title: Protein requirement, egg formation and the hen's ovulatory cycle.
abstract: Protein consumed by the laying hen is overwhelmingly oriented to yolk and albumen formation. Yolk proteins are almost exclusively synthesized in the liver, then transported to developing follicles. Yolk accrual by follicles is continuous and rapid because of hepatic and follicular construction. Albumen is largely synthesized by the tubular gland cells of the magnum. Albumen formation is also continuous; however, the rate appears to be particularly accentuated during the 4 h the ovum is in the magnum. Ovarian sex steroids are necessary for transcription of mRNA for all of the major egg proteins. Circulating sex steroids undergo a transient surge prior to ovulation that not only extends transcription but also appears to enhance translation of existing mRNA. Full realization of this enhancement by the magnum seems to be limited to when the ovum is present. Hens increase their protein intake at this time, presumably in response to associated demands.
mesh_terms: D000418:Albumins / Q000096:biosynthesis; D000818:Animals; D002645:Chickens / Q000502:physiology*; D004044:Dietary Proteins / Q000008:administration & dosage; D004530:Egg Yolk; D004531:Eggs; D005260:Female; D009751:Nutritional Requirements; D010053:Ovary / Q000502:physiology; D010060:Ovulation
chemical_list: D000418:Albumins; D004044:Dietary Proteins