Study On The Structure And Content Of Free Oligosaccharides From Porcine Milk

Early weaning of piglets is an important technique in the modern pig husbandry.However,weaning stress easily causes intestinal injury,thereafter results in digestive system dysfunction,diarrhea,growth check,and even death.It has been well known that milk oligosaccharides play important roles in promoting intestinal health.The comprehensive understanding of the pig milk oligosaccharides is thus expected to help to improve the nutritional value of milk replacer and reduce the intestinal injury caused by weaning stress of piglets.In this paper,free oligosaccharides in porcine milk were studied from two aspects of structure and content.The details of the results are as follows:1.Structural analysis of free oligosaccharides in porcine milkThe structure of porcine milk oligosaccharides was investigated by UHPLC and MALDI-TOF-MS/MS.Free oligosaccharides were extracted using the method of chloroform/methanol and detected by fluorescence derivatization and UHPLC.UHPLC peak fractions can be collected and verified by MALDI-TOF-MS.According to the value of m/z and Glycoworkbench,we can get the possible structures.The elution time of UHPLC peak was converted into the standard GU value.The GU value was comparied with Glycobase 3.2.We can get the corresponding structure.A more accurate structure can be obtained by combining the results of MALDI-TOF-MS and the GU value.The resuts of MALDI-TOF-MS/MS can verify the predicted structures.34 different structures were detected,including 24 neutral oligosaccharides,10 sialylated oligosaccharides,3 fucosylated oligosaccharides.The structures of a3’-GalL、β3’-GalL、β6’-GalL、3’-SL、6’S-β6’-GlcNAcL were the main content in colostrum.The most abundant PMOs were 2’-FL and 3’-SL in normal milk.2.Comparison of free oligosaccharides in porcine milkMilk was collected from three breed of sows(Landrace,Yorshire,Meishan)on days 1,7,14 and 21 of lactation.The standard curve was drawn with maltopentose as standard,and the free oligosaccharides in porcine milk were quantitated.The content of PMOs were analyzed between different lactation period,different varieties and different individuals.The details of the results are as follows:(1)Variation of porcine milk oligosaccharides between three breeds of sowsThe total content of free oligosaccharides in colostrums is quite different between varieties,and the difference gradually decreases with prolongation of lactation.The content of 2’-FL,a3’-GalL,β3’-GalL,β6’-GalL,3’-SL,6’S-β6’-G1cNAcL were also different among varieties.Its difference in colostrum is greater than that of normal milk.(2)Variation of porcine milk oligosaccharides among individualThe individual difference of the total content of PMOs was very large.The content of the six oligosaccharides vary among different individuals.The most abundant PMO was 3’-SL for most individuals across lactation.(3)Changes in porcine milk oligosaccharides across lactationThe content of the PMOs was changed with lactation period.The total MOs abundance was extremely high in day 1;and then there was a significant decline;finally,it almost kept stable.The content of PMOs in colostrum is about 3.5-12.5 times that of content in normal milk.The content of 2’-FL in colostrum was lower than that in the normal milk,while the other 5 kinds of MOs in colostrum were higher than those in the normal milk.The results of this study will help to find the functional oligosaccharide which can be used to modulate the intestinal health of piglets.