64 



SCIENTIFIC AGRICULTURE 



February, 1921. 



There is also a hig'her correlation between this char- 

 acter and total egg production, intensity of egg pro- 

 duction and length of laying period than was the 

 ease with the size of abdomen. 



Thickness of pelvic bones or rather of the body 

 wall including the pelvic bones was estimated as ex- 

 plained before and tlien correlated wit,li production. 

 Only one correlation table is shown herewith, table 6, 

 but the otiiier coefficients of correlation are of the 

 same order. It will be seen that there is no relation 

 to egg production so far as this coefficient of correla- 

 tion shows but an examination of table 6 shows that 

 the high producers are grouped in three clas.ses and 

 that there is an apparent falling off in production 

 of birds with a very t/iin or veiy thick jielvis. Graph 

 I shows the mean production for the different classes 

 in table 6. The classes showing the highest mean 

 production coincide with those that include all the 

 birds in laying condition. These re.sults account for 

 tyhe low coefficient of correlation and indicate that 

 hens with very tliin or very thick pelvis are likely to 

 be relatively poor producers. The optimum thickness 

 is apparently approximately 1-8" — 9-32, but this may 

 be expected to vary somewhat, particularly for differ- 

 ent breeds. 



As mentioned before, Kent (5) found that thickness 

 of pelvis or body wall showed a marked relation to 



laying condition. The mean thickness of pelvis for 

 40 laying hens was 



6.888±.002z" 6.8334 + .0035" 



32 32 



for those that were not laying, .showing that there 

 was no difference in meaJi thickness at the time they 

 were measured. Account nuist be taken, however, of 

 the small number of birds laying and also that some 

 of these were only in laying condition at t/ie time 

 of either the first or second measurement and not for 

 both. Another is the distribution, the layers being 

 all confined to three classes 1-8" — 9-32", while there 

 is a considerable number of birds not in laying con- 

 dition that have thicker pelvic bones and some thin- 

 ner. T;iis is probably explained by the production of 

 eggs preventing excessive deposition of fat while very 

 thin pelvic bones would show that the bird was too 

 thin to be in laying condition. That there is a strong 

 correlation between thickness of pelvis and condition 

 is shown by the coefficient of correlation, — .4644 ± 

 .0316. T,iiis would therefore seem to indicate that 

 little difference is to be expected iu the mean value 

 for layers and nonlayers although the latter are 

 more variable. 



To get an expression for the bending of the pelvic 

 bones, the width at hips was divided into the distance 



GRAPH 1 



