世界山羊选育的现状及展望

保护动物品种的多样性,不仅对维护家畜的环境适应能力来说是非常关键的,还关系到未来动物生产模式的建立和完善。调查结果表明,现在世界山羊育种形势呈现一个矛盾的现象:一方面,发达国家通过完善的选育组织对山羊的乳用、肉用及毛用性能进行改进;另一方面,在一些落后的地方,山羊的产品还都用于农牧民的自身消耗。当前山羊育种情况如下,少数山羊经过了充分的选育过程并具有某些特点和特性;而大多数山羊尚未经过系统、完善的选育。通过分析山羊选育的现状,作者提出了一些建议,可以更有效的开发这一物种的遗传潜质。     

基于高通量测序技术的山羊遗传多样性及其生产性状研究进展

近年来,高通量测序技术的规模化应用及生物信息技术的普及,极大地推动了家畜基因组学的发展,实现了分子育种标记全基因组水平的快速、精准定位,为全基因组选择育种奠定了重要基础。数千年来的驯化和选择,形成了用途多样的山羊品种,如乳用、皮用、绒用及肉用等,为人类提供了丰富的生产和生活资料。国内外学者采用高通量测序技术对山羊的遗传多样性及生产性能的遗传机制进行了研究,以期找到与山羊种质特性相关的基因,从而为山羊的遗传改良提供新的标记。作者对近五年来基于高通量测序技术研究山羊的遗传多样性和产绒、产奶、繁殖等生产性状的研究进展进行了综述,以期为评估山羊优良种质特性和与生产性状相关的优异基因定位的工作提供参考。     

Research Progress on Goat Genetic Diversity and Production Traits Based on High-throughput Sequencing Technology

Recently, the widespread use of high-throughput sequencing technology and the development of bioinformatics have been greatly contributed to the development of farm animal genomics. Whole genome-wide analysis can facilitate the fine mapping of the molecular markers related to the production traits quickly and accurately, thus providing an important theoretical basis for genome selection breeding. Several thousand years of domestication and artificial selection produce many modern goat breeds with high production of milk, fiber, and meat, which become abundant production and living materials for human populations. Researchers have studied the genetic diversity and molecular mechanisms of production traits in goats using high-throughput sequencing technology, in order to identify candidate genes related to the excellent germplasm reliable markers for genetic improvement. In this review, we summarized the five-year research progress on the genetic diversity and production traits of goats including fiber, milk production and reproduction traits, mainly based on high-throughput sequencing technology. This paper provides a reference for the evaluation of the excellent goat genetic resources and the investigation of production trait related genes.     

Small ruminant production in turkey: highlighting in goat production

This paper deals with the effects of structural, governmental and socio-economic conditions linked to small ruminant production, especially goat production. The number of small ruminants in Turkey fell from almost 51,530 in 1990, to 31,761 in 2007. In 1990, the number of small ruminants started to decrease due to structural, genetic and economic reasons such as a lack of state support policies, high costs of inputs, poor performance of local breeds, socio-economic conditions, and migration. In Turkey, the socio-economic and geographical structure make small ruminant production an important profession; it is also a significant source of income in rural regions. 35% of red meat and 12% of milk production is obtained from small ruminants. Although, Turkey has the highest goat population among its border and EU countries, ranks low with milk production. Reasons for the present situation are well evaluated; changes and tendencies in sheep and goat production as well as milk and meat production that are examined and associated with the population of Turkey are widely discussed. In addition, in order to improve the present situation, some technical and structural suggestions are mentioned.     

论提高肉用山羊生产效益的方法与途径

针对影响肉用山羊生产效益的内在遗传、外界环境、生产组织、经营管理等众多因素,全面论述了引进国外优良肉用山羊品种和地方良种,利用杂种优势开展经济杂交;提倡羔羊育肥适时出栏,缩短生产周期;调节母羊繁殖周期,实行一年产两胎、两年三产和三年五产等频密产羔方式,大量繁殖羔羊进行育肥。根据我国现有基础发展农(牧)民肉用山羊生产专业养殖户、肉用山羊育肥专业户和现代化肉用山羊生产联合企业等经营形式,提高肉用山羊生产的规模效益。在此基础上开展肉羊的屠宰初加工和羊肉食品的精加工,充分利用肉羊生产中一切可利用的产品,扩大产品的销售渠道和范围,以最大限度提高肉用山羊生产的经济效益。     

Morphological characterization of Pelibuey sheep in Colima, México

A study was conducted with the objective to characterize the morphology of Pelibuey sheep in the state of Colima, Mexico. A total of 386 sheep were scored for 12 body measurements in addition to live weight and five racial and eight functional indices were calculated. The influence of sex on the body measurements and indices was analyzed, and morphological harmony was determined through Pearson correlation. The sexual dimorphism was 1.21, with males being 67 % heavier than females. Females and males had a high and moderate degree of harmony in their morphological model, respectively. Pelibuey sheep were dolichocephalous, tended to be medium- to large-sized according to the thoracic index, with a convex curve rump; they were a homogeneous breed, well adapted to environmental and production conditions of the state of Colima, Mexico, and show an undefined zootechnical aptitude and therefore a great potential to be oriented towards meat or milk production through genetic selection or terminal crossbreeding systems using specialized breeds.     

Mini review: breeding Awassi and Assaf sheep for diverse management conditions

The Local Awassi, a triple-purpose breed for meat, milk, and carpet–wool production, is a low-prolific, hardy breed that is well adapted to the unfavorable conditions of the Middle East, where it is managed under traditionally extensive to semi-extensive conditions. Breeding work with the Awassi has included within-breed selection, crossbreeding, and gene introgression. Those efforts resulted in a variety of Awassi-derived genotypes that successfully occupy semi-intensive as well as intensive production systems. Thus, within-breed selection resulted in development of the “Improved Awassi”—a dairy-type Awassi strain which, under intensive management, produces over 500 l milk/ewe annually; crossbreeding with the East Friesian breed led to the development of the Assaf dairy breed, which exceeds the Improved Awassi in prolificacy and in year-round breeding activity, and introgression of the B allele of the FecB locus into the Awassi and Assaf breeds resulted in the formation of the prolific Afec Awassi and Afec Assaf strains, with prolificacies of 1.9 and 2.5 lambs born per ewe lambing, respectively. Advanced molecular genetics tools have enabled a better understanding of how the Awassi breed was formed during domestication and have uncovered differences in its genetic structure compared to other breeds. Implementing large-scale selection schemes that implement emerging new information on the sheep genome, overcoming threats of inbreeding depression, and further breeding for high uterine capacity are the new breeding goals for the Awassi, Assaf, and their derivatives.     

Characterization of the village goat production systems in the rural communities of the Eastern Cape,KwaZulu-Natal,Limpopo and North West Provinces of South Africa

Expansion of goat improvement programs requires exploration of the factors that influence the production system and breeding initiatives. Characterization of goat breeds or populations is crucial in providing information on prevalent goat types and their attributes and may suffice as a guideline on conservation, development, and selection for improved productivity. This study investigated the existing village goat production system and phenotypic diversity of the different village populations from four South African provinces. The study further investigated the use of phenotypic attributes to classify goats to breeds or populations. Data was collected from 142 households in 26 villages of the Eastern Cape (n?=?2 villages), KwaZulu-Natal (n?=?6 villages), Limpopo (n?=?13 villages), and North West (n?=?5 villages) provinces through a survey. Individual interviews and focus group discussions revealed that the mean goat herd size per household was least in Limpopo at 13.2?±?12.40 and highest in Eastern Cape (34.18?±?28.36). Flocks had more (p?<?0.05) adults than kids, and the distribution of breeding animals was biased towards does and less bucks. Goats were kept mainly for meat, for selling, and for ritual ceremonies. The goat production system was mainly scavenging. Goat health was a major challenge across households and villages. Qualitative traits such coat, horn, ears, and wattle characteristics were recorded for populations of village goats (n?=?319) and a feral Tankwa breed (n?=?50). The dominant coat pattern was plain (74.53%) with black as the most common coat color (31.98%). Across breeds, a majority (88.08%) of the goats had horns, and 7.59% had wattles while 56.64% had beard. Adult goats (<3 years; n?=?398) were further analyzed for five quantitative traits of chest girth, height, length, and pin bone and there were significant (p?<?0.05) breed differences in all. A stepwise discriminatory procedure was used to rank the quantitative traits according to their discriminatory power to separate breeds or populations. Significant traits were then subjected to canonical discriminant analysis for principle component analysis. Based on the quantitative traits, the Tankwa, Xhosa, and Tswana goats formed their own cluster separated from commercial meat type breeds and the Venda and Zulu ecotypes. The discriminant function analysis correctly classified 90.41% of the Zulu goats and 82.93% of the Xhosa village populations. None of the Savanna goats were correctly classified. The study demonstrated diversity in village goat populations and production systems, which would allow for within population selection in genetic improvement programs. The heterogeneity in the phenotypic traits in the village goats is reflective of the role of village production systems in the maintenance of animal diversity in local populations.     

The role of goats in the Mediterranean areaLe rôle des chévres en zone MéditerranéenneDie Bedeutung der ziegen im Mittelmeerraum

During the past ten years, the number of goats has slowly decreased because of limitation policies in some countries and the greater difficulty in managing this species than sheep or cattle, but opposite trends are now occurring in countries such as France and Greece.Many local breeds, or populations with very different production characteristics, exist in the Mediterranean basin because of various climatic conditions and systems of production.Goats do not have any problems with the Mediterranean vegetation because they select what they graze and eat large portions of bushes and trees when there is very little grass.The goat is more harmful to woody vegetation than other ruminants because it browses. It has been shown that the goat alone is not able to destroy natural vegetation without human help. In the Mediterranean area, the proper management of goats can be used to control bush encroachment by clearing the undergrowth which will reduce the risk of forest fires.Among the production systems used in the Mediterranean area, two systems are mentioned: one using ranges only, or supplemented with cultivated forages, and the other using intensive systems where the range vegetation only meets a small proportion of the needs. The former systems generally produce meat, hair and milk, while the latter are mainly intended for milk and cheese production.Systems based essentially on ranges are very precarious and their maintenance requires specific techniques and administrative assistance. Intensive systems may also be precarious because they generally depend on high milk prices.     

子午岭黑山羊与辽宁绒山羊产肉性能、肉品质、肌肉营养成分和脂肪酸含量比较

1990年,甘肃省庆阳市开始引入辽宁绒山羊对子午岭黑山羊进行杂交改良,但目前尚不清楚2个品种在脂肪酸含量、肌肉营养成分等方面的差异,影响了杂交改良效果。试验旨在分析两个绒山羊品种的产肉性能、肉品质、肌肉营养成分和脂肪酸含量差异,为绒山羊的杂交改良提供理论依据。本研究选取相同饲养管理条件下、9月龄的子午岭黑山羊和辽宁绒山羊公羊各5只,测定其屠宰性能以及背最长肌、前腿肌和后腿肌处的肉品质、脂肪酸含量和肌肉营养成分。结果表明：子午岭黑山羊的胴体重、屠宰率、净肉重、净肉率、眼肌面积、GR值、剪切力和滴水损失低于辽宁绒山羊（P<0.05）,但其肌肉的平均亮度值、色度值、pH₁和pH₂₄高于辽宁绒山羊（P<0.01）。营养成分测定结果表明,子午岭黑山羊肌肉的水分和粗灰分含量高于辽宁绒山羊（P<0.05）,但肌内脂肪和粗蛋白含量低于辽宁绒山羊。在2个山羊品种的肌肉中均检测到11 种饱和脂肪酸（SFA,以棕榈酸和硬脂酸为主）、10种多不饱和脂肪酸（PUFA,以亚油酸和顺-11,14-二十碳二烯酸为主）和6种单不饱和脂肪酸（MUFA,以油酸为主）,子午岭黑山羊肉中的SFA、PUFA、n-3 PUFA、n-6 PUFA含量和PUFA/SFA值均高于辽宁绒山羊（P<0.01）,但MUFA含量低于辽宁绒山羊（P<0.01）。结果表明,辽宁绒山羊有更高的产肉力,但子午岭黑山羊肌肉品质和营养成分更佳,脂肪酸组成和含量更符合人类健康膳食标准。     

奶山羊产奶性状相关基因的筛选与功能研究进展

奶山羊作为乳用品种的山羊,因其具有奶质优良、产奶性能稳定、乳汁营养丰富等特点,逐渐成为畜牧业发展的一大亮点。经过多年的选种选育,我国现已拥有了多个地方奶山羊品种。随着分子育种技术的发展,对于奶山羊产奶性状相关基因的研究越来越多。对奶山羊产奶性状相关基因的研究进展进行综述,以期为奶山羊优秀基因资源的研究、保护和利用提供理论依据。     

Development and application of a crossbreeding simulation model for goat production systems in tropical regions

A deterministic simulation model was developed to estimate biological production efficiency and to evaluate goat crossbreeding systems under tropical conditions. The model involves 5 production systems: pure indigenous, first filial generations (F1), backcross (BC), composite breeds of F1 (CMP(F1)), and BC (CMP(BC)). The model first simulates growth, reproduction, lactation, and energy intakes of a doe and a kid on a 1-d time step at the individual level and thereafter the outputs are integrated into the herd dynamics program. The ability of the model to simulate individual performances was tested under a base situation. The simulation results represented daily BW changes, ME requirements, and milk yield and the estimates were within the range of published data. Two conventional goat production scenarios (an intensive milk production scenario and an integrated goat and oil palm production scenario) in Malaysia were examined. The simulation results of the intensive milk production scenario showed the greater production efficiency of the CMP(BC) and CMP(F1) systems and decreased production efficiency of the F1 and BC systems. The results of the integrated goat and oil palm production scenario showed that the production efficiency and stocking rate were greater for the indigenous goats than for the crossbreeding systems.     

Seasonality of Reproduction in Mammals: Intimate Regulatory Mechanisms and Practical Implications

Farm mammals generally express seasonal variations in their production traits, thus inducing changing availability of fresh derived animal products (meat, milk and cheese) or performances (horses). This is due to a more or less marked seasonal birth distribution in sheep and goats, in horses but not cattle. Birth peak occurs at the end of winter-early spring, the most favourable period for the progeny to survive. Most species show seasonal variations in their ovulation frequency (presence or absence of ovulation), spermatogenic activity (from moderate decrease to complete absence of sperm production), gamete quality (variations in fertilization rates and embryo survival), and also sexual behaviour. The intimate mechanism involved is a complex combination of endogenous circannual rhythm driven and synchronized by light and melatonin. Profound and long-term neuroendocrine changes involving different neuromediator systems were described to play a role in these processes. In most species artificial photoperiodic treatments consisting of extra-light during natural short days (in sheep and goats and mares) or melatonin during long days (in sheep and goats) are extensively used to either adjust the breeding season to animal producer needs and/or to completely overcome seasonal variations of sperm production in artificial insemination centres. Pure light treatments (without melatonin), especially when applied in open barns, could be considered as non-invasive ones which fully respect animal welfare. Genetic selection could be one of the future ways to decrease seasonality in sheep and goats.     

A review on breeding and genetic strategies in Iranian buffaloes (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>)

The aim of current study was to review breeding progress and update information on genetic strategies in Iranian buffaloes. Iranian buffalo is one of the vital domestic animals throughout north, north-west, south and south-west of Iran with measurable characteristics both in milk and meat production. The species plays an important role in rural economy of the country due to its unique characteristics such as resistance to diseases and parasites, having long productive lifespan and showing higher capability of consuming low-quality forage. In Iran, total production of milk and meat devoted to buffaloes are 293,000 and 24,700 tons, respectively. Selection activities and milk yield recording are carrying out by the central government through the Animal Breeding Centre of Iran. The main breeding activities of Iranian buffaloes included the estimation of genetic parameters and genetic trends for performance traits using different models and methods, estimation of economic values and selection criteria and analysis of population structure. Incorporating different aspects of dairy buffalo management together with improved housing, nutrition, breeding and milking, is known to produce significant improvements in buffalo production. Therefore, identifying genetic potential of Iranian buffaloes, selection of superior breeds, improving nutritional management and reproduction and developing the education and increasing the skills of practical breeders can be useful in order to enhance the performance and profitability of Iranian buffaloes.     

The importance of genetic diversity in livestock populations of the future

Farm animal genetic diversity is required to meet current production needs in various environments, to allow sustained genetic improvement, and to facilitate rapid adaptation to changing breeding objectives. Production efficiency in pastoral species is closely tied to the use of diverse genetic types, but greater genetic uniformity has evolved in intensively raised species. In poultry, breeding decisions are directed by a few multinational companies and involve intense selection, the use of distinct production lines, and very large populations. In dairy cattle, the Holstein breed dominates production. Intensive sire selection is leading to relatively rapid inbreeding rates and raises questions about long-term effects of genetic drift. Key questions in management of farm animal genetic diversity involve the distribution of potentially useful quantitative trait locus alleles among global livestock breeds. Experiments with tomato, maize, and mice suggest that favorable alleles can exist in otherwise lowly productive stocks; this cryptic variation may potentially contribute to future selection response. Genetic improvement under relatively intense unidirectional selection may involve both increases in the frequency of favorable additive alleles as well as the progressive breakdown of homeostatic regulatory mechanisms established under the stabilizing selection that is characteristic of natural populations. Recombination among closely linked regulatory loci and new, potentially favorable mutations are possible sources of long-term genetic variation. A greater understanding of the potential that these alternative mechanisms have for supporting long-term genetic improvement and of genetic relationships among global livestock populations are priorities for managing farm animal genetic diversity.     

Goat farming systems in Martinique: management and breeding strategies

To be successful, initiatives to improve farmer's goat production should directly address the needs and objectives of the keepers while promoting rational use of local genetic resources. A survey was carried out to implement a genetic policy governing meat goat farming in Martinique (11400 heads and 33400 ha arable land). The questionnaire comprised a total of 27 items with 306 modalities, and included questions on farm structure, crop and animal productions, management of feeding, reproduction and health control. The sample consisted of 33 farmers with 644 ha and 2680 goats (1286 does and 52 bucks), 97% of does in the studied sample were crossbred, 56% of bucks were" imported" breeds (Boer or Anglo-Nubian). The number of goats per farm varied from 16 to 582. The feeding system was predominantly grazing, according to a rotation (55% of cases) or continuous grazing system (42%). On 62% of farms, the males remained with the females permanently, also 83% of farmers did not resort to methods of controlled-mating. The first criteria used for choosing animals (80 to 90% of answers) of both sex, were development and conformation. Assuming that adaptive together with productive traits are important in tropical zones, it is advisable to better define the maternal lineage of the local livestock (presently very sparse records), to improve reproduction management and culling strategies (poor and inadequate management practices do not support any genetic improvement programme), and to guide the farmers in their decisions by employing concerted interprofessional actions (choice of meat breed, market studies).     

Current situations of animal data recording,dairy improvement infrastructure,human capacity and strategic issues affecting dairy production in sub-Saharan Africa

An online survey on the state of existing dairy data, dairy improvement infrastructure and human capacity in sub-Saharan Africa (SSA) was undertaken with the aim of assessing whether the state of existing animal recording, dairy improvement methods and key issues facing dairy production together with means of addressing the issues differ among countries and regions of SSA. Respondents comprised experts and practitioners in livestock production and genetic resources from research institutes, animal breeding companies, universities, non-governmental organisations and government agricultural ministries. The main dairy farming system in which the respondents were involved was mixed crop-livestock system (30.2%), and this was mainly practised in the private land tenure system (46.3%). Data were analysed using linear model and paired Student t test in R software package. Respondents identified key issues affecting dairy production as poor genetic assessment of imported exotic breeds and crosses in Africa (62.3%), fluctuations in milk prices within both the formal and informal markets (50.9%), no comprehensive sire ranking systems (39.6%), housing and health management regimes which adversely affect milk yield (32.1%), poor market networks for dairy products (25.5%), poor feeding (13.3%), inadequate genetic technologies (9.4%) and poor animal performance recording systems (9.4%). Respondents emphasised the need for updated breeding policies, sire ranking systems, adequate farm management systems, capacity building, across-country collaborations and joint genetic assessments of dairy breeds found in sub-Saharan Africa. The current situation of dairy production though similar for the different countries, differed in order of emphasis and magnitude across the countries and regions in sub-Saharan Africa.

     

Genetic parameters for total lactation yields of milk,fat, protein,and somatic cell score in New Zealand dairy goats

The aim of this study was to estimate genetic parameters for lactation yields of milk (MY), fat (FY), protein (PY), and somatic cell score (SCS) of New Zealand dairy goats. The analysis used 64,604 lactation records from 23,583 does, kidding between 2004 and 2017, distributed in 21 flocks and representing 915 bucks. Estimates of genetic and residual (co) variances, heritabilities, and repeatabilities were obtained using a multiple‐trait repeatability animal model. The model included the fixed effects of contemporary group (does kidding in the same flock and year), age of the doe (in years), and as covariates, kidding day, proportion of Alpine, Nubian, Toggenburg, and “unknown” breeds (Saanen was used as the base breed), and heterosis. Random effects included additive animal genetic and doe permanent environmental effects. Estimates of heritabilities were 0.25 for MY, 0.24 for FY, 0.24 for PY, and 0.21 for SCS. The phenotypic correlations between MY, FY, and PY ranged from 0.90 to 0.96, and the genetic correlations ranged from 0.81 to 0.93. These results indicate lactation yield traits exhibit useful heritable variation and that multiple trait selection for these traits could improve milk revenue produced from successive generations of New Zealand dairy goats.     

Biology of fibre growth and possible genetic and non-genetic means of influencing fibre growth in sheep and goats—a review

This paper reviews the biology of wool, mohair and cashmere growth and the options available to sheep and goat farmers to manipulate the quantity and characteristics of fibre produced to meet processors' requirements. The annual pattern of fibre growth in sheep and fibre producing goats is photodependent and regulated by hormone action. In sheep and Angora goats, fibre growth rate is greater in summer than winter with the amplitude varying between breeds. Cashmere-producing goats grow fibre between the longest and shortest day after which it is shed. The large diversity in fleece and fibre characteristics between genotypes of sheep and goats can be used to change characteristics by selection. Fibre characteristics of greatest importance to processors are all of medium to high heritability. Negative genetic correlations between some important characteristics limit overall genetic progress achievable through selection. The principal non-genetic factors affecting fleece and fibre characteristics in both sheep and goats are age, nutrition, physiological status, disease and shearing regime. Further work is required to gain a greater understanding of biological changes occurring within the follicle and fibre during growth to facilitate the production of fibre of specific characteristics through breeding or altering animal management.     

波尔山羊对我国本地山羊杂交改良的初步效果

目前我国山羊无论存栏数还是产肉量均居世界首位,但各地方品种众多,与世界优良肉用山羊相比普遍体重小、生长慢.从1995年以来我国引进了著名肉用山羊--波尔山羊,各地相继开展了波尔山羊对本地山羊的杂交改良,都取得了显著的效果,杂交后代在生长速度及产肉性能方面都有很大的提高,为加速我国肉用山羊业的发展开创了新的途径.