Ascorbic acid biosynthesis in hens producing strong and weak eggshells

Area of Science:

• Poultry Science
• Animal Nutrition
• Biochemistry

Background:

• Eggshell strength is crucial for poultry production and often declines with hen age.
• Ascorbic acid (vitamin C) plays a role in collagen synthesis, essential for eggshell integrity.
• Reduced eggshell strength in older hens may be linked to decreased ascorbic acid biosynthesis.

Purpose of the Study:

• To investigate if reduced ascorbic acid biosynthesis causes decreased eggshell strength in aged laying hens.
• To compare ascorbic acid levels and synthesis in hens producing strong versus weak eggshells.

Main Methods:

• Two strains of laying hens were used, identifying individuals with strong and weak eggshells.
• Measurements included egg production, egg weight, shell percentage, shell density, and ascorbic acid levels in plasma, adrenal, and liver tissues.
• Renal L-gulonolactone oxidase activity, a key enzyme in ascorbic acid synthesis, was also measured.

Main Results:

• Significant differences in ascorbic acid synthesis and tissue concentrations were observed between the two hen strains.
• No significant interaction between shell strength and strain was found.
• Eggshell strength was not correlated with plasma or hepatic ascorbic acid levels or renal L-gulonolactone oxidase activity in hens of similar egg weight.

Conclusions:

• The hypothesis that reduced ascorbic acid biosynthesis leads to weaker eggshells in aged hens was not supported.
• Factors other than ascorbic acid synthesis likely contribute to the decline in eggshell strength at the end of the production cycle.