The Effects Of Feed Intake Levels On Progesterone Secretion And Embryonic Survival And Embryonic RBP4,FGFR2,OCT4,PGR Gene Expression During Early Pregnancy In Gilts

The present experiment was conducted to study the effect of feed intake level on embryonic survival and progesterone concentration and embryonic RBP4, FGFR2, OCT4 and PGR gene expression during early pregnancy in gilts. A total of 63 Landrace/Yorkshire mixed-breed gilts, every of which body weight was about 110±9.5kg, were randomly allocated to high (H, 2×maintenance feed/d), middle (M, 1.5×maintenance feed/d) or low (L, 0.6×maintenance feed/d) level groups after mating. The gilts were weighted, slaughtered and samples were collected on d12, d25, d35 of pregnancy respectively. The results showed:1. Feed intake levels ly influenced embryonic survival on early pregnancy in gilts. Total embryonic survival on dlsignificant2, d25 and d35 of pregnancy were significantly greater in M than in H and L gilts (P＜0.05). There were no significant difference between H and L (P＞0.05).2. Feed intake levels influenced progesterone concentration in serum and uterine flushing on different pregnancy phase. Serum progesterone concentration of H was very significantly lower than in M and L (P＜0.01). On d12, d25 and d35 of pregnancy, there were no significant difference between M and L (P＞0.05). There was a significantly positive correlation between serum progesterone concentration and embryonic survival on d12 of pregnancy (P＜0.05), there was a significantly negative correlation between serum progesterone concentration and feed intake on d12, d25 and d35 of pregnancy (P＜0.01). On d12, uterine flushing progesterone concentration of H was very significantly lower than L (P＜0.01), and significantly lower than M (P＜0.05), there were no significant difference between M and L (P＞0.05). There was a significantly negative correlation between uterine flushing progesterone concentration and feed intake (P＜0.05). On d25, there were no significant difference in all treatments (P＞0.05).3. Feed intake levels significantly influenced expression of embryonic RPB4, there was a significantly positive correlation between RBP4 expression and embryonic survival (P＜0.05). On d12 of pregnancy, the embryonic RBP4 gene expression of M was very significantly higher than H and L (P＜0.01), L was significantly higher than H (P＜0.05). On d25, embryonic RBP4 gene expression in M was very significantly higher than H (P＜0.01) and significantly higher than L (P＜0.05), there were no significant difference between H and L (P＞0.05). On d35, embryonic RBP4 gene expression in M was significantly higher than H (P＜0.05), there were no significant difference between M and L (P＞0.05), L and H (P＞0.05).4. Feed intake levels significantly influenced expression of embryoneic FGFR2. On d12, d25, d35 of pregnancy, embryonic FGFR2 gene expression in M was very significantly higher than H and L (P＜0.01). There was no significant difference between H and L (P＞0.05).5. Feed intake levels singificantly influenced expression embryonic OCT4. On d12 of pregnancy, the embryonic OCT4 gene expression in H was very significantly lower than M and L (P＜0.001), M was very significantly lower than L (P＜0.01). On d25 and d35, there were no significant difference in all treatments (P＞0.05). Embryonic OCT4 gene expression was decreased with increasing of pregnancy day.6. Feed intake levels have different influense on expression of embryonic PGR in different day of pregnancy. On d12 of pregnancy, embryonic PGR gene expression was no difference in all treatments (P＞0.05). On d25, L was very significantly higher than H (P＞0.01) and significantly higher than M (P＜0.05), there were no significant difference between H and M (P＞0.05). On d35, M was very significantly higher than H and L (P＜0.01), H was significantly lower than L (P＜0.05).Conclusions:(1). Feed intake levels significantly influenced progesterone concentration in serum and uterine flushing. High feed intake increased progesterone clear rate, resulted in low progesterone concentration in serum and uterine flushing, and low progesterone concentration decreased embryonic survival.(2). Feed intake levels significantly affected embryonic RBP4 and FGFR2 expression and there was a positive correlation between embryonic survival and expression of embryonic RBP4. The M feed intake singnifcantly regulated up embryonic RBP4 and FGFR expression, lead to increase of embryonic survival.(3) Feed intake levels influenced embryonic OCT4 and PGR gene expression. Feed intake levels have different influence on embryonic OCT4 and PGR expression in different day of pregnancy. It indicated that feed intake levels have effects on expression of these genes. We presumed that abnormal expression of these genes would influence embryonic survival.