Date Of First Egg Research Articles

The Measurement of Sexual Maturity and Persistency

LERNER and Taylor (1937) have presented evidence that the length of the biological laying year cannot be considered an adequate measure of inherent persistency. They have shown that it is conditioned both by the age at first egg and the age at last egg previous to or at the onset of fall molt. Consequently it reflects both sexual maturity and persistency rather than the latter alone. When it is desired to determine persistency separately and when age at first egg is used to describe sexual maturity, age at last egg presents itself as a measure for such purpose.However, the biological laying year may be determined on the basis of the calendar year rather than on the basis of age. In that case, it may be considered to be conditioned by the date of first egg on the one hand and by the date of last egg on the one .

Effect of Ovarian Injury on Date of First Egg in Fowls

Previous papers by the author have shown that both ovarian and bodily injury caused certain fowls to lay more eggs. It was true also that other hens in the same experiment had their egg production retarded, hence a greater variability among the operated animals (Steggerda ’28 and ’30). In the present experiment the ovary of six-weeks old pullets was injured to note the effect upon the length of time until the first egg was laid. The results indicate a similar stimulation due to the operation since the operated pullets layed on the average sooner than did the control birds.The experiment was carried on at the Poultry Department of the Massachusetts Agricultural College, with birds owned by the College. The author wishes to express his thanks to Prof. J. C. Graham and Supt. John Vondell for the use of the birds and the keeping of the records, also to his .