Urinary hydroxyproline excretion in male and female chickens

Hydroxyproline was measured in 24-hr urine samples at 60 and 120 days of age in male and female broiler chickens that were prepared by the "anus praeternaturalis" technique. Twenty-four-hour urine output did not differ between females and males (32.82 +/- 1.02 ml and 33.98 +/- .54 ml, average +/- SD, respectively), whereas 24-hr urinary hydroxyproline excretion was greater in females than in males after 60 days of age. Urinary hydroxyproline excretion tended to decrease with age in males and increase with age in females. Because most of the hydroxyproline is probably derived from bone collagen, the results suggest that there are differences between mineral exchange processes in female and male chickens.