Evaluating the performance of genomic selection on purebred population by incorporating crossbred data in pigs

Genomic selection(GS)has been widely used in livestock,which greatly accelerated the genetic progress of complex traits.The population size was one of the significant factors affecting the prediction accuracy,while it was limited by the purebred population.Compared to directly combining two uncorrelated purebred populations to extend the reference population size,it might be more meaningful to incorporate the correlated crossbreds into reference population for genomic prediction.In this study,we simulated purebred offspring(PAS and PBS)and crossbred offspring(CAB)base on real genotype data of two base purebred populations(PA and PB),to evaluate the performance of genomic selection on purebred while incorporating crossbred information.The results showed that selecting key crossbred individuals via maximizing the expected genetic relationship(REL)was better than the other methods(individuals closet or farthest to the purebred population,CP/FP)in term of the prediction accuracy.Furthermore,the prediction accuracy of reference populations combining PA and CAB was significantly better only based on PA,which was similar to combine PA and PAS.Moreover,the rank correlation between the multiple of the increased relationship(MIR)and reliability improvement was 0.60-0.70.But for individuals with low correlation(Cor(Pi,PA or B),the reliability improvement was significantly lower than other individuals.Our findings suggested that incorporating crossbred into purebred population could improve the performance of genetic prediction compared with using the purebred population only.The genetic relationship between purebred and crossbred population is a key factor determining the increased reliability while incorporating crossbred population in the genomic prediction on pure bred individuals.

Absolute copy number differences of Y chromosomal genes between crossbred (Bos taurus×Bos indicus) and Indicine bulls

Background： The Y chromosome in mammal is paternally inherited and harbors genes related to male fertility and spermatogenesis. The unique intra-chromosomal recombination pattern of Y chromosome and morphological difference of this chromosome between Bos taurus and Bos indicus make it an ideal model for studying structural variation, especially in crossbred （Bos taurus x Bos indicus） bulls. Copy Number Variation （CNV） is a type of genomic structural variation that gives information complementary to SNP data. The purpose of this study was to find out copy number differences of four Y chromosomal spermatogenesis-related candidate genes in genomic DNA of crossbred and purebred Indicine bulls. Result： Four Y chromosomal candidate genes of spermatogenesis namely, sex determining gene on Ychromosome （SRY）, DEAD box po/ypeptide 3-Y chromosome （DDX3 Y）, Ubiquidn specific peptidase 9, Y-linked （ usPgY）, testis-specific protein on Y chromosome （TSPY） were evaluated. Absolute copy numbers of Y chromosomal genes were determined by standard curve-based quantitative real time PCR. Copy numbers of SRYand TSPYgenes per unit amount of genomic DNA are higher in crossbred than Indicine bulls. However, no difference was observed in DDX3Yand usPgYgene copy numbers between two groups. Conclusion： The present study demonstrates that the structural organization of Y chromosomes differs between crossbred and Indicine bulls which are reproductively healthy as observed from analysis of semen attributes. The absolute copy numbers of SRY and TSPY genes in unit mass of genomic DNA of crossbred bulls are significantly higher than Indicine bulls. No alteration in absolute copies ofDDX3Yand usPgYgene was found between the genome of crossbred and Indicine bulls. This study suggests that the DDX3Yand USPgYare likely to be single copy genes in the genome of crossbred and Indicine bulls and variation in Y chromosome length between crossbred and Indicine bulls may be due to the copy number variation of SRY gene and TSPYarray.

Factors affectingin-vivo fertility of crossbred Egyptian - Italian buffalo semen

Objective:To assess the effect of region, season and year of insemination onin-vivo fertility of Italian-Egyptian crossbred buffalo semen.Methods: A total number of 4799 female buffaloes were inseminated by frozen semen with at least 50% post-thaw motility of Egyptian-Italian crossbred bulls in three localities in Delta, lower Egypt (El-Behira, El-Sharkia and Damietta) during the period of 2013, 2014 and 2015. The pregnancy rate after two months was evaluated during the four seasons.Results:The rate of pregnancy was significantly (P<0.0001) differ among the three localities. The effect of year of insemination on pregnancy rate was significantly higher during 2014 and 2015 than 2013 in El-Sharkia and El-Behira. But in Damietta, the rate of pregnancy was significantly higher in 2014 than 2013 and 2015. There were no significant differences among seasons in El-Behira and Damietta governorates but there was significant (P<0.05) differences in pregnancy rate in El-Sharkia. It was higher in summer, spring and autumn than in winter.Conclusions:Localities, year of insemination and season of the year have effects on fertility of crossbred Egyptian-Italian buffalo semen.

Trans-10,cis-12 conjugated linoleic acid reduces neutral lipid content and may affect cryotolerance of in vitro-produced crossbred bovine embryos

Background：Due to high neutral lipids accumulation in the cytoplasm,in vitro-produced embryos from Bos primigenius indicus and their crosses are more sensitive to chilling and cryopreservation than those from Bos primigenius taurus.The objective of the present study was to evaluate the effects of trans-10,cis-12 conjugated linoleic acid（CLA） on the development and cryotolerance of crossbred Bos primigenius taurus x Bos primigenius indicus embryos produced in vitro,and cultured in the presence of fetal calf serum.Bovine zygotes（n = 1,692）were randomly assigned to one of the following treatment groups：1） Control,zygotes cultured in Charles Rosenkrans 2 amino acid（CR2aa） medium（n = 815） or 2） CLA,zygotes cultured in CR2 aa medium supplemented with 100 μmol/L of trans-10,cis-12 CLA（n =877）.Embryo development（cleavage and blastocyst rates evaluated at days 3 and 8 of culture,respectively）,lipid content at morula stage（day 5） and blastocyst cryotolerance（re-expansion and hatching rates,evaluated 24 and 72 h post-thawing,respectively） were compared between groups.Additionally,selected mRNA transcripts were measured by Real-Time PCR in blastocyst stage.Results：The CLA treatment had no effect on cleavage and blastocyst rates,or on mRNA levels for genes related to cellular stress and apoptosis.On the other hand,abundance of mRNA for the 1-acylglycerol-3-phosphate0-acyltransferase-encoding gene（AGPAT）,which is involved in triglycerides synthesis,and consequently neutral lipid content,were reduced by CLA treatment.A significant increase was observed in the re-expansion rate of embryos cultured with trans-10,cis-12 CLA when compared to control（56.3 vs.34.4%,respectively,P = 0.002）.However,this difference was not observed in the hatching rate（16.5 vs.14.0%,respectively,P=0.62）.Conclusions：The supplementation with trans-10,ds-12 CLA isomer in culture medium reduced the lipid content of in vitro produced bovine embryos by reducing the gene expression of 1-acylglycerol 3-phosphate 0-acyltransferase（AGPAT） enzyme.However,a possible improvement in embryo cryotolerance in response to CLA,as suggested by increased blastocyst re-expansion rate,was not confirmed by hatching rates.

Meat Production Performances of Geese in Different Crossbred Combinations

[ Objective] To study the meat production performance of geese in different crossbred combination, and provide a reference for cultivating new multiplication strains of meat geese. [Method] A total of five goose breeds including Taihu goose （T）, Wulong goose （WL）, Wanxi white goose （WX）, Sichuan white goose （SC） and Sanhua goose （SH） were used as research objects, and eight crossbred combinations were designed. The body measurements, slaughter performance, conventional meat quality and muscle composition of 90-day-old geese in eight crossbred combinations were determined and comparatively analyzed. [ Result] All the body measurement indexes except thud width of WXSC combination were the biggest in the eight crossbred combinations. Contrarily, the body measurement indexes of SHSC combination, including average body weight, body slope length, breast depth, breast width, shank length, neck length and half-diving depth were the lowest in the eight crossbred combinations. The live weight, slaughter weight and abdomen fat weight of WXSC combinations ware 3 291.36, 2 956.46 and 77.84 g, respectively, which were the biggest in eight crossbred combinations. The slaughter rate of SHWL combinations was 92.96%, and more than other crossbred combinations. The shear force of SHT and WXWL combinations were the lowest （3.09 kg） and the highest （3.78 kg）, respectively. The water holding capacities of SCWL and WXSC combinations were the highest （66.46%） and the lowest （61.48%）, respectively. The percentage of moisture content of SHWL and SCT combinations were the highest （73.05%） and the lowest （66.77%）, respectively. The crude protein content of SHT and SHWL combinations were the highest （23.32%） and the lowest （21.94%）, respectively. The percentage of crude fat content of SHT and SCWL combinations were the highest （3.06%） and the lowest （1.67%）, respectively. [ Concusion] The growth rate of WXSC combination is the fastest, and the meat performance of SHT combination is the best.

Effects of Different Protein Energy Ratios on Fattening Performance,Slaughter Performance and Meat Quality of Pigs

[Objectives]Protein energy ratio refers to the proportional relationship between protein and energy levels in animal diets,i.e.,the grams of crude protein corresponding to every megacalorie of energy,which is generally expressed as CP:ME or CP:DE.This study was conducted to investigate the effects of different diets on fattening and slaughter performance and meat quality traits for"L(Large Yorkshire)×L(Landrace)"crossbred pigs.[Methods]Eighteen piglets of L×L crossbred with similar body weights about 51 kg were selected.The piglets were divided into 3 groups randomly and each group was assigned to 3 replicates with 2 piglets in a replicate.Group A was fed diet Ⅰ (control diet),group B was fed the same diet of group A in the first month of the trial but fed diet Ⅱ in second month,and group C consumed diet Ⅲ.All the pigs were fed in the same feeding condition for two months except the different diets during the trial.One pig in similar body weight from each replicate was slaughtered for the determination of slaughter performance and meat quality traits in the end of the trial.[Results]The average daily feed intake(ADFI)of pigs from group B was only(2.32±0.52)kg and significantly lower than those from group A and group C(P<0.05),but no difference was found in average daily gain(ADG) and feed/gain(P>0.05).Also,no differences occurred in the carcass length,back fat thickness,longissimus muscle (LM) area and dressing percentage(P>0.05).In addition,no differences were found in the meat quality traits of shear force,meat color,pH_(45 min),pH_(24 h) and cooking loss(P>0.05).However,the water-holding capacity of meat from group C was(2.58±0.02)ms and significantly lower than that of(2.80±0.20)ms from group A(P<0.05).Although the contents of glutamic acid and cystine in LM from group B was significantly lower than those from group A and group C(P<0.05),no differences occurred in the contents of other amino acids,the total amino acid and total flavor amino acid among the three groups(P>0.05).However,the inosine monophosphate content of LM from group C was only(331.80±11.53)mg/100 g and significantly lower than those of(361.00±6.36)and(366.37±4.80)mg/100 g from group A and B(P<0.05).Even though no differences were found in the contents of DM and CP in LM among the three groups of pigs,the content of intramuscular fat(IMF)in LM from group B and group C was increased by 45.6%and 46.58%respectively from that of group A(P<0.05),but no difference occurred between group B and C(P>0.05).[Conclusions]DietsⅡ and Ⅲ in this study caused no differences in fattening and slaughter performance of L×L crossbred pigs,but the effects on some meat traits were still significant,especially on the improvement of intramuscular fat in experimental pigs.Therefore,they could improve the meat quality of crossbred pigs to a certain extent.

不同比例梅山猪血缘生长育肥猪肉质及肌纤维组织学特性研究

选不同比例梅山猪血缘 (梅山猪血缘比例为 0 ,1/ 8,1/ 4,3/ 8,1/ 2 ,1)的杂种仔猪 6 8头 ,采用单因子试验设计 ,在同一营养水平 (DE :前期 14 2 1MJ/kg ,后期 13 79MJ/kg ;CP :15 % ,13 % ;Lys:0 75 % ,0 6 5 % )下 ,研究不同比例梅山猪血缘对不同体重阶段生长育肥猪肉质及肌纤维组织学特性的影响。结果表明 :梅山及其杂种猪与杜大猪相比 ,肉色好 (P <0 0 5 ) ,pH值正常 (P <0 0 1) ,肌内脂肪含量高 (P <0 0 1) ,分布均匀 ,系水力高 (P <0 0 5 ) ,无异常肉发生 ,其它常规化学成分分析差异不显著 (P >0 0 5 ) ;肌纤维直径随梅山猪血缘比例增加逐渐变细 。

不同比例梅山猪血缘生长育肥猪生产性能和胴体品质研究

选不同比例梅山猪血缘 (梅山猪血缘比例为 0 ,1/ 8,1/ 4,3/ 8,1/ 2 ,1)的杂种仔猪 6 8头 ,采用单因子试验设计 ,在同一营养水平 (DE :前期 14 2 1MJ/kg ,后期 13 79MJ/kg ;CP :15 % ,13% ;Lys:0 75 % ,0 6 5 % )下 ,研究不同比例梅山猪血缘对不同体重阶段生长育肥猪生产性能 (平均日增重、饲料 /增重 )和胴体品质 (平均膘厚、眼肌面积、瘦肉率等 )的影响。结果表明 :梅山猪与国外猪种杂交后 ,1/ 2梅山 ,1/ 4梅山 ,1/ 8梅山杂种猪各阶段生产性能显著高于纯种梅山猪 (P <0 0 1) ,90kg屠宰时 ,其瘦肉率分别比梅山猪提高 10 0 3% ,12 14% ,14 0 4% ;眼肌面积分别提高40 9% ,5 1 75 % ,5 2 6 % ;平均膘厚分别降低 3 3% ,2 8% ,18 2 5 % ;与杜洛克×大白 (下称杜大 )杂种猪生产性能相比 ,试验前期 (2 0～ 5 5kg)的差异小于试验后期 (5 5～ 90kg) ;整个试验期 ,杜大杂种猪的生产性能和胴体品质与纯种梅山及其杂种猪差异极显著 (P <0 0 1) ,随梅山猪血缘增加 ,杂种猪的生产性能、瘦肉率和眼肌面积逐渐降低 ,背部

含不同比例梅山猪血缘杂交肉猪肉质及肌纤维组织学特性研究

选不同比例梅山猪血缘(梅山猪血缘比例为0,1/8,1/4,3/8,1/2,1)的杂种仔猪68头,采用单因子试验设计,在同一营养水平(DE:前期14.21MJ/kg,后期13.79MJ/kg;CP:15%,13%;Lys:0.75%,0.65%)下,研究不同比例梅山猪血缘对不同体重阶段生长肥育猪肉质及肌纤维组织学特性的影响。结果表明,梅山及其杂种猪与杜大猪相比,肉色好(P<0.05),pH正常(P<0.01),肌内脂肪含量高(P<0.01),分布均匀,系水力高(P<0.05),无异常肉发生,其它常规化学成分分析差异不显著(P>0.05);肌纤维直径随梅山猪血缘比例增加逐渐变细,而随体重增加逐渐增大。

含不同比例梅山猪血缘杂交猪肥育性能的比较研究

选不同比例梅山猪血缘 (梅山猪血缘比例为 0 ,1 /8,1 /4,3 /8,1 /2 ,1 )的杂交仔猪 68头 ,采用单因子试验设计 ,在同一营养水平 (DE :前期 1 4.2 1兆焦 /公斤 ,后期 1 3 .79兆焦 /公斤 ;CP :1 5 % ,1 3 % ;Lys :0 .75 % ,0 .65 % )下 ,研究不同梅山猪血缘比例对不同体重阶段生长育肥猪肥育性能 (平均日增重、饲料 /增重 )的影响。结果表明 ,梅山猪与国外猪种杂交后 ,1 /2梅山 ,1 /4梅山 ,1 /8梅山杂交猪各阶段肥育性能显著高于纯种梅山猪 (P <0 .0 1 ) ;与杜洛克×大白 (下称杜×大 )杂交猪相比 ,试验前期 (2 0—5 5kg)的差异小于试验后期 (5 5—屠宰 ) ;整个试验期 ,杜×大杂交猪的肥育性能与纯种梅山及其杂交猪差异极显著 (P <0 .0 1 ) ,随梅山猪血缘增加 ,杂交猪的肥育性能逐渐降低 ;同一血缘不同体重阶段生长育肥猪随体重 (或饲养天数 )增加 ,饲料利用效率 (F/G)呈三次曲线变化 (P <0 .0 1 ) ,平均日增重 (ADG)则呈二次曲线变化 (P <0 .0 1 )。

含不同比例梅山猪血缘杂交肉猪胴体品质研究

选不同比例梅山猪血缘 (梅山猪血缘比例为 0 ,1 / 8,1 / 4 ,3 / 8,1 / 2 ,1 )的杂交仔猪 68头 ,采用单因子试验设计 ,在同一营养水平 (DE :前期 1 4.2 1兆焦 /千克 ,后期 1 3 .79兆焦 /千克 ;CP :1 5 % ,1 3 % ;Lys:0 .75 % ,0 .65 % )下 ,研究不同梅山猪血缘比例对不同体重阶段生长肥育猪胴体品质 (平均膘厚、眼肌面积、瘦肉率等 )的影响。结果表明 :梅山猪与国外猪种杂交后 ,1 / 2梅山 ,1 / 4梅山 ,1 / 8梅山杂交猪的胴体品质显著高于 (P <0 .0 1 )纯种梅山猪。在同一体重下 (1 1 0kg) ,3 / 8梅山 ,1 / 2梅山和纯种梅山猪的平均膘厚显著高于其它血缘组 (P <0 .0 1 ) ,1 / 8梅山 ,1 / 4梅山和杜×大杂交猪间差异不显著 (P >0 .0 5 ) ;瘦肉率和眼肌面积随梅山猪血缘比例增加 ,逐渐下降 ;同一血缘不同体重阶段生长肥育猪随体重 (或饲养天数 )增加 ,平均膘厚、眼肌面积、瘦肉率呈显著二次曲线变化 (P <0 .0 1 ) ,肥育猪在适宜体重下屠宰 。

皮南牛适宜级进杂交代数的研究

本研究选择12月龄皮南杂交(皮埃蒙特牛×本地南阳牛)公牛F1、F2、F3各30头,在7、8、9月份进行统一育肥试验,探讨夏季湿热气候对不同杂交后代生长发育状况的影响,以寻找皮埃蒙特牛与南阳本地黄牛适宜的级进杂交代数。结果表明,级进F2杂交个体比F1和F3更能适应当地夏季较为强烈的湿热气候,并保持优良的产肉性能,故杂交选育宜在F2代基础上进行。