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S C T E N T I 1-" i C A G R I C U L T U R E. January. 1921. 



The Relation of the Keel Bone to Egg Production 



V. S. A.siiiuiidson, Poultry Department, University of Britisli C'oluniliia. 



Introduction. 



For the past fifty years poulti-y has been selected 

 for fine feathers, graceful curves and other features 

 adding to their beauty. It was taken for granted for 

 manj' years that egg production would take care of it- 

 self. Within the last twenty years this viewpoint has 

 been gradually changing, particularly ^^^thin the last 

 few years. 



This change has come aliout partly through the or- 

 ganization of egg farms where it was foinid that show 

 points did not necessarily mean a good layer. Another 

 factor was the observation by certain breeders that 

 there was a change in size accompanying the change 

 from the laying to the nonlaying condition or vice 

 versa. This led to the development of so-called .sj'stems 

 for culling hens for egg production. These were based 

 on observations bj' the inventor of the "system" but 

 were not backed by actual evidence. One of the best 

 Iviiown nf these was the so-called Ilogan "system"' 

 wliich M-ill be dealt with later. 



Within the last few years experiment stations have 

 taken up the M-ork of determining whether there is an 

 egg type and in what way certain structural character- 

 istics are associated with production. Wilkins "15 did 

 some work indicating the clianges that would l)e ex- 

 pected to take place in a hen's appearance when 

 changing from the laying to the nonlaying condition. 

 The first and practically only extensive work done 

 to date is that of Kent (5) in connection with a study 

 of constitutional vigor. He has shown quite clearly 

 that many of the anatomical characters studied in this 

 experiment are related to laying conditions. A general 

 type as indicating productive ability is also pretty 

 generally accepted but not enough data are as yet 

 available .showing to what extent total ;niniial jiroduc- 

 tion varies with variation in structure. 



Object. 



The object of this experiment was to determine to 

 what extent the keel bone is related to egg production 

 and further to determine whether its relative position 

 is in any way related to total production, or the dis- 

 tribution of egg production. A study was also made of 

 the size of abdomen and the pelvic structures to deter- 

 mine their relation to egg production and partly to test 

 the reliability of the Hogan "s.ystem. "" A study of the 

 measurements taken in their relation to broodiness was 

 also made because of the effect of this condition on 

 total egg production. The object in each case was to 

 determine to what extent variation in structure is re- 

 lated to variation in production with a view to finding 

 their value in selecting birrls for egg production. 



Stock. 



Eight pens of single comb White Leghorn hens from 

 the general heredity experiment flocks of the Poultry 

 Department, at Cornell University, were used in this 

 experiment. Two of these pens were made up of low 

 line birds and six of high line birds or birds bred for 

 high egg production. Besides these about twenty liens 

 culled for market were measured. The total ntimber 



of birds used in the following tables is 280. Over half 

 the birds measured were finishing their first laying 

 year while the rest were finishing their second year of 

 laying. 



The birds within each line are fairly homogeneous 

 so far as breeding goes Init no attempt was made to 

 compare the high and low liiies. The range of pro- 

 duction was as great as might have been expected with 

 unselected birds and it is believed that the birds used 

 are a fairly representative random sample of single 

 comb White Leghorn hens. 



Measurements. 



All measurements were made by the writer, another 

 person holding the birds. The accuracy of the measure- 

 ments depends somewhat on the man holding the bii-ds 

 but it was impossible to have the same man do this all 

 the time. This disadvantage was probably sufficiently 

 offset by the care taken with the measurements. The 

 measurements were all made the latter part of October 

 and early part of November 1919, the period covering 

 about four weeks. 



The measurements, were made with calipers measur- 

 ing to millimeters. No attempt was made to measure 

 closer than thi.s but in averaging results all figures 

 were carried to hundredths of a centimeter. All except 

 about ten birds were measured twice and some showing 

 slight discrepancies were measured three times. Of the 

 ten birds measured onlj- once, one died, while the others 

 were sold before a second measurement was made. The 

 results from these were, however, fairl.v consistent with 

 the rest so that there probably was little or no error 

 from this source. The weights of all birds were rec- 

 orded each time that thej' were mea.sured, and the 

 average weight used. For this purpose a spring balance 

 weighing to ten grams was used and the weight 

 estimated to the nearest five grams. 



The following were recorded : — 



1. WEIGHT. 



2. LENGTH OF KEEL.— Measured by pressing the 

 calipers on the ends of the keel. This measurement was 

 quite consistent, rarely varying more than one mil; 

 meter on anv bird for the different times measured. 



3. CURVATUHE OF THE KEEL.— To get this three 

 measurements were made ■\\-ith the calipers, one from 

 the antero ventral, one from the midventral and one 

 from the postero ventral surface of the keel to a point 

 selected on the back. This point was the antero dorsal 

 surface of the ilium which forms a prominence easily 

 felt on the back of tlie fowl. The accuracy of these 

 three measurements depended largely on the pressure 

 exerted. Great care was taken to discover anj- dis- 

 crepancies and where these occurred, a third measure- 

 ment was taken to ensure accuracy, the average for the 

 three being used. 



4. ABDOMEN. — Measured by placing the thumbs 

 one against the end of the left pelvic bone and the other 

 against the posterior end of the keel. The calipers were 

 then placed against the thumbs. As with the last 

 measurements, accuracy depended largel.v on the press- 

 ure exerted, particularly on the keel, and it was neces- 

 sary to exerei.se care in iiaving the birds all held in the 



