| Oxidative stress can not only reduce the reproductive performance of sows,but also lead to abnormal placenta function,affect the absorption of fetal nutrients,and then affect the health of newborn piglets.Catalase(CAT)is a key enzyme in the ROS free radical scavenging system.It may play a regulatory role in alleviating oxidative stress during sow production and improve sow fertility and improving newborn piglets’ health.A total of 40 pregnant sows with similar parity of 90 days of gestation were assigned randomly and equally into the control(CON)group(fed a basal diet)and CAT group(fed a basal diet supplemented with 2.0 g/d CAT).The mechanism of catalase regulating reproductive performance and placental nutrient transport of sows was studied from the following four aspects:(1)The effects of CAT supplementation in late gestation diet on reproductive performance of sows and blood physiological and biochemical indexes of piglets;(2)Effects of CAT supplementation in late gestation diet on antioxidant capacity of sows and newborn piglets;(3)Effects of CAT supplementation in late gestation diet on nutrient metabolism and placental function of sows and newborn piglets;(4)Effects of CAT supplementation in late gestation diet on intestinal microbial diversity of sows and intestinal development of newborn piglets.The main results are as follows:Part Ⅰ: Effects of CAT supplementation in late gestation diet on reproductive performance of sows and blood physiological and biochemical indexes of piglets.(1)CAT supplementation significantly reduced the weak litter rate(P<0.05),and increased the average body weight of newborn piglets by 5.8%(P>0.10).(2)Compared with the control group,dietary CAT supplementation in late gestation significantly increased the contents of ALB,GLU and TG in serum of sows(P<0.05),significantly decreased the content of ALP(P<0.05),and tended to increase ALT,LDH,IgG and IgM(P<0.10);In addition,exogenous CAT significantly decreased the contents of TP,ALB,ALT,LDH,BUN,GLU and HDL-C4 in umbilical cord serum(P<0.05),and significantly increased the content of ALP in umbilical cord serum(P<0.05).Dietary supplementation of CAT in late gestation of sows significantly increased the levels of TP,ALT,IgG,IgM and TG in serum of newborn piglets(P<0.05),significantly decreased the content of HDL-C4 in serum of newborn piglets(P<0.05),and tended to increase serum ALP and BUN of newborn piglets(P<0.10).Collectively,CAT supplementation in sow diet during late gestation reduced IUGR rate,and regulated glucose and lipid metabolism and protein metabolism in serum of sows and their offspring,suggesting that exogenous CAT may reduce IUGR rate by regulating lipid and protein metabolism in sow and newborn piglets.Part Ⅱ: Effects of CAT supplementation in late gestation diet on antioxidant capacity of sows and newborn piglets.(1)Compared with the control group,dietary CAT supplementation significantly increased serum GSH activity of farrowing sows(P<0.05),and tended to increase T-AOC(P<0.10);Furthermore,CAT activity was significantly increased(P<0.05)and T-AOC tended to increase in cord blood(P<0.10),and serum CAT activity significantly increased in newborn piglets(P<0.05).(2)Dietary CAT supplementation in late gestation significantly increased the concentrations of Ca and Mn in plasma of sows(P<0.05),but extremely significantly decreased the concentrations of Zn in plasma of sows(P<0.01),and exogenous CAT significantly decreased the concentration of Mg and Zn(P<0.05),and extremely significantly increased the concentration of Mn in cord blood(P<0.01).Furthermore,dietary CAT supplementation in late gestation significantly increased the concentrations of Ca,Mg,Cu and Mn in serum of newborn piglets(P<0.05).(3)Dietary CAT had a tendency to down-regulate Cu/Zn SOD mRNA expression in placenta of sows(P<0.10),but tended to up-regulate GPX1,GPX4 and CAT mRNA expression in ileum of newborn piglets(P<0.10).(4)Compared with the control group,exogenous CAT tended to increase the content of placental mitochondria(P<0.10).In addition,exogenous CAT significantly up-regulated the mRNA expressions of PGC-1α,Nrf2,TFAM and ATP Synthase in placenta(P < 0.01),while,the mRNA expression levels of Sirt1 and Nrf1 were up-regulated(P< 0.10).(5)Dietary CAT supplementation significantly increased the number of ileum mitochondria(P<0.05),and tended to down-regulate TFAM mRNA expression in jejunum of newborn piglets(P<0.10).However,Nrf2,PGC-1α and ATP synthase gene expression levels in ileum were significantly up-regulated(P<0.05).The above results suggest that exogenous CAT can improve GSH activity and T-AOC in serum of sows,which may be related to the regulation of CAT on mineral elements of sows and offspring piglets,it is beneficial to relieve oxidative stress of sows.Exogenous CAT may regulate the expression of genes related to placental mitochondrial function(PGC-1α,Nrf2,ATP Synthase)to improve the content of placental mitochondria,which may be related to the increase of CAT in cord blood,consequently,it is beneficial to relieve oxidative stress in placental tissues.In addition,adding CAT to sows diet during late gestation can increase serum CAT level of offspring piglets.At the same time,it may regulate the mRNA expression levels of key functional genes(PGC-1α,Nrf2,ATP Synthase)and antioxidase-related genes(GPX1,GPX2,CAT mRNA)in ileum of newborn piglets,so as to improve ileum mitochondrial content and antioxidant level of newborn piglets.This may help maintain the balance of oxidation and antioxidant activity in newborn piglets.Part Ⅲ: Effects of CAT supplementation in late gestation diet on nutrient metabolism and placental function of sows and newborn piglets.(1)Compared with the control group,dietary CAT supplementation at late gestation significantly decreased the contents of C18:0,C20:3N6 and SFA(P<0.01),and significantly increased the levels of C16:1,C18:1N9C,C18:3N3 and MUFA in plasma of sows(P<0.05).while,there was a trend of decreasing C20:4N6 and increasing the level of PUFA N-3 and PUFA N-3 / N-6(P<0.10).In addition,exogenous CAT significantly decreased plasma levels of Tyr(P<0.01)and Ser(P<0.05),and tended to decrease plasma levels of Val and Glu on parturition day(P<0.10).(2)Compared with the control group,exogenous CAT significantly decreased the levels of C16:0,C18:0 and SFA in plasma of newborn piglets(P<0.05),and also tended to decrease the content of C12:0 in plasma and increase the level of C18:3N6 in liver of newborn piglets(P<0.10).At the same time,exogenous CAT significantly increased the contents of Leu,Ile,His,Cys and Tyr in plasma of newborn piglets(P<0.05).In addition,CAT significantly decreased plasma Thr and Ser levels in umbilical cord(P<0.05),and extremely significantly increased Ile and Phe levels(P<0.01),but tended to increase Asp and decrease Cys content(P<0.10).(3)CAT supplementation in late gestation significantly up-regulated mRNA expression levels of FABP1,Nf-κB and PPARα in placenta(P<0.01).Secondly,CAT significantly up-regulated mRNA expression levels of SNAT1,CAT-1 and m TOR in placenta(P<0.05),but significantly down-regulated mRNA expression level of SLC7A7 in placenta(P<0.05).(4)Compared with the control group,dietary CAT supplementation in late gestation significantly increased the mRNA level of FABP1 in jejunum of newborn piglets(P<0.05),and showed a trend of up-regulating the mRNA expression levels of FADS1,SREBP1 and ATGL(P<0.10).Secondly,dietary CAT supplementation at late gestation significantly increased mRNA expression levels of LAT,EAAT2 and SLC1A1 in jejunum of newborn piglets(P< 0.05).Taken together,(1)Dietary supplementation of CAT in sows during late gestation increased plasma MUFA content and decreased SFA content and free amino acid contents such as Tyr,Ser,Val and Glu,which might be because CAT promoted the synthesis and utilization of monounsaturated fatty acids.(2)Dietary CAT supplementation in late gestation of sows decreased the contents of C16:0,C18:0 and SFA in plasma of newborn piglets,upregulated the mRNA expressions of Nf-κB and PPARα in placental tissue,and increased the mRNA expressions of FADS1,SREBP1 c and FABP1 in intestinal tract of newborn piglets,suggesting that,exogenous CAT may regulate the plasma fatty acid ratio of newborn piglets by affecting the expression of key genes of lipid metabolism in placenta and small intestine.(3)Dietary CAT supplementation in late gestation of sows increased the contents of Leu,Ile,His,Cys and Tyr in plasma of newborn piglets.First,exogenous CAT may affect placental amino acid transport by regulating mRNA expression levels of placental amino acid transporters SNAT1,CAT-1 and SLC7A7.Furthermore,exogenous CAT may promote the transport and absorption of amino acids by increasing the mRNA expressions of amino acid transporters LAT,EAAT2 and SLC1A1 in jejunum of newborn piglets.Part Ⅳ: Effects of CAT supplementation on intestinal microbial diversity of sows and intestinal development of newborn piglets during late gestation(1)Compared with the control group,CAT supplementation in late gestation significantly increased Chao1 index and Shannon index of fecal microorganisms of sows in late gestation(P<0.05).In addition,at phylum level,exogenous CAT significantly increased the abundance of spirochetes,Bacteroides and Archaea in sow feces(P<0.05),and significantly decreased the abundance of Firmicutes(P<0.01).At the same time,at the family level,exogenous CAT significantly increased the abundances of spirochaceae,Methanobacteriaceae and Spirobacteriaceae,but significantly decreased the abundances of Streptococcaceae and Clostridium(P<0.05).(2)Compared with the control group,dietary CAT supplementation significantly increased ileum villus height of newborn piglets(P<0.05),and tended to increase duodenal villus height(P<0.10).Collectively,the addition of CAT in sows diet increased the Alpha diversity of sow fecal microflora,enhanced the enrichment degree of fecal microflora,and significantly increased the abundance or evenness index.In addition,exogenous CAT regulated the structure and abundance of sow fecal microflora.Furthermore,CAT supplementation in sows diet increased the villus height of ileum and duodenum of newborn piglets,and improved the intestinal health of newborn piglets,it was beneficial to the absorption of nutrients.In conclusion,exogenous CAT may regulate oxidative stress and nutrient absorption and metabolism of mother-piglets through the following pathways.First,adding CAT to sow diets during late gestation enhanced antioxidant capacity of sows,placentas and newborn piglets,which may alleviate oxidative stress in sows.In addition,dietary supplementation of CAT in sows during late gestation can affect nutrient absorption and utilization of sows and their offspring by regulating nutrient transporters in placenta and mRNA expression levels of genes related to fatty acid and amino acid transport in intestinal tract of newborn piglets,which may be related to CAT alleviating oxidative stress in the body.Finally,exogenous CAT increased the Alpha diversity of sow fecal flora,and changed the microbial colony structure and abundance.While,the villus development of newborn piglets was improved,which further promoted the absorption of nutrients.Therefore,adding CAT to the sow diet in late gestation can reduce the weak litter rate and improve the reproductive performance of sows to a certain extent,which provides theoretical support for the further application of CAT in animal feed. |
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