MAP3K5基因在畜禽剩余采食量表型调控中的研究进展

随着分子遗传学的发展,已经鉴定出了影响剩余采食量（RFI）的大量数量性状位点和候选基因。有丝分裂原活化蛋白3激酶5（MAP3K5）,也称凋亡信号调节激酶1（ASK1）,属于MAPK超家族基因之一。目前,已有细胞外信号调节蛋白激酶（ERK）、c-Jun N-末端激酶（JNK）和p38丝裂原激活蛋白激酶（p38-MAPK）这3个MAPK家族成员在哺乳动物细胞中被克隆和鉴定,其主要作用机制是介导3条MAPKs信号通路,从而影响家畜的生长、体型及产奶性状等。课题组在前期对RFI的研究中筛选出与牛剩余采食量相关的MAP3K5基因,但其功能作用尚不明确,笔者在此基础上回顾了该基因的结构、生物学功能,概述了该基因在主要畜禽采食量变异及人类肥胖表型中的功能及作用,并从遗传学的角度重点分析了MAP3K5基因在畜禽RFI表型调控中的可能机制。通过对MAP3K5基因在畜禽RFI表型调控中的研究进展进行综述,期望为后期深入开展MAP3K5基因在畜禽采食量性状调控中的分子机制研究提供思路;对于其他可能通过MAP3K5基因影响畜禽表型的因素（如肠道菌群）有待进一步探讨。     

高、低剩余采食量肉牛下丘脑组织中差异表达基因分析

为了分析高、低剩余采食量(residual feed intake, RFI)相关肉牛下丘脑组织中的基因表达图谱,探讨差异表达基因与牛RFI表型变异间的关系,试验选择高剩余采食量(HRFI)、低剩余采食量(LRFI)秦川牛各3头,分为HRFI组和LRFI组,采集下丘脑组织样本,从中提取总RNA进行转录组测序,筛选出RFI相关差异表达基因,对这些基因进行GO功能注释和KEGG通路富集分析,并利用STRING数据库构建差异表达基因的蛋白质相互作用网络图,最后随机选取6个差异表达基因进行实时荧光定量PCR验证。结果表明：HRFI组和LRFI组中均存在1 538个差异表达基因,包括AGRP、PMCH等与采食相关的基因,GH1、MTNR1A和RYR2等与代谢相关的基因,此外差异基因主要富集于钙信号通路、cAMP信号通路和昼夜节律等通路中。通过蛋白质相互作用网络筛选出3个核心子网络和7个核心基因。实时荧光定量PCR验证结果与转录组测序结果一致。说明下丘脑组织中AGRP、PMCH、GH1、MTNR1A和RYR2等差异表达基因及钙信号通路、cAMP信号通路和昼夜节律等多条通路可能参与调控肉牛RFI。     

杜洛克公猪背膘厚度、日增重、日采食量和饲料效率相关性状的遗传参数估计

对384头扬翔华系杜洛克公猪生长育肥阶段背膘厚度(BF)、日增重(ADG)、日采食量(ADFI)、饲料转化率(FCR)和剩余采食量(RFI)5个性状用DMU程序进行遗传参数估计探究杜洛克公猪的遗传参数。结果表明, ADFI和RFI的遗传方差占表型方差的比例分别为87.73%和84.91%;BF和ADG的遗传方差占表型方差的比例分别是58.77%和58.91%;RFI与BF、ADG的表型相关系数均为零,而遗传相关系数分别为-0.22和0.15;RFI与ADFI的表型、遗传相关系数分别为0.98和0.99,RFI与FCR的表型、遗传相关系数分别为0.44和0.81。多性状模型与单性状模型的估计遗传力基本趋于一致,ADG和FCR遗传力分别是0.27和0.19,属于低遗传力性状;而BF、ADFI和RFI的估计遗传力在0.31～0.46范围,属于中等遗传力性状。     

杜洛克猪MAP3K5基因多态位点与生长、饲料利用性状的关联分析

试验旨在研究MAP3K5基因多态性与杜洛克猪生长、饲料利用性状的关联性。利用Illumina SNP60芯片测序结果比较发现了MAP3K5基因的4个SNPs位点（Ssc1：30769583 A>C;Ssc1：30781169 A>G;Ssc1：30940839 A>G;Ssc1：30962276 G>A）。统计获得MAP3K5基因的4个SNPs位点的基因型频率及等位基因频率,发现4个SNPs为低度－中度的多态突变位点。对MAP3K5基因多态性与生长、饲料利用性状的关联性进行分析,结果表明,杜洛克猪Ssc1：30769583 A>C位点CC基因型个体与AA基因型个体相比剩余采食量（RFI）性状降低了133.08 g/d（P<0.05）;Ssc1：30781169 A>G位点的GG基因型个体与AG基因型个体相比RFI性状降低了116.18 g/d（P<0.05）,ADFI性状降低了0.23 kg/d（P<0.05）;Ssc1：30940839 A>G位点的GG基因型个体与AG基因型个体相比饲料转化率（FCR）性状降低了0.10%（P<0.05）;Ssc1：30962276 G>A位点的AA基因型个体与GG基因型个体相比ADG性状降低了0.04 kg/d（P<0.05）。试验初步认为MAP3K5基因4个SNPs位点的多态性对杜洛克猪的RFI、ADFI、FCR和ADG具有一定影响。     

肉牛剩余采食量与瘤胃微生物菌群关系北大核心CSCD

剩余采食量(RFI)是肉牛实际采食量与预期采食量之间的差值,是评定肉牛饲料效率的有效指标。肉牛的能量代谢差异在很大程度上可以解释其RFI差异,而肉牛瘤胃中复杂的微生物菌群结构在瘤胃发酵及其能量代谢方面起着重要作用。因此本文主要对最近几年国外采用PCR-变性梯度凝胶电泳(DGGE)、文库克隆测序、实时定量PCR和高通量测序技术研究肉牛RFI表型与瘤胃中的细菌菌群和甲烷菌菌群结构之间的关系所取得的进展进行总结,并介绍RFI的主要预测模型。     

基于猪剩余采食量的分化选择与遗传进展

猪剩余采食量(Residual Feed Intake,RFI)是一个有效评价生猪饲料效率的新性状,用剩余采食量来提高生猪饲料效率是当前养猪界的重要研究方向。本试验测定了2个世代198头军牧1号公猪的周采食量、日增重(ADG)和背膘(BF)等性状,和母猪453头母猪日增重(ADG)和背膘(BF)等性状,然后建立了饲料效率育种值估计模型,以剩余采食量(RFI)为主选性状,ADG和BF为辅助约束性状,通过遗传评估按育种值高低分为高RFI和低RFI 2个群体。在这2个分化群体内进行同质选配2个世代后计算其遗传进展。结果显示,RFI、ADG、BF的遗传力分别为0.15、0.22、0.28。G0代选择群体高、低RFI之间,RFI、ADG、BF性状的育种值差异分别是1.48、0.40、0.56个标准差;G1代高、低RFI测定群体之间3个性状的育种值差异分别是1.52、0.56、0.18个标准差。原始群体与G1代测定群体相比,高RFI群体的RFI、ADG、BF的遗传进展分别是0.732、-0.274、0.101个标准差,低RFI群体的RFI、ADG、BF的遗传进展是-0.788、0.283、-0.079个标准差。此外,肉质检测结果显示2群体间无显著差异。结果表明,用RFI作为主选性状可有效改变猪的饲料效率,建立饲料效率分化品系,遗传进展良好。     

肉牛剩余采食量的概念和实践应用

剩余采食量(RFI)是实际采食量与预测采食量的差值,是衡量肉牛饲料效率的新指标。文章简要介绍了RFI的概念、测定方法、应用RFI的益处,以及影响肉牛RFI的一些生理因素,包括采食量、消化率、体组织代谢、活动量、体温调节等。最后,文章讨论了RFI在肉牛生产实践中的应用。     

剩余采食量在反刍动物生产中的研究进展

剩余采食量(RFI)是一种评价饲料利用效率的有效指标,与料重比和增重饲料比这2种评价饲料利用效率的指标相比,可以避免不同体形和不同生长时期动物之间饲料利用效率的固有差异,可以使饲料利用效率的评价更加科学。随着科学技术发展,压力传感器系统、图像信息系统能够更加快捷有效地帮助收集采食量的相关数据。研究发现,低RFI的反刍动物对粗饲料的消化能力更强,同时不同RFI的反刍动物瘤胃细菌组成也存在差异,而且在瘤胃中挥发性脂肪酸运输的关键基因与RFI具有相关性。虽然不同RFI的家畜屠宰性能和胴体性状的差异在不同种家畜的研究中还没得到一致的结果,但是在繁殖育种中选育低RFI的家畜可以提高生产效率,节约饲料成本。因此,RFI在规模化养殖中的应用可以为提高牧场生产管理水平、增加经济效益提供帮助。     

反刍动物剩余采食量在瘤胃功能上的差异和相关分子生物学机制

剩余采食量(RFI)已广泛用于测定各种家畜的饲料效率,通过实际采食量与预期采食量之差来衡量。瘤胃是反刍动物的主要消化器官,瘤胃微生物相对丰度和活性决定反刍动物的饲料效率。本文主要概述反刍动物瘤胃发酵参数、甲烷的排放、瘤胃微生物和瘤胃上皮细胞与RFI差异之间的关系,旨在明确瘤胃功能与反刍动物饲料利用效率之间的关系,为今后选育低RFI动物提供新的研究方向。     

家畜剩余采食量性状候选基因的研究进展

为提高养殖企业的经济效益,实现快速稳定发展,满足我国人民对家畜产品的需求,科研人员力求在不影响家畜生长、育肥及繁殖性能的前提下,提高饲料利用效率,降低饲养成本。利用剩余采食量(residual feed intake,RFI)相对值(即实际采食量与预测采食量的差值),进行家畜选择能够实现这一目标。RFI是衡量动物饲料效率的有效指标,被广泛应用。RFI越低的动物,饲料利用效率越高。RFI性状受很多因素影响,如日粮因素、环境条件、健康状况、遗传因素等。在日粮、环境以及健康状况相似时,个体遗传因素是控制RFI性状的主要因素。目前对剩余采食量性状遗传因素的研究仍处于探索阶段,控制性状的主效基因以及标志性基因还需要挖掘。笔者就近些年研究RFI的候选基因进行总结,为深入研究控制RFI性状的分子机制提供思路。     

Association Analysis on MAP3K5 Gene Polymorphism Site with Growth and Feed Efficiency Related Traits in Duroc Pigs

This study was aimed to analyze the association of four SNPs of MAP3K5 gene with growth and feed efficiency related traits in Duroc populations. Four SNPs(Ssc1:30769583 A>C;Ssc1:30781169 A>G;Ssc1:30940839 A>G;Ssc1:30962276 G>A)of MAP3K5 gene in Duroc populations were obtained by porcine SNP60 BeadChip（Illumina). The genotype frequency and allele frequency of four SNPs of MAP3K5 gene were analyzed,the result showed that four SNPs were the low-moderate mutation SNPs.The polymorphism of MAP3K5 gene and its association with feed efficiency related traits in Duroc population were analyzed. The results indicated that CC genotype individuals in Ssc1:30769583 A>C had significant lower RFI（133.08 g/d）than AA genotype individuals（P<0.05);GG genotype individuals in Ssc1:30781169 A>G had significant lower RFI（116.18 g/d）and ADFI（0.23 kg/d）than AG genotype individuals（P<0.05);GG genotype individuals in Ssc1:30940839 A>G had significant lower FCR（0.10%）than AG genotype individuals（P<0.05);AA genotype individual in Ssc1:30962276 G>A had significant lower ADG（0.04 kg/d）than GG genotype individuals（P<0.05). All in all,the results suggested that four SNPs polymorphisms of MAP3K5 gene had the significant impact on RFI, ADFI, FCR and ADG traits in Duroc pigs.     

Simultaneous Bayesian estimation of genetic parameters for curves of weight,feed intake,and residual feed intake in beef cattle

Rates of gain and feed efficiency are important traits in most breeding programs for growing farm animals. The rate of gain (GAIN) is usually expressed over a certain age period and feed efficiency is often expressed as residual feed intake (RFI), defined as observed feed intake (FI) minus expected feed intake based on live weight (WGT) and GAIN. However, the basic traits recorded are always WGT and FI and other traits are derived from these basic records. The aim of this study was to develop a procedure for simultaneous analysis of the basic records and then derive linear traits related to feed efficiency without retorting to any approximation. A bivariate longitudinal random regression model was employed on 13,791 individual longitudinal records of WGT and FI from 2,827 bulls of six different beef breeds tested for their own performance in the period from 7 to 13 mo of age. Genetic and permanent environmental covariance functions for curves of WGT and FI were estimated using Gibbs sampling. Genetic and permanent covariance functions for curves of GAIN were estimated from the first derivative of the function for WGT and finally the covariance functions were extended to curves for RFI, based on the conditional distribution of FI given WGT and GAIN. Furthermore, the covariance functions were extended to include GAIN and RFI defined over different periods of the performance test. These periods included the whole test period as normally used when predicting breeding values for GAIN and RFI for beef bulls. Based on the presented method, breeding values and genetic parameters for derived traits such as GAIN and RFI defined longitudinally or integrated over (parts of) of the test period can be obtained from a joint analysis of the basic records. The resulting covariance functions for WGT, FI, GAIN, and RFI are usually singular but the method presented here does not suffer from the estimation problems associated with defining these traits individually before the genetic analysis. All the results are thus estimated simultaneously, and the set of parameters is consistent.     

提高猪饲料效率的测定与选择

为提高猪饲料效率的选择,本试验测定一些与猪饲料效率相关的生产性状并进行遗传评估。方法：测定60头军牧1号白猪后备公猪的采食量、体增重、背膘厚等生产性状,用猪剩余采食量（RFI）和饲料转化率（FCR）作为评价饲料效率的两个指标,并对其遗传参数进行评估。结果：测定期内军牧1号公猪群体FCR均值为2．61,RFI的标准差为77．52。RFI与FCR的遗传力分别是0．35、0．33,RFI与ADFI（日采食量）、ADG（日增重）、BF（背膘厚）的遗传相关分别是0．89、0．12、-0．05,FCR与ADFI、ADG、BF的遗传相关分别是0．55、-0．65、-0．11。结论：军牧1号白猪品种内饲料效率存在较大的遗传差异,由于RFI与ADG遗传相关很低,因此用RFI作为选择性状可有效提高猪的饲料效率。     

Detailed genetic analysis of feeding behaviour in Romane lambs and links with residual feed intake

Breeding strategies based on feed efficiency are now implemented in most animal species using residual feed intake (RFI) criteria. Although relevant, the correlated responses of feeding behaviour traits resulting from such selection on RFI are poorly documented. We report the estimated feeding behaviour at three time levels (visit, meal and day) and genetic parameters between the feeding behaviour traits and their links with RFI and its components. Feed intake, feeding duration at three time levels (per visit, meal and day), feeding rate, number of visits and time‐between‐visits were estimated for 951 Romane lambs fed via automatic concentrate feeders. Heritability estimates of feeding behaviour traits ranged from 0.19 to 0.54 with higher estimates for the day level than the visit level. Daily feed intake was not genetically linked to feed intake at the visit level, whereas feeding duration between visit and day levels was moderately correlated (R_g = +0.41 ± 0.12). RFI was not significantly correlated with feeding rate, but was positively linked to feed intake and feeding duration at the day level (+0.73 ± 0.09 and +0.41 ± 0.13, respectively) and negatively at the visit level (?0.33 ± 0.14 and ?0.22 ± 0.17, respectively). Selecting animals with lower RFI values might modify their feeding behaviour by increasing feed intake and feeding duration at the visit level but decrease the number of visits per day (+0.51 ± 0.14).     

Triennial Lactation Symposium: Opportunities for improving milk production efficiency in dairy cattle

Increasing feed costs and the desire to improve environmental stewardship have stimulated renewed interest in improving feed efficiency of livestock, including that of US dairy herds. For instance, USDA cost projections for corn and soybean meal suggest a 20% increase over 2010 pricing for a 16% protein mixed dairy cow ration in 2011, which may lead to a reduction in cow numbers to maintain profitability of dairy production. Furthermore, an October 2010 study by The Innovation Center for US Dairy to assess the carbon footprint of fluid milk found that the efficiency of feed conversion is the single greatest factor contributing to variation in the carbon footprint because of its effects on methane release during enteric fermentation and from manure. Thus, we are conducting research in contemporary US Holsteins to identify cows most efficient at converting feed to milk in temperate climates using residual feed intake (RFI), a measure used successfully to identify the beef cattle most efficient at converting feed to gain. Residual feed intake is calculated as the difference between predicted and actual feed intake to support maintenance and production (e.g., growth in beef cattle, or milk in dairy cattle). Heritability estimates for RFI in dairy cattle reported in the literature range from 0.01 to 0.38. Selection for a decreased RFI phenotype can reduce feed intake, methane production, nutrient losses in manure, and visceral organ weights substantially in beef cattle. We have estimated RFI during early lactation (i.e., to 90 d in milk) in the Beltsville Agricultural Research Center Holstein herd and observed a mean difference of 3.7 kg/d (P < 0.0001) in actual DMI between the efficient and inefficient groups (±0.5 SD from the mean RFI of 0), with no evidence of differences (P > 0.20) in mean BW, ADG, or energy-corrected milk exhibited between the 2 groups. These results indicate promise for using RFI in dairy cattle to improve feed conversion to milk. Previous and current research on the use of RFI in lactating dairy cattle are discussed, as well as opportunities to improve production efficiency of dairy cattle using RFI for milk production.     

Genetic correlations between males, females and castrates for residual feed intake, feed conversion ratio, growth rate and carcass composition traits in Large White growing pigs

Data were collected in the course of a divergent selection experiment for residual feed intake (RFI) of Large White growing pigs. This data set was used to estimate (i) heritability for RFI and genetic correlations of RFI with growth and carcass traits within the three sexes (male, castrate and female) and (ii) genetic correlations between sexes for these traits. Individual feed intake of animals raised in collective pens was measured by single-place electronic feeders on 1121 males (candidates for selection), 508 females and 535 castrates (sibs of candidates). Variance components were estimated using the REML methodology applied to a multitrait animal model. Estimates of heritability for RFI were 0.16 ± 0.04, 0.16 ± 0.08 and 0.23 ± 0.10 for males, females and castrates, respectively. Estimates of genetic correlations between sexes for homologous traits were not significantly different from 1 (0.88 to 0.99 for RFI, 0.79 to 0.99 for growth traits and 0.65 to 0.99 for carcass composition traits). The relatively low genetic correlations between castrates and males or females for backfat thickness (0.65 and 0.69, respectively) suggest the presence of genotype by sex interactions for this trait.