AbstractThis article discusses the provision of protein to breeding hens; protein deposition in breeding hens; response to amino acids in broiler breeder hens; protein utilization in breeding hens; dietary protein supply and breeding males; dietary protein supply and embryonic development; carry-over effects of maternal protein supply; empirical evidence about protein supply to breeding birds; integration: a model of protein utilization in female broiler breeders; and some reference is made to turkey and duck breeders, but most of the evidence and discussion refers to broiler breeders.