Patterns of alteration in boar semen quality from 9 to 37 months old and improvement by protocatechuic acid

Background Comprehending the patterns of alteration in boar semen quality and identifying effective nutritional interventions are crucial for enhancing the productivity of commercial pig systems.This study aimed to examine the alteration in semen quality in boars,and assess the impact of protocatechuic acid(PCA)on semen quality during the phase of declining semen quality.Methods In Exp.1,a total of 38 Pig Improvement Company(PIC)boars were selected and their semen quality data were recorded from the age of 9 to 37 months.In Exp.2,18 PIC boars(28 months old)were randomly assigned into three groups(n=6)and fed a basal diet,a basal diet containing 500 or 1,000 mg/kg PCA,respectively.The experiment lasted for 12 weeks.Results The semen volume,concentration,and total number of spermatozoa in boars exhibited an increase from 9 to 19 months old and showed a significant linear decreased trend in 28,24,and 22 months old.Sperm motility displayed an upward trajectory,reaching its peak at 20 months of age,and showed a significant linear decreased trend at 20 months old.Dietary supplementation of PCA demonstrated an effect to mitigate the decrease in semen volume,concentration of spermatozoa,total number of spermatozoa(P>0.05),and significantly increased the sperm motility(P<0.05).Moreover,supplementation of 1,000 mg/kg PCA significantly increased the sperm viability(P<0.05).Analysis on cellular signaling pathways revealed that PCA restored serum testosterone levels and alleviated oxidative damage by upregulating the expression of HO-1,SOD2,and NQO1 in testicular stromal cells.Notably,PCA can enhance phosphorylation by selectively binding to AMP-activated protein kinase(AMPK)protein,thereby improving sperm mitochondrial function and augmenting sperm motility via PGC-1/Nrf1.Conclusions These data elucidated the pattern of semen quality variation in boars within the age range of 9 to 37 months old,and PCA has the potential to be a natural antioxidant to enhance sperm quality through modulation of the AMPK/PGC-1/Nrf1 signaling pathway.

Dietary Bacillus spp.enhanced growth and disease resistance of weaned pigs by modulating intestinal microbiota and systemic immunity

Background:Previous research has shown that dietary supplementation of Bacillus spp.probiotics exerts beneficial effects on animals’growth.However,limited studies have evaluated the efficacy of Bacillus spp.on weaned pigs and their effects on host gut health and microbiome,and systemic immunity using a disease challenge model.The objective of this experiment was to investigate the effects of two Bacillus spp.strains(Bacillus subtilis DSM 32540 and Bacillus pumilus DSM 32539)on growth performance,diarrhea,intestinal health,microbiome,and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli(ETEC).Results:Pigs in PRO1(Bacillus subtilis DSM 32540)had greater(P<0.05)body weight on d 7 and 14 PI,greater(P<0.05)ADG from d 0 to 7 and d 7 to 14 PI,compared with pigs in CON(Control).Pigs in PRO1 had milder(P<0.05)diarrhea on d 2 and 3 PI compared with pigs in CON.However,no differences were observed in growth performance and diarrhea score between PRO2(Bacillus pumilus DSM 32539)and CON groups.Supplementation of PRO1 decreased(P<0.05)lymphocyte counts on d 7 and 14 PI,compared with CON.Supplementation of PRO1 and PRO2 both reduced(P<0.05)total coliforms in mesenteric lymph nodes on d 21 PI.Pigs in PRO2 had greater(P<0.05)goblet cell number and sulfomucin percentage in duodenal villi and greater(P<0.05)sialomucin percentage in jejunal villi than pigs in CON.Supplementation of PRO1 up-regulated(P<0.05)MUC2 gene expression in jejunal mucosa and reduced(P<0.05)PTGS-2 and IL1B gene expression in ileal mucosa on d 21 PI,compared with CON.Pigs in PRO1 had reduced(P<0.05)relative abundance of families Lachnospiraceae,Peptostreptococcaceae and Pasteurellaceae in the ileum.Conclusions:Supplementation of Bacillus subtilis DSM 32540 improved growth performance,alleviated diarrhea severity,enhanced gut health,and reduced systemic inflammation of weaned pigs infected with ETEC F18.Although Bacillus pumilus DSM 32539 was able to alleviate systemic inflammation,it had limited impacts on growth performance and severity of diarrhea of ETEC F18 challenged weaned pigs.

The application of antimicrobial peptides as growth and health promoters for swine

With the widespread ban on the use of antibiotics in swine feed, alternative measures need to be sought to maintain swine health and performance, Antimicrobial peptides （AMPs） are part of the nonspecific defense system and are natural antibiotics produced by plants, insects, mammalians, and micro-organisms as well as by chemical synthesis. Due to their broad microbicidal activity against various fungi, bacteria and enveloped viruses AMPs are a potential alternative to conventional antibiotics for use in swine production. This review focuses on the structure and mechanism of action of AMPs, as well as their effects on performance, immune function and intestinal health in pigs. The aim is to provide support for the application of AMPs as feed additives replacing antibiotics in swine nutrition.

Effects of dietary protein restriction on muscle fiber characteristics and m TORC1 pathway in the skeletal muscle of growing-finishing pigs

Background： To investigate the effects of dietary crude protein（CP） restriction on muscle fiber characteristics and key regulators related to protein deposition in skeletal muscle, a total of 18 growing-finishing pigs（62.30 ± 0.88 kg）were allotted to 3 groups and fed with the recommended adequate protein（AP, 16 % CP） diet, moderately restricted protein（MP, 13 % CP） diet and low protein（LP, 10 % CP） diet, respectively. The skeletal muscle of different locations in pigs, including longissimus dorsi muscle（LDM）, psoas major muscle（PMM） and biceps femoris muscle（BFM） were collected and analyzed.Results： Results showed that growing-finishing pigs fed the MP or AP diet improved（P 〈 0.01） the average daily gain and feed： gain ratio compared with those fed the LP diet, and the MP diet tended to increase（P = 0.09） the weight of LDM. Moreover, the ATP content and energy charge value were varied among muscle samples from different locations of pigs fed the reduced protein diets. We also observed that pigs fed the MP diet up-regulated（P 〈 0.05） muscular m RNA expression of all the selected key genes, except that myosin heavy chain（My HC） IIb,My HC IIx, while m RNA expression of ubiquitin ligases genes was not affected by dietary CP level. Additionally, the activation of mammalian target of rapamycin complex 1（m TORC1） pathway was stimulated（P 〈 0.05） in skeletal muscle of the pigs fed the MP or AP diet compared with those fed the LP diet.Conclusion： The results suggest that the pigs fed the MP diet could catch up to the growth performance and the LDM weight of the pigs fed the AP diet, and the underlying mechanism may be partly due to the alteration in energy status, modulation of muscle fiber characteristics and m TORC1 activation as well as its downstream effectors in skeletal muscle of different locations in growing-finishing pigs.

Developmental changes in intercellular junctions and Kv channels in the intestine of piglets during the suckling and post-weaning periods

Background： The intestinal epithelium is an important barrier that depends on a complex mixture of proteins and these proteins comprise different intercellular junctions. The purpose of this study was to investigate the postnatal and developmental changes in morphology, intercellular junctions and voltage-gated potassium（Kv） channels in the intestine of piglets during the suckling and post-weaning periods.Results： Samples of the small intestine were obtained from 1-, 7-, 14-, and 21-d-old suckling piglets and piglets on d 1, 3, 5, and 7 after weaning at 14 d of age. The results showed that the percentage of proliferating cell nuclear antigen（PCNA）-positive cells and alkaline phosphatase（AKP） activity, as well as the abundances of E-cadherin,occludin, and Kv1.5 m RNA and claudin-1, claudin-3, and occludin protein in the jejunum were increased from d 1to d 21 during the suckling period（P 〈 0.05）. Weaning induced decreases in the percentage of PCNA-positive cells,AKP activity and the abundances of E-cadherin, occludin and zonula occludens（ZO）-1 m RNA or protein in the jejunum on d 1, 3 and 5 post-weaning（P 〈 0.05）. There were lower abundances of E-cadherin, occludin and ZO-1m RNA as well as claudin-1, claudin-3 and ZO-1 protein in the jejunum of weanling piglets than in 21-d-old suckling piglets（P 〈 0.05）. The abundances of E-cadherin, occludin, ZO-1 and integrin m RNA were positively related to the percentage of PCNA-positive cells.Conclusion： Weaning at 14 d of age induced damage to the intestinal morphology and barrier. While there was an adaptive restoration on d 7 post-weaning, the measured values did not return to the pre-weaning levels, which reflected the impairment of intercellular junctions and Kv channels.

Abnormal adipose tissue-derived microbes drive metabolic disorder and exacerbate postnatal growth retardation in piglet

Postnatal growth retardation(PGR)frequently occurs during early postnatal development of piglets and induces high mortality.To date,the mechanism of PGR remains poorly understood.Adipose tissue-derived microbes have been documented to be associated with several disorders of metabolism and body growth.However,the connection between microbial disturbance of adipose tissue and pig PGR remains unclear.Here,we investigated piglets with PGR and found that the adipose tissue of PGR piglets was charac-terized by metabolism impairment,adipose abnormality,and specific enrichment of culturable bacteria from Proteobacteria.Gavage of Sphingomonas paucimobilis,a species of Sphingomonas genus from the alphaproteobacteria,induced PGR in piglets.Moreover,this bacterium could also lead to metabolic disorders and susceptibility to acute stress,resulting in weight loss in mice.Mechanistically,multi-omics analysis indicated the changes in lipid metabolism as a response of adipose tissue to abnormal microbial composition.Further experimental tests proved that one of the altered lipids phosphatidylethanolamines could rescue the metabolism disorder and growth retardation,thereby suppressing the amount of Sphingomonas in the adipose tissue.Together,these results highlight that the microbe–host crosstalk may regulate the metabolic function of adipose tissue in response to PGR.

Applications and prospects of functional oligosaccharides in pig nutrition:A review

Oligosaccharides are low molecular weight carbohydrates between monosaccharides and poly-saccharides,which consist of 2 to 20 monosaccharides linked by glycosidic bonds.They have the effects of promoting growth,regulating immunity,improving the structure of intestinal flora,and are anti-inflammatory and antioxidant.With the comprehensive implementation of the antibiotic prohibition policy in China,oligosaccharides as new green feed additive have been paid more attention.Oligosac-charides can be divided into the following 2 categories according to their digestive characteristics:one is easy to be absorbed by the intestine,called common oligosaccharides,such as sucrose and maltose oligosaccharide;the other is difficult to be absorbed by the intestine and has special physiological functions,called functional oligosaccharides.The common functional oligosaccharides include mannan oligosaccharides(MOS),fructo-oligosaccharides(FOS),chitosan oligosaccharides(COS),xylo-oligosaccharides(XOS)and so on.In this paper,we review the types and sources of functional oligo-saccharides,their application in pig nutrition,and the factors limiting their efficacy in recent years.This review provides the theoretical basis for further research of functional oligosaccharides,and the future application of alternative antibiotics in pig industry.

Effects of main active components of rosemary on growth performance,meat quality and lipid metabolism in finishing pigs

Rosemary extracts have been widely used as feed additives in recent years.This study aimed to investigate the effects of rosmarinic acid(RA)and ursolic acid(UA),the main active components of rosemary,on growth performance,meat quality and lipid metabolism in finishing pigs.A total of 72 finishing pigs(Landrace;initial age of 150 d)were randomly divided into 3 treatments with 8 replicates of 3 pigs each,and fed a basal diet or diet containing 500 mg/kg of RA or UA.The results showed that dietary supplementation of RA or UA had no significant effect on the growth performance and carcass traits of finishing pigs(P>0.05).However,both RA and UA significantly increased the triglyceride(TG)level in soleus muscle(P<0.001).Supplementation of RA increased the expression of genes related to lipogenesis and transport including fatty acid synthase(FAS)(P<0.001),sterol regulatory element binding protein-1c(SREBP1c)(P<0.001)and peroxisome proliferator-activated receptorγ(PPARγ)(P<0.05),while UA increased the expression of fatty acid transport protein 1(FATP1),a gene related to lipid uptake(P<0.05).However,RA reduced the expression of adipogenesis-related gene acetyl-coenzyme A carboxylase a(ACCa)(P<0.01).Characterization of cecal microbiota indicated that RA increased the microbial richness(chao 1,P<0.001)and diversity(observed species,P<0.01).Further analysis of the genera revealed that RA increased the relative abundance of Bacteroides and g-UCG-005(P<0.05),and UA enriched Prevotella(P<0.001).Correlation analysis showed that g-UCG-005 was positively correlated with the expression of FAS,carnitine palmitoyl transferase 1B(CPT1B),SREBP1c and PPARγ(P<0.01).In conclusion,dietary supplementation of RA or UA may increase fat deposition in muscle of finishing pigs by regulating lipid metabolism and gut microbiota.

Physiological function and application of dietary fiber in pig nutrition:A review

Dietary fiber(DF),divided into soluble dietary fiber(SDF)and insoluble dietary fiber(IDF),has attracted increasing attention in the field of pig nutrition.Although DF reduces nutrient digestibility and inhibits energy deposition in most cases,fiber-rich feeds have been widely used in pig diets.This is not only because of lower feed costs,but also from the continuous discovery about the nutritional value of DF,mainly including the improvement of piglet intestinal health and sow reproductive performance.The addition timing has also been further considered,which potentially enables the nutritional value of DF to be accurately used in applicable pig models.Furthermore,fiber degrading enzymes have been shown to alleviate the anti-nutritional effects of DF and have ensured the improvement effect of fiber on intestinal health in young piglet models.However,the regulatory effect of fiber on pork quality is still unclear,which requires consideration of the wide range of fiber sources and the complexity of the basic diet composition,as well as the impact of pig breeds.Taken together,future research needs to gain more insight into the combined effects of SDF and IDF,processing methods,and addition timing to improve the nutritional value of DF,and further explore the physiological functions and regulatory mechanisms of DF fermentation products short-chain fatty acids in pigs.

Serum biochemical parameters and amino acids metabolism are altered in piglets by early-weaning and proline and putrescine supplementations

The study was to investigate the effect of early-weaning stress and proline(Pro)and putrescine(Put)supplementations on serum biochemical parameters and amino acids(AA)metabolism in suckling and post-weaning pigs.Blood and small intestinal mucosa were harvested from suckling piglets at 1,7,14,and 21 d of age and piglets on d 1,3,5,and 7 after weaning at 14 d of age,as well as from piglets received oral administration of Pro and Put from 1 to 14 d old.In suckling piglets,the serum glucose,albumin and total cholesterol levels were increased(P<0.05)with increasing age,whereas the serum globulin,urea nitrogen(BUN),alkaline phosphatase(ALP)and aspartate aminotransferase(AST)levels were lowered(P<0.05).The concentrations of most serum AA and the AA transporters related gene expressions were highest in 7-d-old piglets(P<0.05),whereas the phosphorylation status of the mammalian target of the rapamycin(mTOR)signaling pathway in the small intestine increased in piglets from 1 to 21 d old(P<0.05).Weaning at 14 d old increased(P<0.05)the BUN and triglycerides levels in serum,as well as jejunal solute carrier family 7 member 6(SLC7A6),ileal SLC36A1 and SLC1A1 mRNA abundances at d 1 or 3 post-weaning.Weaning also inhibited(P<0.05)the phosphorylation levels of mTOR and its down-stream ribosomal protein S6 kinase 1(S6K1)and 4E-binding protein-1(4EBP1)in the small intestine of weanling pigs.Oral administration of Put and Pro decreased(P<0.05)serum ALP levels and increased(P<0.05)intestinal SLC36A1 and SLC1A1 mRNA abundances and mTOR pathway phosphorylation levels in post-weaning pigs.Pro but not Put treatment enhanced(P<0.05)serum Pro,arginine(Arg)and glutamine(Gln)concentrations of weaning-pigs.These findings indicated that early-weaning dramati-cally altered the biochemical blood metabolites,AA profile and intestinal mTOR pathway activity,and Pro and Put supplementations improved the AA metabolism and transportation as well as activated the intestinal mTOR pathway in weanling-pigs.Our study has an important implication for the broad application of Pro and Put in the weaning transition of piglets.

Opportunities of prebiotics for the intestinal health of monogastric animals

The goal of prebiotic applications from different sources is to improve the gut ecosystem where the host and microbiota can benefit from prebiotics.It has already been recognized that prebiotics have potential roles in the gut ecosystem because gut microbiota ferment complex dietary macronutrients and carry out a broad range of functions in the host body,such as the production of nutrients and vitamins,protection against pathogens,and maintenance of immune system balance.The gut ecosystem is very crucial and can be affected by numerous factors consisting of dietary constituents and commensal bacteria.This review focuses on recent scientific evidence,confirming a beneficial effect of prebiotics on animal health,particularly in terms of protection against pathogenic bacteria and increasing the number of beneficial bacteria that may improve epithelial cell barrier functions.It has also been reviewed that modification of the gut ecosystem through the utilization of prebiotics significantly affects the intestinal health of animals.However,the identification and characterization of novel potential prebiotics remain a topical issue and elucidation of the metagenomics relationship between gut microbiota alteration and prebiotic substances is necessary for future prebiotic studies.

Glutamine,glutamate,and aspartate differently modulate energy homeostasis of small intestine under normal or low energy status in piglets

Weaning stress may cause reduced energy intake for maintenance of mucosal structure.Gln,Glu,and Asp are major energy sources for the small intestine.This study investigated whether Gln,Glu,and Asp improve the intestinal morphology via regulating the energy metabolism in weaning piglets.A total of 198 weaned piglets were assigned to 3 treatments:Control(Basal diet+1.59%L-Ala);T1(Basal diet+1%L-Gln+0.5%L-Glu+0.1%L-Asp);T2(Low energy diet+1%L-Gln+0.5%L-Glu+0.1%L-Asp).Jejunum and ileum were obtained on d 5 or 21 post-weaning.T1 enhanced growth performance.T1 and T2 treatments improved small intestinal morphology by increasing villus height,goblet cell number and decreasing crypt depth.Days post-weaning affected the efficacy of T2,but not T1,on energy metabolism.At normal energy supplementation,Gln,Glu,and Asp restored small intestinal energy homeostasis via replenishing the Krebs'cycle and down-regulating the AMPK(adenosine monophosphate activated protein kinase)pathway.As these are not sufficient to maintain the intestinal energy-balance of piglets fed with a low energy diet on d 5 post-weaning,the AMPK,glycolysis,beta-oxidation,and mitochondrial biogenesis are activated to meet the high energy demand of enterocytes.These data indicated that Gln,Glu,and Asp could restore the energy homeostasis of intestinal mucosa of weaning piglets under normal energy fed.Low energy feeding may increase the susceptibility of piglets to stress,which may decrease the efficacy of Gln,Glu,and Asp on the restoration of energy balance.These findings provide new information on nutritional intervention for insufficient energy intake in weaning piglets.

Extraction and identification of the chyme proteins in the digestive tract of growing pigs

This study aimed to explore the rule of degradation of dietary proteins by identifying chyme proteins in different segments of the digestive tract of growing pigs, using proteomics techniques. Six growing pigs were fed a corn-soybean meal-based diet for 7 days. The feedstuff and chyme proteins were separately extracted and separated with SDS-PAGE. 2 D LCMS/MS combined with protein database searching identified 1,513 proteins in different segments of the gastrointestinal tract, the number of identified exogenous proteins gradually decline from the stomach to colon, with large amounts in the duodenum to the large intestine.More corn proteins than soybean proteins were identified both in the feedstuff and chyme, and these were significantly decreased after digestion in the stomach. More membrane proteins than non-membrane proteins were identified in whole digestive tract.These results regarding the profiles of chyme proteins in different segments of the gastrointestinal tract would provide useful information for optimizing feed formula in pigs.

Dietary zero-dimensional fullerene supplementation improves the meat quality,lipid metabolism,muscle fiber characteristics,and antioxidative status in finishing pigs

With the increasing demand for high-quality pork,more nutritional substances have been studied for the regulation of meat quality.Zero-dimensional fullerenes(C60)can modulate the biological behavior of a variety of cell lines and animals.In this study,we report the biological effects of C60 on finishing pigs at different concentrations.A total of 24 barrows(Duroc×Large White×Landrace),with an average body weight of 21.01±0.98 kg,were divided into 3 groups and each treated daily with C60(100 or 200 mg per kg feed)or a control diet until the end of the experiment.Our results showed that dietary C60 supplementation improved flesh color,marbling scores,and flavor amino acid contents of longissimus dorsi(LD)of growing-finishing pigs(P<0.05).C60 improved meat quality by regulating lipid metabolism and muscle fiber morphology by mediating the expression of genes,L-lactic dehydrogenase(LDH),myosin heavy chain(MyHC)IIa,MyHCIIb,peroxisome proliferator-activated receptor γ(PPARγ),and fatty acid transport protein 1(FATP1)(P<0.05).Moreover,C60 substantially promoted the mRNA expression of antioxidant enzyme genes(P<0.05),which also contributed to improving meat quality.These findings have important implications for the application of C60 in the livestock industry,especially for improving the meat quality of fattening pigs.

Myokine interleukin-15 expression profile is different in suckling and weaning piglets

Interleukin-15(IL-15) is a cytokine highly expressed in skeletal muscle. The objective of the present study was to investigate the development of muscle IL-15 expression in suckling piglets and in early weaning piglets(day 14) at each level, that is, mRNA, protein, and secretion. Eight litters(eight piglets per litter) of newborn healthy piglets(Large × White × Landrace) with a similar initial weight(1618.0 ± 140.1 g) were chosen and divided into two groups, Group one used suckling piglets that were killed, respectively, at days 1,7,14,21, and group two used early(day 14) weaning piglets that were killed respectively, at days 15, 17, 19, 21. In group one, IL-15 gene expression levels increased significantly(P < 0.05) along with increased body weight over time. IL-15 protein expression levels in piglets at day 21 of age were higher(P < 0.05) than those in piglets at other ages, and there was no difference(P > 0.05)among piglets at other ages. These findings indicated that increased IL-15 mRNA expression did not result in a corresponding increase of its protein expression. In group two, which used early weaning piglets from days 15-19, IL-15 mRNA and protein expression levels increased constantly(P < 0.05) and were higher(P < 0.05) than those in suckling piglets. Moreover, there was no gain of body weight(P > 0.05) compared with suckling piglets at day 14 of age. However, IL-15 protein expression levels in early weaning piglets at day 21 of age dropped significantly(P < 0.05) to the levels as suckling piglets at day 21 of age, while body weight increased(P < 0.05) markedly to the levels as suckling piglets at day 21 of age. In both groups, the serum IL-15 levels of piglets decreased significantly(P < 0.01) over time. Taken together, our results indicate that IL-15 expression differs in suckling piglets and in weaning piglets. It is speculated that IL-15 may play an important role in counteracting the effects of early weaning stress.

The profiles of mitochondrial respiration and glycolysis using extracellular flux analysis in porcine enterocyte IPEC-J2

The porcine intestinal mucosa require large amounts of energy for nutrient processing and cellular functions and is vulnerable to injury by weaning stress involving bioenergetics failure. The mitochondrial bioenergetic measurement in porcine enterocytes have not been defined. The present study was to establish a method to measure mitochondrial respiratory function and profile mitochondrial function of IPEC-J2 using cell mito stress test and glycolysis stress test assay by XF24 extracellular flux analyzer. The optimal seeding density and concentrations of the injection compounds were determined to be 40,000 cells/well as well as 0.5 μ M oligomycin, 1 μM carbonyl cyanide p-trifluoromethoxy-phenylhydrazone(FCCP) and 1 μM rotenone & antimycin A, respectively. The profiles of mitochondrial respiration and glycolysis confirmed that porcine enterocyte preferentially derived much more energy from glutamine than glucose. These results will provide a basis for further study of mitochondrial function and bioenergetics of the porcine small intestine.