| The reproductive ability of sows is low and health problems are prominent in China pig production.In recent years,studies have found that dietary fiber can improve the reproductive performance of sows while regulating the body’s immune function,but it was reported inconsistent about the appropriate fiber level which improved sow reproductive performance.To research the effects of different dietary fiber levels on reproductive performance and immunity,sows of 3 to 6 parities and single-factor test design were used.190 Danish Landrace sows were selected and allotted to 6 experimental group in accordance with the principle of the same back fat and parity(average breeding backfat:14.39 mm;average parities:3.51): control group(2.4% crude fiber level,n=30),3.0% crude fiber group(3.0% CF,n=33),and 3.5% Crude fiber group(3.5% CF,n=32),4% Crude fiber group(4% CF,n=32),4.5% Crude fiber group(4.5% CF,n=31),5% Crude fiber group(5% CF,n=32).Each experimental group was fed fiber diet of different levels during gestation.All experimental groups were fed the same diet during lactation and all sows were fed ad libitum.During the experiment,the sow backfat was recorded at 30 th,60th,90 th,110th days of pregnancy,farrowing,and weaning.The sow reproductive performance was recorded at farrowing,and the feed intake of sows and growth performance of piglets were recorded during the lactation period.At the 30 th,60th,90 th,and 110 th days of pregnancy and on the day of farrowing,10 ml of blood was collected from the sows at 4 hours after meal,and blood levels of progesterone,estradiol,serotonin IgG,IgM,and cytokines were measured.We collected 10 ml of blood at piglet parturition and weaning to measure IgG,IgM,and cytokine levels in the blood.We collected sow faeces at 110 days of gestation to determine faeces SCFAs levels and collected sow colostrum and ordinary milk for milk composition analysis.The results as follows:(1)Dietary treatments have a tendency to increase the litter size of sows(P=0.072).5% CF significantly increased the number of live litters compared to CON and 3.0% CF(P<0.05).Dietary treatments had no significant effect on the number of healthy piglets,birth weight of piglets,litter weight at birth,stillbirth rate,weaning weight,weight gain of weaning litter,weight of weaned pigs,and daily gain of piglets(P>0.05).Dietary treatments had a trend to increase feed intake at the third week of lactation(P=0.081).Feed intake throughout the lactation,4% CF,5% CF,3.5% CF were significantly higher than those in CON(P<0.05).Diet treatment did not affect the wean-to-estrus interval.(P>0.05)Pregnancy 1-40 days fecal index,3.5% CF,4.5% CF,5% CF were significantly higher than CON(P<0.05),There was no significant difference between 3% CF,4% CF and other experimental groups(P>0.05).Dietary treatment had no significant effect on the components of sow colostrum and regular milk(P>0.05).Dietary treatment has a tendency to improve the heart organ index of piglets.(P=0.09)(2)Effect of dietary treatment on the level of SCFAs in feces: There was no significant effect of dietary treatment on the levels of acetate and propionate of the feces at pregnancy 110 days(P> 0.05).5%CF significantly increased fecal butyrate levels compared to other test groups(P< 0.05).(3)Effects of dietary treatment on progesterone,estradiol,and serotonin: dietary treatment had no significant effect on blood progesterone levels at 60 th day and 110 th day of pregnancy(P> 0.05).Dietary treatments had a tendency to reduce estradiol levels at 110 days of pregnancy(P= 0.085).The level of blood estradiol at 60 th day of pregnancy was significantly higher in CON than 3.5% CF,4.5% CF,and 5% CF(P< 0.05).Diet treatment had a tendency to increase serum levels of serotonin at 110 th day of pregnancy(P= 0.091),and had no significant effect on serotonin levels at 90 th day of pregnancy(P> 0.05).(4)Effects of dietary treatment on blood antibodies and cytokines: IL-10 levels at 30 th of pregnancy,CON,3.0% CF were significantly lower than 5% CF(P< 0.05),dietary treatment had no significant effect on IL-10 levels at sow110 th day of pregnancy,farrowing,and at the day of birth of piglets(P> 0.05).The level of TNF-α in sows at 30 th day of pregnancy was significantly higher in CON and 3.0% CF than 5% CF(P< 0.05).The level of TNF-α in the newborn piglets,5% CF,and 4.5% CF were significantly lower than those in CON and 3.5% CF groups(P<0.05).The 4% CF was significantly lower than the CON(P< 0.05).Diet treatment had no significant effect on TNFa levels at sow 110 th day of gestation,farrowing,and at weaning of the offspring(P> 0.05).Dietary treatments had no significant effect on the levels of IL-6 and IFN-γ of sows and piglets.IgG levels of 110 th day of gestational,5% CF,4% CF were significantly higher than CON,3% CF(P<0.05).Dietary treatment had no significant effect on IgM levels at 110 th day of pregnancy(P> 0.05).Dietary treatment had no significant effect on IgM levels of offspring piglets(P> 0.05).Diet treatment had no significant effect on IgG and IgM levels of weaned piglets(P> 0.05).Conclusion:(1)Adding different levels fiber to the diet increased litter sizen of sow,live litter sizen,feed intake during lactation and improved sow fecal scores(2)Adding different levels fiber to the diet increased serum IgG levels at 110 th day of gestation,therefore humoral immunity was improved in certain level,moreover changed sows at 30 th day of gestation and newborn piglets serum levels of inflammatory factor.To summarize the effects of fiber levels on sow reproductive performance and immune index,we found that the optimal fiber level for this experiment was 5% CF group. |
