The level of feed intake affects embryo survival and gene expression during early pregnancy in gilts.

Appropriate feed intake level would enhance embryo survival. This study investigated the relationship among feed intake level, embryo survival, hormone secretion and mRNA expression. Fifty-four Landrace x Yorkshire crossbred gilts were allotted to three treatment groups of high (H, 2 x maintenance), medium (M, 1.2 x maintenance) and low (L, 0.6 x maintenance) after mating, to study the effect of feed intake levels on embryo survival, hormone secretion and mRNA expression of leptin, obesity receptor (ob-R), signal transducer and activator of transcription-3 (STAT3), DNA methyltransferase 1 (DNMT1), retinol-binding protein 4 (RBP4), fibroblast growth factor receptor 2 (FGFR2) and progesterone receptor (PGR) in embryos. Blood samples and embryos were collected for hormone concentrations determination and gene expression analysis. Slaughter weight, total weight gain and net weight gain were affected (p < 0.05) by dietary treatment. Embryonic survival was 80.23% and 78.45% in M group on days 25 and 35 of pregnancy, respectively, and was greater (p < 0.05) in M than H and L groups. Serum insulin-like growth factor-I and leptin concentrations enhanced (p < 0.05) with the increased feed intake, but progesterone concentrations were lower (p < 0.05) in H than M and L groups and no difference (p > 0.05) between M and L on days 25 and 35 of pregnancy. Real-Time PCR indicated that gene expression pattern of leptin, ob-R, STAT3 and DNMT1 were the highest (p < 0.05) in H group on days 25 and 35 of pregnancy. Transcript expression level of RBP4 and FGFR2 were the highest (p < 0.05) in M group on days 25 and 35 of pregnancy. Significantly higher (p < 0.05) expression of PGR was observed in L group on day 25 and in M group on day 35 of pregnancy. Our data suggest that 1.2 x maintenance feed intake level promoted the appropriate hormone secretion and enhanced genes expression in RBP4, FGFR2 and PGR, and thus resulted in better embryo survival compared with the high and low groups.