title: Effects of vitamin D(3) -enriched diet on egg yolk vitamin D(3) content and yolk quality.
abstract: A 40-wk experiment was conducted using Hy-Line W-36 laying hens (19-wk old) to investigate the impact of feeding cholecalciferol-enriched diets on egg yolk quality. Feeds were enriched with 4 cholecalciferol levels, 9700 (diet 2), 17200 (diet 3), 24700 (diet 4), and 102200 (diet 5) IU/kg feed. The control (diet 1) contained 2200 IU cholecalciferol/kg feed. Eggs from each replicate group of enriched diets were collected daily and the yolks were pooled into 2-d period during the first 2 wk. During weeks 3, 4, 6, 8, 12, 16, 20, 24, 28, 32, 36, and 40, pooled samples were generated by daily collection of 3 consecutive days of egg production. The cholecalciferol content of egg yolk from the enriched diets increased rapidly during the first 3 wk. The peak cholecalciferol concentrations in egg yolk that occurred at week 3 were 865, 1641, 2411, and 34815 IU/100 g egg yolk (wet basis) from diet 2 to 5. The average cholecalciferol concentration in yolk during weeks 3 to 40 and the deposition rate of cholecalciferol during the first 3 wk were both linearly increased with the dietary cholecalciferol level when the feed contained no more than 24700 IU/kg cholecalciferol. Egg yolk lipid profile (total lipid content, fatty acid composition, phospholipid composition, and unsaponifiables), physical and functional properties (yolk viscosity and emulsifying property), and sensory quality of hard-boiled egg yolk were not affected by the cholecalciferol enrichment in the feed.
  
  
  CONCLUSIONS
  A linear dose-response relationship between dietary vitamin D(3) level and egg yolk vitamin D(3) content was established at relatively low enrichment levels. Such relationship can be used to formulate feed to achieve a target egg vitamin D level. High vitamin D yolk showed no difference from the conventional yolk in other compositional, functional, and sensory properties.
authors: Dept. of Food Science and Human Nutrition, Iowa State Univ., Ames, IA 50011, USA.
authors: Linxing
authors: L
authors: Yao
authors: Tong
authors: T
authors: Wang
authors: Michael
authors: M
authors: Persia
authors: Ronald L
authors: RL
authors: Horst
authors: Mallory
authors: M
authors: Higgins
mesh_terms: D000328:Adult; D000821:Animal Feed; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000032:analysis*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004530:Egg Yolk / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D063427:Food Quality; D006801:Humans; D008297:Male; D013649:Taste
chemical_list: D005227:Fatty Acids; D002762:Cholecalciferol