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is not due to the absence of records, but rather to the form in which they have been presented. The individual is the unit of variation, and only when the records are presented in terms of individual production can any adequate idea of the variability be obtained. In many cases the pen totals only are given and the variation in egg production of the individual birds is ignored. We have been content with selecting a few comparisons from publications which provided the raw data in such form that they could be treated by the same methods as have been used in our own analysis. In order to secure as wide a geographical distribution as possible for the comparison, we have included averages obtained in egg laying competitions in South Africa, Australia, Canada and England. Other constants for Wyandottes in most of these localities could not be calculated because individual records were not reported. The data for comparison are contained in Table 3.
Caution is necessary in connection with the interpretation of the evident differences in mean egg production in this table. The size of the flocks in which the birds are kept is not always the same, being usually smaller in the foreign contests as stated in the foot-notes to the table. Again very little is to be added to these means as a correction for "out"
percentage of which, where this could be ascertained, being very small, averaging less than one per cent for all English contests. Other difficulties in the way of comparing production in widely different environments of groups of birds comprising all the varieties of one breed will doubtless suggest themselves to the poultryman. Nevertheless, certain of the differences are so great as to be of undoubted significance. In comparing American production with foreign, only those samples contained in the Vineland and Storrs Contests should be used, for the Maine constants are from a much earlier period and relate to production in an experimental flock housed under widely different conditions from those obtaining under contest management.
Bearing these limitations in mind, we may turn to the table and examine the differences in the various constants. In the first place, all of the foreign data are from England or British possessions, where the contest idea originated and
CONSTANTS OF VARIATION IN FIRST YEAR EGG PRODUCTION OF WYANDOTTES
AT OTHER PLACES.
1) Vineland, N. J.
Contest 1915-19 12) Victoria Contest
1) Bulletin 338; New Jersey Agr'l. Exp. Station October 1, 1919. Replacements included. Percentage
of out eggs 2.35 to be added to mean. Ten bird pens. 2) Bulletin 110; Part I U. S. D. A. Bur. Animal Indus. pp 49-50 Large flocks. 3) This bulletin. Ten bird pens. Replacements omitted. Out eggs 2.26 percent. 4) Report of Twelve Months Poultry Laying Competition held in conjunction with the Utility Poultry Club at Harper Adams Agr'l. College, Newport, Salop 1912-13, and 1913-14.
Six bird pens.
Replacements omitted. Out eggs both years. 34 percent. 1918-19 report in Utility Poultry Journal Vol. II, Dec. 1, 1919. In this year only small flock totals complete and used. Out eggs .88
percent 5) Report of the Twelve Months Poultry Egg Laying Competition held at Seddlescombe, Sussex. Util.
ity Poultry Club 1913-14. Four bird pens and large flocks combined. Replacements omitted. Out
eggs .6 percent. 6) Report of National Egg Laying Test 1918-19 held at Dodnash Priory, Bentley, Suffolk. p 74 Utility
Poultry Journal Vol. IV, No. 11 Dec. 1919. Six bird pens. Replacements included. 1.3 percent
out eggs. Report of 1920-21 test in Utility Poultry Journal VI:12 p. 370 1.00%_out. 7) Farmers' Bulletin No. 66, Dept. Agr. New South Wales. 1913. Ten years Egg Laying Tests at
Hawkesburg Agr'l. College and Exp. Farm, Richmond, N. S. W. Weighted first year mean for
all varieties of Wyandottes. Replacements included. Out eggs not reported. Six bird pens. 8) South Australia Dept. of Agr. Official reports of Egg Laying Competitions held at the Government
Poultry Station, Agr. College, Roseworthy, So. Aust. 1908-09; 1910-11 and 1911-12. 9) Ditto for Parafield, So. Aust. 1913-14. Six bird pens. Replacements included. Out eggs not reported. 10) Quoted from Bul. 110 Part I, U. S. D. A. Bur. Animal Indus. p 54. Weighted mean White and
Silver Wyandottes. 11) Union of South Africa, Dept. of Agr. Report on the Fifth Egg Laying Competition held at the school
of Agriculture and Experimental Farm, Potchefstroom. Weighted mean for all varieties of Wyan. dottes. Four bird pens. Out eggs not reported, but 1.07 percent unmarketable eggs omitted from
total. 12) Province of British Columbia, Dept. of Agr. Report of the Third International Egg Laying Contest
Oct 28. 1913 to Sept. 27. 1914. Eleven months total only. Replacements included. Out eggs not reported. Six bird pens.
where it has undergone its greatest development. In the second place, the means of production are in general significantly higher than in the American contests. The variability of the English Wyandottes in egg production is lower, both in absolute variability as measured by the standard deviation and in relative variability as measured by the coefficient of variation. Of the variability of the colonial birds in this respect we can have no exact information in the absence of individual records, but the impression gained from the pen variability and range of these birds is that they resemble the English Wyandottes. Further discussion of the significance of these facts will be found in the section on the general trend of egg production in Wyandottes.
DIFFERENCES IN THE ANNUAL EGG PRODUCTION OF
WYANDOTTES IN THIS CONTEST (a) Mean production.
The mean annual egg production has varied considerably from year to year. An examination of Table 2 and Figure 2 will demonstrate how large this variation has been. The mean production fell from about 155 eggs in 1911 to the low mean of about 148 eggs in 1913; rose abruptly to the high means of nearly 169 eggs in 1915 and 1917, and fell in the intervening year, 1918, to about 147 eggs, which is the lowest production recorded for any of the nine years. The major changes are not gradual but rather abrupt, indicating distinct differences in either the fowls entered in the contest or the conditions in the different years. It must be remembered that the annual means are computed on a different lot of pullets in each year and that there is probably little relationship between the pullets submitted in different years since they come generally from different breeders. A more important consideration than this is that the numbers of birds from which the records are obtained in any one year are in general too small to constitute a random sample of the breed. Before inquiring into the meaning of these differences in annual production, it will be necessary to determine which differences are statistically significant; i. e. which differences are inherent in the material and not due merely to the ordinary deviations encountered in taking two small samples of a population. In general, only those differences need be considered as possibly real or significant which are greater than three times their probable errors.
When the differences between each pair of years are computed together with their probable errors, it is found that (1) the mean production in 1915 and 1917 was significantly higher than in an other years except 1919 and 1914; (2) mean egg production in 1918 was significantly lower than mean production in 1914, 1915, 1917 and 1919; (3) mean production was significantly lower in 1913 than in 1915 and 1917.(7)
Of the thirty-six possible differences between different pairs of years only these twelve were found to be statistically (7) The table used in determining the significance of these differences is given in Appendix Table III.
significant. The differences between the other years are probably due to the errors of random sampling alone. The differences found suggest a division of the years into three categories as regards mean egg production: (1) the high years 1915 and 1917, (2) the "low" years 1918 and 1913(8) and the intermediate years 1911, 1912, 1914, 1916, and 1919 none of which differs significantly from each other. We have, the efore, to seek explanations only for the low mean production in 1918 and 1913 and the high means in 1915 and 1917.
The reasons for the low production in 1918 are more readily found. In this year, due to conditions brought about by the war, the care of the birds was far from normal. The attendants, in whom interest and experience are requisite to the best results in any poultry enterprise, were continually changing. Trapnesting, cleaning, feeding and care of the health of the birds often had to be entrusted to inexperienced and unskilled help with the result that the records made by all of the breeds in the contest were lower in 1918 than in
year. We need have little hesistancy in ascribing the low mean production of 1918 to environmental causes. Concerning 1913, the conditions causing low production are less certainly known except that weather and other conditions were apparently abnorinal for the first five months of the contest.
In 1915 and 1917, on the other hand, the environmental conditions were apparently similar to those of other normal years. In general as will be shown later, these were not years of extremely high production in the other breeds. It is probable, therefore, that the reasons for the high mean production of the Wyandottes in these years must be sought in the birds themselves. Since the Wyandottes observed in the contests in these years were significantly superior in fecundity to those submitted in other years, it is probable that they were possessed of innate abilities to lay more eggs. These explanations appear, in the light of the facts cited and others to be considered when the four breeds are compared, to be the most probable ones for the differences noted. They give further indications
(8) Note-From other data it is known that 1913 was a year of abnormally low preduction in all the breeds in the contest. It is included with the low group although its differences from the neang of the intermediate years are not statistically signit. cant.