Acute decrease in vitellogenin synthesis by deprivation of food and water in laying hens

Area of Science:

• Reproductive Endocrinology
• Avian Physiology

Background:

• Egg production in poultry is sensitive to nutritional and environmental stressors.
• Vitellogenin is a key yolk precursor protein synthesized in the liver and regulated by hormones.

Purpose of the Study:

• To investigate the impact of food and water deprivation on vitellogenin synthesis and egg production in hens.
• To examine the relationship between reproductive hormone levels and egg laying cessation.

Main Methods:

• Single Comb White Leghorn hens were subjected to short-day photoperiods followed by food and water deprivation.
• Circulating levels of vitellogenin, luteinizing hormone (LH), progesterone, estradiol 17 beta (E2), thyroxine (T4), and triiodothyronine (T3) were measured using RIA.
• Body weight, egg production rate, and reproductive organ weights were monitored.

Main Results:

• Food and water deprivation led to significant body weight loss and cessation of egg production.
• Circulating vitellogenin levels decreased drastically, correlating with reduced egg laying.
• Reproductive hormone levels (LH, progesterone, E2) declined, with E2 showing an abrupt decrease.
• Thyroid hormone levels (T4, T3, rT3) showed dynamic changes in response to photoperiod and deprivation.

Conclusions:

• Decreased egg production due to food and water deprivation is closely linked to reduced vitellogenin synthesis and impaired gonadal and pituitary functions.
• Recovery of egg production is associated with the restoration of reproductive organ weight and circulating levels of key hormones and vitellogenin.