畜禽基因组选择的研究进展

基因组选择（genomic selection,GS）是继标记辅助选择（marker-assisted selection,MAS）之后发展起来的新一代畜禽遗传评估的新方法。近年来,不少学者从各方面对GS在畜禽育种中的运用进行了研究,结果发现,与其他方法相比,GS优势明显,是当前畜禽遗传育种领域的研究热点。作者系统地阐述了GS估计染色体片段效应的方法及其准确性比较,详细介绍了影响GS准确性的因素、GS的经济效益,以及世界各国学者研究GS在实际育种中的应用情况,最后简述了中国畜禽育种开展GS策略所面临的挑战及其展望。     

整合生物学先验信息的全基因组选择方法及其在家畜育种中的应用进展

相较于传统的育种方法,全基因组选择（genomic selection,GS）通过对拟留种的个体进行早期选择和增加选择的准确性进而加快育种的遗传进展。通过改进GS方法无法再缩短育种的世代间隔,因而如何提高GS的准确性以获得额外的遗传进展一直是GS研究的核心问题。当前,各种组学技术不断成熟,从公开的资料或前期的研究积累获取生物学先验信息已比较容易。因而,如何在GS模型中整合已知的先验信息进而提高GS的准确性以获得额外的遗传进展成为当前育种研究的热点问题。本文对生物学先验信息的类型以及整合先验信息的GS方法进行综述,探讨了这些方法在家畜育种中的应用和前景,以期为家畜育种中开展整合生物学先验信息的GS研究提供借鉴与参考。     

家禽基因组选择研究进展

基因组选择(Genomic selection,GS)是新一代畜禽遗传评估方法,具有早期选择准确率高、可缩短世代间隔、对于低遗传力性状以及难以测量或测量费用较高的性状选择效率高等优点,目前已经广泛应用于奶牛育种中。本文综述了基因组选择方法在家禽中的研究进展,并对我国家禽实施基因组选择方法进行展望。     

全基因组选择在猪育种上的研究进展

全基因组选择(Genomic selection,GS),即全基因组范围内的标记辅助选择(marker-assisted selection,MAS)。因其具有可缩短世代间隔,提高年遗传进展;早期选择准确率高;同时还能提高低遗传力、难以测量性状选择效率等诸多优点,目前已成为动物遗传育种领域的研究热点。文内围绕"什么是GS"、"为什么选用GS"以及"影响GS的因素"这3个方面全方位诠释了GS。重点阐述了GS在猪育种中的应用现状,并结合GS在奶牛上的成功应用,简述了GS在猪育种上的展望。     

畜禽基因组选择方法研究进展

畜禽的选种选育在生产中至关重要,育种值估计是选种选育的核心。基因组选择（genomic selection,GS）是利用全基因组范围内的高密度标记估计个体基因组育种值的一种新型分子育种方法,目前已在牛、猪、鸡等畜禽育种中得到应用并取得了良好的效果。该方法可实现畜禽育种早期选择,降低测定费用,缩短世代间隔,提高育种值估计准确性,加快遗传进展。基因组选择主要是通过参考群体中每个个体的表型性状信息和单核苷酸多态性（single nucleotide polymorphism,SNP）基因型估计出每个SNP的效应值,然后测定候选群体中每个个体的SNP基因型,计算候选个体的基因组育种值,根据基因组育种值的高低对候选群体进行合理的选择。随着基因分型技术快速发展和检测成本不断降低,以及基因组选择方法不断优化,基因组选择已成为畜禽选种选育的重要手段。作者对一些常用的基因组选择方法进行了综述,比较了不同方法之间的差异,分析了基因组选择存在的问题与挑战,并展望了其在畜禽育种中的应用前景。     

基因组选择在羊育种中的应用研究进展

基因组选择(genomic selection,GS)已经作为新一代畜禽遗传评估方法应用于奶牛育种中,并取得了显著成效。随着羊参考基因组的不断完善,以及不同密度SNP芯片的推出和商业化推广,新西兰、澳大利亚、法国等相继将基因组选择应用到羊育种中,揭开了羊育种的新时代。本研究总结了国内外羊基因组选择的研究现状、影响因素、优势以及存在问题和展望,以期为中国羊开展基因组选择育种提供参考。     

全基因组选择在猪育种中的应用

全基因组选择(Genomic selection,GS)是一种全基因组范围内的标记辅助选择方法。利用全基因组遗传标记信息对个体进行遗传评估,能够更加准确地早期预测估计育种值,降低近交系数,大大提高猪育种的遗传进展。随着猪全基因组测序的完成和猪60kSNP芯片的商业化,全基因组选择已经成为猪育种研究领域的新热点。本文综述了全基因组选择的分析方法、计算方法和影响因素,并阐述了全基因组选择在猪育种中的应用情况和发展趋势。     

基因组选择在家畜改良上的研究进展

基因组选择（GS）是全基因组范围内的分子标记辅助选择,目前被证明是利用DNA标记信息改善复杂性状最有效的方法。本文简要概述了基因辅助选择以及标记辅助选择;重点介绍了GS,包括GS的实施策略与育种值估计方法,GS的准确性获得以及对GS方法的比较,总结了当前家畜上利用GS加速遗传改良的应用进展;并对家畜在GS上的应用前景进行展望。     

奶牛遗传评定法的研究进展

在育种工作实践中,准确可靠的遗传参数估计和个体育种值预测是卓有成效的育种工作的前提条件,育种值的估计叫作遗传评定.奶牛的遗传评定法是畜禽遗传育种研究中最深入、应用最广泛、效果最好的方法之一,尤其是近年来,随着科学技术的发展、育种值估计法的不断改进及估计精确度的不断提高(总的趋势是在保证一定准确性前提下尽可能简化),使奶牛群体生产水平大幅度地提高.     

基于基因组重测序的地方畜禽选择信号研究进展

选择信号是畜禽进化过程中遗留在基因组上的遗传印记,探究种群间选择信号的特征有助于了解种群遗传进化和选择进展,将正向选择应用于育种可提高育种进程。重测序等相关分子技术的发展为研究基因组进化影响表型提供了方法和机会。本文综述了基于基因组测序技术的地方畜禽在长期驯化中的选择信号,为地方畜禽的进化发展研究提供了理论基础。     

富集型鸡笼的发展和应用

为了改善笼养蛋鸡的福利状况,富集型鸡笼产生并被广泛应用。作者介绍了富集型鸡笼的产生和发展概况,并对富集型鸡笼在生产实践中对蛋鸡的影响进行了探讨,评价了未来富集型鸡笼在中国的应用前景。     

商业化家禽生产对全球家禽遗传资源的影响

家禽的生物学特性和经济学特性(如繁殖率高、繁殖周期短、单位成本低、育种材料易于携带和运输以及经济节约型规模化养殖)使家禽业成为畜牧业中最先进的行业。在所有动物物种中,家禽的育种程度最高。所有牲畜品种中,家禽具有最高的饲料转化率,且无论在发展中国家还是发达国家,禽肉的消费比率逐年增长。据世界粮农组织动物生产及卫生司预测,发展中国家禽肉消费年增长率将由目前的25%增加到2030年的34%。另一方面,家禽产业结构的快速调整已成为威胁家禽遗传资源的重要因素。目前,全世界已有30%的家禽品种濒临灭绝,9%的家禽品种已经灭绝。此外,遗传多样性丢失、消费涉及的动物福利以及环境问题也对家禽资源产生威胁。因此,家禽业是政府决策过程中权衡各种因素的理想案例,如食品安全与农业生物多样性、公共投资与私人投资、规模化养殖与小规模养殖、创造就业机会与自谋职业、标准和食品安全与食物多样性等。本文重点关注家禽遗传多样性、家禽育种、家禽研究的公共投资和私人投资以及食品安全等方面的问题。     

Pregnancy recognition signaling mechanisms in ruminants and pigs

Maternal recognition of pregnancy refers to the requirement for the conceptus（embryo and its associated extraembryonic membranes） to produce a hormone that acts on the uterus and/or corpus luteum（CL） to ensure maintenance of a functional CL for production of progesterone;the hormone required for pregnancy in most mammals.The pregnancy recognition signal in primates is chorionic gonadotrophin which acts directly on the CL via luteinizing hormone receptors to ensure maintenance of functional CL during pregnancy.In ruminants,interferon tau（IFNT） is the pregnancy recognition signal.IFNT is secreted during the peri-implantation period of pregnancy and acts on uterine epithelia to silence expression of estrogen receptor alpha and oxytocin receptor which abrogates the oxytocin-dependent release of luteolytic pulses of prostaglandin F2-alpha（PGF） by uterine epithelia;therefore,the CL continues to produce progesterone required for pregnancy.Pig conceptuses secrete interferon delta and interferon gamma during the peri-implantation period of pregnancy,but there is no evidence that they are involved in pregnancy recognition signaling.Rather,pig conceptuses secrete abundant amounts of estrogens between Days 11 to 15 of pregnancy required for maternal recognition of pregnancy.Estrogen,likely in concert with prolactin,prevents secretion of PGF into the uterine venous drainage（endocrine secretion）,but maintains secretion of PGF into the uterine lumen（exocrine secretion） where it is metabolized to a form that is not luteolytic.Since PGF is sequestered within the uterine lumen and unavailable to induce luteolysis,functional CL are maintained for production of progesterone.In addition to effects of chorionic gonadotrophin,IFNT and estrogens to signal pregnancy recognition,these hormones act on uterine epithelia to enhance expression of genes critical for growth and development of the conceptus.     

Improving efficiency of sow productivity： nutrition and health

This reviews research focused to understand the nutrient requirement and balance to meet the needs of fetal growth,mammary growth,and milk production.This summary will handle how feeding strategies can be adjusted according to the nutrient needs for a sow to enhance productivity and health.Most research data used in this summary are based on the studies conducted by the authors between 1996 and 2013.Nutrient requirements of sows are affected by stage of gestation and parity of sows.Dietary antioxidant concentrations need to be re-evaluated for its sufficiency in sow diets especially to prevent excessive oxidative stress during late gestation and lactation.When feeding sows,consideration of phase feeding of gestating sows and parity feeding of lactating sows could enhances production longevity and health of sows.Use of selected nutrients and additives seems to help productivity and health of sows.     

The immune modifying effects of amino acids on gut-associated lymphoid tissue

The intestine and the gut-associated lymphoid tissue（GALT） are essential components of whole body immune defense,protecting the body from foreign antigens and pathogens,while allowing tolerance to commensal bacteria and dietary antigens.The requirement for protein to support the immune system is well established.Less is known regarding the immune modifying properties of individual amino acids,particularly on the GALT.Both oral and parenteral feeding studies have established convincing evidence that not only the total protein intake,but the availability of specific dietary amino acids（in particular glutamine,glutamate,and arginine,and perhaps methionine,cysteine and threonine） are essential to optimizing the immune functions of the intestine and the proximal resident immune cells.These amino acids each have unique properties that include,maintaining the integrity,growth and function of the intestine,as well as normalizing inflammatory cytokine secretion and improving T-lymphocyte numbers,specific T cell functions,and the secretion of IgA by lamina propria cells.Our understanding of this area has come from studies that have supplemented single amino acids to a mixed protein diet and measuring the effect on specific immune parameters.Future studies should be designed using amino acid mixtures that target a number of specific functions of GALT in order to optimize immune function in domestic animals and humans during critical periods of development and various disease states.     

Achievements and Prospects of Aquaculture and Aquafeed Industry in China

This article presents a comprehensive review on the achievements obtained in the past a few decades and the prospects in aquaculture and aquafeed industry in China. The total production of aquaculture in China increased from 2.38 million tons in 1978 to 36 million tons in 2008, growing 15 times in 30 years.     

Arginine Intake and Carbohydrate to Lipid Ratios Affect Gene Expression of Anabolic Hormones in Largemouth Bass,Micropterus Sahnoides

Nutritional factors influence regulation of growth hormone （GH）, insulin-like growth factor-Ⅰ （IGF-Ⅰ） and insulin （INS） in fish. But so far there are no published studies describing how single indispensable amino acids and different carbohydrate to lipid ratios influence those systems. Therefore, the present study aimed to evaluate whether arginine （Arg） intake and carbohydrate to lipid ratios would affect expression of GH, IGF-Ⅰ and INS in largemouth bass.     

The Effects of Size-fractionated Fish Hydrolysate in the Diet on Growth,and Feed Utilization of Turbot （Scophthalmus maximus）

Four experimental diets were fed to turbet to examine the effect of fish bydrolyside and ultra filtered fish hydrolysafe on growth performate feed utilization and growth regulation using diets low in dietary fish meal inclusion. Diets A, B contained 3.7%,1.2% fish hydrolysate to replace fish meal respectively and the fish hydrolysate in two diets was ultra filtered to keep low molecular weight compounds. The diets A,     

Use of a post-production fractionation process improves the nutritional value of wheat distillers grains with solubles for young broiler chicks

Background： Post-production fractionation of wheat distillers grains with solubles（DDGS） increases their crude protein content and reduces their fiber content.This experiment was conducted to determine the effects of fractionation of wheat DDGS on apparent total tract digestibility（ATTD） and performance when fed to broiler chicks（0–21 d）.Methods： A total of 150,day-old,male broiler chicks（Ross-308 line;Lilydale Hatchery,Wynyard,Saskatchewan） weighing an average of 49.6 ± 0.8 g were assigned to one of five dietary treatments in a completely randomized design.The control diet was based on wheat and soybean meal and contained 20% regular wheat DDGS.The experimental diets contained 5,10,15 or 20% fractionated wheat DDGS added at the expense of regular wheat DDGS.Results： The ATTD of dry matter and gross energy were linearly increased（P 0.01） as the level of fractionated wheat DDGS in the diet increased.Nitrogen retention was unaffected by level of fractionated wheat DDGS（P 0.05）.Weight gain increased linearly（P = 0.05） as the level of fractionated wheat DDGS in the diet increased.Feed intake,feed conversion and mortality were unaffected by level of fractionated wheat DDGS in the diet（P 0.05）.Conclusions： Post-production fractionation of wheat DDGS improves their nutritional value by lowering their fiber content and increasing their content of crude protein and energy.These changes in chemical composition supported increased weight gain of broilers fed wheat DDGS.