THE ADDITION OF EGGS TO THE HEN’S CLUTCH BY REPEATED INJECTIONS OF OVULATIONINDUCING HORMONES

Abstract

The hen usually lays her eggs at the rate of one a day for several days, misses a day, and then approximately repeats this performance. Her clutch may vary in length from 1 egg to more than 100, but generally it contains fewer than 4 or 5 eggs. Ovulation does not occur on the day the terminal egg of the clutch is laid, but some 14 to 18 hours later, or early in the morning of the following day (Warren and Scott, 1935). Previous work has shown that ovulation can be induced in the normal hen by anterior pituitary gonadotrophin (Fraps, Olsen, and Neher, 1942) and by progesterone (Fraps and Dury, 1943). In regularly laying hens the first follicle of an oncoming clutch can be caused to ovulate readily by as much as 24 hours’ prematurity, and, by properly timed injections, oviposition of the terminal egg of one clutch and ovulation of the first follicle of a succeeding clutch approximate the relation characteristic of normal intraclutch successions (Fraps, 1942). Thus a normal 2-egg clutch became a 3-egg clutch, the normal 3-egg clutch became a 4-egg clutch and so on. The purpose of the present study was to induce repeated ovulations in hens of low or moderate production by adding a first ovulation at or near the end of a 2-egg clutch and, by repeating injections of appropriate hormones at 24, 26 or 28 hourly intervals, to force ovulations until the ovary failed to respond.