Effects Of Dietary Protein Level During Late Gestation On Growth Of Hu Lambs And Colostrum Proteome

The current study was conducted to determine the effects of dietary protein levels in late gestation on the colostrum proteome and growth of lambs,which will provide a theoretical basis for ewes feeding and management during the late gestation and the lambs cultivate,and a certain reference to the mechanism of milk protein expression.1.Effects of maternal dietary protein levels in late gestation on growth of Hu ewes and lambsA total of 108 healthy Hu ewes with similar body weight were selected.They were synchronized for oestrus and mated at the adjacent three days,and then divided into three groups supplied with 9.00% low protein,12.03% medium protein,and 15.01% high protein during late gestation 90 days,respectively.After delivery,twin lambs in each group were selected for the later growth trail.The results showed that the average daily weight of ewes had no significant difference(P>0.05).The birth weights of lambs in the high protein group were significant higher than those of the medium protein group and low protein group(P<0.05),while no no significant difference was observed between medium protein group and low protein group(P>0.05);The body weights of lambs in the high protein group at 7 days and 30 days were significant higher than individuals in the low protein group(P<0.05),and there was no significant difference between the medium protein group and the high protein group(P>0.05);There was no significant difference in body weight of lambs at 14 days among three groups(P>0.05).The body weights of lambs at 60 days and 180 days had an increasing tendency with the increasing dietary protein levels(P=0.061,P=0.076).There was no significant effect on average daily gains of lambs during 0~7 d,7~14 d,14~30 d,0~60 d,60~180 d,0~180 d(P>0.05);The average daily gains of lambs during 30~60 d had an increase tendency in the medium protein group and high protein group than the low protein group(P=0.061).The income of the low protein,medium protein and high protein weaning lambs was 559.68 yuan,616.32 yuan and 618.56 yuan respectively.In the present experimental conditions,the suitable level of protein was 12.03% for the Hu ewes in late gestation.2.Effects of maternal dietary protein levels in late gestation on colostrum whey proteome of Hu ewesThe colostrum of all ewes with twin lambs at 1 d was collected.The 2-DE and MALDI-TOF/TOF MS technology were used to the isolation and identification of differentially expressed proteins.The results indicated that there were 12 differentially expressed protein spots,which identified four proteins,including polymeric immunoglobulin receptor subunit X2,albumin,Ig?1 chain,and Ig? chain.3.Effects of maternal dietary protein levels in late gestation on colostrum fat globule membrane proteomeThe iTRAQ technology was used to analyze the difference of milk fat globule membrane proteins in colostrum of ewes with different dietary protein levels.In total,1529 proteins were identified,and 273 were differentially expressed proteins among three groups.The GO richment analysis showed that the differential proteins were mainly involved in biological processes of response to external stimulation,skin development and secretion,etc;with molecular function of transition metal ion binding,RAGE receptor binding and glycosaminoglycan binding,etc;showed cellular components of the formation of polymeric cytoskeletal fiber,supramolecular complex and supramolecular fiber.The KEGG pathway analysis showed that differential proteins were involved in fatty acid biosynthesis,interleukin signaling pathway,and porphyrin and chlorophyll metabolism pathways.In addition,18 differential proteins showed a continuous up-regulation with the increasing of protein level in diet,including GIT ARFGAP,ribosomal proteins,and low density lipoprotein receptor etc.By contrast,20 differential proteins revealed a continuous down-regulation,including cell division cycle 37,syndecan,and laminin etc.In summary,in the present experimental conditions,the level of dietary protein of Hu ewes had a significant effect on the lambs' birth weight,weaning weight,and lambs' weaning economic benefits.The suitable level of protein was 12.03%.The level of dietary protein affected the expression of whey protein and milk fat globule membrane protein in Hu ewe's colostrum.There were 12 different protein spots in whey protein,including four proteins such as polymeric immunoglobulin receptor subunit X2,albumin,Ig?1 chain,and Ig? chain.There were 273 differential proteins in the milk fat globule membrane proteins,18 differential proteins showed a continuous up-regulation with the increasing of protein level in diet,including GIT ARFGAP,ribosomal proteins,and low density lipoprotein receptor.20 differential proteins showed a continuous down-regulation with the increasing of protein level in diet,including cell division cycle 37,syndecan,and laminin etc.