| The present research was conducted to investigate the effect of dietary energysources and levels on oocytes maturation in vitro and expression of growthdifferentiation factor 9(GDF-9), bone morphogenetic protein 15(BMP-15), FSH receptor(FSHR), LH receptor (LHR) of cumulus-oocyte complexes (COCs) in gilts. 54Landrace/Yorkshire crossed gilts (59±4.2 kg) were randomly allocated to 3×2factorial experiment. Three energy levels and energy sources were adopted, high (H),middle(M) and low(L) levels were 2.8 maintenance energy requirement, 3.2, 3.6 for60-80kg and 2.45, 2.8, 3.2 maintenance energy requirement for 80kg, respectively,energy sources were mixed fat and corn starch. On day 19 after beginning of the secondestrous cycle (detection of onset of estrus, day 1), all gilts were killed, COCs wererecovered from large(＞3mm) and small(＜3mm) follicles from each gilt, respectively.Some COCs from large follicles were matured in vitro, another and COCs from smallfollicles were analysed for gene expression.The results show:1. Energy sources had no effect on number of large, small follicles, ovulation rateand ovarian weight in gilts. The number of large follicles and ovulation rate were higherfor gilts fed H energy level than for those fed M and L (P＜0.05), there was no differencebetween M and L. The numbers of small follicle were higher for L than M and H, nodifference between M and L. The ovarian weight were lower for L than M (P＜0.05) andH(P＜0.01), not difference between M and H.2. Energy sources had no effect on cumulus expansion. After In vitro maturation(IVM) 24 hours. Cumulus expansion were higher for gilts fed H energy level than forthose fed L (P＜0.05), there was no difference between M and L or H. (P＞0.05).3. Energy sources had significant effect on oocytes maturation. After IVM 48 hoursoocytes reached metaphaseⅡ(MⅡ) were higher for gilts fed the starch diet than for those fed the fat diet (P＜0.05). Oocytes reached MⅡwere higher for gilts fed H energy levelthan for those fed M and L (P＜0.01), and were higher for gilts fed M than L (P＜0.05).4. Energy sources had no effect on BMP-15mRNA expression, but had significanteffect on GDF-9 mRNA expression. In COCs from large follicle, compared with gilts forfed fat, those fed starch had higher GDF-9 mRNA expression (P＜0.05); gilts fed Lenergy level had higher GDF-9 and BMP-15mRNA expression than M (P＜0.05) and H(P＜0.05); there was not difference between M and H. GDF-9 and BMP-15 mRNAexpression were higher in COCs from small follicle than large follicle in all treatments (P＜0.01).5. Energy sources had no effect on FSHR mRNA expression, compared with giltsfor fed fat, those fed starch had higher (P＜0.01) LHR mRNA expression. LHR mRNAexpression was higher in H than in M and L (P＜0.05), there was no difference betweenM and L. With energy level increased, FSHR mRNA expression increased (P＜0.05).It is concluded that:1. The gilts fed different energy level had significant effect on ovarian development,number of big follicle and ovulation rate were higher for gilts fed H. Different energysource had no effect on ovarian development.2. The gilts fed different energy level had effect on cumulus expansion and oocytesmaturation during IVM. The gilts fed starch had more advantage for oocytes maturationwhich had the largest proportion in high energy level. Different energy source had noeffect on cumulus expansion, but oocyte maturation was higher for gilts fed starch thanfor fed fat.3. The gilts fed different energy level had significant effect on GDF-9, BMP-15 andFSHR,LHR mRNA expression in COCs from large follicle before ovulation. For giltsfed high energy level, increased FSHR,LHR mRNA expression and decreasing GDF-9and BMP-15 mRNA expression had advantage for oocytes maturation.4. Compared with anestrous gilts, estrous gilts had higher LHR mRNA expression,lower GDF-9,BMP-15,FSHR mRNA expression in ovary, the difference of thesegene expression may be related to estrous. |
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