Dietary Supplementation Of Cysteamine During Late Gestation And Lactation Of Sows: Effects On Performance, Oxidative Stress Of Sows And Their Offspring

In modern swine production,many factors are prone to cause progressive oxidative stress during the reproductive cycle of the sow,which in turn reduces the production efficiency of the sow.Our previous study showed that cysteamine(CS)can significantly alleviate oxidative stress of weaned piglets.However,few studies have focused on the effect of dietary CS on oxidative stress damage and reproductive performance of sows.Therefore,the purpose of this study was to investigate the effects of dietary supplementation of CS on oxidative stress and reproductive performance of sows,and to elucidate its mechanism of action by taking placenta redox state and mitochondrial biological function as entry points.Experiment 1: The purpose of this experiment was to investigate the effects of dietary supplementation with different sources of antioxidants on oxidative stress transmission and reproductive performance of sows.A total of 63 multiparous Landrace × Yorkshire sows were randomly assigned into three different dietary treatments based on parity and body weight(BW)at day 83 of gestation.The three experimental treatments were defined as follows:(1)sows fed a control diet(Control,CON);(2)sows fed a basal diet supplemented with 500mg/kg CS(CS500);(3)sows fed a basal diet supplemented with 500 mg/kg N-acetyl-cysteine(N-acetyl-cysteine,NAC500).The experiment lasted from day 85 of gestation to day 21 of lactation.The blood of sows and piglets was collected to analyze oxidative stress parameters.At farrowing,the placentas were collected to measure its indicators on mitochondrial biosynthesis and oxidative stress.The results showed that:(1)Compared with the CON group,the CS500 group had a lower stillbirth rate(P<0.05)and a proportion of low birth weight(LBW,<1.0 kg)piglet(P<0.05)in low yield sow(i.e.,number of born alive piglets less than15),and those in the NAC500 group only showed a downward tendency(P=0.06).(2)Compared with the CON group,the CS500 group showed a significant increase(P<0.05)in sows’ serum total antioxidant capacity(T-AOC)and glutathione(GSH)at farrowing,an increase in sow’s serum T-AOC at weaning,as well as an increase of GSH of serum in neonatal piglets with normal birth weight(NBW,1.4-1.6 kg).(3)Despite no notable differences in oxidative parameters of the placenta of NBW among dietary treatments(P>0.05),the CS500 group had higher relative gene expression of catalase(CAT)and nuclear factor-E2-related factor2(Nrf2)in placenta of neonatal piglets LBW than those in the CON group(P<0.05).Moreover,relative gene expression of Mn-superoxide dismutase(Mn-SOD)and Nrf2 in the placenta of LBW piglets in the NAC500 group were significantly higher(P<0.05)than those in the CON group.(4)Besides,the number and volume of placenta mitochondria in the CS500 and NAC500 group were higher than those in the CON group,and the swelling degree was alleviated in the CS500 group.(5)In addition,the levels of ATP had a upward tendency(P=0.09)in the CS500 group than in the CON group,and the relative gene expression of β subunit of mitochondrial H+-ATP synthase(ATB5B)in the placenta of LBW in the CS500 group were significantly higher than those in the CON group(P<0.05),and the relative expressions of cytochrome c(Cyt C)and peroxisome proliferator activated receptor-γ coactivator-1α(PGC1α)had a upward tendency(P=0.08 and P=0.09)in the CS500 group than those in the CON group.In addition,the relative gene expression of Cyt C,PGC1α,and ATB5 B in the placenta of LBW piglets in the NAC500 group were significantly higher than those in the CON group(P<0.05).Conclusion: The CS500 group increased the antioxidant capacity in the serum of sows and their offspring may attribute to alleviate the oxidative damage of the placenta,and enhance the placental mitochondrial biosynthesis and function,thereby reducing the stillbirth rate.The overall effects of CS were better than those of NAC.Experiment 2: Based on the above results and to obtain greater economic benefits,the aim of this experiment was to further determine effects of different levels of CS on oxidative stress and reproductive performance of sows.A total of 84 multiparous Landrace × Yorkshire sows were randomly assigned into four different dietary treatments based on parity and BW at day 83 of gestation.The four dietary treatments consisted of a gestation or lactation basal diet(CON),or the CON diet supplemented with 100,300,500 mg/kg CS.The results showed that:(1)Compared with the CON group,the CS100 group showd a decrease of the rates of stillbirth(P<0.05),an increase of placental efficiency and vascular density of LBW piglets(P<0.05),as well as an increase of birth weight in low yield sow.(2)Moreover,compared with the CON group,the CS100 group showed an increase of serum levels of sows at farrowing and weaning(P<0.05),an increase of colostrum GSH levels(P<0.05),a decrease of colostrum malondialdehyde(MDA)level of sows(P<0.05),as well as an increase of GSH of serum and placenta in NBW piglets(P<0.05).(3)Dietary supplementation with different levels of CS has no significant effect on the body weight and changes of sows at all stages(P>0.05),but the backfat loss during lactation during the CS500 group increased significantly compared to the CON group(P<0.05).(4)Besides,the economic benefits showed that the feed cost of producing each NBW piglet in the CS100 group was 0.5 yuan lower than that in the CON group.As the amount of cysteamine increased,backfat loss during lactation was linear or quadratic curve model.Conclusion: Different levels of dietary CS does not have a significant dose effect on improving the antioxidant capacity of sows,but the CS100 group showed the best effects on reducing the stillbirth rate and promoting placental vascular development,as well as the lowest feed cost.In summary,dietary supplementation of CS can alleviate oxidative stress and stillbirth of sows.The mechanism may be related to the reduction of sow placental oxidative damage and the protection of mitochondrial function.Although the overall effects of CS were better than that of NAC,the excessively high dose of CS during lactation caused the sow backfat loss to increase.Comprehensive consideration,100 mg/kg is the appropriate level of CS for sow diets.