Effects of dietary 25-hydroxycholecalciferol on growth, production performance, eggshell quality and bone traits of brown egg layers housed under commercial conditions

  • Author / Creator
    Silva, Felipe A
  • The effects of dietary 25-hydroxycholecalciferol (25OHD) on growth, production performance, eggshell quality and bone characteristics of laying hens were evaluated in a field trial in Colombia. At day 1 of age, a total of 17,750 Hy-Line Brown pullets were placed on a commercial farm, in 3 houses and randomly distributed in 6 treatments with 4 replicates each; at 13 wk of age, 10,800 pullets were transferred to the layer farm, maintaining the same treatments, but divided into 9 replicates per treatment. Treatments were: a Positive Control (PC) with 25OHD plus vitamin D3 at 2,760 and 3,000 IU/kg, respectively fed throughout the trial, a Negative Control (NC) with vitamin D3 only (3,000 IU/kg) fed during the entire trial, and treatments with the PC diet fed from day 1 to either 15 (Early), 17 (Prelay), 34 (Peak), or 50 (Late) wk of age, and then switched to the NC diet until 90 wk of age. Feed intake (FI), mortality and egg production were recorded daily and analyzed along with BW and FCR at each diet change. To evaluate eggshell quality and bone traits, 45 eggs per treatment were randomly sampled every two to three weeks to measure eggshell strength (ESS) and thickness, whereas 1 to 2 birds per pen (n=54) was euthanized at 15, 34 and 90 wk of age, to assess bone mineral density by quantitative computed tomography, and breaking strength. Data were analyzed by ANOVA or analysis of covariance, and orthogonal contrasts were performed to compare treatments fed 25OHD versus the NC. Dietary 25OHD decreased FCR at 3 wk, increased BW up to 8 wk, and FI up to 12 wk of age. At 26 and 84 wk of age, infectious coryza was observed, decreasing egg production and livability in all treatments. To 34 wk, NC hens had the lowest egg production, and highest FCR, PC and Peak hens had the highest egg production and lowest FCR; there were no differences within a dietary phase after this point. By 87 wk of age, Peak treatment resulted in the highest cumulative egg production and lowest FCR. Overall, the PC treatment resulted in higher ESS than the Early treatment, while PC and Early groups had greater shell thickness compared to NC. At 34 wk of age, shank cortical density at 30% of the total length from the proximal epiphysis of NC hens was nearly significantly the lowest among treatments (P= 0.076), whereas at 90 wk of age, the NC hens had lower BBS than Early hens. Additionally, orthogonal contrast revealed a significant enhancement of cumulative egg production by the end of production, and greater shell quality from 53 to 87 wk of age when 25OHD was added throughout the cycle, compared to the NC group. Dietary 25OHD up to 34 wk of age had a positive impact on early development and egg production from the onset of lay to peak production, whereas 25OHD supplementation throughout the cycle promoted greater eggshell quality, especially at older ages without compromising bone integrity over time.

  • Subjects / Keywords
  • Graduation date
    2017-11:Fall 2017
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Agricultural, Food, and Nutritional Science
  • Specialization
    • Animal Science
  • Supervisor / co-supervisor and their department(s)
    • Douglas Korver
  • Examining committee members and their departments
    • Martin Zuidhof (Agricultural Food and Nutritional Science)
    • Jianping Wu (Agricultural Food and Nutritional Science)
    • Doug Korver (Agricultural Food and Nutritional Science)