[Carotenoid and vitamin A content in the liver and yolk of eggs of laying hens as dependent on the phosphorus level in the diet [On the problem related to the increase of egg productivity]]

albumen d'oeuf carotenoide carotenoides carotenoids egg albumen fosforo gallina ponedora layer chickens laying performance performance de ponte phosphore phosphorus poule pondeuse ration rations rendimiento en la postura retinol urss ussr vitellus yema de huevo