Effects Of Dietary Supplementation With Lysozyme During Late Pregnancy And Lactation Stage On The Performance Of Lactation Sows

The health status of sow during lactation period directly determines the weaning weight,the rate of oestrus after weaning and weaning performance of piglets.During the lactation,severe back fat loss and low immunity can cause metritis,limb hoof disease,mastitis and lead to the sow estrus difficult,can't stand up,poor quality of breast milk,and lack of milk,resulting the sow elimination and piglets grow slowly.Lysozyme as a kind of hydrolase,can sterilize bacteria by destroy bacteria cell wall structure,effective sterilization mechanism to make people think that it can be used as a substitute for antibiotics.In order to know application of lysozyme in sow,present study aims to investigate the effect of different level of lysozyme on the performance and immune function in lactating sow,to explore the application of lysozyme used as feed additive in lactating sow.These would provide the reference value for the lysozyme further popularization and application in animal production.The 60 sows with good body condition,average back fat thickness at 14.07 ± 2.58 mm,and pregnancy(3~6 parties)at the 85 th day were selected.The sows were randomly allocated to three treatment groups(four replicates in each treatment during pregnancy,five sows in each replicate,and one farrowing bed for each sow during the lactation period).Control group(CON): basic diet,Lysozyme A group(LZM A): basal diet and lysozyme 150g/t,Lysozyme B group(LZM B): basal diet and lysozyme 300g/t.The treatment was conducted from day 85 of pregnancy to the end of weaning.The thickness of the back fat was measured on day 85,day 100 of pregnancy period and day 1(parturition day)and day 21 of lactation period.At the first day of lactation,eight sows were selected from each treatment to collect the placenta tissue.Blood samples and milk samples were collected on day 1,day 7 and day 21 of the lactation period.On the day of weaning,eight piglets were randomly selected to collect blood samples.Recorded the sow reproduction performance,feed intake during lactation period,re-estrus time after weaning.Adopt fully automatic biochemical analyzer to determine serum biochemical metabolism index.Uses the Nanjing JianCheng ELISA kit to determine the immune index.Using infrared analyzer to determination the conventional index of breast milk.Use the BIO-RAD CFX96 real-time fluorescent quantitative PCR for placenta tissue gene analysis.The results are as follows:(1)There was no significant difference among the treatments of the amount of backfat thickness,the increase of backfat thickness during pregnancy and the reduction of backfat during lactation period(P>0.05).There was no significant difference on the number of newborn piglets,the number of live piglets,the number of weak piglets,birth weight,birth litter weight,weaning weight,weaning litter weight(P>0.05)among the treatment groups.The number of stillbirth in the LZM B treatment group was significantly lower than LZM A treatment group(P<0.05),but no significant difference compared with CON treatment group(P>0.05).In the LZM treatment groups,the feed intake of sow on lactation period was increased,the weaning-estrous interval(WEI)was shortened(P<0.05).The rate of re-breeding rate and conception rate was no significant difference among the treatments(P>0.05).The LZM treatment groups' piglet diarrhea rate was significantly lower than that in the CON group(P<0.05).Piglet fur index among the groups was no significant differences(P>0.05).(2)Compare with the CON treatment group,LZM treatment groups increased the sow's total protein content in the serum of the first day of lactation(P < 0.05),but no significant effect on total protein,globulin,albumin,glutamate transaminase,glutamate transaminase in the serum on day 7 and day 21 of lactation(P>0.05).Serum total protein content of piglets in LZM treatment groups was significantly increased(P<0.05),the content of albumin and globulin had a tendency to improve(P=0.089,P=0.068).The sow's serum immunoglobulin G content in the LZM treatment groups had a tendency to increase on day 1 and day 7 of lactation(P=0.05,P=0.088).Serum immunoglobulin M content in the LZM treatment group was increased on the first day of lactation(P<0.05),and there was a rising tendency on the day 7 and day 21 of lactation(P=0.092,P=0.058).Serum interleukin-10 content had a tendency to increase on the first day(P=0.081)and increased significantly on the day 7 of lactation(P<0.05).Serum interleukin-6 and tumor necrosis factor-alpha were no significant difference among the treatments(P>0.05).The piglet's serum immunoglobulin A,immunoglobulin G,immunoglobulin M and interleukin-10 content in the LZM treatment groups were increased compare with the CON treatment group(P<0.05).Interleukin-6 and tumor necrosis factor-alpha were not different among the treatments(P>0.05).(3)In the LZM treatment groups,the content of immunoglobulin A in sow's whey was significantly increased on the day 1 and day 7 of lactation(P<0.05)and had a tendency to increase on the day 21 of lactation(P=0.064).Lactose,fat,milk protein and total solids were no significant difference among the treatments(P>0.05).(4)The content of LZM in sow's serum on the day 1,day 7 and day 21 of lactation was not different in each treatment(P>0.05).The content of LZM in sow's whey on the day 1,day 7 of lactation was not different in each treatment(P>0.05).The content of LZM in piglet's serum on the day of weaning was not different in each treatment(P>0.05).(5)The mRNA expression levels of sow placental tissue's interleukin-6,interleukin-10,tumor necrosis factor-alpha and poly immunoglobulin receptor were not different in each treatment(P>0.05).There was no significant difference in the concentration of interleukin-6,interleukin-10,tumor necrosis factor-alpha and secretory immunoglobulin A in sow placental tissue among the treatments(P>0.05).In conclusion,this study indicates that supplementing sow diets with lysozyme from late gestation to lactation stage increase sow ADFI during the lactation,promote sow reproduction performance by shortening the WEI,and improve the maternal and offspring health status as indicated by immunological characteristics and decreased the diarrhea rate of piglets.