February, 1921. 



SCIENTIFIC AGRICULTURE 



61 



aetei-s studied is in about the same order f"r both 

 ^gg protluction and size of egg'. While none shows 

 an exceptionally high correlation to production or 

 to weight of egg, all those showing a correlation 

 are important and should be considered collectively 

 rather than over-emphasising any one when selecting 

 birds. 



It will be seen by referiiug to table 7, that there is 

 a marked relation shown by the characters moa.sured 

 to weight of birds. The same holds true for tlie 

 measurements with respect to each other. This is an 

 important point to bear in mind when selecting birds, 

 for a hen may have depth, widt/i at hips and other 

 indications of being a good layer simply because of 

 her size. 



General Deductions. 



1. (a) Length and curvature of keel hone show no 



relation to total egg production, 

 (b) Straightne.s>s of keel is apparently affected by 

 precocity. 



2. Depth of body as shown by distance from back 

 to keel Ls related to egg production and more 

 particularly to iuten.sity of production. 



3. The greater the distance between the pelvic 

 bones and the greater the widt/i at hips, the 

 better a hen is likely to be as a layei-, pro- 

 vided thLs is not due to exce.«sive size for the 

 breed or strain. 



4. The less bending there is of the pelvic bonas 

 the better a hen is likely to be as a layer. 



5. A large abdomen, other things being equal, is 

 indicative of laying ability. 



6. (a) The optimum thickness or pelvis for the strain 



of Leghorns studied is approximately 1-8" to 

 9-32". In other ^vOrds, a hen with a very 

 thin or very thick pelvis (body wall) is likely 

 to be a relatively poor producer, 

 (b) A 'hen that has been brood.y during the sum- 

 mer will have a rfelatively t/vicker pelvis than 

 a nonbroody hen in the fall. 



7. (a) The optimum w^eight for the strain of Leg- 



horns studied apparently is approximately 3 



or 3 1-3 to 4 1-3 pounds, 

 (b) Birds that are very large or very small for 



their bi-eed or strain are- likel,y to be relatively 



poor producei-s. 

 (e) A bird that is very thin in the fall is likely 



to be a poor producer. 



8. (a) There is no relation between size of egg and 



total production or intensity of production, 

 (b) Length of keel is related to size of egg, i. e., a 



long keel is indicative of a large egg. 

 (e) Anatomical e^iaracters related to e.gg produc- 



tion are also related to size of egg. That is, 

 large birds, as indicated by weight, depth, size 

 of abdomen, width at hips and distance be- 

 tween pelvic bones, are likely to lay large eggs. 



9. One or two anatomical characters are not 

 enough for selecting layei"s. As many as pos- 

 sible .should be used. 



10. The present experiment indicates that there is 

 an "egg-type". 



Biblio^aphy. 



1. Anon. 1917-18. 



Sixth poultiy egg laying competition extend- 

 ing over twelve montjis 1917-18. E. S. R. 41, 

 4; 1919 digest from Utility Poultry Journal. 

 (Harper Adams Coll) 3," No. 12, pp. 1-28. 



2. Atwood, Horace. 1909. 



Some factors affecting the vigor of incuba- 

 tor chicks. W. Va. Agr. Expt. Sta. Bull. 124. 



3. Benjamin, Earl W. 1914. 



A Study of the Variation and Inheritance 

 of Size, Shape and Color of Eggs. Cornell 

 University Thesis. 



4. Hogan, Walter, 1914. 



The Call of the Hen (American School of 

 Poultrj- Husbandry). 



5. Kent, 0. B. 1917. 



Con.stitutional Vigor iu Callus Domesticas. 

 Cornell University Thesis. 



6. Lewis H. R., Hannas, R. R., and Wene, E. H. 1919. 



The Fir.st Two Years of tbe Viueland Con- 

 test. New Jersey Agr. Expt. Sta. Bull. 338. 



7. Patterson, C. T. and Quisenberrj', T. E. 1915. 



Missouri State Pnultrv Expt. Sta. (Mountain 

 Grove), Bull. No. 10," page 34. 



8. Potter T. F. 1905. 



Don't Kill the Laying Hen. 



9. Whitaker, Helen Dow. 1918. 



Hoganiziug vs Trapnesting in Determining 

 Egg Production. Rel. P. Journal, Vol. XXV, 

 No. 2. April 1918. 



10. Wilkins, R. H. 1915. 



A Study of t;ie Reproductive System of the 

 Female Domestic Fowl. Cornell University 

 Thesis. 



Acknowledgement. 



I wish to thank Dr. 0. B. Kent for suggesting this 

 experiment and for much helpful advice in earrj-ing 

 out tbe experiment as well as for -the use of prepared 

 records of the birds. I also wish to thank Dr. H. H. 

 Love for many valuable suggestions as to the bio- 

 metrical interpretation of the data. Credit is also 

 due to IMr. A. B. Holdeu aJid his a.ssistant for t,iieir 

 cheerful cooperation in measuring the birds. 



Subject. 



Table 9. 

 Relative. 



Weight of Egg Weiglit of Bird 



" Length of Keel 



" Total Egg Production 



" Di.st. Back — Posterior End of Keel 



" " Di.stanee Keel — Pelvics 



" Width at Hips 



" " Distance between Pelvics 



Coefficient of 

 Correlation. 

 .3838 ±.0344 

 .2532±.0377 



— .0118±.0403 

 .3593 ±.0351 

 .2194±.03S3 

 .2779 ±.0372 

 .2438±.0379 



