Abstract
Out of a stock of the Plymouth Rock of 83-86% broodiness, three cocks which were not made broody by Prolactin-injection, and two hens of no and very weak broodiness, were selected. As the result of 5 years (1950-1954) of interbreeding of these five parental birds and their offsprings, a total of 129 hens were obtained. Of these hens, only five showed broodiness and all the rest were proved to be non-broody. Table 3 shows the percentages of broody hens occurred in each experimental year: the average rate of broodiness abruptly decreasing from original 84.5% to 3.8%. This result indicates the usefulness of prolactin-injection method for broodiness elimination in the domestic fowl.
