Endocrine Factors Controlling Erythrocyte Concentration in the Blood of the Domestic Fowl

Hematological changes associated with egg production: estrogen dependence and repeatability

“…However, similar differential effects on estrogendependent reproductive traits have been documented here and in previous studies: tamoxifen treatment causes a robust decrease in egg size (Williams, 2000;Williams, 2001;Wagner and Williams, 2007), whereas exogenous estradiol does not increase egg size (Christians and Williams, 1999;Williams, 1999). Although previous studies have reported that estradiol treatment induces anemia (range -2 to -15%) in domestic fowl (Domm and Taber, 1946;Sturkie and Eiel, 1966), pilgrim geese (Hunsaker, 1968), Japanese quail (Nirmalan and Robinson, 1972;Nirmalan and Robinson, 1973;Garcia et al, 1984), rain quail (Deshmukh and Suryawanshi, 1982) and white-crowned sparrows (Kern et al, 1972), these studies all used non-breeding birds, which would have low baseline levels of endogenous estrogens. To our knowledge, our study is the first to assess effects of physiological levels of estradiol on hematological parameters in laying females specifically within the context of egg production.…”

Hematological changes associated with egg production: direct evidence for changes in erythropoiesis but a lack of resource dependence?

“…However, our results provide strong support for the hypothesis that erythropoiesis is transiently suppressed during egg-laying and that the recovery from anemia is relatively longlasting, extending through incubation and hatching periods. Decreased hematocrit, red blood cell counts and hemoglobin concentration did not recover at clutch completion, but showed evidence of recovery to baseline pre-breeding levels at hatching, consistent with the estimated timescale for regenerative erythropoiesis following experimentally induced anemia [7-14 days (Domm and Taber, 1946;Clark et al, 1988)]. More importantly, there was significant time-dependent variation in (1) the proportion of reticulocytes, which increased at clutch completion but peaked at hatching 10-12 days after clutch completion, and (2) in mean red blood cell volume, which showed a significant increase at clutch completion.…”

“…newly produced red blood cells are larger than mature cells (Campbell and Ellis, 2007)] or in the proportion of reticulocytes, since dilution per se would not change rates of red blood cell turnover (production and degradation of cells). By contrast, if anemia involved transient, estrogen-dependent suppression of erythropoiesis, we predicted that (1) decreased hematocrit, cell number and hemoglobin concentration would not recover at clutch completion since it takes 7-14 days for regenerative erythropoiesis to restore red blood cell numbers following experimentally induced anemia (Domm and Taber, 1946;Clark et al, 1988), and (2) there would be a marked increase in immature red blood cells (reticulocytes) post-laying and a corresponding increase in mean cell volume [i.e. reticulocytes are larger than mature cells (Campbell and Ellis, 2007)].…”

Blood: Physical Characteristics, Formed Elements, Hemoglobin, and Coagulation

“…Prolonged androgen administration increased hematocrit in chickens at sea level approximately 45% (Burton and Smith, 1972) and about the same degree at high altitude (12,500 ft). Domm and Taber (1946) and others have reported that red cell numbers in the castrate male are nearly the same as in the female; when androgen was administered to castrates, the numbers approached the normal male level. Sturkie and Textor (1960), however, found the number in male castrate chickens to be intermediate between those for normal males and females.…”

“…Female castrates (poulards) have the same number of red cells as normal females, indicating that estrogen has no positive effect on erythropoiesis but that androgen does. Older work by Domm and Taber (1946) indicates that thyroxine has a erythropoietic effect; this tends to counteract the negative effect of estrogen, as later demonstrated by Gilbert (1963) and by Sturkie (1951).…”