Dietary supplementation of laminarin improves the reproductive performance of sows and the growth of suckling piglets

Background Maternal nutrition is essential in keeping a highly efficient production system in the pig industry.Laminarin has been shown to improve antioxidant capacity,reduce the inflammatory response,and favor the homeostasis of intestinal microbiota.However,the effect of dietary supplementation of laminarin on the reproductive performance of sows and the growth of suckling offspring remains unknown.Methods A total of 40 Landrace×Yorkshire multiparous sows on d 85 of gestation,similar in age,body weight(BW),parity and reproductive performance,were randomly divided into four dietary treatments with 10 sows per treatment,receiving a control diet(basal pregnancy or lactating diets)and a basal diet supplemented with 0.025%,0.05%and 0.10%laminarin,respectively.The experiment lasted from d 85 of gestation to d 21 of lactation.Results Laminarin supplementation linearly increased number born alive per litter(P=0.03),average daily feed intake(ADFI,P<0.01),and total milk yield of sows during the lactation of 1–21 d(P=0.02).Furthermore,maternal laminarin supplementation increased the average daily gain(ADG)of piglets while tending to reduce the culling and death rate before weaning.In addition,alterations to the composition of colostrum and milk,as well as to serum inflammatory cytokines and immunoglobulins of sows were observed.The fecal microbiota profile of sows supported the improvement of reproductive performance in sows and the growth performance in suckling offspring.Conclusions Dietary supplementation of laminarin during late pregnancy and lactation could significantly improve reproductive performance of sows and growth performance of piglets.

Effects of improved amino acid balance diet on lysine mammary utilization, whole body protein turnover and muscle protein breakdown on lactating sows

Background The study objective was to test the hypothesis that low crude protein(CP)diet with crystalline amino acids(CAA)supplementation improves Lys utilization efficiency for milk production and reduces protein turnover and muscle protein breakdown.Eighteen lactating multiparous Yorkshire sows were allotted to 1 of 2 isocaloric diets(10.80 MJ/kg net energy):control(CON;19.24%CP)and reduced CP with“optimal”AA profile(OPT;14.00%CP).Sow body weight and backfat were recorded on d 1 and 21 of lactation and piglets were weighed on d 1,14,18,and 21 of lactation.Between d 14 and 18,a subset of 9 sows(CON=4,OPT=5)was infused with a mixed solution of 3-[methyl-2H3]histidine(bolus injection)and[13C]bicarbonate(priming dose)first,then a constant 2-h[13C]bicarbonate infusion followed by a 6-h primed constant[1-13C]lysine infusion.Serial blood and milk sampling were performed to determine plasma and milk Lys enrichment,Lys oxidation rate,whole body protein turnover,and muscle protein breakdown.Results Over the 21-d lactation period,compared to CON,sows fed OPT had greater litter growth rate(P<0.05).Compared to CON,sows fed OPT had greater efficiency of Lys(P<0.05),Lys mammary flux(P<0.01)and whole-body protein turnover efficiency(P<0.05).Compared to CON,sows fed OPT tended to have lower whole body protein breakdown rate(P=0.069).Muscle protein breakdown rate did not differ between OPT and CON(P=0.197).Conclusion Feeding an improved AA balance diet increased efficiency of Lys and reduced whole-body protein turnover and protein breakdown.These results imply that the lower maternal N retention observed in lactating sows fed improved AA balance diets in previous studies may be a result of greater partitioning of AA towards milk rather than greater body protein breakdown.

Standardized ileal digestibility of amino acids in soybean meal fed to non-pregnant and pregnant sows

Background Two studies were designed to determine standard ileal crude protein(CP)and amino acid(AA)digestibility of soybean meal(SBM)from different origins fed to non-pregnant and pregnant sows.Seven solvent-extracted SBMs from soybeans produced in the USA,Brazil,and China were selected.In Exp.1,eight different diets were created:a nitrogen(N)-free diet and 7 experimental diets containing SBM from different origins as the only N source.Eight non-pregnant,multiparous sows were arranged in an 8×8 Latin square design(8 periods and 8 diets).In Exp.2,the diet formula was the same as in Exp.1.Eight gestating sows(parity 3)were assigned to 4 different diets in a replicated 4×3 Youden square design(three periods and four diets)in mid-gestation and again in late-gestation stages.Results When fed to non-pregnant and late-gestating sows,the standardized ileal digestibility(SID)of CP and most AAs from different SBM were not significantly different(P>0.05).When fed to mid-gestating sows,the SID values for Arg,His,Lys,Phe,Cys,Gly,Ser,and Tyr in SBM 1 were lower than in SBM 4 and 5(P<0.05),whereas SID for Leu from SBM 5 was higher than in SBM 1 and 4(P<0.05).SID values for Ile,Ala,and Asp from SBM 4 were lower than in SBM 1 and 5(P<0.05).Sows had significantly greater SID values for Lys,Ala,and Asp during mid-gestation when compared with late-gestation stages(P<0.05).Mid-gestating sows had greater SID value for Val and lower SID value for Tyr when compared with non-pregnant and late-gestating sows(P<0.01),whereas non-pregnant sows had significantly greater SID value for Met when compared with gestating sows(P<0.01).Conclusions When fed to mid-gestating sows,the SID values for most AAs varied among SBM samples.The SID values for Lys,Met,Val,Ala,Asp,and Tyr in SBM were affected by sow gestation stages.Our findings provide a cornerstone for accurate SBM use in sow diets.

Gut microbiota affects the estrus return of sows by regulating the metabolism of sex steroid hormones

Background Sex hormones play important roles in the estrus return of post-weaning sows.Previous studies have demonstrated a complex and bi-directional regulation between sex hormones and gut microbiota.However,the extent to which the gut microbiota affects estrus return of post-weaning sows is largely unknown.Results In this study,we first screened 207 fecal samples from well-phenotyped sows by 16S rRNA gene sequencing and identified significant associations between microbes and estrus return of post-weaning sows.Using metagenomic sequencing data from 85 fecal samples,we identified 37 bacterial species that were significantly associated with estrus return.Normally returning sows were characterized by increased abundances of L.reuteri and P.copri and decreased abundances of B.fragilis,S.suis,and B.pseudolongum.The changes in gut microbial composition significantly altered the functional capacity of steroid hormone biosynthesis in the gut microbiome.The results were confirmed in a validation cohort.Significant changes in sex steroid hormones and related compounds were found between normal and non-return sows via metabolome analysis.An integrated analysis of differential bacterial species,metagenome,and fecal metabolome provided evidence that normal return-associated bacterial species L.reuteri and Prevotella spp.participated in the degradation of pregnenolone,progesterone,and testosterone,thereby promoting estrogen biosynthesis.Furthermore,the microbial metabolites related to sow energy and nutrient supply or metabolic disorders also showed relationships with sow estrus return.Conclusions An integrated analysis of differentially abundant bacterial species,metagenome,and fecal metabolome revealed the involvement of L.reuteri and Prevotella spp.in sow estrus return.These findings provide deep insight into the role of gut microbiota in the estrus return of post-weaning sows and the complex cross-talk between gut microbiota and sex hormones,suggesting that the manipulation of the gut microbiota could be an effective strategy to improve sow estrus return after weaning.

Productive and physiological implications of top-dress addition of branched-chain amino acids and arginine on lactating sows and offspring

Background Branched-chain amino acids(BCAAs),including L-leucine(L-Leu),L-isoleucine(L-Ile),L-valine(L-Val),and L-arginine(L-Arg),play a crucial role in mammary gland development,secretion of milk and regulation of the catabolic state and immune response of lactating sows.Furthermore,it has recently been suggested that free amino acids(AAs)can also act as microbial modulators.This study aimed at evaluating whether the supplementation of lactating sows with BCAAs(9,4.5 and 9 g/d/sow of L-Val,L-Ile and L-Leu,respectively)and/or L-Arg(22.5 g/d/sow),above the estimated nutritional requirement,could influence the physiological and immunological parameters,microbial profile,colostrum and milk composition and performance of sows and their offspring.Results At d 41,piglets born from the sows supplemented with the AAs were heavier(P=0.03).The BCAAs increased glucose and prolactin(P<0.05)in the sows’serum at d 27,tended to increase immunoglobulin A(IgA)and IgM in the colostrum(P=0.06),increased the IgA(P=0.004)in the milk at d 20 and tended to increase lymphocyte%in the sows’blood at d 27(P=0.07).Furthermore,the BCAAs tended to reduce the Chao1 and Shannon microbial indices(P<0.10)in the sows’faeces.The BCAA group was discriminated by Prevotellaceae_UCG-004,Erysipelatoclostridiaceae UCG-004,the Rikenellaceae_RC9_gut_group and Treponemaberlinense.Arginine reduced piglet mortality pre-(d 7,d 14)and post-weaning(d 41)(P<0.05).Furthermore,Arg increased the IgM in the sow serum at d 10(P=0.05),glucose and prolactin(P<0.05)in the sow serum at d 27 and the monocyte percentage in the piglet blood at d 27(P=0.025)and their jejunal expression of NFKB2(P=0.035)while it reduced the expression of GPX-2(P=0.024).The faecal microbiota of the sows in Arg group was discriminated by Bacteroidales.The combination of BCAAs and Arg tended to increase spermine at d 27(P=0.099),tended to increase the Igs(IgA and IgG,P<0.10)at d 20 in the milk,favoured the faecal colonisation of Oscillospiraceae UCG-005 and improved piglet growth.Conclusion Feeding Arg and BCAAs above the estimated requirements for milk production may be a strategy to improve sow productive performance in terms of piglet average daily gain(ADG),immune competence and survivability via modulation of the metabolism,colostrum and milk compositions and intestinal microbiota of the sows.The synergistic effect between these AAs,noticeable by the increase of Igs and spermine in the milk and in the improvement of the performance of the piglets,deserves additional investigation.

Multi‑omics analysis reveals gut microbiota‑ovary axis contributed to the follicular development difference between Meishan and Landrace×Yorkshire sows

Background The mechanism by which Meishan(MS)sows are superior to white crossbred sows in ovarian follicle development remains unclear.Given gut microbiota could regulate female ovarian function and reproductive capacity,this study aimed to determine the role of gut microbiota-ovary axis on follicular development in sows.Methods We compared the ovarian follicular development,gut microbiota,plasma metabolome,and follicular fluid metabolome between MS and Landrace×Yorkshire(L×Y)sows.A H_(2)O_(2)-induced cell apoptosis model was used to evaluate the effects of multi-omics identified metabolites on the apoptosis of porcine ovarian granulosa cells in vitro.Results Compared with L×Y sows,MS sows have greater ovary weight and improved follicular development,including the greater counts of large follicles of diameter≥5 mm,secondary follicles,and antral follicles,but lesser atretic follicles.The ovarian granulosa cells in MS sows had alleviated apoptosis,which was indicated by the increased BCL-2,decreased caspases-3,and decreased cleaved caspases-3 than in L×Y sows.The ovarian follicular fluid of MS sows had higher concentrations of estradiol,progesterone,follicle-stimulating hormone,luteinizing hormone,and insulin like growth factor 1 than L×Y sows.Gut microbiota of MS sows formed a distinct cluster and had improved alpha diversity,including increased Shannon and decreased Simpson than those of L×Y sows.Corresponding to the enhanced function of carbohydrate metabolism and elevated short-chain fatty acids(SCFAs)in feces,the differential metabolites in plasma between MS and L×Y sows are also mainly enriched in pathways of fatty acid metabolism.There were significant correlations among SCFAs with follicular development,ovarian granulosa cells apoptosis,and follicular fluid hormones,respectively.Noteworthily,compared with L×Y sows,MS sows had higher follicular fluid SCFAs concentrations which could ameliorate H_(2)O_(2)-induced porcine granulosa cells apoptosis in vitro.Conclusion MS sows have more secondary and antral follicles,but fewer atretic follicles and apoptotic ovarian granulosa cells,as well as harbored a distinctive gut microbiota than L×Y sows.Gut microbiota may participate in regulating ovarian follicular development via SCFAs affecting granulosa cells apoptosis in sows.

A behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant,mid-gestation,and late-gestation sows

Background:Although thermal indices have been proposed for swine,none to our knowledge differentiate by reproductive stage or predict thermal comfort using behavioral and physiological data.The study objective was to develop a behavior and physiology-based decision support tool to predict thermal comfort and stress in multiparous(3.28±0.81)non-pregnant(n=11),mid-gestation(n=13),and late-gestation(n=12)sows.Results:Regression analyses were performed using PROC MIXED in SAS 9.4 to determine the optimal environmental indicator[dry bulb temperature(TDB)and dew point]of heat stress(HS)in non-pregnant,mid-gestation,and lategestation sows with respiration rate(RR)and body temperature(TB)successively used as the dependent variable in a cubic function.A linear relationship was observed for skin temperature(T_(S))indicating that TDB rather than the sow HS response impacted T_(S)and so T_(S)was excluded from further analyses.Reproductive stage was significant for all analyses(P<0.05).Heat stress thresholds for each reproductive stage were calculated using the inflections points of RR for mild HS and TB for moderate and severe HS.Mild HS inflection points differed for non-pregnant,mid-gestation,and late gestation sows and occurred at 25.5,25.1,and 24.0℃,respectively.Moderate HS inflection points differed for non-pregnant,mid-gestation,and late gestation sows and occurred at 28.1,27.8,and 25.5℃,respectively.Severe HS inflection points were similar for non-pregnant and mid-gestation sows(32.9℃)but differed for late-gestation sows(30.8℃).These data were integrated with previously collected behavioral thermal preference data to estimate the TDB that non-pregnant,mid-gestation,and late-gestation sows found to be cool(TDB<TDB preference range),comfortable(TDB=TDB preference range),and warm(TDB preference range<TDB<mild HS).Conclusions:The results of this study provide valuable information about thermal comfort and thermal stress thresholds in sows at three reproductive stages.The development of a behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant,mid-gestation,and late-gestation sows is expected to provide swine producers with a more accurate means of managing sow environments.

Effects of dietary coenzyme Q10 supplementation during gestation on the embryonic survival and reproductive performance of high‑parity sows

Background Fertility declines in high-parity sows.This study investigated whether parity-dependent declines in embryonic survival and reproductive performance could be restored by dietary coenzyme Q10(CoQ10)supplementation.Methods Two experiments were performed.In Exp.1,30 young sows that had completed their 2nd parity and 30 high-parity sows that had completed their 10^(th)parity,were fed either a control diet(CON)or a CON diet supple-mented with 1 g/kg CoQ10(+CoQ10)from mating until slaughter at day 28 of gestation.In Exp.2,a total of 314 post-weaning sows with two to nine parities were fed the CON or+CoQ10 diets from mating throughout gestation.Results In Exp.1,both young and high-parity sows had a similar number of corpora lutea,but high-parity sows had lower plasma CoQ10 concentrations,down-regulated genes involved with de novo CoQ10 synthesis in the endome-trium tissues,and greater levels of oxidative stress markers in plasma and endometrium tissues.High-parity sows had fewer total embryos and alive embryos,lower embryonic survival,and greater embryo mortality than young sows.Dietary CoQ10 supplementation increased the number of live embryos and the embryonic survival rate to levels simi-lar to those of young sows,as well as lowering the levels of oxidative stress markers.In Exp.2,sows showed a parity-dependent decline in plasma CoQ10 levels,and sows with more than four parities showed a progressive decline in the number of total births,live births,and piglets born effective.Dietary supplementation with CoQ10 increased the number of total births,live births,and born effective,and decreased the intra-litter covariation coefficients and the percentage of sows requiring farrowing assistance during parturition.Conclusions Dietary CoQ10 supplementation can improve the embryonic survival and reproductive performance of gestating sows with high parity,probably by improving the development of uterine function.

Dietary fiber during gestation improves lactational feed intake of sows by modulating gut microbiota

Background The feed intake of sows during lactation is often lower than their needs.High-fiber feed is usually used during gestation to increase the voluntary feed intake of sows during lactation.However,the mechanism underlying the effect of bulky diets on the appetites of sows during lactation have not been fully clarified.The current study was conducted to determine whether a high-fiber diet during gestation improves lactational feed intake(LFI)of sows by modulating gut microbiota.Methods We selected an appropriate high-fiber diet during gestation and utilized the fecal microbial transplanta-tion(FMT)method to conduct research on the role of the gut microbiota in feed intake regulation of sows during lactation,as follows:high-fiber(HF)diet during gestation(n=23),low-fiber(LF)diet during gestation(n=23),and low-fiber diet+HF-FMT(LFM)during gestation(n=23).Results Compared with the LF,sows in the HF and LFM groups had a higher LFI,while the sows also had higher peptide tyrosine tyrosine and glucagon-like peptide 1 on d 110 of gestation(G110 d).The litter weight gain of piglets during lactation and weaning weight of piglets from LFM group were higher than LF group.Sows given a HF diet had lower Proteobacteria,especially Escherichia-Shigella,on G110 d and higher Lactobacillus,especially Lactobacil-lus_mucosae_LM1 and Lactobacillus_amylovorus,on d 7 of lactation(L7 d).The abundance of Escherichia-Shigella was reduced by HF-FMT in numerically compared with the LF.In addition,HF and HF-FMT both decreased the perinatal concentrations of proinflammatory factors,such as endotoxin(ET),lipocalin-2(LCN-2),tumor necrosis factor-α(TNF-α),and interleukin-1β(IL-1β).The concentration of ET and LCN-2 and the abundance of Proteobacteria and Escheri-chia-Shigella were negatively correlated with the LFI of sows.Conclusion The high abundance of Proteobacteria,especially Escherichia-Shigella of LF sows in late gestation,led to increased endotoxin levels,which result in inflammatory responses and adverse effects on the LFI of sows.Add-ing HF during gestation reverses this process by increasing the abundance of Lactobacillus,especially Lactobacil-lus_mucosae_LM1 and Lactobacillus_amylovorus.

Maternal Supplementation of Saccharomyces cerevisiae var. boulardii to Sows from Late Gestation through Lactation Impacts the Neutrophil Function of the Sow and the Innate Immune Status of Progeny Short-Term

The primary objective of this study was to evaluate the potential immunomodulatory effect of maternal supplementation of Saccharomyces cerevisiae var. boulardii (Scb) from late gestation until the end of lactation on the immune phenotype of her progeny. Eighteen sows were fed 2 boluses per day of Saccharomyces cerevisiae var. boulardii CMCN-1079 (probiotic;PRO, n = 9) or placebo (CON, n = 9) starting at gestational day (GD) 84 and continuing until 21 days post-farrowing (end of lactation). Sow blood samples were collected every 7 days post-supplementation during gestation and 24-h post-farrowing and end of lactation. Blood samples were taken from 84 female pigs (n = 42 per sow treatment group) at 1, 7, 14, 21, 28, and 35 days old to assess innate and adaptive immune measures. Minimal effects of Scb supplementation were found on sow immune status during gestation and lactation, except for PRO-treated sows that had enhanced neutrophil function (P and mitogen-induced lymphocyte proliferation after 51 days of treatment (P < 0.0001). Overall, pigs from PRO-treated sows had higher C5a- and IL-8-induced neutrophil chemotaxis, NK cytotoxicity, and mitogen-induced B-lymphocyte proliferation than those from CON sows (P inimal effect on the sows but postnatal maternal exposure to Saccharomyces cerevisiae var. boulardii supplementation modulated the immune status of the progeny beyond the lactation period resulting in those from PRO-treated sows having more enhanced neutrophil function and B-cell proliferative response in the short term. Therefore, these data imply that including yeast probiotics in maternal diets may have carry-over effects in priming offspring’s immune function, especially neutrophil function and B-cell proliferation in the short term.

Current strategies for reproductive management of gilts and sows in North America

Many advances in genetic selection, nutrition, housing and disease control have been incorporated into modern pork production since the 1950s resulting in highly prolific females and practices and technologies, which significantly increased efficiency of reproduction in the breeding herd. The objective of this manuscript is to review the literature and current industry practices employed for reproductive management. In particular the authors focus on assisted reproduction technologies and their application for enhanced productivity. Modern maternal line genotypes have lower appetites and exceptional lean growth potential compared to females of 20 yr ago. Thus, nutrient requirements and management techniques and technologies, which affect gilt development and sow longevity, require continuous updating. Failure to detect estrus accurately has the greatest impact on farrowing rate and litter size. Yet, even accurate estrus detection will not compensate for the variability in the interval between onset of estrus and actual time of ovulation. However, administration of GnRH analogs in weaned sows and in gilts after withdrawal of altrenogest do overcome this variability and thereby synchronize ovulation, which makes fixed-time AI practical. Seasonal infertility, mediated by temperature and photoperiod, is a persistent problem. Training workers in the art of stockmanship is of increasing importance as consumers become more interested in humane animal care. Altrenogest, is used to synchronize the estrous cycle of gilts, to prolong gestation for 2-3 d to synchronize farrowing and to postpone post-weaning estrus. P.G. 600~ is used for induction of estrus in pre-pubertal gilts and as a treatment to overcome seasonal anestrous. Sperm cell numbers/dose of semen is significantly less for post cervical AI than for cervical AI. Real-time ultrasonography is used to determine pregnancy during wk 3-5. PGF2a effectively induces farrowing when administered within two d of normal gestation length. Ovulation synchronization, single fixed-time AI and induced parturition may lead to farrowing synchronization, which facilitates supervision and reduces stillbirths and piglet mortality. Attendance and assistance at farrowing is important especially to ensure adequate colostrum consumption by piglets immediately after birth. New performance terminologies are presented.

Dietary arginine supplementation in multiparous sows during lactation improves the weight gain of suckling piglets

This study investigated the effects of dietary arginine （Arg） supplementation, just during lactation, on sow and litter per- formance, plasma concentrations of metabolites and hormones, and milk yield and composition in multiparous sows. Thirty-one sows were randomly assigned to 3 dietary treatments supplemented with 0.0 （control, n=10）, 0.5% （n=10）, or 1.0% （n=11） L-Arg-HCI, respectively. Experimental diets were provided to the sows from d 3 to 21 of lactation. Plasma and milk samples were collected at d 14 and 21 of lactation. The average daily gain （ADG） of piglets from sows fed diets supplemented with 0.5 or 1.0% L-Arg-HCI at d 3 to 14 of lactation, were higher than that of controls （P〈0.05）. Maternal supplementation with 1.0% L-Arg-HCI also increased ADG of piglets between d 3 and 21 of lactation than that of the controls （P〈0.05）. There was no significant effect of supplementation on average daily feed intake （ADFI）, body weight loss, and backfat thickness loss of lactating sows. Supplementation with 0.5 or 1.0% L-Arg-HCI had a trend towards increasing milk yields and milk fat contents （0.05〈P〈0.10）; milk protein and lactose were unchanged. Supplementation with 1.0% L-Arg- HCI increased plasma concentrations of prolactin and insulin in sows at d 14 and 21 of lactation, and plasma concentrations of non-esterified fatty acid （NEFA）, insulin-like growth factor-1 （IGF-1）, and nitric oxide （NO） in sows at d 21 of lactation, when compared to the controls （P〈0.05）. Supplementation with 1.0% L-Arg-HCI increased IGF-1 and spermine in milk at d 14 of lactation, relative to the controls （P〈0.05）. Plasma Arg concentrations at d 14 and 21 of lactation, as well as plasma NO level and milk IGF-1 at d 21 of lactation, were increased, while plasma urea nitrogen （PUN） concentration at d 14 and 21 of lactation was decreased, by supplementation with 0.5 or 1.0% L-Arg-HCI when compared to the controls （P〈0.05）. Collectively, dietary supplementation of multiparous sows with Arg, just during lactation, is beneficial for enhancing litter weight gain but the complete mechanism remains to be determined and may involve in the maternal endocrine changes and milk polyamines contents.

Effects of magnesium on the performance of sows and their piglets

The objective of this study was to evaluate the effects of supplemental magnesium （Mg） on the performance of gilts and parity 3 sows and their piglets. Fifty-six grits （Trial 1） and 56 sows （Trial 2） were assigned to one of 4 treatments according to their mating weight, respectively. The treatments comprised corn-soybean meal based gestation and lactation diets （0.21% magnesium） supplemented with 0, 0.015, 0.03, or 0.045% Mg from mating until weaning. The results showed that magnesium supplementation significantly （P 〈 0.05） reduced the weaning to estrus interval in both gilts and sows. There were significant effects （P 〈 0.05） of supplemental magnesium on the total number of piglets born, born alive and weaned in sows. In late gestation and lactation, the digestibility of crude fiber （quadratic effects, P 〈 0.05）, and crude protein （P 〈 0.05）, were significantly influenced by magnesium in gilts and sows, respectively. There were differences among the 4 groups in terms of the apparent digestibility of dry matter and crude fiber in sows （P 〈 0.0S） during both early and late gestation. The apparent digestibility of gross energy was increased for sows in late gestation （P 〈 0.05）, and lactation （quadratic effects, P 〈 0.0S）. At farrowing and weaning, serum prolactin levels and alkaline phosphate activities linearly increased in sows as the Mg supplementation increased （P 〈 0.0.5）. Serum Mg of sows at farrowing and serum urea nitrogen of sows at weaning was significantly influenced by Mg supplementation （P 〈 0.05）. The Mg concentration in sow colostrum and the serum of their piglets were increased by supplemental magnesium （P 〈 0.05）. In addition, growth hormone levels were linearly elevated （P 〈 0.05） in the serum of piglets suckling sows. Our data demonstrated that supplemental magnesium has the potential to improve the reproduction performance of sows, and the suitable supplemental dose ranged from 0.015% to 0.03%.

Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

Background:The study objective was to test the hypothesis that 1)lowering dietary crude protein(CP)increases dietary energetic efficiency and reduces metabolic heat associated with lactation,and 2)excessive dietary leucine(Leu)supplementation in a low CP diet decreases dietary energetic efficiency and increases metabolic heat associated with lactation.Methods:Fifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets(10.80 MJ/kg net energy):1)control(CON;18.75%CP),2)reduced CP with a near ideal or optimal AA profile(OPT;13.75%CP)and 3)diet OPT with excessive Leu(OPTLEU;14.25%CP).Sow body weight and backfat were recorded on day 1 and 21 of lactation and piglets were weighed on day 1,4,8,14,18,and 21 of lactation.Energy balance was measured on sows during early(day 4 to 8)and peak(day 14 to18)lactation,and milk was sampled on day 8 and 18.Results:Over 21-day lactation,sows fed OPT lost body weight and body lipid(P<0.05).In peak lactation,sows fed OPT had higher milk energy output(P<0.05)than CON.Sows fed OPTLEU tended(P=0.07)to have less milk energy output than OPT and did not differ from CON.Maternal energy retention was lower(P<0.05)in OPT and OPTLEU compared to CON sows,and did not differ between OPTLEU and OPT sows.Sows fed OPT had higher(P<0.05)apparent energy efficiency for milk production compared to CON.Heat production associated with lactation was lower(P<0.05)or tended to be lower(P=0.082),respectively,in OPT and OPTLEU compared to CON sows.Conclusion:The OPT diet,in peak lactation,improved dietary energy utilization for lactation due to less urinary energy and metabolic heat loss,and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization.Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk,partially explaining the effectiveness of OPT diet over CON diets.

Modified halloysite nanotubes reduce the toxic effects of zearalenone in gestating sows on growth and muscle development of their offsprings

Background： Zearalenone （ZEN） is an estrogenic mycotoxin that is primarily produced by Fusarium fungi and has been proven to affect the reproductive capacity of many species to varying degrees. The present experiment was designed to study the maternal persistent effects of zearalenone toxicity in gestating sows on growth and muscle development of their offsprings, and the alleviation of zearalenone toxicity by modified halloysite nanotubes （MHNTs）. Methods： Eighteen sows were fed with one of three dietary treatments that included the following： （1） a control diet, （2） a contaminated grain diet （with 50 % moldy corn, 2.77 mg/kg ZEN）, and （3） a contaminated grain diet （with 50 % moldy corn, 2.76 mg/kg ZEN） ＋ 1% MHNTs. Each sow was exclusively fed its experimental diets from 35 to 70 d of gestation at a total of 2 kg daily. Muscle samples were collected from six piglets per treatment at birth, weaning and finishing. Results： The results showed that feeding the sows with the ZEN-contaminated diets from 35 to 70 d of gestation decreased the ADG, ADFI and G：F of their offsprings （P 〈 0.05）. The muscle fiber numbers in the newborn, weaning and growing-finishing pigs and the muscle fiber diameters at birth and weaning were also decreased by maternal ZEN exposure （P 〈 0.05）. The expressions of IGF-I, IGF-II, Myf-5 and Mstn at birth and IGF-II, Pax7, Myf-5 and MyoD1 at weaning were altered by feeding gestating sows with ZEN-contaminated diets （P 〈 0.05）. The MHNTs reduced most of the ZEN-induced toxic effects： the ADG and ADFI on growth performance, the muscle fiber numbers at weaning and finishing and the muscle fiber diameters at weaning （P 〈 0.05）. The expression levels of IGF-II and Mstn in newborn piglets and IGF-II and Myf-5 in weaning piglets were also prevented by adding 1% MHNTs （P 〈 0.05）. Conclusions： The present study demonstrated that the offsprings of sows fed with ZEN-contaminated diets from 35 to 70 day of gestation exhibited weakening on growth performance, physiological changes in their muscle fibers and alterations of mRNA expression in their muscle tissues, and also indicated that MHNTs prevented most of the ZEN- induced weakening in the muscle tissues.

The effect of the ratio of standardized ileal digestible lysine to metabolizable energy on growth performance,blood metabolites and hormones of lactating sows

A total of 335 lactating sows （Landrace x Large White） were used in two experiments to determine the optimum ratio of standardized ileal digestible lysine （SID-Lys） to metabolizable energy （ME） for mixed parity sows during lactation. In Exp. 1, 185 sows （weighing an average of 256.2 ± 6.5 kg and having an average parity of 3.4 ± 0.3） were allocated to one of six experimental diets in a completely randomized block design within parity groups （1, 2, and 3＋）. The experimental diets were formulated to contain 3.06, 3.16, 3.20, 3.25, 3.30 or 3.40 Mcal/kg of ME and each diet was fed to the sows throughout a 28 day lactation. All diets provided a similar SID-lysine level （0.86%）. As a result, the diets provided a SID-Lys：ME ratio of 2.81, 2.72, 2.69, 2.65, 2.61 or 2.53 g/Mcal ME. Sow feed intake was significantly （P 〈 0.01） affected by the energy content of the diet as well as by sow parity. Using regression analysis, feed intake was shown to be maximized at 3.25, 3.21, 3.21 and 3.21 Mcal/kg of ME for parity 1, 2, 3＋ sows and the entire cohort of sows respectively （quadratic; P 〈 0.01）. In addition, the result of feed intake can be expressed as 2.65, 2.69, 2.69 and 2.68 g/Mcal based on analysis of SID-Lys：ME ratio. Litter weight gain was affected by dietary treatment for parity 3＋ sows and the entire cohort （P 〈 0.01）. Based on regression analysis, litter weight gain was maximized at 3.25 and 3.24 Mcal/kg of ME for parity 3＋ （quadratic; P 〈 0.01） and the entire cohort （quadratic; P 〈 0.01）. Similarly, the result of litter weight gain could be expressed as 2.65 and 2.66 g/Mcal of SID- Lys：ME ratio. Therefore, 3.25 Mcal/kg of ME was selected for Exp. 2 in which 150 sows （weighing 254.6 ± 7.3 kg and having an average parity of 3.4 ± 0.4） were allocated to one of five treatments in a completely randomized block design within parity （1, 2, and 3＋）. The experimental diets were formulated to contain 2.1, 2.4, 2.7, 3.0 or 3.3 g/Mcal of SID-Lys：ME ratio with all diets providing 3.25 Mcal/kg of ME. The diets were fed to the sows throughout a 28 day lactation. Sow body weight loss was affected by dietary treatment （parity 3＋ sows, P = 0.02; entire cohort, P 〈 0.01） and by sow parity （P 〈 0.01）. Litter weight at weaning and litter weight gain were affected by dietary treatment for parity 1, 2, 3＋ sows and the entire cohort （P 〈 0.01） as well as by sow parity （P 〈 0.01）. Plasma urea nitrogen （P 〈 0.01）, creatinine （P 〈 0.01） and non-esterifide fatty acids （P = 0.04） were decreased as the SID-Lys：ME ratio of the diet increased. Insulin-like growth factor-1 （P = 0.02）, estradiol （P 〈 0.01） and luteinizing hormone （P = 0.02） were increased as the SID-Lys：ME ratio in diet increased. Based on a broken-line model, the estimated SID-Lys： ME ratio to maximize litter weight gain was estimated to be 3.05 g/Mcal.

A systematic review and meta-analysis of dietary fat effects on reproductive performance of sows and growth performance of piglets

Effects of added fat in sow diets on the sows’reproductive performance and offspring growth performance are influenced by multiple factors such as genetics,nutrition,parity,ambient temperatures,and farm management.Individual studies cannot cover all these factors.With the view to address this challenge,we searched all studies that were published from 1986 to 2020,and performed a systematic review and meta-analysis on the fat effect.In total,19 papers were collected and analyzed.Fat supplementation in sow diets during late gestation and lactation decreased average daily feed intake(ADFI,P<0.05)and tended to increase average daily energy intake(ADEI,P=0.11).It had no impact on litter weights at birth(P=0.40)or weaning(P=0.46).It increased total numbers of piglets at birth(P=0.07),but had no effect on liveborn per litter(P=0.90)or survival rate(P=0.48)of piglets to weaning.Fat supplementation had no significant effect on sow body weight loss(P=0.67)or backfat thickness changes(P=0.66),but sows fed diets with added fat had increased milk fat concentration(P=0.03)and shorter wean to estrus intervals(WEI,P=0.01).In specific circumstances,fat supplementation tended to improve growth performance of piglets with low litter weights at birth(P=0.14),or when the sows lost large amounts of body weight during lactation(P=0.11).The level of supplemented fat was 10%and higher would decrease liveborn per litter at neutral temperature(P=0.10).The meta-analysis revealed that fat supplementation to sows diet during late gestation and lactation can be beneficial for sow reproductive performance and litter growth performance.

Zearalenone toxicosis on reproduction as estrogen receptor selective modulator and alleviation of zearalenone biodegradative agent in pregnant sows

Background:Zearalenone(ZEA)is a resorcylic acid lactone derivative derived from various Fusarium species that are widely found in food and feeds.The molecular structure of ZEA resembles that of the mammalian hormone 17β-oestradiol,thus zearalenone and its metabolites are known to compete with endogenous hormones for estrogen receptors binding sites and to activate transcription of oestrogen-responsive genes.However,the effect of long-term low-dose ZEA exposure on the reproductive response to Bacillus subtilis ANSB01G culture for first-parity gilts has not yet been investigated.This study was conducted to investigate the toxic effects of ZEA as an estrogen receptor selective modulator and the alleviating effects of Bacillus subtilis ANSB01G cultures as ZEA biodegraders in pregnant sows during their first parity.Results:A total of 80 first-parity gilts(Yorkshire×Landrace)were randomly assigned to four dietary treatments during gestation:CO(positive control);MO(negative control,246μg ZEA/kg diet);COA(CO+B.subtilis ANSB01G culture with 2×10^(9)CFU/kg diet);MOA(MO+B.subtilis ANSB01G culture with 2×10^(9)CFU/kg diet).There were 20 replications per treatment with one gilt per replicate.Feeding low-dose ZEA naturally contaminated diets disordered most of reproductive hormones secretion and affected estrogen receptor-αand estrogen receptor-βconcentrations in serum and specific organs and led to moderate histopathological changes of gilts,but did not cause significant detrimental effects on reproductive performance.The addition of Bacillus subtilis ANSB01G culture to the diet can effectively relieve the competence of ZEA to estrogen receptor and the disturbance of reproductive hormones secretion,and then ameliorate toxicosis of ZEA in gilts.Conclusions:Collectively,our study investigated the effects of feeding low-dose ZEA on reproduction in pregnant sows during their first parity.Feeding low-dose ZEA could modulate estrogen receptor-αand-βconcentrations in specific organs,cause disturbance of reproductive hormones and vulva swelling,and damage organ histopathology and up-regulate apoptosis in sow models.Diet with Bacillus subtilis ANSB01G alleviated negative effects of the ZEA on gilts to some extent.

Phytogenic Feed Additive for Sows： Effects on Sow Feed Intake, Serum Metabolite Concentrations, IgG Level, Lysozyme Activity and Milk Quality

The objective of this study was to investigate the influence ofa phytogenic feed additive （PFA） to late-gestation （d 90） and lactation sows on their reproduction performance. Sixty Large White × Landrace primiparous sows were divided into four groups （fifteen sows per group）. The control group was fed with basal diet, the others were fed with basal diet supplemented with 0.02%, 0.04% and 0.06% PFA, respectively. Compared with the control, the sows in 0.04% PFA group had higher feed intake during lactation and higher litter weaning weight （P 〈 0.05）. At farrowing, glucose level in 0.04% PFA sows was higher than the control and sows in 0.02% PFA had the highest IgG content among the treatments （P 〈 0.05）. On day 7 of lactation, serum urea nitrogen contents were lower in response to PFA supplementation compared to the control （P 〈 0.05）. At the same time, sows fed the 0.06% PFA diet increased the lysozyme activity （P 〈 0.05）. The levels of milk lactose and IgG were increased in 0.02% and 0.04% PFA groups （P 〈 0.05）. In conclusion, feeding PFA improved sows and litter performance, serum metabolite concentrations, lgG level and lysozyme activity at postpartum and milk quality.

Effects of Gamma-Aminobutyric Acid on Performance of Lactating Sows during Heat Weather

[ Objective] To study the effects of gamma-aminobutyric acid （GABA） on performance of lactating sows during heat stress. [ Metbod] A total of 14 sows at the same parity and with close expected date of childbirth and similar body we：,ght were randomly divided into control group and experimental group. They were fed a common basal diet and a GABA （300 mg/kg） supplementary diet, respectively. The trial lasted for 21 d. [ Result ] The daily feed intake, lactation yield and average daily gain of piglets in the experimental group were increased by 9.4%, 28.5% and 10.7%, respectively. The backfat of lactating sows was decreased less, and the same with the weaning-oestrus interval. The survival ratio of piglets was increased by 4.5%. Compared with the control group, the content of lactose and fat increased significantly, but other components almost did not change. [Conclusien] Supplementing GABA in diet can improve the performance of lactating sows and promote the growth of piglets effectively.