Peripheral Blood Response to Reproductive Stimulation in Mallards

Abstract

This study examined the use of several blood parameters to monitor reproductive response to environmental conditions. The fluctuation of serum proteins and the concentrations of three ions were examined in relation to natural and artificial reproductive stimulation in the mallard (Anas platyrhynchos). Blood samples were collected weekly on one untreated group of birds and at 2- or 3-day intervals on in- dividuals during artificial stimulation experiments. Hormonal treatment consisted of periodic injections of either 17-B-estradiol or a crude solution of ground chicken pituitary glands. The duration of the study was from October 14, 1965, to March 3, 1966. Of the three ions analyzed (K+, Ca, Na?), only calcium levels showed a consistent correlation with both natural and artificial stimulation. Serum calcium values had a mean of 10.8 mg/100 mg during the unstimulated period; a mean of approximately 15 mg/ 100 mg during stimulation but before egg laying; and levels in excess of 18 mg/100 mg after egg laying began. Serum protein levels show that reproductive stimulation resulted in increased total protein, re- duced albumin, and increased globulin fractions. The results produced a shift in the albumin-to-globulin ratio from a mean of 2.0 before stimulation, to approximately 0.9 during stimulation but before egg lay- ing, and a value less than 0.8 during active laying. All of the serum changes observed during natural re- productive development were duplicated by 17-B-estradiol treatment alone.