Nutritional factors which affect egg yolk pigmentation in laying hens

Potrošači preferiraju intenzivniju boju žutanjka i povezuju je sa zdravljem i kvalitetom proizvoda. Karotenoidi su glavne komponente koje doprinose pigmentaciji te se ovisno o vrsti i koncentraciji karotenoida povedava ili smanjuje intenzitet boje. Karotenoidi koji doprinose pigmentaciju su ksantofili od kojih su najznačajniji lutein i zeaksantin. Uz vrstu i koncentraciju, bitan je i omjer žutih i crvenih karotenoida koji bi trebao iznositi 3:1. Da bi se deponirala određena koncentracija i vrsta karotenoida u žutanjak bitan je izvor koji može biti prirodnog ili sintetskog podrijetla. Uz određenu prisutnost karotenoida u hrani, potrebno je uzeti u obzir i njihovu interakciju s drugim komponentama u obroku kao i njihov gubitak prilikom skladištenja i prerade hrane. Kako bi se postigla preferirana boja žutanjka bitno je da životinja unese dovoljnu količinu karotenoida putem hrane jer ih životinje ne mogu same sintetizirati. Iz toga razloga pigmentacija može biti smanjena zbog smanjene konzumacije hrane koja može biti uzrokovana različitim čimbenicima. Način držanja kokoši nesilica utječe na pigmentaciju žutanjka jajeta jer o njemu ovisi količina i vrsta karotenoida koje kokoši unesu. Isto tako, prilikom različitih bolesti dolazi do smanjene pigmentacije uzrokovane smanjenjem unosa hrane, iskorištavanja karotenoida u obrambene svrhe i smanjene apsorpcije karotenoida.Consumers prefer intensive colour of egg yolk which they associate with hen’s health and quality of eggs. Carotenoids are main compounds contributing to yolk pigmentation and depending on the compound and its concentration contribute more or less to colour intensity. Carotenoids that are contributing to yolk pigmentation are xanthophylls with lutein and zeaxanthin as the most important. Besides the carotenoid compound and its concentration, the ratio of yellow and red carotenoids, which should be 3:1, also plays a significant role in egg yolk pigmentation. In order to achieve deposition of a certain concentration of the carotenoid compound in yolk, the diet source is important and carotenoids could be of natural or synthetic origin. Alongside the presence of carotenoids in diet, it is important to take into consideration their interaction with other diet components and their loss during storage and feed processing. In order to achieve the preferred colour ofthe egg yolk, the hen must consume specific amounts of carotenoids because animals can not synthesize carotenoids on their own. For that reason, pigmentation can decrease because of decreased diet intake, which can be caused by various factors. Accommodation of laying hens affects yolk pigmentation because of the different carotenoids and their contents in diets of different systems. Also, various diseases decrease yolk pigmentation due to the decreased diet intake, utilisation of carotenoids in health defence and reduced absorption of carotenoids