Submitted to: Biology of Reproduction Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 23, 1997
Publication Date: N/A
Technical Abstract: When porcine fetuses are crowded, additional fetal mortality occurs before Day 40 (D40) of gestation (term = 114 days). Prior to D40, liver erythropoiesis is also initiated, and the importance of mature erythrocytes (ERY) and their precursors (ERYP) for oxygen transport suggests that abnormal erythropoiesis could reduce fetal survival. A study was conducted to examine erythropoiesis at three fetal ages (D24, D30, D40) using three pig models with different uterine environments (UE): intact white crossbred (INT), unilaterally hysterectomized-ovariectomized white crossbred (UHO), and intact prolific Chinese Meishan (MS) gilts (n=5-9 gilts and 2-3 fetuses/gilt for each age and UE combination). Only on D40 was fetal survival in UHO (68.7 +/- 4.7%) reduced (p<.04) compared with INT and MS gilts (87.9 +/- .05%). Blood ERY plus ERYP concentrations (erythron) did not differ with UE but increased ninefold (p<.01) with fetal age. Blood hemoglobin did not differ with UE (p=.55) but increased fourfold (p<.01) between D24 (1.4 +/- .2 g/100 ml) and D40 (6.5 +/- .2). On D24, blood polychromatophilic rubricytes were the predominant ERYP (85.4 +/- 3.3%) and did not differ among UE (p=.80). ERY were essentially absent. At D30, four ERYP stages constituted 94.7% of the erythron and were similar among UE. By D40, ERY (61.7 +/- 2.4%) predominated in all UE. In MS on D40, reticulocytes were 18% fewer (p<.01) than in INT or UHO fetuses. Plasma erythropoietin decreased (p<.01) between D30 and D40 in fetuses of all UE; concentrations in MS on D30 (8.2 +/- .8 mUnits/ml) and D40 (7.0 +/- .8) were 33% less (p<.01) than those in INT and UHO fetuses. In summary, dramatic changes in porcine erythropoiesis occur between D24 and D40 with some evidence for differences among UE and breeds.