Uterine Environment and Breed Effects on Erythropoiesis and Liver Protein Secretion in Late Embryonic and Early Fetal Swine1

Abstract

In this study we investigated erythropoiesis and fetal liver protein secretion during late embryonic (Day 24 and Day 30) and early fetal (Day 40) development in pigs from domestic white crossbred (WC) gilts with a normal (intact; INT) or crowded (unilateral hysterectomized/ovariectomized; UHO) uterine environment, or from prolific Chinese Meishan (MS) gilts. Increased fetal weight, fetal liver weight, placental weight, total red blood cells, hematocrit, blood hemoglobin content, and maternal plasma erythropoietin (EPO) levels were observed as gestation advanced. Cultured fetal liver secretion of transferrin and a protein of Mr 12500 and pI 7.5 also increased as gestation advanced. Fetal plasma EPO declined between Day 30 and Day 40. Differential counts of circulating erythroid precursors revealed a decline in basophilic erythroblasts and polychromatic erythroblasts between Day 24 and Day 40, an increase in orthochromatic erythroblasts on Day 30 followed by a drop on Day 40, and an increase in the percentage of reticulocytes/ erythrocytes from < 1.0% to approximately 90% of circulating red blood cells between Day 24 and Day 40. Differences among the treatment groups included a lower fetal survival percentage in UHO (vs. INT or MS) on Day 40, and higher maternal hematocrits, fetal weights, fetal hematocrits, fetal EPO levels, and liver transferrin secretion in WC vs. MS pigs. MS pigs had a lower percentage of polychromatic erythroblasts overall and a higher percentage of orthochromatic erythroblasts on Day 24 followed by a higher percentage of erythrocytes on Day 40 than WC pigs, suggesting a more mature erythron (circulating red blood cells plus erythropoietic tissue) in the MS pigs. Covariate analysis indicated that MS had larger placentae per unit of body weight than did WC. Conclusions were that 1) Days 24-40 of gestation is a critical time for fetal erythropoiesis in pigs as well as survival in a crowded uterine environment, 2) the MS breed may differ in the development of the fetal erythropoietic system because of altered fetal or uterine physiology, and 3) the UHO procedure did not significantly affect erythropoiesis in the fetuses studied but did alter fetal survival and the relationship between fetal weight and both hematocrit and hemoglobin on Day 40.

Secreted and Placental Membrane Forms of Folate-Binding Protein Occur Sequentially During Pregnancy in Swine1

“…fluid coincides with the time when fetal erythropoiesis is being initiated in the liver [6,21,22]. It also coincides with the critical period for fetal loss in the crowded uterus, which occurs around Day 40 of pregnancy [22,23].…”

“…By contrast, the affinity is the lowest between Days 50 to 70 and increases thereafter. Increased placental folate binding up to Day 50 of pregnancy may be needed to meet the requirement of the developing conceptus as fetal erythropoiesis is being initiated in the liver around Day 30 and reaches a maximum by Day 50 [6,21,22,25].…”

“…Deficiencies in folate lead to abnormal erythropoiesis [3] and birth defects [4]. Previous results suggest that the amount of folate available to the developing conceptus influences fetal erythropoiesis [5] and fetal erythropoiesis influences uterine capacity of swine [5][6][7]. In addition, it has been reported that folate supplements increased the survival rate of fetuses 1 Supported by CSREES grant 2001-35203-11241.…”

Haplotype Analysis of Ferritin Heavy Chain Affects Stillborn Piglets on Large White X Landrace Crossbred Sows

“…A day 24-40 of gestation is a critical time progression for fetal erythropoiesis in pigs as well as survival in a crowded uterine environment. The uterine environment had little overall effect on erythropoiesis in white crossbreed pigs but did affect fetal survival, and crowding may compromise erythropoiesis in small fetuses (Pearson et al, 1998). Selection for increased ovulation rate has been very successful.…”

Folic acid and vitamin B12 in reproducing sows: New concepts

“…Indeed, the total vitamin B 12 concentration in uterine horns at 15 d of gestation represents between 180 and 300% of the total concentration in plasma, with the total volume of plasma being estimated at 4% of body weight (Matte . The physiological mechanism underlying this transfer is not well understood in pigs although one of the known B 12 carriers, transcobalamin I, has been identified in porcine endometrial tissues (Pearson et al 1998). Moreover, Guay et al (2002b) showed that a dietary supplement of 160 ppb similar to that used by Frederick and Brisson (1961) could be an efficient way to increase B 12 status as measured by the variation of plasma B 12 in early gestation (up to day 15).…”