畜禽遗传评定方法的研究进展

畜禽遗传评定是畜禽育种的重要内容。目前畜禽遗传评定方法中应用最广的是基于表型信息的BLUP动物模型。基因组学的发展和应用产生了大量分子遗传标记,结合分子遗传标记信息的遗传评定方法MBLUP随之产生。MBLUP将成为一种快速有效的畜禽遗传评定方法。本文主要介绍了畜禽遗传评定方法的研究进展和发展趋势。 Abstract:Genetic evaluation is one of the most important components in livestock breeding program.Best linear unbiased prediction (BLUP) Animal Model,which based on phenotypic information,has become the most widely accepted method for genetic evaluation of domestic livestock.Large numbers of molecular genetic markers have been discovered as the development and application of genomics.Some new methods (Marked Assisted BLUP,MBLUP) for genetic evaluation have being developed,which incorporating molecular genetic markers information into genetic evaluation.MBULP will be a rapid and efficient method for genetic evaluation of domestic livestock.The aim of the paper is to introduce the development and current situation of the methods for livestock genetic evaluation.     

Structural and functional genomics in domestic animals: the way to understand the phenotype

Molecular approaches to genome analysis in livestock are reviewed by discussing the contribution of molecular genome analysis to the identification of the genetic variation underlying phenotypic variation (structural genome analysis) and to the definition of the trait-associated and environment-affected gene expression (functional genome analysis) as an important prerequisite to understanding the formation of a phenotype. Aspects of using mapped 'quantitative trait loci' (QTL) or gene variants as well as the identified trait-associated and environment-affected gene expression profile in livestock production are expounded.     

The effect of climate change on the occurrence and prevalence of livestock diseases in Great Britain: a review

There is strong evidence to suggest that climate change has, and will continue to affect the occurrence, distribution and prevalence of livestock diseases in Great Britain (GB). This paper reviews how climate change could affect livestock diseases in GB. Factors influenced by climate change and that could affect livestock diseases include the molecular biology of the pathogen itself; vectors (if any); farming practice and land use; zoological and environmental factors; and the establishment of new microenvironments and microclimates. The interaction of these factors is an important consideration in forecasting how livestock diseases may be affected. Risk assessments should focus on looking for combinations of factors that may be directly affected by climate change, or that may be indirectly affected through changes in human activity, such as land use (e.g. deforestation), transport and movement of animals, intensity of livestock farming and habitat change. A risk assessment framework is proposed, based on modules that accommodate these factors. This framework could be used to screen for the emergence of unexpected disease events.     

Compositional analysis of dairy products derived from clones and cloned transgenic cattle

Cloning technology is an emerging biotechnological tool that could provide commercial opportunities for livestock agriculture. However, the process is very inefficient and the molecular events underlying the technology are poorly understood. The resulting uncertainties are causing concerns regarding the safety of food products derived from cloned livestock. There are similar concerns for livestock produced by biotechnologies which enable the purposeful introduction of genetic modifications. To increase the knowledge about food products from animals generated by these modern biotechnologies, we assessed compositional differences associated with milk and cheese derived from cloned and transgenic cows. Based on gross composition, fatty acid and amino acid profiles and mineral and vitamin contents, milk produced by clones and conventional cattle were essentially similar and consistent with reference values from dairy cows farmed in the same region under similar conditions. Whereas colostrum produced by transgenic cows with additional casein genes had similar IgG secretion levels and kinetics to control cows, milk from the transgenic cows had a distinct yellow appearance, in contrast to the white color of milk from control cows. Processing of milk into cheese resulted in differences in the gross composition and amino acid profiles; 'transgenic' cheese had lower fat and higher salt contents and small but characteristic differences in the amino acid profile compared to control cheese.     

Gene targeting,genome editing: from Dolly to editors

One of the most powerful strategies to investigate biology we have as scientists, is the ability to transfer genetic material in a controlled and deliberate manner between organisms. When applied to livestock, applications worthy of commercial venture can be devised. Although initial methods used to generate transgenic livestock resulted in random transgene insertion, the development of SCNT technology enabled homologous recombination gene targeting strategies to be used in livestock. Much has been accomplished using this approach. However, now we have the ability to change a specific base in the genome without leaving any other DNA mark, with no need for a transgene. With the advent of the genome editors this is now possible and like other significant technological leaps, the result is an even greater diversity of possible applications. Indeed, in merely 5 years, these ‘molecular scissors’ have enabled the production of more than 300 differently edited pigs, cattle, sheep and goats. The advent of genome editors has brought genetic engineering of livestock to a position where industry, the public and politicians are all eager to see real use of genetically engineered livestock to address societal needs. Since the first transgenic livestock reported just over three decades ago the field of livestock biotechnology has come a long way—but the most exciting period is just starting.     

Increase in bacterial community diversity in subsurface aquifers receiving livestock wastewater input

Despite intensive studies of microbial-community diversity, the questions of which kinds of microbial populations are associated with changes in community diversity have not yet been fully solved by molecular approaches. In this study, to investigate the impact of livestock wastewater on changes in the bacterial communities in groundwater, bacterial communities in subsurface aquifers were analyzed by characterizing their 16S rDNA sequences. The similarity coefficients of restriction fragment length polymorphism (RFLP) patterns of the cloned 16S ribosomal DNAs showed that the bacterial communities in livestock wastewater samples were more closely related to those in contaminated aquifer samples. In addition, calculations of community diversity clearly showed that bacterial communities in the livestock wastewater and the contaminated aquifer were much more diverse than those in the uncontaminated aquifer. Thus, the increase in bacterial-community diversity in the contaminated aquifer was assumed to be due to the infiltration of livestock wastewater, containing high concentrations of diverse microbial flora, into the aquifer. Phylogenetic analysis of the sequences from a subset of the RFLP patterns showed that the Cytophaga-Flexibacter-Bacteroides and low-G+C gram-positive groups originating from livestock wastewater were responsible for the change in the bacterial community in groundwater. This was evidenced by the occurrence of rumen-related sequences not only in the livestock wastewater samples but also in the contaminated-groundwater samples. Rumen-related sequences, therefore, can be used as indicator sequences for fecal contamination of groundwater, particularly from livestock.     

Increase in Bacterial Community Diversity in Subsurface Aquifers Receiving Livestock Wastewater Input

Despite intensive studies of microbial-community diversity, the questions of which kinds of microbial populations are associated with changes in community diversity have not yet been fully solved by molecular approaches. In this study, to investigate the impact of livestock wastewater on changes in the bacterial communities in groundwater, bacterial communities in subsurface aquifers were analyzed by characterizing their 16S rDNA sequences. The similarity coefficients of restriction fragment length polymorphism (RFLP) patterns of the cloned 16S ribosomal DNAs showed that the bacterial communities in livestock wastewater samples were more closely related to those in contaminated aquifer samples. In addition, calculations of community diversity clearly showed that bacterial communities in the livestock wastewater and the contaminated aquifer were much more diverse than those in the uncontaminated aquifer. Thus, the increase in bacterial-community diversity in the contaminated aquifer was assumed to be due to the infiltration of livestock wastewater, containing high concentrations of diverse microbial flora, into the aquifer. Phylogenetic analysis of the sequences from a subset of the RFLP patterns showed that the Cytophaga-Flexibacter-Bacteroides and low-G+C gram-positive groups originating from livestock wastewater were responsible for the change in the bacterial community in groundwater. This was evidenced by the occurrence of rumen-related sequences not only in the livestock wastewater samples but also in the contaminated-groundwater samples. Rumen-related sequences, therefore, can be used as indicator sequences for fecal contamination of groundwater, particularly from livestock.     

Giardiasis as a re-emerging infectious disease and its zoonotic potential

The reasons for considering giardiasis as a re-emerging infectious disease are presented, with emphasis on Giardia infections in child care centres, livestock and pets, and the role of zoonotic transmission. However, the aetiology and control of giardiasis is complicated by the genetic and phenotypic variability of Giardia species infective to mammals. Of particular significance has been the uncertainty about host specificity and the question of zoonotic transmission. The recent application of molecular characterisation procedures based on PCR has made an enormous contribution to an understanding of the genetic structure of Giardia populations, and this is reviewed in the context of the zoonotic transmission and molecular epidemiology of Giardia infections.     

畜禽生产性状主效基因定位技术与方法研究进展

鉴定畜禽重要生产性状形成的关键遗传因子,揭示其产生的分子遗传机制,对动物新品种的培育及特色遗传资源的开发利用具有重要意义。高通量分析技术诞生前,标记数量性状位点(quantitative trait loci,QTL)连锁分析和候选基因分析法作为鉴定畜禽生产性状QTL和主效基因主要方法,但由于其技术局限性,性状因果基因鉴定的效率并不高。人类基因组计划(human genome project, HGP)开启了以大数据为特征的生命科学研究的序幕,在HGP完成后的20余年间,快速发展的高通量分析技术使人们研究生物学问题的思路和方法发生了巨大改变。本综述就近年来被广泛用于畜禽重要性状的候选基因定位的方法与技术进行了较全面的综述,以期为同行提供参考。     

雷州半岛规模化畜禽养殖污染现状与对策

本文根据2001年畜禽养殖污染调查,结果表明雷州半岛现有规模化畜禽养殖场413个,畜禽类尿产生量及其污水产生量分别为3.29×10⁵t·a^-1和1.98×10⁶t·a^-1,其中猪场粪尿及其污水产生量分别为2.48×10⁵t·a^-1和1.22×10⁶t·a^-1万吨/年,分别占全半岛总量的75.35%和61.85%,是畜禽养殖主要污染源;全半岛畜禽养殖产污主要分布在雷州市、麻章区、遂溪县和吴川市,文中还就畜禽养殖的污染问题,提出相应的环境管理与防治对策。     

广州市畜禽养殖业污染空间分布研究

基于广州市畜禽养殖场畜禽养殖量数据,采用排泄系数法和分区统计,估算广州市畜禽养殖污染物产生量及其空间分布特征,探讨畜禽养殖污染物流失对水体环境的影响。研究结果表明:(1)广州市畜禽养殖业分布呈明显的圈层结构,畜禽养殖场呈现围绕中心城区的环状分布,城郊区县是畜禽养殖业的分布重点。(2)广州畜禽养殖场污染物流失总量较高,尤其是近郊区县污染物流失严重。(3)畜禽养殖污染物对流溪河、东江、增江、西航道等水体造成影响。针对广州市畜禽养殖业发展现状和空间分布特征提出畜禽养殖业污染防治对策,为行业污染防治和环境管理提供科学依据,为区域畜禽养殖业可持续发展研究提供参考。     

Protozomics: trypanosomatid parasite genetics comes of age

Trypanosomatid protozoans cause important diseases of humans and their domestic livestock. Various molecular genetic tools are now allowing rapid progress in understanding many of the unique aspects of the molecular and cell biology of these organisms. Diploidy and the lack or difficulty of sexual crossing has been a challenge for forward genetics, but powerful selections and functional complementation have helped to overcome it in Leishmania. RNA interference has been adapted for forward genetics in trypanosomes, in which it is also a powerful tool for reverse genetics. Interestingly, the efficacy of different genetic tools has steered research into different aspects of the biology of these parasites.     

Prevalence and risk factors assessment of mange mites in livestock of Malakand Division,Pakistan

Mange mites represent a serious problem in livestock farming due to their worse effect on animals health, reducing milk and meat production. The status of mange mites prevalence was unknown from the livestock present in Malakand Division, Pakistan. Hence, the present study was conducted to determine the prevalence and risk factors assessment of mange mites in livestock of Malakand Division, Pakistan. Villages and livestock herds were visited for data collection and sampling for one year from September 2017 to August 2018. The diagnosis of mange infestation was carried out from skin scrapings collected from symptomatic animals. A total of 1437 animals were screened (240 sheep, 658 cows, 340 buffalos, 199 goats) from selected localities of the Malakand Division. The overall prevalence was 2.37%, with the highest prevalence in buffalos (5.0%) and lowest (0.42%) in sheep (p < 0.05). The locality also significantly affect the prevalence of mange mites in livestock, with a higher percentage (8.14%) in the Ouch area. The prevalence was higher in winter (3.78%) than in summer (1.07%). The prevalence was high (p < 0.05) in young animals (≤1 year) (4.7%) as compared to adults (>1 year) (1.15%). Gender was also a significant risk factor for mange infestation. The infestation was higher in females (2.85%) as compared to males (0.64%) (p < 0.05). Herd size of less than ten animals had a significantly high prevalence rate (3.69%) compared to >10 animals (1.89%). Animals having an infection history >15 days infected more than animals having infection history ≤15 days. This study documented for the first-time epidemiology of mange mites in livestock of Malakand Division, Pakistan. Further studies involving molecular characterization of mange mites will increase our understanding on the spread of mange mites in Malakand Division livestock.     

Rift Valley fever knowledge,mitigation strategies and communication preferences among male and female livestock farmers in Eastern Province,Rwanda

The Government of Rwanda reported an outbreak of Rift Valley fever (RVF) in the Eastern Province in 2018. To respond to the outbreak, vaccination and education campaigns about the disease were carried out. Because RVF cases continue to be detected in Rwanda and the disease impacts livelihoods and health, accurate knowledge and communication are imperative. The objectives of this study were to evaluate knowledge and risk perceptions of RVF transmission among livestock farmers in Nyagatare District, Eastern Province, Rwanda, and to compare RVF knowledge, risk perceptions, and farming practices between male and female livestock farmers. This cross-sectional, quantitative study was conducted in selected sectors of Nyagatare District in the Eastern Province of Rwanda in June 2019. A 34-question survey was used to ask about demographics, livestock ownership, risk perceptions about zoonotic diseases and livestock management, RVF knowledge, preferred communication sources and information sharing strategies, and protective strategies for RVF mitigation while working with livestock. Livestock farmers were interviewed at three milk collection centers, two village meeting points, a farm cooperative meeting, and during door-to-door visits in villages. In total, 123 livestock farmers were interviewed. The survey found that most livestock farmers lacked knowledge about epizootic and zoonotic transmission of RVF, more male livestock farmers were familiar with RVF and risk mitigation strategies, and female livestock farmers are not viewed as reliable sources of information. Additionally, most livestock farmers had not vaccinated their animals against RVF despite past vaccination campaigns. Radio was the most popular communication channel. These findings show that RVF knowledge and information sharing are inadequate among livestock farmers in Eastern Province. Therefore, vaccination and education campaigns may need to be reevaluated within the context of these trends in order to prepare for future RVF outbreaks.     

A comment on the distribution of historical and contemporary livestock grazing across Australia: Implications for using dingoes for biodiversity conservation

Summary Understanding the causes of faunal declines is important for preserving Australia’s threatened fauna. Both predation and livestock grazing have been investigated as potential causes of declines, but some studies struggle to account for historical grazing impacts due to the lack of historical information on livestock distribution and grazing intensity. This article summarises some trends in the extent of historical and contemporary livestock grazing on mainland Australia. The cumulative effects of historical livestock grazing are discussed in the light of studies investigating the influences of predation and livestock grazing on faunal declines.     

利用畜禽粪便饲养家蝇的技术及应用

随着畜牧业的发展,粪便的污染和蛋白饲料的缺乏已成为养殖业中急待解决的两个突出问题。近些年来,利用蝇蛆转化畜禽粪便,蝇蛆作为饲料来养殖禽畜的技术渐趋成熟。文章归纳并综述了利用禽畜粪便养殖蝇蛆的理论和技术,对蝇蛆饲料和蛆粪有机肥的应用和效果做了简要的阐述。     

The zoonotic transmission of Giardia and Cryptosporidium

The molecular characterisation of Giardia and Cryptosporidium has given rise to a more epidemiological meaningful and robust taxonomy. Importantly, molecular tools are now available for 'typing' isolates of the parasites directly from clinical and environmental samples. As a consequence, information on zoonotic potential has been obtained although the frequency of zoonotic transmission is still poorly understood. Analysis of outbreaks and case-control studies, especially when coupled with genotyping data, is slowly providing information on the public health significance of zoonotic transmission. Such studies support the hypothesis that Cryptosporidium hominis is spread only between humans but that the major reservoir for Cryptosporidium parvum is domestic livestock, predominantly cattle, and that direct contact with infected cattle is a major transmission pathway along with indirect transmission through drinking water. The situation is less clearcut for Giardia duodenalis but the evidence does not, in general, support zoonotic transmission as a major risk for human infections. However, for both parasites there is a need for molecular epidemiological studies to be undertaken in well-defined foci of transmission in order to fully determine the frequency and importance of zoonotic transmission.     

Generation and applications of monoclonal antibodies for livestock production

Monoclonal antibodies (MCAs) have found widespread applications in livestock production. Although the generation of murine MCAs is at present a routine, the production of homologous MCAs, especially important for in vivo applications, is still hampered by the lack of efficient homologous fusion partners for immortalization of antibody producing lymphocytes of livestock species. At present, MCAs are used in immunodiagnostic tests e.g. to monitor livestock reproduction and quality of livestock products. In the future MCAs will also be used in immunosensors for real-time and on-site applications in the same areas. The commercial application of MCAs for the immunomodulation of (pharmacologically induced) physiological processes underlying important (re)production traits is at present limited to the use of anti-PMSG MCAs in PMSG-induced superovulation. However, many potentially interesting applications are under investigation (e.g. immunopotentiation of growth hormone to enhance growth; immunocytolysis of adipocytes to increase lean meat production; immunoneutralization of GnRH for immunocastration; immunoimitation of hormone activity with anti-idiotype antibodies). Attempts to use specific MCAs for the sexing of embryos have been disappointing, mainly because of the relatively low accuracy. In the future, MCAs against membrane proteins which are specific for X- or Y-chromosome bearing spermatozoa might be used for bulk separation of livestock sperm. In general, it is expected that engineered (homologous) recombinant MCAs will largely contribute to the development of a new generation of rapid immunodiagnostic tests and effective immunomodulation applications. They will further increase the use of MCAs in livestock production.     

Cytogenetic tests for animal production: state of the art and perspectives

Cytogenetic tests are effective tools for monitoring the health status of livestock and improving their genetic value. Cytogenetic screening allows for the detection of animals carrying chromosomal aberrations and to avoid using them as breeders. Progress in karyotype monitoring, with new molecular probes and automation, has greatly increased the productivity of this procedure. Several genotoxicity tests are available to detect the possible presence and effects of pollutants or drugs. Among these, the micronucleus test and the Comet assay are the most convenient in terms of costs and benefits. Finally, analysis of telomeres, the end of chromosomes and markers of genomic instability, may be developed into a new marker of stress and genetic value.