Modification of intra-ovarian follicular distributions in broiler breeder hens by ad libitum or restricted feeding

1. Ovarian follicles in broiler hens from 3 lines fed ad libitum or food restricted were examined at point of lay and from 2 of these lines at 47 weeks of age. The lines were Ross 1 birds and birds selected to be lean or fat on the basis of their plasma very low density lipoprotein concentrations at 7 weeks of age. 2. Follicles of diameter greater than 1.4 mm were classified into size groups, and the numbers in these groups in the anterior and posterior halves of the ovary were compared for the effects of line and feeding régimen. 3. There were more yellow follicles (> 8 mm diameter) in the anterior half of the ovary, and this difference was greater for ad libitum birds. Ad libitum feeding did not influence the number of yellow follicles in the posterior segment of the ovary. 4. The increase in numbers of yellow follicles in the anterior segment of the ovary differed according to line at point of lay, but not at 47 weeks of age. 5. Birds of 47 weeks of age showed higher numbers of follicles 1.4-6 mm in diameter in the posterior segment of the ovary, and smaller numbers of follicles 6-8 mm in diameter. Thus, although large numbers of white follicles were in the earlier stages of growth, there were fewer ovulable yellow follicles because of higher levels of atresia.