Re-evaluation of the Vitamin D3 Requirement for Growing Chickens
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Three experiments were conducted with the purpose of re-evaluating the vitamin D3 requirement of growing chickens. Due to intense genetic selection in the poultry industry, it is probable that modern strains have altered their nutritional requirements. Therefore, it is necessary to re-evaluate their ability to respond to modern feeding strategies. In the first experiment, broiler chickens were obtained from different commercial hatcheries and fed a basal vitamin D3-deficient starter diet with the objective of evaluating the variability in maternal deposition of vitamin D3 in the egg yolk. No significant (p>0.05) differences were found in the initial serum concentrations of 25-hydroxycalciferol (25-OH-D3) within sources of broiler chickens. Maternal vitamin D reserves will deplete around day 10 regardless of the initial concentration in newly hatched chickens. In the second experiment, 500 Ross-308 broiler chickens were sampled after being fed with 3,850 IU/kg cholecalciferol (D3) or 3,850 IU/kg D3 plus one of two sources of 25-OH-D3 for a 24-h period at different time points to evaluate the dynamics of serum 25-OH-D3, and identify if there was any “circadian-type” trend in the broiler´s response to dietary 25-OH-D3 over time, as well as identify important information about the effect of age in the metabolism of 25-OH-D3 and bone ash mineralization. Both sources showed a significant linear increase in serum 25-OH-D3 concentrations (p<0.05) over the 24-h exposure to treatment diets. Finally, for the third experiment, 96 Hy-line chickens were placed in a very controlled environment and a concentrated liquid form of vitamin D3 (Pure Life® Labs) was directly gavaged in precise increasing amounts to re-evaluate the requirement of this metabolite for growth performance and bone mineralization. The estimated requirement for growing leghorn chickens was 800 IU/kg D3 for maximum growth and bone mineralization. Results of these studies show that in order to produce a vitamin D3-deficient status in young broiler chickens, it is necessary to have strict control on the breeder’s diet. The supplementation of 25-OH-D3 increases the probability of maximum biological function with regard vitamin D. The re-evaluation of the vitamin D3 requirement for leghorn chickens suggests that the NRC (1994) minimum vitamin D3 requirement of 200 IU/kg might be inadequate for modern poultry leghorn strains.
Leyva Jimenez, Hector Enrique (2015). Re-evaluation of the Vitamin D3 Requirement for Growing Chickens. Master's thesis, Texas A & M University. Available electronically from