to the mitogen. Spleen cells from mice immunized with A431 cells were fused with mouse myeloma P3NP cells. One of the isolated hybridoma lines, B4G7, secreted a monoclonal antibody of the IgG class which inhibits the binding of ¹²⁵I-EGF to A431 and human fibroblasts, but not of mouse 3T3 cells. This inhibition was partial (65-70%) and Scatchard analysis of the binding data suggested that antibody preferentially interacts with a low affinity class of EGf receptors. The antibody specifically precipitated EGF receptor from radiolabeled cells. This monoclonal antibody was crosslinked to subunit A of toxic ricin through a disulfide bond. The resulting conjugate inhibited protein synthesis of A431 cells at 4 x 10⁻¹¹M and exhibited substantial cell killing. Using this conjugate we isolated a variant of A431 cells, designated C1-B7, with approximately 30 times less EGF binding capacity. Contrary to the parental A431, this variant is resistant to EGF-induced suppression of cell growth and appears to have lost most of the low affinity receptors. The high affinity type EGF receptors retained by the variant are 170,000 Mr and susceptible to EGF-induced phosphorylation, presumably on tyrosine residues. In membrane prepared from this variant, besides the EGF receptor, a low molecular weight component of as yet unknown nature is highly phosphorylated in an EGF-independent manner.