Effects of maternal nutrition on the initiation of secondary wool follicles in foetal sheep.

The initiation of secondary (S) wool follicles usually takes place between about 95 and 135 days of gestation. Severe underfeeding during the first half of this period did not significantly inhibit the initiation of S follicles, but severe underfeeding during the latter half of this period resulted in a significantly lower number of S follicles and this number was not increased by refeeding ewes to a high level between 132 days and term. A similar reduction in S follicle initiation was effected when ewes were moderately underfed throughout most of pregnancy, but when the ewes were refed between 120 days of gestation and term the numbers of S follicles initiated were not significantly different from those of a group of well-fed animals. It is concluded that S follicle initiation is most affected by maternal undernutrition between about 115 and 135 days of gestation.