Effects of dietary fiber content and different fiber-rich ingredients on endogenous loss of fat and fatty acids in growing pigs

Background: Determination of the endogenous loss of fat(ELF) is used to adjust for the estimation of true total tract digestibility(TTTD) of fat in diets and ingredients.Any factor which affected ELF may further affect the digestibility of fat,including sources and concentrations of fat and fiber in the diet.There are some reports of determining the ELF using regression methods based on different levels of fat intake,while reports on effects of dietary fiber content and different fiber-rich ingredients in pig diets on ELF are very limited.Therefore,the objective of this study was to determine the effects of dietary fiber content and different fiber-rich ingredients on endogenous losses of fat and fatty acids at the end of ileum and throughout the entire intestinal tract in growing pigs.Methods: In Exp.1,the effect of fiber content on endogenous loss of fat was determined using six growing pigs(Duroc × Landrace × Yorkshire;27.6 ± 2.4 kg),fitted with a T-cannula at the end of ileum.The experimental design was a 6 × 6 complete Latin square design with six periods of feeding and six diets.The six experimental fat-free diets were formulated to include graded levels of neutral detergent fiber(NDF)(0,40,80,120,160 and 200 g/kg) and soybean hull(SH) was the only fiber source,providing 0,75,150,225,300 and 375 g/kg,respectively.Chromic oxide was included at4 g/kg in all diets as an indigestible marker.In Exp.2,six crossbred growing barrows(27.6 ± 1.6 kg) were used and the experimental design was the same as for Exp.1.The six fat-free diets were formulated to include six common fiber-rich ingredients and the concentration of NDF was 100 g/kg.The six fiber-rich ingredients were defatted rice bran(DRB),sugar beet pulp(SBP),rice hull(RH),corn germ meal(CGM),SH and wheat bran(WB) and they were fed at represented250,270,145,250,170 and 280 g/kg in the diet,respectively.Results: In Exp.1,the endogenous loss of fatty acids profile did not change as dietary NDF increased in growing pigs.The endogenous losses of fat,C16:0,C18:0,C18:1,C18:2,total unsaturated fatty acids(UFA) and total saturated fatty acids(SFA) in growing pigs at the end of ileum and throughout the entire intestinal tract increased linearly as NDF content of diets increased.The endogenous losses of fat,as well as C16:0 and C18:0 throughout the entire intestinal tract also increased quadratically as NDF content of diets increased.The ELF increased from 0.71 to 3.14 g/kg of dry matter intake(DMI) and 0.56 to 8.21 g/kg DMI at the end of ileum and throughout the entire intestinal tract in growing pigs,respectively.The ELF occurred in the hindgut except for the growing pigs fed 0 and 4% NDF in their diets.The endogenous losses of C16:0 and UFA occurred primarily in the upper regions of the gut and the greatest endogenous losses of C18:0 occurred in the hindgut.The endogenous losses of fat,individual SFA and total SFA throughout the entire intestinal tract were much greater than that at the end of ileum.However,the endogenous losses of individual UFA and total UFA were less throughout the intestinal tract than at the end of ileum.In Exp.2,the endogenous losses of fat at the end of ileum were greater in growing pigs fed CGM or WB diets.The endogenous loss of fatty acids profile changed to a slight degree at the end of ileum that the endogenous loss of UFA(particularly C18:1 and C18:2) in growing pigs fed CGM or WB diets were greater(P < 0.01) than that for the other four diets.The greatest(P < 0.01) endogenous loss of SFA(particularly C18:0) was in growing pigs fed the RH diet.The endogenous losses of fat,C16:0,C18:0 and SFA over the entire intestinal tract were much greater in growing pigs fed CGM or WB diets,whereas the lowest values were in growing pigs fed DRB diet.The ELF at the end of ileum in growing pigs fed CGM or WB diets were 3.50 or 4.17 g/kg DMI,respectively,and the ELF over the entire intestinal tract was 7.23 or 7.38 g/kg DMI.The contribution in percentage of ELF in the upper gut was greater than that in the hindgut of growing pigs fed DRB and RH diets,while the ELF in the upper gut and hindgut were equal in growing pigs fed SBP,CGM and WB diets.On the whole,the endogenous losses of C18:1 and C18:2 throughout the entire intestinal tract in growing pigs fed the six fiber-rich ingredients diets were less than losses at the end of ileum,whereas the endogenous loss of fat,C16:0,C18:0 and SFA were greater throughout the intestinal tract than at the end of ileum.Conclusion: The profile of loss in endogenous fatty acids did not change as dietary NDF increased in growing pigs and the endogenous losses of fatty acids(C16:0,C18:0,C18:1 and C18:2) fat,UFA and SFA increased linearly as NDF content increased in the diets of pigs.The endogenous losses of fat or fatty acids at the end of ileum were greater in growing pigs fed RH,CGM or WB diets.The endogenous losses of fat,fatty acids(C16:0 and C18:0) and SFA were greater over the entire intestinal tract in pigs fed CGM or WB diet,while these values were the lowest in growing pigs fed the DRB diet.The contribution in percentage losses of fat in the upper gut were greater than in the hindgut of growing pigs fed DRB and RH diets,while the contribution of losses of fat in the upper gut and hindgut were equal in growing pigs fed SBP,CGM and WB diets.In addition,the endogenous loss of individual or total UFA was less over the entire intestinal tract of growing pigs fed fiber diets than that at the end of ileum,and the greatest endogenous losses of fat,individual or total SFA were over the entire intestinal tract.Therefore,differences in fiber content and the nature of fiber-rich ingredients in diets of pigs have different effects to the endogenous losses of fat or fatty acids.Considering the requirement of fat or fatty acids of pigs,careful attention must be paid that the endogenous losses of fat and fatty acids when fiber ingredients are used in diets of pigs.

Genome-wide scan for selection signatures based on whole-genome re-sequencing in Landrace and Yorkshire pigs

We performed a genome-wide scan to detect selection signatures that showed evidence of positive selection in the domestication process by re-sequencing the whole genomes of Landrace and Yorkshire pigs.Fifteen annotated elements with 13 associated genes were identified using the Z-transformed FST(Z(FST))method,and 208 annotated elements with 140 associated genes were identified using the Z-transformed heterozygosity(ZHp)method.The functional analysis and the results of previous studies showed that most of the candidate genes were associated with basic metabolism,disease resistance,cellular processes,and biochemical signals,and several were related to body morphology and organs.They included PPP3CA,which plays an essential role in the transduction of intracellular Ca2+-mediated signals,and WWTR1,which plays a pivotal role in organ size control and tumor suppression.These results suggest that genes associated with body morphology were subject to selection pressure during domestication,whereas genes involved in basic metabolism and disease resistance were subject to selection during artificial breeding.Our findings provide new insights into the potential genetic variation of phenotypic diversity in different pig breeds and will help to better understand the selection effects of modern breeding in Landrace and Yorkshire pigs.

Regional selection of insecticides and fungal biopesticides to control aphids and thrips and improve the forage quality of alfalfa crops

The efficacies of biological and conventional chemical insecticides against two major insect pests of alfalfa(aphids and thrips)were compared in three sites across China’s alfalfa belt.In addition,the persistence of the residues of chemical insecticides in alfalfa and their influence on the quality of alfalfa hay were examined.Efficacy varied among the different biological and chemical insecticides.The chemical insecticides were significantly more effective than biopesticides in a short time-frame.The efficacy period of biopesticides was significantly longer than that of chemical insecticides,and the corrected mortality rate of aphids in all regions was above 50%at 14 days after application.The analysis of pesticide residues showed that the residual doses of all the pesticides were within the allowed ranges after the safe period.The acid detergent fiber and neutral detergent fiber contents in alfalfa hay were higher and the protein content was lower in chemical insecticide treatments than in biopesticide treatments in Hebei.The relative feeding value of alfalfa hay treated with Metarhizium anisopliae IPP330189 was the highest among the treatments.Compared with chemical insecticides,the yield of alfalfa hay was higher in the biopesticides treatments.Biopesticides show a stronger control effect on insect populations and also a better improvement in the quality of alfalfa hay than chemical insecticides.This study provides a basis for exploring and developing a comprehensive control regime for alfalfa insect pests in the different alfalfa-growing regions in China,and for reducing chemical insecticide usage and improving forage quality.

Induction of Apoptosis in the Immature Mouse Testes by a Mixture of Melamine and Cyanuric Acid

The toxicity of melamine has attracted much attention since the recent outbreaks of renal injury in pets and infants. Previous studies indicated that melamine by itself had low toxicity, whereas a mixture of melamine and cyanuric acid （M＋CA） could cause serious renal damage. At present, most researches on the toxicity of M＋CA are focused on the kidney. However, little is known about the adverse effects of this mixture on the reproductive system. In the present study, the toxicity of M＋CA to testes was investigated. Immature male mice were orally dosed with 0, 0.6, 3, and 15 mg kg-1 d-1 of a 1：1 M＋CA for 28 d. Pathological changes occurred in germ cells, such as loose arrangement, reduced numbers and karyopyknosis, indicating that this mixture was toxic to spermatogenesis. Compared with the control group, the TUNEL- positive germ cells increased significantly and the ratio of Bcl-2 to Bax, total antioxidant capacity and superoxide dismutase activity decreased significantly in the 3 and 15 mg kg-1 d- M＋CA treated group, while the activities of caspase-3, caspase- 8 and caspase-9 remained unchanged. The results suggest that M＋CA can induce apoptosis in the mice testes. The downregulation of Bcl-2/Bax and oxidative stress may play a pivotal role in the induction of apoptosis by M＋CA in mice testes.

Identifying SNPs associated with birth weight and days to 100 kg traits in Yorkshire pigs based on genotyping-by-sequencing

Birth weight(BW)and days to 100 kg(D100)are important economic traits that are both affected by polygenes.However,the genetic architecture of these quantitative traits is still elusive.Genotyping-by-sequencing(GBS)data containing a large number of single nucleotide polymorphisms(SNPs)have become a powerful tool in genomic analysis.To better understand their complex genetic structure,a total of 600 Yorkshire pigs were sequenced using GBS technology.After quality control,279787 SNPs were generated for subsequent genome-wide association study(GWAS).A total of 30 genome-wide SNPs(P<1.79 E–07)were identified for D100.Furthermore,a total of 22 and 2 suggestive SNPs(P<3.57 E–06)were detected for D100 and BW,respectively.Of these,one locus located on SSC12(position:46226512 bp)were evaluated to affect both BW and D100 in Yorkshire pigs,indicating the pleiotropism in different traits.Considering the function of candidate genes,two genes,NSRP1 and DOCK7,were suggested as the most promising candidate genes involved in growth traits.Thus,use of GBS is able to identify novel variants and potential candidate genes for BW and D100,and provide an opportunity for improving pig growth traits using genomic selection in pigs.

Epigenome-wide DNA methylation analysis reveals differentially methylation patterns in skeletal muscle between Chinese Chenghua and Qingyu pigs

Chenghua(CH)pig and Qingyu(QY)pig are typical Chinese native fatty breeds.CH pig is mainly distributed in Chengdu Plain,while QY pig is widely distributed throughout the mountain areas around the Sichuan Basin.There are significant differences in their phenotypic traits,including body image,growth performance,and meat quality.This study compared several meat quality traits of CH and QY pigs and conducted a genome-wide DNA methylation analysis using reduced representation bisulfite sequencing(RRBS).It was observed that the pH at 45 min(pH_(45min),P=5.22e-13),lightness at 45 min(L^(*)_(45min),P=4.85e-5),and lightness at 24 h(L^(*)_(24h),P=3.57e-5)of CH pigs were higher than those of QY pigs.We detected 10699 differentially methylated cytosines(DMCs)and 2760 differentially methylated genes(DMGs)associated with these DMCs.Functional analysis showed that these DMGs were mainly enriched in the AMPK signaling pathway,Type II diabetes mellitus,Insulin signaling pathway,mTOR signaling pathway,and Insulin resistance.Furthermore,15 DMGs were associated with fat metabolism(ACACA,CAB39,CRADD,CRTC2,FASN,and GCK),muscle development(HK2,IKBKB,MTOR,PIK3CD,PPARGC1A,and RPTOR),or meat quality traits(PCK1,PRKAG2,and SLC2A4).The findings may help to understand further the epigenetic regulation mechanisms of meat quality traits in pigs and provide new basic data for the study of local pigs.

Construction of a high-density genetic linkage map and identification of flowering-related QTL in erect milkvetch(Astragalus adsurgens)

Erect milkvetch(Astragalus adsurgens)is a perennial legume forage crop with economic and ecological value in livestock grazing and soil-erosion control in arid and semiarid areas worldwide.Genomic information and molecular tools to support breeding and research in the species are limited.The objectives of this investigation were to map its genome using DNA markers and to identify quantitative trait loci(QTL)in the species.An F1 mapping population of 250 plants was developed from a cross between two parents with differing flowering-related traits.A high-density genetic linkage map containing 4821 markers on eight linkage groups(LGs)with a total genetic length of 1395 cM and a mean interval of 0.29 cM between adjacent markers was constructed with SLAF-seq technology.Comparative genomic analyses revealed the highest genome sequence similarity(8.71%)between erect milkvetch and Medicago truncatula,followed by Glycine max(7.65%),Cicer arietinum(7.53%),and Lupinus angustifolius(5.21%).A total of 64 significant QTL for flowering-related traits on six LGs were detected,accounting for 9.38 to 19.1%of the associated phenotype variation.Five and 48 key candidate genes for floret number and inflorescence length were identified based on the Glycyrrhiza uralensis genome.These candidate genes were involved in ubiquitination/degradation,pollen development,cell division,cytokinin biosynthetic process,and plant flowering.These findings shed light on the regulation of flowering traits in erect milkvetch and provide genomic resources for future molecular breeding of the crop.

Characteristics of genetic basis copy number variation in production and adaptation traits of Chinese indigenous sheep

Copy number variations(CNVs)range in size from 50 base pairs(bp)to several megabases(Mb)and encompass various types of structural variations,such as insertions,deletions,duplications,and complex multiallelic events(MacDonald et al.,2014).These genomic alterations modulate phenotype by altering gene dosage and transcriptional regulation,and are key drivers of biological evolution and determinants of genetic diversity and phenotypic variation.In recent years,CNVs have been detected in the genomes of various livestock species(Yuan et al.,2021;Chen et al.,2022).Upadhyay et al.(2017)conducted a comprehensive analysis of CNV distribution in the European cattle genome and determined that the Kit gene is associated with color-sidedness in English longhorn cattle.Another study presented extensive genome-wide information on CNVs in wild,commercial,and local chicken breeds to gain an integrated understanding of the domestication process and exclusively identified the genes involved(Chen et al.,2022).

Diets enriched with finely ground wheat bran alter digesta passage rate and composition of the gut microbiome in sows

We investigated the effects of finely ground wheat bran on the nutrient digestibility, digesta passage rate,and gut microbiota structure in sows. A 3 × 3 Latin square design with 3 test periods and 3 experimental diets was used. Six non-pregnant sows(parity: 5 to 7) were randomly assigned to 3 experimental diets with 2 replicates per treatment in each period. Each period lasted 19 d(12 d for adaptation and 7 d for experiment). The experimental diets included(a) a basal corn and soybean meal diet(CON),(b) a basal diet with 20% coarse wheat bran(CWB;particle size: 605 μm), and(c) a basal diet with 20% fine wheat bran(FWB;particle size: 438 μm). The results demonstrated that the apparent total tract digestibility of neutral detergent fiber, acid detergent fiber and energy were reduced(P < 0.05) in the FWB and CWB groups compared with those in the CON group. Viscosity of digesta increased(P < 0.001) in FWB-fed sows. The passage rate of digesta from the mouth to the ileum decreased(P < 0.001) in FWB-fed sows. Peptide YY(PYY) concentration increased(P = 0.01) in FWB-fed sows after 30 min of feeding.In the FWB group, the relative abundance of Lactobacillaceae at the family level increased(P < 0.05) in the ileal digesta. At the class level, the relative abundance of Clostridia in feces decreased(P < 0.05) in FWB-fed sows. FWB enhanced the concentration of butyrate in feces compared with CON and CWB(P = 0.04). These results suggest that dietary supplementation with finely ground wheat bran reduces the passage rate of digesta, increases the abundance of beneficial microorganisms, and elevates the concentration of short-chain fatty acids and PYY in sows. These findings indicate that the addition of finelyground wheat bran to the diets of sows is more effective than using coarse wheat bran for improving their satiety and intestinal microbial composition.