| Physiological differences in nursing mother can affect the metabolism and lifelong wellbeing of the offspring with the same genetic background through maternal milk.Different genetic backgrounds also play important roles in influencing the development of the newborns.However,few studies have focused on the interplay of nursing factor and breed factor on the growth and metabolism of the newborns.It is difficult to differentiate the impacts of the nursing mother and the breed in affecting lipid metabolism in animals during their early life.Pigs have been proved to possess similar nutritional requirements and metabolic responses to diet changes compared to human beings,and have been widely used in human clinical and experimental researches.The present study used postnatal cross-fostering approach to dissect the differentital effects of nursing mother and breed factors by using two different pig breeds.One is Meishan,an obese Chinese domestic breed;the other is Yorkshire,a lean western breed.The two breeds have been proved with distinct milk composition,lipid metabolism,gut microflora and other metabolic pathways.Thus by this cross-fostering model.the present study investigated the roles of nursing sows and breed on lipid metabolism of the offspring through the analysis of genes,enzymes,blood metabolites and other parameters involved in lipid metabolism.1 Effects of cross-fostering on the growth performance,digestive ability,serum parameters and VFA concentrations of Meishan and Yorkshire pigletsFirstly,we determined the content of milk protein,milk fat and lactose(P<0.01).The results showed that the lactation age had significant difference on the three parameters,and the milk protein and lctose level were significantly affected by breed(P<0.05).The body weight gain,organ indices,blood biochemical parameters,digestive enzymes in stomach,jejunum and pancreas were determined in Meishan and Yorkshire piglets.The results showed that breed significantly affected the BWG of the periods 0?28,28?49 and 0?49(P<0.01),and they were higher in Yorkshire piglets than in Meishan piglets(P<0.05).Nursing mother had a significantly influence on BWG from 0 to 28d after birth(P<0.01),and it was higher in piglets nursed by Yorkshire sows than in piglets nursed by Meishan sows(P<0.05);BWG of the period(0?49)tended to be significantly affected by nursing mother(0.05<P<0.1).Nursing mother has minor impact on organ indices,which only significantly affected liver index at day 49(P<0.05).Breed had significant influences on liver index at day 14(P<0.05),as well as the indices of stomach and large intestine at day 49(P<0.05).To be interested those indices in Meishan piglets were all higher than in Yorkshire piglets(P<0.05),which indicated that Meishan piglets had a stronger ability in digestion and absorption.What's more important,the BFT and RBFT were significantly affected by breed but not nursing mother(P<0.01),which in Meishan piglets were higher than in Yorkshire piglets at day 14 and 49(P<0.05).At day 14,nursing mother is the predominant factor influencing TC,HDL-c,LDL-c and TG;at day 49,both the two factors had no significant influences on those parameters ever(P>0.05).For the digestive enzymes activities,breed significantly affected the activities of gastric amylase and pancreatic lipase(P<0.05),while nursing mother affected gastric amylase significantly at day 14(P<0.05);at day 49,breed was the critical factor affecting the digestive enzymes,of which jejunal lipase,pancreatic lipase and pancreatic amylase were significantly higher in Meishan piglets than in Yorkshire piglets(P<0.05).The TVFA concentration of cecum,colon and feces in Meishan piglets were significantly higher than those in Yorkshire piglets at day 14 and 49,respectively(P<0.01).At day 14,nursing mother had significant effects on acetate and propionate of cecum(P<0.01),but these effects diminished or vanished at day 49.The results of the inner-breed cross-fostering proved that the procedures of the cross-fostering used in this assay did not dignificantly affectthe results of inter-breed cross-fostering,and illustrated the strong credibility of this research.2 Effects of cross-fostering on lipid metabolism related enzymes,hormones and genes of Meishan and Yorkshire pigletsIn order to know the effects of cross-fostering on lipid metabolism of Meishan and Yorkshire piglets,the enzymes,hormones and genes related to lipid metabolism at day 14 and day 49 were determined.The results showed that nursing mother had huge effects on the enzymes at day 14,and did not affect them at day 49 significantly.At day 14,Meishan piglets nursed by biological mother had a significantly higher activity of liver MDH(P<0.05)but a lower HL(P<0.01)than whom nursed by fostered mother,Yorkshire piglets nursed by biological mother had a significantly higher activity of HL than whom nursed by fostered mother(P<0.01).Piglets nursed by Yorkshire sows had significantly increased activity of TL compared with piglets nursed by Meishan sows(P<0.05),but decreased activity of HSL of fat tissue(P<0.05);the activities of LPL and TL were tended to be significantly affected by breed(0.05<P<0.1).At day 49,Meishan piglets had a higher activity of HSL than Yorkshire piglets(P<0.05),and the effects of nursing mother diminished or vanished.Lipid metabolism related genes can be differently affected by nursing mother and breed in different tissue at different time points.In liver,at day 14,they were mainly affected by nursing mother,of which Yorkshire piglets nursed by biological mother had higher mRNA levels of SREBP-1c(P<0.05),PPARy(P<0.01)and ACC(P<0.05)than fostered Yorkshire piglets.These differences did not appear between Meishan piglets nursed by biological mother and fostered mother;breed could significantly affect the mRNA level of APOB(P<0.05),and tended to significantly affect HSL(0.05<P<0.1).At day 49,breed became the predominant factor influencing genes.Of them,Meishan piglets had a lower mRNA level of PPAR?(P<0.05)but a higher mRNA level of ACOX(P<0.05),and PPARy in Yy was higher than in My(P<0.05),ACOX in Mm lower than in Ym(P<0.05).Through the alterations of these enzymes and genes in liver,we know the ability of lipogenesis and lipolysis was both affected at day 14 and day 49,but,with time going on,effects of nursing on them diminished or vanished.In fat tissue,at day 14,breed significantly affected the mRNA levels of FAS and CPT(P<0.05).Meishan piglets had a higher mRNA level of FAS(P<0.05)but a lower mRNA level of CPT(P<0.05)than Yorkshire piglets.At day 49,the mRNA levels of FAS and HSL were higher in Meishan piglets than in Yorkshire piglets(P<0.05),and nursing mother had no significant effects on the genes determined.3 Effects of cross-fostering on blood metabolomics of Meishan and Yorkshire pigletsTo investigate the Effects of cross-fostering on host metabolism,including lipid metabolism,blood metabolomics of Meishan and Yorkshire piglets was analyzed by GC/MS at day 14 and day 49.The results showed that 60 metabolites in serum were identified at day 14 and 49.At day 14,glycine,phenylalanine,threonine,?-alanine and succinic acid were affected by nursing mother(P<0.05),while creatinine(P<0.05),lysine(P<0.05)and critic acid(P<0.01)were influenced by breed.To be interested,they were all amino acids involved in amino acid metabolism pathway except succinic acid and critic acid,which were related to TCA cycle.Meishan fostered piglets increased metabolites involved in phenylalanine metabolism,alanine metabolism and TCA cycle compared with Yorkshire fostered piglets.And Meishan piglets had increase in arginine and proline metabolism and biotin metabolism,whereas decrease in TCA cycle.At day 49,breed was the most predominant factor affecting 2-hydroxybutyric acid,3-hydroxybutyric acid,D-lactic acid,glyceric acid,pyruvate and threonine(P<0.05),which were related to the pathway of lipid oxidation,synthesis and degradation of ketone bodies,pyruvate metabolism,glycerol oxidation,TCA cycle and glycine,serine and threonine metabolism respectively.And those metabolites mentioned above were higher in Meishan piglets than in Yorkshire piglets.Succinic acid was the only metabolite influenced by nursing mother at day 49(P<0.05).There were significant differences in metabolites and metabolic pathways at day 14 and 49.The metabolites of VIP>lwere listed in Supplementary table 4.Enrichment set analysis revealed that protein biosynthesis was significantly affected by breed or nursing mother at 14 and 49 days. |
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