The Relationships of Clutch Length and Egg Position on Ovarian Follicular Growth in Laying Hens

To analyze characteristics of follicular rapid growth patterns in relation to clutch length and egg position in various clutch lengths, Sudan black and red were alternately injected intravenously into laying hens. The average growth period tended to decrease as clutch size increased, and this was accompanied by an increase in growth rate. The number of growing follicles and the total amount of daily yolk deposition in layers with short clutches were less than in layers exhibiting long clutches. The growth period tended to decrease as egg position advanced in clutches of 2 to 6 eggs. Follicular volume at ovulation also tended to be less in terminal (Ct) follicles in clutches of 2 to 5 eggs. Follicular growth rate was generaly reduced in the first egg of a clutch (Cl) and increased in the Ct follicles. Comparison of growth patterns between Ct and Cl follicles led to the detection of two growth patterns. In the first pattern, the growth period of the Ct follicle was equal to that of the Cl follicle and a one day skip was found between the transformation days of the two follicles; in the second pattern, Ct and Cl follicles entered into the rapid growth phase on consecutive days, but the Cl follicle took one day longer than the Ct follicle to reach ovulation.