KMK OK l.A'^INC AND I'.CC I'UODIH IION IM 



•_'. Menu iciiittr rlittch nizf. 



Tlie term clutch repres«^iits tlic mmilicr nf cfifi" l;ii<l on Miccc.><si\ c (biys. 

 I'lu- size of clutcli vjiries widely, witli a mean of from 1 to 21 ep:gs in the 

 population .studies. The total number of clutches from first egg to March 

 tirst was tabulated for each pullet. The number of eggs up to March first 

 was then divided by the number of clutches to obtain the mean winter 

 clutch size. In this manner ;i miMsurc of intensity was jirrivcd ;it without 

 employing the time interval. Moreover, it offers an index to the cajiacity 

 of the rei)r(>ductive organs for elaiiorating eggs on successive days. An 

 cb.jectionablc feature is apparent in that no evidence is ol)tained relative 

 to the ability of the birds to continue producing a definite clutch size. 



'A. Xet xc'iiitf-r rate. 



Net winter rate is determineil by dividing the total number of eggs 

 from first pullet egg to March tirst by the number of days from first egg to 

 .March first less all pauses of four or more days from Xoveml)er first to 

 .March first. This method expresses the rate of laying excluding winter 

 pause and an occasional liroody pause before March first. Compared with 

 mean clutch length, net winter rate is probably a sujierior measure of in- 

 tensity because it covers a definite time limit. 



\. .linuKil rate. 



Annual rate is indicative of the gross rate of laying from first pullet 

 egg to the onset of complete molt. This rate is obtained by dividing the 

 total eggs laid during the period by the number of days from first egg to 

 the beginning of complete molt in the late summer or fall if within 364 

 (lays from the date of first pullet egg. In cases where molting does not 

 begin until after the 365-day period, time is figured at 365 days. The rate 

 thus obtained does not make allowance for time lost in winter pause or for 

 iionproduction during broody ])eriods. Such a rate is, therefore, but a 

 crude ai)i)ro\irii.itioii of annual intensity. 



Character of Birds Used. 



The birds used in these studies are identical with those reported (ui in 

 .NFassachusetts .Agricultural Experiment Station Technical Bulletins 7, 8 

 and 9, except that data on the flock hatched in 1925 are added. All records 

 were made during the pullet year and all birds are pure bred Rhode Island 

 Reds. The flocks are somewhat heterogeneous in character including, in 

 addition to the major portion bred for high fecundity, a smaller propor- 

 tion bred each year for non-br()odiness, intense broodiness, high batcli- 

 ..bility, good color, and inbreeding studies. 



Scope of This Report. 



-Vs previously stated, four measures of intensity are made use of here. 

 .Vttention is given to some prominent environmental influences and to in- 

 lierited traits that may affect intensity. Major consideration is given to 

 tiie relation of intensity to winter and annual jiroduction. The report is 

 divided into sections .V. B, (" and 1) oti the basis of the four criteria of 

 intensity emjiloyed. 



