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Effects of mid- to late gestational energy source on jejunal crypt cell proliferation in the ewe and fetus
Recent studies show that maternal energy source during gestation affects fetal and postnatal growth, even when energy requirements are met. Small intestinal growth has previously been affected in ewe models of developmental programming resulting in altered ewe metabolism and fetal growth. We hypothesized that maternal and fetal jejunal proliferation would be responsive to gestational energy source. Single and twin-bearing mature Polypay ewes (n = 14; single service sire) were fed 1 of 3 energy sources beginning on d 67 ± 3 of gestation: ad libitum alfalfa haylage (HL), limit-fed whole shelled corn with additional CP to meet NRC recommendations (CN), or limit-fed corn dried distillers grains with solubles (DG). From d 116 of gestation until terminal surgeries, ewes fed HL were supplemented with corn gluten feed (10.4% of dietary DM) to account for late gestational energy demands of fetal growth. On d 130 ± 1 of gestation, non-survival surgeries were performed, and ewes were euthanized. The small intestine was weighed, and jejunal mucosal tissue was collected. Jejunal samples were immersion fixed and embedded in paraffin, sectioned and stained, and images were taken for analysis of proliferating nuclei. Data were analyzed with gestational energy source and fetal number as fixed effects; sex was included in the model for fetal parameters. Ewe (P = 0.96) and fetal (P = 0.66) BW at surgery were not affected by energy source during gestation. Energy source tended (P = 0.11) to affect ewe jejunal mass (g and % BW), where ewes fed CN had greater (P = 0.04) jejunal mass than HL. Despite this, total small intestinal, duodenal, and ileal masses (g and % BW) were not affected (P > 0.75) by energy source. There were no differences (P = 0.33) in ewe jejunal proliferation (%) due to energy source. Fetal small intestinal relative mass (% BW) tended (P = 0.11) to be affected by maternal energy source. Fetuses from DG ewes had greater (P = 0.04) relative small intestinal mass than CN. There were no differences (P = 0.20) in fetal small intestinal actual mass (g) among maternal energy sources. Fetal jejunal proliferation tended (P < 0.15) to be affected by maternal energy source. Specifically, fetal lambs from DG ewes tended (P= 0.07) to have greater proliferation than HL. Data suggest that maternal energy source during gestation may affect ewe and fetal small intestinal growth, which could impact whole animal measures.
Keywords:
developmental programming, pregnancy, small intestine