ANNUAL MOLT IN R. L REDS 3 



show clearly that many hens continue to lay while shedding wing primary feathers. 

 He noted also that wing secondaries and main tail feathers are not usually molted 

 until after laying ceases, and that molting of wing primaries was generally very 

 orderly. Low producing hens molted earlier and stopped laying earlier than 

 high producers. He observed that the period of non-production during the 

 shedding of the wing primary feathers is very important in its effect on annual 

 egg production, but the absolute length of time consumed in shedding the ten 

 wing primary feathers is not important in its relation to preceding egg production. 



Hays and Sanborn (1930), in a study of the non-productive period associated 

 with annual molt in Rhode Island Reds, showed that intense layers and persistent 

 layers generally stopped laying for a shorter period while in annual molt. They 

 found a significant negative correlation between previous egg production and the 

 length of the non-productive period during molt. Family mortality had no sig- 

 nificant effect on molt duration. Second-year egg production was greatly reduced 

 by a long period of non-production following the first-year record. 



Greenwood (1936) found evidence that molting is affected by the activity of 

 the gonads, and that time of molt has a genetic basis in females. His data also 

 suggest that the thyroid gland may be responsible for the onset of molt. 



Lippincott and Card (1939) stress the importance of late molting and also of 

 the ability to lay and molt at the same time. They point out that hens probably 

 do not lay while molting unless they are increasing or maintaining their body 

 weight. 



Hays and Sanborn (1939) showed that the length of the laying year in Rhode 

 Island Reds could be increased about 100 days by selective breeding. Their 

 data indicate that the length of the laying year is the most important character 

 affecting annual egg production and that it is governed by inheritance. 



JuU (1940) stressed the importance of late molting in relation to egg production 

 and called attention to the fact that late molting generally means a short period 

 of non-production. 



Lerner and Taylor (1941) reported an intimate negative correlation between 

 the date of last egg at the close of the first laying year and the duration of the 

 period of non-production associated with annual molt. Their data included 

 the records of 289 Single Comb White Leghorn females, giving a value of —.525 

 for the correlation coefficient and linear regression. 



Hays (1943) pointed out that late molting does not reduce subsequent hatch- 

 ability, a fact of very great importance in poultry breeding. 



EXPERIMENTAL PLAN 



Observations on males and females hatched in March and April of the pre- 

 ceding year began on July 25 and continued at bi-weekly intervals, usually to 

 near the end of the calendar year. Most observations included the following 

 feather regions: neck (cervical), breast (pectoral), thigh (femoral), lower leg (tib- 

 ial), back (dorsal), and wing primaries. In recording the progress of molt, the 

 grades suggested by Marble (1930) were used. The "0" grade indicated that no 

 feathers had been shed; the "slight" grade indicated the beginning of molt; the 

 "medium" grade indicated that about half of the feathers had been shed; the 

 "large" grade indicated well-advanced molt; and "complete" indicated that all 

 feathers had been dropped. The number of wing primaries shed was recorded 

 at each observation. Each bird was also weighed on each day of observation. 



During the first three years, observations were made on three generations to 

 secure data on the molting behavior of the stock. The birds used included both 

 production and exhibition Rhode Island Reds. Observation confirmed that the 



