Some factors affecting egg weight in domestic fowls

PART I. FACTORS AFFECTING EGG WEIGHT IN THE DOMESTIC FOWL.S.C. White Leghorn and White Wyandotte pullets housed behind ordinary glass and not given adequate amounts of vitamin D gave significantly lower average egg weights than comparable pens given adequate quantities of the anti-rachitic vitamin. The egg size was not significantly less in the irradiated ergosterol pen than it was in the cod liver oil pen. There was no significant difference in the egg weights for lighted and unlighted pens of Single Comb White Leghorn pullets. An all-in-one ration in pellet form gave significantly larger egg size than the same ration in mash form for both pullets and yearlings of the White Leghorn breed. Under the conditions of the experiment, both green food and oyster shell proved of value in increasing egg size when supplementing "All in one" rations. Fish meal proved definitely of greater value for egg size than decorticated extracted earth nut meal (peanut meal) and was slightly more valuable than extracted soya bean meal or meat meal. A mineral supplement did not materially increase the egg size when used with a meat meal ration, unlimited oyster shell being available. When a standard ration was fed to Cuckoo Leghorn Rhode Island Red cross pullets, egg size was not materially affected by the feeding of extra quantities of dried skim milk. When two rations of similar constitution and mineral analysis, but varying in protein content, were compared, there was no significant difference in egg size. There were no significant differences in egg size for either pullets or yearling Leghorns when fish meal replaced meat and bone meal, dried butter milk replaced dried skim milk, or decorticated earth nut meal (peanut meal) replaced extracted soya bean meal in a mixed protein ration. A mixed protein ration did not give a larger egg size than a simple protein ration. There were indications in several of the experiments that about April or May there is a turning point in an egg weight cycle. Further research is required to determine the relation of the protein and mineral content of the ration to the size of the eggs produced. It has not been possible to confirm previous work that proteins or minerals are of special value in regard to egg weight.PART II SEX LINKAGE IN THE DOMESTIC FOWL,PART III. A LEG COLOUR CHIMERA. A POSSIBT,F CASE OF SOMATIC MUTATION IN THE DOMESTIC FOWL.PART IV. A CASE OF POSSIBLE NON -DISJUNCTION IN THE DO /0STIC FOWL.PART V. THE INHERITANCE OF THE RE FACTOR IN THE RABBIT