Effects of an Induced Molt and Shell Quality on the Physical Dimensions and Mineral Composition of Eggs and Intrauterine pH ,

Abstract

Abstract The relationship between force-molting and egg shell quality on the physical dimensions, water vapor conductance, air pore characteristics, and shell mineral content of eggs was investigated in Experiment 1. Hard-shelled (HS) and soft-shelled (SS) eggs were collected at 0700 or 1100 hr from force-molted and nommolted hens between 95 and 99 weeks of age. For Experiment 2, intrauterine pH was measured in vivo, immediately following the oviposition of a HS, SS, or shell-less (SL) egg by 107-week-old force-molted and nonmolted hens. Egg weight, percent shell, shell surface area, water vapor conductance, pore density, and the number of pores/egg were similar among HS eggs produced by molted and nonmolted hens, while shell weight, shell thickness, shell volume, shell calcium, pore radius, and total pore area were significantly greater in eggs produced by molted than nonmolted birds. Shell thickness, percent shell, and shell phosphorus content were greater in HS eggs collected at 0700 hr than 1100 hr. Shells from HS eggs were thicker content were greater in HS eggs collected at 0700 hr than 1100 hr. Shells from HS eggs were thicker and had higher ash, calcium, magnesium, and phosphorus contents when compared to shells from SS eggs. Shell manganese levels were lower in HS eggs produced postmolt, while molting did not affect the shell manganese content of SS eggs. The number of pores/cm2 were lower in HS than SS eggs. No significant differences due to molt type or egg type were observed for intrauterine pH measured in vivo following the oviposition of HS, SS, or SL eggs.