実験1∿5において4鶏種より得た1040個の鶏卵について, 材料検査機と富士平式卵殻強度計で長径方向又は短径方向より加圧して, 卵殻破壊強度を測定し, その卵殻の厚さと鶏卵比重との相関係数を求め, 卵殻破壊強度の測定方法について2・3の検討を行なった。卵殻破壊強度は材料検査機の方が高い値を示し, 加圧方向より見れば, 短径方向より加圧した方が低い値を示し, 変動係数も低かった。また, 両機の卵殻破壊強度と卵殻の厚さの間にr=(0.42)^∿(0.84)^, 卵殻破壊強度と鶏卵比重との間にr=0.44∿^(0.74)^の有意な相関が認められた。長径方向より加圧した場合, 富士平式卵殻強度計値X_1と材料検査機の卵殻破壊値Y_1 (kg)の間にY_1 (kg)=0.27+1.12X_1 (r=(0.93)^)また, 短径方向より加圧した場合, 富士平式卵殻強度計X^2と材料検査機の卵殻破壊強度値Y_2(kg)の間にY_2(kg)=-0.22+1.25X_2(r=(0.97)^)が得られた。The present study was conducted to compare the performances of two apparatuses and the derection of application in measuring egg shell strength. A total of 1040 eggs, collected from four commercial laying strains which were fed in wire cages, were used in five frials. Two readings were obtained using two apparatuses in the following : A) a testing machine (Tensilon UTM-4L type) and Fujihira egg shell strength tester. These two readings were made with of the compressive force measuring along the major axis and the minor axis of the egg. Specific gravity of the eggs was deterimined by immersing them in a series of saline solutions of ranging from 1.060 to 1.115. The average shell thickness of three points at the equatorial region was measured to the nearest 10μ.m. using a vice caliper. The shell membrances were removed in this measurement. All date were subjected to correlation analyses and regression analyses. The results are summarized as follows : 1) The egg shell strength measured by the Fujihira shell strength tester was lower than that by the Tensilon UTM-4L. 2) The egg shell strength and its coefficients of variation measured along the minor axis were lower than those along the major axis. 3) The correlation coefficients between the shell strength measured by both apparatuses and the shell thickness, ranged from (0.42)^ to (0.85)^ in all trial, and all values were highly significant. 4) The correlation coefficients between shell strength and egg specific gravity, ranged from (0.44)^ to (0.74)^ with all values being highly significant. These correlation coefficients were in good apreement with the date by many other researchers. 5) Linear relationship was found between the egg Strength (X)=measured by Fujihira shell strength tester and the egg strength (Y)=measured by Tensilon UTM-4L. 6) Regression formulas between those two are as follows : i) Compression along the major axis : Y_1 (kg)=0.27+1.12X_1 (r=(0.93)^) where Y_1(kg)=shell strength by the Tensilon UTM-4L, X_1=shell strength by the Fujihira shell strength tester. ii) Compression along the minor axis : Y_2(kg)=-0.22+1.25X_2(r=(0.97)^) where Y_2(kg)=shell strength by the Tensiron UTM-4L, X_2=shell strength by the Fujihira shell strengh tester
