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At present, we wish to know whether these groups differ one from another in respect to a winter cycle. Such a difference should probably be most apparent between high producers (210 eggs and over) and low producers (104 eggs and under). This is probable, because we know that winter production is an anomaly in wild fowls and has been developed arti icially by selection of extreme variates (or of mutants) in this direction, and because the chief increases in fecundity have been additions to seasons other than the normal season of egg laying in the spring. The seasonal distribution of egg production in low and high producers is shown in Table 10 and Fig. 7. Voting at present only the winter months, we cannot fail to remark the very great differences between the classes in the percentage of the total yearly production which occurs at this period. The rate of production is likewise different, being steadily upward in the low producers, while in the high producers the large increase in December over November production is followed by a very slow increase in January and February. The increase of February over January is in fact probably not significant. March shows a sudden increase in both classes marking the opening of the spring period. The uniform rate of production of the high producers is in marked contrast with the rising rate of the low producers. No let-up in this rate occurs to indicate the looked for pause between the winter and spring production. If we follow the percentage production in the winter months down through the various fecundity classes in Table 9, we find that the changes from the “low" type of winter production to the "high” type are continuous and gradual. High winter production is not attained by a discontinuous change such as we might expect if it were due to the addition intact of a separate and distinct cycle to the laying year. As far as the evidence from these Wyandottes is concerned, therefore, we must conclude that evidence of a distinct cycle is lacking, when all the birds are considered together or when the group is broken up into smaller classes differing in annual fecundity.
2. Spring Period.
The usual spring cycle of production is undoubtedly exhibited by these Wyandottes. This cycle in fact is probably present in all breeds of poultry and species of wild birds, since upon fecundity at this, the mating time, depends the reproduction and hence the survival of the species. Its inception is attended by an increase in mean production of March over February; a decrease in variability and the fact that practically every bird in the flock is laying in March. It is, however, de ined better by the general character of egg production during the whole period than by conditions surrounding its beginning or its ending, since we have seen that by all the criteria applied, the change from winter production into spring production is a gradual one. The winter period of fecundity was a time of increasing egg production; the spring is a period of stationary production. It is a climax of which the winter production was a foreshadowing, and the subsequent production an aftermath. In the case of these Wyandottes, this reproductive climax is extraordinarily sustained, since production is maintained at the same level through three months, March, April, and May.
3. Summer Period.
The ending of the spring or normal reproductive cycle is as poorly defined as its beginning. Ordinarily, broodiness ensues after the heavy spring production and a marked reduction in laying activities is noticeable. Conventionally the last of May is taken to mark the close of the reproductive cycle and the opening of the summer period. In the Wyandottes, however, this cessation is delayed and egg production in June is very similar in mean and variability, to egg production in the spring months. After June, egg production reaches a new stationary level lasting through July, August, and September. June may then be considered, on the basis of fecundity either as a part of the spring or summer cycle. The truth is undoubtedly that egg laying in this and in the summer months generally is not a result of a separate or induced physiological cycle, but merely a continuation of the one chief spring production period. The mechanism of reproduction, having been wound up, is only slowly running down. One factor in the running down in mean production after the spring cycle is the onset of broodiness and the cessation of laying on the part of broody birds. This has not had a serious effect on summer production in Wyandottes for a high mean production is maintained and the
number of zero producers (in this case usually birds which have stopped laying) is relatively small_2.7 per cent of the flock in June, 4.1 per cent in July, and 4.5 per cent in August (see Table 11). The slight increase in mean production in August, which has been already noted, probably indicates not only the maintenance of high egg production which is the striking feature of summer production, but also the recovery from broodiness on the part of a few affected birds.
4. Autumn Period.
If the characteristic of autumn production be the entrance of many of the birds into a period of reproductive quiescence accompanied by a molt, then in the Wyandottes this period is represented by but one month, October. September production) differs only slightly from August in the mean, in variability and in numbers of birds which have ceased laying. September belongs more properly, then, with the summer months in that egg production is maintained and nearly all the birds are laying. The change from September to October is, however, sharp. Mean egg production falls from 14.06 to 10.07; the coefficient of variability rises sharply from 50.10 to 75.09 and the percentage of the flock not laying rises from 6.7 per cent to 20.7 per cent (see Table 7). The onset of moulting in so far as it can be gauged by egg production is, therefore, relatively late in Wyandottes. They are good summer and fall producers and their leading position among the breeds submitted to the contest probably owes much to their superiority in these periods.
ANALYSIS OF EGG PRODUCTION IN THE SEPARATE Months
No attempt has been made to analyse exhaustively the frequency distributions of the separate months, since from the tabled frequencies (Appendix Table II) a close resemblance can be traced to the distributions for Barred Rocks which have been carefully analysed and illustrated by Pearl and Surface. In general the frequency distribution for each month is bimodal, indicating a division of all the birds in any one month into two groups. One group, with a modal production of no eggs (or very few eggs) may be called the zero (or low) producers. In the months before March these are chiefly birds
TABLE 10 'ARISON OF Low, MEDIUM AND Hon PRODUCING HENS ON THE Basis CF MONTHLY DISTRIBUTION OF EGG PRODUC
A-Actual DisTKIBUTION OF Eggs
B_PERCENTAGE DISTRIBUTION OF Eggs.
Class Frequency Nov. Dec, Jan.
Feb. Mar. Apr.
2496 2399 2213 2220
PERCENTAGE DISTRIBUTION OF EGGS IN THE FOUR SEASONS.
Winter Spring Summer Autumn Total
Med. 691 21.67 34.12 29.04. 15.17 100.00
which have not yet begun to lay; in the months after May this group although small is made up in large part of birds in which reproduction has taken place and then ceased until the next spring. The other group is characterized by a mode (as determined by observation only) of from 16 to 22 or 23 eggs. These are the good layers, and they are least numerous of course in the winter and fall months when the lower group is largest.
TABLE 11 PERCENTAGE OF FLOCK LAYING ZERO EGGS IN THE SEPARATE
GENERAL CHANGES IN THE SEASONAL DISTRIBUTION
OF EGG PRODUCTION In this section an answer is to be sought to the questions; Are there any indications of a general tendency on the part of the Wyandottes submitted during the nine years to lay a larger or smaller proportion of their eggs in any particular month or season? Has the seasonal distribution of egg production remained the same throughout the contests or has it changed and if so, how! Ever since fowls have been bred particularly for egg production, breeders have tried to change the normal seasonal distribution by increasing fecundity in the months when eggs are scarce and consequently high in price. Various systems of feeding and housing, the equalization of the length of days throughout the year by means of artificial lighting and the selection of high winter layers as breeders are all efforts in this direction. The last named effort together with