The Effects of Dietary Phosphorus, Vitamin D3, and 25-Hydroxy Vitamin D3 Levels on Feed Intake, Productive Performance, and Egg and Shell Quality in Two Strains of Force-Molted White Leghorns1

ABSTRACT A total of 576 force-molted hens were used to investigate the effect of dietary phosphorus level, and the source and level of vitamin D3 on egg production and shell quality. The experiment was a 2 X 2 X 2 X 3 factorial design with two strains of hens, two levels of available phosphorus (.34 and.60%), and two sources of D3 (25-hydroxy vitamin D3 and vitamin D3) at three levels (8, 16, 24 Mg/kg); the diets were provided ad libitum for 84 days (from 646 to 730 days of age). Egg and shell quality measurements were taken on eggs laid over a 4-day period when the hens were 727 days of age. Dietary phosphorus level, and D3 source and level had no significant (P>.05) effect on 730-day body weight, feed intake and efficiency, egg production and yield, shell weight, percent shell, shell weight per unit surface area, Haugh units, blood spots, egg specific gravity, nondestructive deformation, compression fracture force, and shell thickness. There were significant differences among strains for the aforementioned variables except feed intake, egg weight, Haugh units, and blood spot incidence. Few interactions were found between the main effects. Results indicate that no improvement in shell quality of eggs from force-molted hens was obtained by decreasing the level of phosphorus or substituting 25-hydroxy vitamin D3 for vitamin D3 in the diet