Effects Of Fat Source And Encapsulation On Growth Performance,Nutrients Utilization,fatty Acids Absorption And Gut Microbiota Of Nursery Pigs

Fat was used as an important energy source to promote growth performance in nursey diet.However,the deficiency of digestive system in nursery pigs restricted the fat utilization.Fat encapsulation was considered as an effective process to promote the utilization of dietary fat.To evaluate the effects of fat source and encapsulation on growth performance,digestion and absorption,and intestinal health of nursery pigs,four experiments were carried out as following.Part 1: Effect of fat source and encapsulation on growth performance,nutrient utilization,blood parameters and digestive enzyme activity.Two experiments were conducted to evaluate 1)effects of encapsulation of palm oil and coconut oil on growth performance,feed intake,feed efficiency and blood parameters,and 2)effects of encapsulation of palm oil and coconut oil on apparent total tract digestibility(ATTD)of nutrients,and the activity of digestive enzymes in nursery pigs.In Exp.1,540 pigs(weaned at 21 d,8.23±0.22 kg)were allotted to five treatments based on a randomized complete block design(as-fed basis).Pigs were fed basal diets with 5 different fat sources: 6.0% soybean oil(SBO),6.0% palm oil(PO),6.0% palm oil from encapsulated fat(EPO),6.0% coconut oil(CO),and 6.0% coconut oil from encapsulated fat(ECO)respectively,with 6 pens per treatment and 18 pigs per pen for a 4-wk feeding trial.Dried casein and whey powder used for encapsulation were included at identical levels in all diets.Pigs fed encapsulated fat had increased(P ? 0.05)ADG during d 0 to 14,d 14 to 28 and overall,decreased(P ? 0.05)F/G during d 0 to 14 and overall,decreased(P ? 0.05)DI compared to pigs fed unencapsulated fat,whereas ADG of pigs fed ECO was not different from pigs fed EPO and CO.There were no differences in ADFI among treatments.Pigs fed encapsulated fat had decreased(P ? 0.05)SUN at d 14 and 28,and VLDL-C at d 14 compared to pigs fed unencapsulated fat.In Exp.2,30 pigs(28 d of age,8.13 ± 0.10 kg BW)were housed individually(n = 6 per treatment)and allotted to 5 treatments as described in Exp.1.Pigs were fed ad libitum for 4 weeks to measure ATTD of diets weekly and digestive enzyme activity at wk 4.Five dietary treatments were the same as in Exp.2 with additional 3.5 kg/T chromic oxide added as an inert marker.Pigs fed EPO had increased(P ? 0.05)ATTD of DM,GE and EE compared to pigs fed PO,fat encapsulation had less effect on coconut oil compared to palm oil.There is little effect on ATTD of CP.Pigs fed encapsulated fat had increased pancreatic lipase(P ? 0.05)and trypsin(P = 0.05)activity compared to unencapsulated fat.In conclusion,this study indicates that encapsulation of palm oil improved growth performance,ATTD of diets in nursery pigs,pancreatic lipase and trypsin activity in nursery pigs,decreased DI,SUN and VLDL-C,whereas the limited effects of encapsulated coconut oil were likely due to the high digestibility of the medium chain triglycerides(MCT)abundant in coconut oil.Part 2: Effect of fat source and encapsulation on fatty acid composition of digesta in the gastrointestinal tract.The animals,treatments and diets were consistent with Exp.2 mentioned above.Pigs were euthanized after 28 days of feeding,stomach,jejunum,ileum,cecum and colon were separated,the digesta of each segment in the distal part were collected,fatty acid composition analysis was performed.The fatty acids content in stomach,jejunum and ileal digesta had significantly differences in all treatments(P < 0.05),and the digestion and absorption rate of fat in jejunum was significantly greater than that in stomach and ileum,while the digestion and absorption of palm oil in jejunum was not different from that in ileum.Shorter chain length of saturated fatty acids and more hydrogen bonds in unsaturated fatty acids accompanied with greater digestion and absorption rate in jejunum,with an exception of palm oil.The absorption rate of C18:0 in jejunum and ileal digesta in all treatments were significantly lower than that of other fatty acids.The digestion and absorption rate of palm oil was enhanced by encapsulation,and the change of long-chain saturated fatty acids was greater than that of long-chain unsaturated fatty acids.Encapsulated coconut oil had increased digestion and absorption rate of C14:0,C16:0 and C18:0 in jejunum compared to coconut oil,and the change of C18:1 was less than that of long-chain saturated fatty acids.The results showed that jejunum was the main segment of fat digestion and absorption,and the main digestion and absorption area of palm oil was switched from jejunum to ileum.Encapsulation of palm oil enhanced the digestion and absorption rate of total fatty acids,whereas encapsulation of coconut oil enhanced the long chain saturated fatty acids digestion in the jejunum.Part 3: Effect of fat source and encapsulation on fatty acid sensory receptor,transport protein and apolipoprotein m RNA expression in the gastrointestinal tract.The animals,treatments and diets were consistent with Exp.2 mentioned above.Pigs were euthanized after 28 days of feeding,stomach,duodenum,jejunum and ileum were separated,the intestinal mucosa in distal part of each segment was collected,real-time PCR was performed to evaluated the relative m RNA expression of related gene.The results showed that fat encapsulation enhanced the relative expression of GPR120 m RNA in duodenal and jejunal mucosa(P < 0.05),and EPO was greater(P < 0.05)than that in SBO and CO.SBO had increased(P < 0.05)relative expression of FATP4 m RNA in stomach and small intestinal mucosa compared with PO,EPO and ECO.Fat encapsulation enhanced the relative expression of FAT/CD36 m RNA in duodenum(P = 0.098)and ileum(P < 0.05),PO and EPO had increased relative expression of FAT/CD36 m RNA in stomach(P < 0.05)and jejunum(P = 0.098)compared to CO and ECO.SBO and EPO tended to enhance the relative expression of I-FABP m RNA in stomach,duodenum and ileum compared to other treatments,EPO had increased(P < 0.05)relative expression in jejunum compared to SBO,CO and ECO.Fat encapsulation enhanced the relative expression of IL-FABP m RNA in jejunum compared to unencapsulated oil(P < 0.05),SBO,PO and EPO had increased(P < 0.05)relative expression in duodenum compared to CO and ECO.Fat encapsulation enhanced the relative expression of L-FABP m RNA in duodenum compared to unencapsulated oil(P < 0.05),pigs fed diets contained palm oil had increased(P < 0.05)relative expression of L-FABP m RNA in stomach and jejunum compared to pigs fed diets contained coconut oil.Pigs fed diets contained palm oil had increased(P < 0.05)relative expression of Apo B48 m RNA in duodenum and jejunum compared to pigs fed diets contained coconut oil,SBO was not different from CO and ECO.Fat encapsulation tended to enhance the relative expression of Apo A-I m RNA compared to unencapsulated ones(P = 0.052),pigs fed diets contained palm oil tended to enhance the relative expression of Apo A-I m RNA in duodenum compared to pigs fed diets contained coconut oil(P < 0.05).Pigs fed SBO had increased(P < 0.05)relative expression of Apo A-IV m RNA in duodenum compared to PO,EPO and ECO,pigs fed SBO had increased(P < 0.05)relative expression of Apo A-IV m RNA in jejunum and ileum compared to other dietary treatments.The results showed that encapsulation of palm oil and coconut oil enhanced the relative expression of GPR120 m RNA in duodenum and jejunum compared to unencapsulated ones.The membrane fatty acid transporter FATP4 inclined to transport the long-chain unsaturated fatty acids,while the membrane transportation of longchain saturated fatty acids depended on FAT/CD36.Long chain fatty acids enhanced the m RNA expression of I-FABP,IL-FABP and L-FABP.The relative m RNA expression of Apo B48(duodenum and jejunum)and Apo A-I(duodenum)were significantly affected by longchain saturated fatty acids,and the effect of medium-chain fatty acids on the expression of related genes in intestinal epithelial cells was lower than that of long-chain fatty acids.Part 4: Effect of fat source and encapsulation on gut microbiota of nursery pigs.The animals,treatments and diets were consistent with Exp.2 mentioned above.Pigs were euthanized after 28 days of feeding,the duodenum,jejunum,ileum,cecum and colon were separated,the digesta in distal part of each segment was collected,total bacteria DNA was extracted,following with a 16 s r DNA high-throughput sequencing,the abundance of gut microbiota was analyzed using bioinformatic methods,and the correlation analysis between bacteria abundance and the phenotypic character of growth performance and digestibility was performed.The results showed that the dominant flora in small intestine digesta was different from large intestine.The dominant phyla in small intestine was Firmicutes,Proteobacteria and Actinobacteria,while the dominant phyla in large intestine was Firmicutes,Bacteroides and Proteobacteria.In duodenum and jejunum,pigs fed PO had increased(P < 0.05)Alpha diversity index Chao1,Observed species and PD whole tree compared to other groups,and pigs fed PO had increased(P < 0.05)Alpha diversity index Shannon compared to other treatments.The results of Beta diversity analysis showed that the bacteria composition in duodenum and jejunum digesta in PO were different from other treatment groups,and CO was different from ECO.Compared with SBO,pigs fed PO and CO had decreased(P < 0.05)abundance of Firmicutes in jejunum,and increased(P < 0.05)abundance of Proteobacteria and Actinobacteria.Pigs fed encapsulated palm oil and coconut oil had increased(P < 0.05)abundance of Firmicutes and decreased(P < 0.05)abundance of Proteobacteria and Actinobacteria in jejunum compared to unencapsulated ones.The abundance of genus which can utilize fat(Anaerovibrio,Phascolarctobacterium)and fiber(Ruminococcaceae)to produce short-chain fatty acids and the abundance of genus which are the potential pathogenic bacteria was negative correlated with ADG,ATTD of EE and GE,and positive correlated with F/G.The results showed that pigs fed palm oil had decreased abundance of beneficial bacteria,and increased abundance of pathogenic bacteria in duodenum and jejunum,and significantly improved the diversity of gut microbiota in small intestine digesta,changed the composition of gut microbiota.Pigs fed coconut oil had similar changes.Pigs fed encapsulated palm oil and coconut oil had positive effect on the intestinal flora disturbance that caused by palm oil and coconut oil feeding.In conclusion,the results showed that encapsulation of palm oil increased digestibion and absorption rate of fatty acids,promoted the expression of fatty acids absorption and transportation related genes in the intestinal epithelial cells,adjusted the secretion of pancreatic lipase and trypsin,improved the digestibility of nutrients,maintained the balance of gut microbiota,reduced the diarrhea incidence,resulted in improved growth performance and health status compared to pigs fed palm oil.Encapsulation of coconut oil had similar effect,but the effect was less than encapsulation of palm oil.