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.

A Retrodirective Array Enabled by CMOS Chips for Two-Way Wireless Communication with Automatic Beam Tracking

This article proposes and demonstrates a retrodirective array(RDA)for two-way wireless communication with automatic beam tracking.The proposed RDA is enabled by specifically designed chips made using a domestic complementary metal-oxide semiconductor(CMOS)process.The highly integrated CMOS chip includes a receiving(Rx)chain,a transmitting(Tx)chain,and a unique tracking phaselocked loop(PLL)for the crucial conjugated phase recovery in the RDA.This article also proposes a method to reduce the beam pointing error(BPE)in a conventional RDA.To validate the above ideas simply yet without loss of generality,a 2.4 GHz RDA is demonstrated through two-way communication links between the Rx and Tx chains,and an on-chip quadrature coupler is designed to achieve a nonretrodirective signal suppression of 23 dBc.The experimental results demonstrate that the proposed RDA,which incorporates domestically manufactured low-cost 0.18 lm CMOS chips,is capable of automatically tracking beams covering±40with a reduced BPE.Each CMOS chip in the RDA has a compact size of 4.62 mm^(2) and a low power consumption of 0.15 W.To the best of the authors’knowledge,this is the first research to demonstrate an RDA with a fully customized CMOS chip for wireless communication with automatic beam tracking。

Reference-frame-independent quantum key distribution with two-way classical communication

The data post-processing scheme based on two-way classical communication(TWCC)can improve the tolerable bit error rate and extend the maximal transmission distance when used in a quantum key distribution(QKD)system.In this study,we apply the TWCC method to improve the performance of reference-frame-independent quantum key distribution(RFI-QKD),and analyze the influence of the TWCC method on the performance of decoy-state RFI-QKD in both asymptotic and non-asymptotic cases.Our numerical simulation results show that the TWCC method is able to extend the maximal transmission distance from 175 km to 198 km and improve the tolerable bit error rate from 10.48%to 16.75%.At the same time,the performance of RFI-QKD in terms of the secret key rate and maximum transmission distance are still greatly improved when statistical fluctuations are considered.We conclude that RFI-QKD with the TWCC method is of practical interest.

Beamforming Design for IRS-and-UAV-Aided Two-Way Amplify-and-Forward Relay Networks in Maritime IoT

In this paper,an intelligent reflecting surface(IRS)-and-unmanned aerial vehicle(UAV)-assisted two-way amplify-and-forward(AF)relay network in maritime Internet of Things(IoT)is proposed,where ship1(S1)and ship2(S2)can be viewed as data collecting centers.To enhance the message exchange rate between S1 and S2,a problem of maximizing minimum rate is cast,where the variables,namely AF relay beamforming matrix and IRS phase shifts of two time slots,need to be optimized.To achieve a maximum rate,a low-complexity alternately iterative(AI)scheme based on zero forcing and successive convex approximation(LC-ZF-SCA)algorithm is presented.To obtain a significant rate enhancement,a high-performance AI method based on one step,semidefinite programming and penalty SCA(ONSSDP-PSCA)is proposed.Simulation results show that by the proposed LC-ZF-SCA and ONS-SDP-PSCA methods,the rate of the IRS-and-UAV-assisted AF relay network surpass those of with random phase and only AF relay networks.Moreover,ONS-SDP-PSCA perform better than LC-ZF-SCA in aspect of rate.

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.

Effect of Concentrate to Roughage Ratio on Cost Effective Growth Performance of Brahman Crossbred Calves

An experiment was conducted to evaluate the growth performance and cost per gain of Brahman × local crossbred bull calves receiving three diets with varying concentrate to roughage ratio （C：R） of 75：25, 65：35 and 55：45 on dry matter （DM） basis. Twelve bull calves （aging 11.5 ±1.2 months and 170.8 ± 13.0 kg live weight） divided into three equal groups were fed on three diets. The diets were balanced to 14.5% crude protein （CP） level and 10.5 MJ metabolizable energy （ME） per kg DM, formulating different concentrate mixtures. German grass （Echinoclora grousgali） and paddy straw were offered at 2：1 ratio on DM basis as roughages. The results revealed that C：R ratio did not affect （P 〉 0.05） the intake of feed and nutrients, feed efficiency （7.04, 6.94 and 6.76） and average daily gain （981,958 and 976 g）. Digestibility of nutrients was not affected （P 〉 0.05） by C：R. Animals fed diet with C：R = 55：45 had the lowest feed cost （Bangladeshi Taka 136.8 BDT/kg live weight gain）, which was increased （147.5 B DT and 153.8 BDT） non-significantly （P 〉 0.05） with the increasing level of concentrate. The diet consisting of 55% concentrate mixture showed similar results with the diet consisting of 75% concentrate mixture, but was comparatively economic. Therefore, considering the growth performance and cost per kg gain of Brahman crossbred growing calves, it may be concluded that the diet consisting of 55：45 C：R may be used for economic beef production.

Investigating the Efficiency Coefficient of Pile Group in Clay Under Two-Way Lateral Load

This research investigates the behavior of a 2×2 pile group under two-directional lateral loads in addition to the vertical load.Through three-dimensional numerical modeling based on Flac 3D software,the study examines the total bearing capacity and efficiency coefficient of the pile group,considering factors such as the angle of lateral load,relative pile spacing,and relative stiffness of the pile-soil system.The findings highlight the significance of these factors in understanding and predicting the response of pile groups to changing lateral load directions.The results reveal that increasing the angle of the lateral load from 0°to 45°enhances both the maximum total lateral load and the efficiency coefficient of the pile group.When the relative stiffness of the pile-soil system significantly increases,soil stiffening occurs and reducing the relative spacing of the piles from 7 to 3 times the diameter of the piles diminishes the influence of the pile group.Consequently,the response of the pile group to lateral loads becomes more linear,with only a slight alteration in the maximum total lateral load and the efficiency coefficient when the lateral load is angled from 0°to 45°.Conversely,increasing the relative distance between the piles,specifically from 3 to 7 times the diameter of the piles,amplifies the influence of the pile group.Both the maximum total lateral load and the efficiency coefficient of the pile group exhibit an observed increase.These provide insights for designing pile groups and optimizing their performance under lateral loading conditions.

Secrecy Outage Probability for Two-Way Integrated Satellite Unmanned Aerial Vehicle Relay Networks with Hardware Impairments

In this paper,we investigate the secrecy outage performance for the two-way integrated satellite unmanned aerial vehicle relay networks with hardware impairments.Particularly,the closed-form expression for the secrecy outage probability is obtained.Moreover,to get more information on the secrecy outage probability in a high signalto-noise regime,the asymptotic analysis along with the secrecy diversity order and secrecy coding gain for the secrecy outage probability are also further obtained,which presents a fast method to evaluate the impact of system parameters and hardware impairments on the considered network.Finally,Monte Carlo simulation results are provided to show the efficiency of the theoretical analysis.

蒸汽压片玉米对肉牛生长性能、屠宰性能和肉品质的影响

为了研究蒸汽压片玉米对肉牛生长性能、屠宰性能和肉品质的影响,试验拟选用40头体重(224.05±14.56)kg的西门塔尔杂交肉牛,随机分为4组,每组5个重复,每个重复2头肉牛。对照组饲粮中添加粉碎玉米,试验Ⅰ组~Ⅲ组分别用33%、66%、100%的蒸汽压片玉米替代粉碎玉米。预试期7 d,正式试验期120 d。结果显示,试验Ⅱ组和试验Ⅲ组末重比对照组分别提高了6.27%(P<0.05)和10.64%(P<0.01),试验Ⅰ组~Ⅲ组总增重比对照组分别提高了7.56%(P<0.05)、21.29%(P<0.01)和33.45%(P<0.01),试验Ⅰ组~Ⅲ组宰前活重比对照组分别提高了2.64%(P<0.05)、6.59%(P<0.01)和10.25%(P<0.01),试验Ⅱ组和Ⅲ组料重比极显著低于对照组(P<0.01)。试验Ⅱ组和Ⅲ组胴体重、净肉重均极显著高于对照组(P<0.01)。试验Ⅱ组和Ⅲ组牛肉中粗蛋白的含量极显著高于对照组(P<0.01),试验Ⅲ组粗脂肪显著高于对照组(P<0.05),试验Ⅲ组的pH_(45 min)值和失水率显著低于对照组(P<0.05)。试验Ⅰ组~Ⅲ组养殖效益比对照组分别提高了15.36%、48.04%和77.98%。研究表明,用蒸汽压片玉米替代肉牛饲粮中普通粉碎玉米可以提高西门塔尔杂交肉牛的生长性能和屠宰性能,改善牛肉品质,提高了肉牛养殖的经济效益,在饲粮中使用100%的蒸气压片玉米替代普通粉碎玉米效果较好。

发酵玉米芯对肉牛生长性能、瘤胃发酵参数及菌群的影响

本试验旨在研究发酵玉米芯对肉牛生长性能、瘤胃发酵参数及菌群的影响。选用60头体况良好、13月龄左右、体重[(395±32)kg]相近的西门塔尔杂交牛,随机分为3组,每组20个重复,每个重复1头牛。对照组饲喂不添加发酵玉米芯的全混合日粮,试验1组饲喂添加10%发酵玉米芯的全混合日粮,试验2组饲喂添加20%发酵玉米芯的全混合日粮,预试期7 d,正试期93 d。结果显示:1)试验1、2组的平均日采食量和平均日增重显著高于对照组(P<0.05),料重比显著低于对照组(P<0.05)。2)试验1、2组瘤胃液氨态氮(NH_(3)-N)浓度与对照组相比均显著升高(P<0.05),试验2组瘤胃液微生物蛋白(MCP)浓度与对照组和试验1组相比显著提高(P<0.05);各组瘤胃液pH无显著差异(P>0.05);2个试验组瘤胃液总挥发性脂肪酸(TVFA)浓度均显著低于对照组(P<0.05),但乙酸、丙酸、戊酸摩尔百分比及乙酸/丙酸值没有显著变化(P>0.05);2个试验组瘤胃液丁酸摩尔百分比显著低于对照组(P<0.05),而异丁酸和异戊酸摩尔百分比均显著高于对照组(P<0.05)。3)门水平上,拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)为3组肉牛瘤胃菌群中的主要优势菌门。试验1、2组Bacteroidetes的相对丰度显著高于对照组(P<0.05),试验2组Firmicutes的相对丰度显著低于对照组(P<0.05)。属水平上,3组的主要优势菌属均为普雷沃氏菌属(Prevotella)、拟杆菌目未鉴定属(unidentified Bacteroidales)。试验1、2组普雷沃氏菌科未鉴定属(unidentified Prevotellaceae)的相对丰度显著高于对照组(P<0.05),同时试验1组还显著高于试验2组(P<0.05);对照组Ruminococcus和甲烷短杆菌属(Methanobrevibacter)的相对丰度显著高于试验1、2组(P<0.05);试验2组的梭菌目未分类属(unclassified Clostridiales)和毛螺菌科未鉴定属(unidentified Lachnospiraceae)的相对丰度显著低于对照组和试验1组(P<0.05)。综上所述,饲粮中添加发酵玉米芯能够提高肉牛的生长性能,改善瘤胃发酵环境,同时影响瘤胃菌群在门水平和属水平上的组成。

Two-way中继系统中的双向中继选择及功率分配策略

通过中继选择和功率分配,可以达到提高two-way中继系统总速率的目的。综合考虑中继节点处的接收信噪比和中继节点到目的节点间的信道增益,提出了two-way AF中继系统中的双向中继选择策略(BRS);同时,在总功率受限的条件下,建立了two-way AF中继系统中的优化功率分配模型,通过对模型进行数学分析求解,提出了一种自适应的最优功率分配策略(OPA)。仿真结果证明两种策略均能提高系统总速率。

Two-way中继系统中基于最小化中断概率的功率分配策略

为了降低Two-way中继系统中断概率,提出了一种Two-way中继系统中基于最小化中断概率的功率分配策略。首先推导了Two-way中继系统中断概率的闭合表达式,然后在总功率受限的条件下,提出了一种最小化中断概率的最优功率分配策略(OPA),通过拉格朗日乘数法对该优化模型进行了求解。仿真结果证明了该策略能够有效降低系统的中断概率,提高系统性能。

Characteristics of Deposition of Inosine Monophosphate(IMP) and Intramuscular Fat(IMF) in Muscles of Jinghai Yellow Chicken and Its Crossbreeds

[Objective] This study aimed to investigate the characteristics of deposition of inosine monophosphate （IMP） and intramuscular fat （IMF） in muscles of Jinghai yellow chickens and its crossbred.[Method] The characteristics of IMP and IMF deposition of 112-day-old Jinghai yellow chickens （J×J） and its two different 70-day- old crossbreeds （J×B and B×B） were analyzed. The IMP content in breast muscle and leg muscle were determined by HPLC. [Result] The contents of IMP and cor- rected inosine monophosphate （IMPc） in breast muscle were significantly or ex- tremely significantly higher than that in leg muscle of the chickens in the three groups whether in male or female chickens （P〈0.05 or P〈0.01）. There were no sig- nificant difference in the contents of IMP and IMPc between hens and roosters （P〉 0.05）. The fresh degree of breast muscle and leg muscle was 96,11%-98.16% and 87.22%-93.07%, respectively. And the fresh degree of breast muscle was higher than that of leg muscle. In the three groups, the IMF content in leg muscle was significantly higher than that in breast muscle whether in male or female chickens （P〈0.05）. The contents of IMF in breast muscle and leg muscle were 0.36%-0.75% and 1.84%-2.38%, respectively. The iMP content in breast muscle of chickens in Bx J group was extremely significantly higher than that in breast muscle of chickens in JxJ group （P〈0.01）, but the contents of IMPc and iMF of breast muscle and leg muscle of the chickens in the three groups had no significant difference （P〉0.05）. [Conclusion] To sum up, the freshness and flavor significantly differ between the breast muscle and leg muscle of chickens, but show no significant difference among the three groups.

枫泾猪及杜(美系)枫杂交猪肌纤维特性及肌肉营养、质构品质的差异研究

该研究以杜枫[美系杜洛克猪(父)×枫泾猪(母)]F1代猪和枫泾猪[枫泾猪(父)×枫泾猪(母)]为研究对象,分别选用10只6月龄杜枫杂交F1代猪和10只8月龄枫泾猪的胸段背最长肌(longissimus thoracis,LT),检测其肌纤维特性、肌肉营养成分和质构品质,旨在比较枫泾猪和杜枫杂交F1代猪肉质的差异,为枫泾猪开发利用及新品种培育提供基础数据。结果表明:枫泾猪LT肌纤维密度极显著低于杜枫杂交F1代猪(P<0.01),LT肌原纤维直径和肌节长度大于杜枫杂交F1代猪(P<0.05,P<0.01);枫泾猪肌肉中色氨酸、苏氨酸、亮氨酸、赖氨酸、天冬氨酸、丝氨酸、谷氨酸、脯氨酸、丙氨酸、酪氨酸、精氨酸和羟脯氨酸的含量、苦味氨基酸比例、非必需氨基酸总量和氨基酸总量显著高于杜枫杂交F1代猪(P<0.05)。枫泾猪肌肉的十七碳酸含量、γ-亚油酸、α-亚麻酸、二高-γ-亚麻酸、花生四烯酸、多不饱和脂肪酸总量显著高于杜枫杂交F1代猪(P<0.05),杜枫杂交F1代猪肌肉中的油酸、花生一烯酸的含量及单不饱和脂肪酸总量显著高于枫泾猪(P<0.05)。枫泾猪肌肉的硬度显著低于杜枫杂交F1代猪(P<0.01),但内聚性和回复性显著优于后者(P<0.01)。可见,枫泾猪猪肉的氨基酸营养丰富,苦味氨基酸和多不饱和脂肪酸含量突出,质构品质优于杜枫杂交F1代猪;枫泾猪与美系杜洛克猪杂交后肌纤维密度增加,肌肉中单不饱和脂肪酸含量显著升高。

热应激对杜湖杂交公羔生理指标、血清生化指标、抗氧化功能和瘤胃发酵参数的影响

本试验旨在探究热应激对杜湖杂交公羔生理指标、血清生化、抗氧化功能和瘤胃发酵参数的影响,为绵羊热应激监测及预防提供理论依据,采用单因素完全随机试验,将18只体重相近[(27.51±0.96)kg]的6月龄杜泊×湖羊杂交一代公羔随机分为3组,每组6只,分别饲养于3个独立的环控舱中,其中:Ⅰ组为对照组(THI=71.78),Ⅱ组为中度热应激组(THI=84.83),Ⅲ组为重度热应激组(THI=91.35)。试验期12 d,预试期5 d,正试期7 d。结果表明,热应激可显著提高羊的呼吸频率、皮肤温度和直肠温度(P<0.05),尤其在15:00,Ⅱ组和Ⅲ组呼吸频率、皮肤温度和直肠温度极显著高于Ⅰ组(P<0.01);Ⅲ组TP和GLB含量显著低于Ⅰ组(P<0.05);Ⅲ组T-AOC显著低于Ⅰ组(P<0.05),Ⅲ组SOD水平极显著低于Ⅰ组(P<0.01),Ⅲ组MDA水平极显著高于Ⅰ组(P<0.01);Ⅲ组pH显著低于Ⅰ组和Ⅱ组(P<0.05);Ⅱ组NH 3-N浓度显著低于Ⅰ组(P<0.05);Ⅲ组TVFA浓度、乙酸浓度和丁酸浓度均极显著高于Ⅰ组(P<0.01),乙丙比显著高于Ⅰ组(P<0.05);Ⅱ组丙酸浓度显著高于Ⅰ组(P<0.05)。综上所述,热应激导致杜湖杂交公羔生理状况发生改变,抗氧化能力降低,并改变了瘤胃内环境及发酵方式。重度热应激危害更大。

2种营养水平饲粮对2种牛生长性能、养分表观消化率、血清生化指标和粪便微生物区系的影响

本试验旨在研究2种营养水平饲粮对2种生长牛生长性能、养分表观消化率、血清生化指标和粪便微生物区系的影响。采用2×2双因素随机试验设计,选取月龄(6月龄左右)、体重[(204.63±23.65) kg]相近的安格斯(♂)×黑西门塔尔(♀)杂交牛(安黑杂交牛)和西门塔尔牛各12头(公母各占1/2),分别随机分为2组,分别饲喂低营养水平[试验前期,综合净能(NE_(mf))为5.42 MJ/kg,粗蛋白质(CP)含量为9.66%;试验后期,NE_(mf)为5.57 MJ/kg,CP含量为9.05%]和高营养水平(试验前期,NE_(mf)为5.77 MJ/kg,CP含量为12.47%;试验后期,NE_(mf)为6.00 MJ/kg,CP含量为10.44%)饲粮。预试期12 d,正试期62 d,分为试验前期(第1~31天)和试验后期(第32~62天)2个阶段,最后8 d进行消化试验。结果表明:与西门塔尔牛相比,安黑杂交牛试验前期平均日增重(ADG)(P=0.076)、对有机物(P=0.051)和CP(P=0.087)的表观消化率、血清尿素氮(UN)含量(P=0.077)和谷草转氨酶活性(P=0.070)有提高的趋势,对中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的表观消化率显著提高(P<0.05)。与低营养水平组相比,高营养水平组试验前期干物质采食量(DMI)、试验后期ADG、DMI和饲料转化率(FCR)以及试验全期ADG和DMI显著提高(P<0.05),试验全期FCR(P=0.085)和血清总胆固醇(P=0.077)含量有提高趋势;低营养水平组NDF和ADF表观消化率显著高于高营养水平组(P<0.05)。品种和营养水平对血清UN含量有显著交互作用(P<0.05)。2种牛粪便微生物在门水平上的优势菌群为厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes),各组间相对丰度无显著差异(P>0.05);在属水平上,高营养水平组粪便苏黎世杆菌属(Turicibacter)相对丰度显著高于低营养水平组(P<0.05)。综上所述,安黑杂交牛的ADG和对CP、OM、NDF和ADF的表观消化率优于西门塔尔牛;高营养水平饲粮更有利于肠道有益菌相对丰度的提高,促进生长牛的快速生长。

不同因素对特哈杂交绵羊消化道线虫感染情况的影响

【目的】研究季节、性别、组别和群别对特克塞尔和哈萨克(以下简称特哈)杂交绵羊中消化道线虫(gastrointestinal nematodes,GIN)感染强度、体重、红细胞比容和特异性抗体免疫球蛋白G(immunoglobulin G,IgG)含量的影响,为绵羊消化道线虫的防治和抗消化道线虫育种等方面的研究提供参考依据。【方法】采集特哈杂交绵羊直肠粪便及颈静脉血液,称量体重。用饱和盐水漂浮法对消化道线虫虫卵进行定性检测,运用改良的McMaster法进行消化道线虫虫卵计数,计算感染率和感染强度;使用兽用全自动血液细胞分析仪对血液进行红细胞比容检测;制备线虫L3期幼虫体细胞抗原,运用间接ELISA法测定绵羊血清中特异性抗体IgG含量。【结果】特哈杂交绵羊消化道线虫感染率较高,为94.44%,呈中度感染,鉴定出毛圆属线虫(Trichostrongylus spp.)、捻转血矛线虫(Haemonchus contortus)、奥斯特属线虫(Ostertagia spp.)、羊仰口线虫(Bumastomum trigonocephalum)、夏伯特属线虫(Chabertia spp.)、马歇尔属线虫(Marshallagia spp.)、细项属线虫(Nematodirus spp.)、食道口属线虫(Oesophagostomum spp.)和球鞘毛首线虫(Trichuris globuulosa)共9种消化道线虫。季节对绵羊消化道线虫感染强度和体重有显著影响(P<0.05),春季绵羊消化道线虫感染强度显著高于夏季(P<0.05),夏季绵羊体重显著高于春季(P<0.05)。性别对绵羊消化道线虫感染强度、体重和红细胞比容有显著影响(P<0.05),公羊消化道线虫感染强度显著高于母羊(P<0.05),公羊体重显著高于母羊(P<0.05),母羊红细胞比容显著高于公羊(P<0.05)。组别对体重有显著影响(P<0.05),F2×哈绵羊体重显著高于F2和F2×F1绵羊(P<0.05),F1×F1绵羊体重显著高于F2×F1绵羊(P<0.05),F2×F2绵羊体重显著低于其余组别的绵羊(P<0.05)。群别对绵羊消化道线虫感染强度有显著影响(P<0.05),1群绵羊消化道线虫感染强度显著高于2和3群(P<0.05),3群绵羊消化道线虫感染强度显著高于2群(P<0.05)。所有因素均对特异性抗体IgG含量没有显著影响(P>0.05)。【结论】季节、性别、组别和群别对绵羊消化道线虫感染情况存在影响,可根据因素对感染情况的影响和各因素不同水平之间的差异对绵羊选择不同的防治措施,为抗消化道线虫育种策略提供理论依据。