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.     

羊胎儿期皮肤毛囊发育及调控机制的研究概述

中国绵山羊养殖历史悠久,品种资源丰富,在国民经济中起重要作用。羊毛按纤维类型可分为同质毛和异质毛,同质毛的特点是被毛由同一类型的羊毛纤维组成,其特点是羊毛的纤维直径、长度、卷曲等外表特征基本相同,异质毛的特点是被毛中兼有绒毛、有髓毛、无卷曲和少卷毛等不同类型的羊毛纤维,其化学、物理性能均不相同。毛囊是控制哺乳动物被毛生长的重要器官,是唯一具有周期性发育并可终生再生的器官,控制着被毛发生发育与自然脱落。毛囊依据其形成时间和结构可分为初级毛囊(primary follicles)和次级毛囊(secondary follicles),初级毛囊生长髓质发达的粗毛,次级毛囊产生无髓毛的绒毛。有髓毛较粗长且弯曲少,多用于加工粗纺织品、毛毯、地毯、毡制品;无髓毛直径一般不超40 μm,弯曲多,是毛纺工业的优质原料。毛囊的发育受到不同信号通路和基因的影响,如Wnt信号通路、骨形态发生蛋白质(BMP)信号通路、成纤维细胞生长因子(FGF)信号通路、音猬因子(SHH)信号通路、Notch信号通路等以及角蛋白家族基因、BMPs家族基因、同源异型盒基因(Hox)等。作者对国内外对绵山羊胎儿期皮肤毛囊发育及调控机制进行综述,以期为提高以绵山羊被毛产量及改善被毛品质为主要育种目标的选育提供参考。     

ELISA技术在畜产品安全检测中的应用

酶联免疫吸附试验 (Enzyme-L inkedImmunosorbent Assay,EL SA)主要是将抗原(或抗体 )吸附于固相载体 ,在载体上进行免疫酶染色 ,最后底物显色用肉眼或分光光度计判定结果的一种检测方法。随着生活水平的不断提高 ,人们越来越关注食品中各种有害物质对健康的影响。对食品中各种有害物质的监测显得越来越重要。畜产品作为食品的重要组成部分 ,其安全检测也不容忽视。检测畜产品中有害物质的方法很多 ,大多数需要昂贵的仪器设备 ,且操作繁琐 ,成本较高。酶联免疫吸附法因其具有操作简便、快速准确等优点 ,成为畜产品中药物残留、毒素、农药、微生物检测中最重要的检测技术之一 ,得到人们的青睐 ,展示了很好的应用前景     

Sensitivity of two-stage sampling to detect sheep biting lice (Bovicola ovis) in infested flocks.

The sampling distribution of Bovicola ovis (Schrank) on sheep was examined in two flocks, one with a light and one with a heavy infestation of lice. The derived distributions were used to calculate the sensitivity of detecting lice on individual sheep and in flocks by fleece parting regimes that varied in number of parts per animal and number of sheep per flock, different scenarios of flock sizes, proportion infested and louse density were examined. Lice were aggregated among fleece partings in the heavily infested flock and described by a negative binomial distribution with k values between 0.3 and 1.92. The distribution was indistinguishable from Poisson in the lightly infested flock. The assumed distribution had little effect on sensitivity, except when only one fleece part per animal was examined. On individual sheep where louse density was 0.5 per 10 cm part or greater, there were only marginal gains from inspecting more than 10 parts per animal. Increasing the number of sheep inspected always increased sensitivity more than increasing number of parts per sheep by an equivalent amount. This advantage was greatest in situations where a low proportion of sheep in the flock were infested with a high density of lice, and less where a low proportion of sheep were infested with a low density of lice, or a high proportion of sheep were infested with a high density of lice.     

Diagnosis of bovine tuberculosis

Extract

In any scheme for the eradication of bovine tuberculosis, the aim is to do so as efficiently as possible. There are a number of tests which can be used on the living animal which attempt to classify it as “tuberculous” or “non-tuberculous”. The fate of the animal probably depends on the result. Unfortunately, none of these tests is perfect. It is important, then, to know the relative merits of these tests and. how they should be used.     

Parameter estimates for greasy fleece weight of Rambouillet sheep at different ages

Variance components for greasy fleece weight in Rambouillet sheep were estimated. Greasy fleece weight was modeled either as repeated measurements on the same trait or as different traits at different ages. The original data were separated according to the age of the ewe at shearing into three classes; 1 yr, 2 and 3 yr, and older than 3 yr. An animal model was used to obtain estimates of genetic parameters with a REML algorithm. Total numbers of animals in pedigrees for the different age classes were 696, 729, and 573, respectively, and 822 for the repeated measures model across ages. The animal model included direct genetic, permanent environmental, and residual environmental random effects and fixed effects for age of ewe, shearing date as contemporary group, and number of lambs born. Days between shearings was used as a covariate. Single-trait analyses were initially done to obtain starting values for multiple-trait analyses. A repeated measures model across ages was also used. Estimates of heritability by age group were .42, .50, and .58 from three-trait (age class) analyses and for the repeated measures model the estimate was .57. Estimates of genetic correlations between fleece yields for 1 yr and 2 and 3 yr, 1 yr and >3 yr, and 2 and 3 yr and >3 yr classes were .88, .89, and .97, respectively. These estimates of genetic correlations suggest that a repeated measures model for greasy fleece weight is adequate for making selection decisions.     

家蝇在动物疫病传播中的作用研究概况

家蝇体内外携带有成千上万种微生物,这些微生物包括致病性微生物和非致病性微生物,诸多研究发现家蝇携带的病原微生物包括细菌、病毒、支原体、衣原体、寄生虫等,数量可达百种;这些病原微生物对家蝇本身并无危害,但是对人和动物却危害严重,甚至可以引起畜禽的死亡。论文通过概述家蝇的特性、体内外携带病原体种类与数量、传播病原的方式及引起的疾病类型等方面,了解家蝇在动物疫病传播过程中的地位,明确家蝇在动物疫病传播过程中起到不容忽视的作用,同时揭示了在畜禽饲养过程中消灭苍蝇是非常重要的一项举措,也是减少动物疫病传播的重要手段之一。     

蛋鸡饲料中有毒有害物质研究进展

饲料作为动物营养的主要来源,其安全性关乎动物健康和人类食品安全.然而饲料在生产、加工、贮存、运输等过程中可能污染有毒有害物质,并通过食物链在畜禽体内富集,最终进入人类体内,危害人体健康.现代社会人们对食品安全关注度日益增强,为畜禽提供绿色、健康、无污染的饲料,确保畜禽产品的卫生安全已成为重要的研究方向.文章简要概述蛋鸡...     

Lack of evidence for cytoplasmic effects for four traits of Polypay sheep

Analyses of birth and weaning weights, fleece weights of ewes, and number born per litter of Polypay sheep collected at the U.S. Sheep Experimental Station from 1978 through 1998, confirmed previous analyses of three other dual-purpose breeds that cytoplasmic effects do not contribute to variation in these four traits. In general, estimates of genetic parameters that would be needed for national genetic evaluation were similar to previous estimates for Columbia, Rambouillet, and Targhee sheep, although estimates of direct heritability for Polypay were somewhat less for birth weight, slightly greater for weaning weight, significantly greater for fleece weight, and the same for number born as for those three breeds. For birth weight only, evidence was found for important dam x year or dam x number born interactions, which are essentially litter effects, as was found for the other dual-purpose breeds. There were 11,896, 11,104, 7,748, and 7,831 records for birth and weaning weights, fleece weight, and number born per litter, with 255 to 316 sires of animals with records. There were 260 and 261 cytoplasmic lines for fleece weight and number born, and 861 and 882 for weaning and birth weights.     

Estimation of (co)variance components and genetic parameters of greasy fleece weights in Muzaffarnagari sheep

Variance components and genetic parameters for greasy fleece weights of Muzaffarnagari sheep maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India, over a period of 29 years (1976 to 2004) were estimated by restricted maximum likelihood (REML), fitting six animal models including various combinations of maternal effects. Data on body weights at 6 (W6) and 12 months (W12) of age were also included in the study. Records of 2807 lambs descended from 160 rams and 1202 ewes were used for the study. Direct heritability estimates for fleece weight at 6 (FW6) and 12 months of age (FW12), and total fleece weights up to 1 year of age (TFW) were 0.14, 0.16 and 0.25, respectively. Maternal genetic and permanent environmental effects did not significantly influence any of the traits under study. Genetic correlations among fleece weights and body weights were obtained from multivariate analyses. Direct genetic correlations of FW6 with W6 and W12 were relatively large, ranging from 0.61 to 0.67, but only moderate genetic correlations existed between FW12 and W6 (0.39) and between FW12 and W12 (0.49). The genetic correlation between FW6 and FW12 was very high (0.95), but the corresponding phenotypic correlation was much lower (0.28). Heritability estimates for all traits were at least 0.15, indicating that there is potential for their improvement by selection. The moderate to high positive genetic correlations between fleece weights and body weights at 6 and 12 months of age suggest that some of the genetic factors that influence animal growth also influence wool growth. Thus selection to improve the body weights or fleece weights at 6 months of age will also result in genetic improvement of fleece weights at subsequent stages of growth.     

呕吐毒素对畜禽肠道健康的影响及相关研究进展

呕吐毒素是饲料原料中最为常见，对畜禽健康危害最大的一种霉菌毒素，其给畜牧业生产造成极大经济损失。大量研究结果发现，动物肠道可能是呕吐毒素进入机体内产生毒理作用的重要靶器官，因此，呕吐毒素诱导的动物肠道健康损伤也成为目前的一个研究热点。本文结合近年来国内外相关研究进展，综述了饲料中呕吐毒素污染对畜禽肠道健康的影响与毒理机制，以及相关防治措施，为饲料生产及畜禽健康养殖提供一些参考。 [关键词] 饲料|呕吐毒素|畜禽|肠道健康     

Genetic parameters among weight, prolificacy, and wool traits of Columbia, Polypay, Rambouillet, and Targhee sheep

Genetic parameters for Columbia, Polypay, Rambouillet, and Targhee sheep were estimated using REML with animal models for prolificacy, weight, and wool traits. All bivariate analyses included a covariance between additive genetic effects for the two traits plus appropriate additional covariances. Number of observations by breed ranged from 5,140 to 7,095 for prolificacy traits, from 7,750 to 9,530 for weight traits, and from 4,603 to 34,746 for wool traits. Heritability estimates ranged from .03 to .11 for prolificacy traits (litter size at birth and litter size at weaning), from .09 to .26 for weight traits (birth weight and average daily gain), and from .25 to .53 for wool traits (fleece weight, fleece grade and staple length). Estimates of direct genetic correlations among prolificacy and among weight traits were positive and ranged from .58 to 1.00 and .18 to 1.00, respectively. Estimates of direct genetic correlation between fleece weight and staple length were positive (.50 to .70) but were negative between fleece weight and fleece grade (-.60 to -.34) and between staple length and fleece grade (-.72 and -.40). Prolificacy and wool traits were essentially uncorrelated. Weight and prolificacy traits were slightly positively correlated. Weight traits had a moderate positive direct genetic correlation with fleece weight and staple length, but were uncorrelated with fleece grade. These estimates of genetic parameters between prolificacy, weight, and wool traits can be used to construct multiple-trait selection indexes for dual-purpose sheep.     

Genotypic expression at different ages: II. Wool traits of sheep.

Genetic parameters for wool traits for Columbia, Polypay, Rambouillet, and Targhee breeds of sheep were estimated with single- and multiple-trait analyses using REML with animal models. Traits considered were fleece grade, fleece weight, and staple length. Total number of observations ranged from 11,673 to 34,746 for fleece grade and fleece weight and from 3,500 to 11,641 for staple length for the four breeds. For single-trait analyses, data were divided by age of ewe: young ages (age of 1 yr), middle ages (ages of 2 and 3 yr), and older ages (age greater than 3 yr). Heritability estimates averaged over breeds for fleece grade decreased from .42 at a young age to .37 for older ages. For fleece weight, heritability estimates averaged .52, .57, and .55 within the successively older groups. Heritability estimates for staple length averaged .54 for young and middle age classes. Few older ewes had staple length measurements. After single-trait analyses, new data sets were created for three-trait analyses with traits defined by three age classes when animals were measured. Heritability estimates with three-trait analyses, except for a few cases, were somewhat greater than those from single-trait analyses. For fleece grade, the genetic correlations averaged over breeds were .72 for young with middle, .42 for young with older, and .86 for middle with older age classes. For fleece weight, the average genetic correlations were .81, .83, and .98. For staple length, the average genetic correlation for young with middle age classes was .82. Estimates of genetic correlations across ages varied considerably among breeds. The average estimates of correlations suggest that fleece grade may need to be defined by age, especially for the Columbia and Rambouillet breeds. For fleece weight and staple length, however, the average correlations suggest no need to define those traits by age.     

Multiple effects of an additional growth hormone gene in adult sheep

Molecular genetics provides an increasing capacity to modulate the function of individual genes, but the practical implications of these technologies are still poorly understood. This study examined adult Merino or Merino-cross sheep that had an additional copy of the ovine GH gene with a modified metal-lothionine promoter, which resulted in a doubling of the plasma concentration of GH. Previous work showed that up to the age of 18 mo, GH sheep grew faster and had less s.c. fat, with only minor effects on fleece production. The present paper describes characteristics of reproduction, wool production, and animal health of these sheep during the following 2 yr of adult life. Ewes with the GH gene had a greater ovulation rate (1.78 vs. 1.35; P <0.05), but bore fewer lambs, apparently due to greater fetal loss after mating. Grease fleece weight was increased (P <0.05) due mainly to a greater content of suint (9.1 vs. 7.7 +/- 0.4%, P <0.01), which was associated with a deeper color of the raw wool. Effects on clean fleece weight and fiber diameter were not consistent between years. The GH sheep had swollen metatarsal and metacarpal joints, which was associated with a need for more frequent hoof-trimming, and more GH than control sheep died during the experiment (P <0.001). All of these changes are consistent with previously reported effects of increased plasma GH. Results of this study show that increased activity of a single gene (GH) affected several production characteristics and predisposed the animals to a number of distinct health problems, some of which developed after the normal age of genetic selection.     

Temporal relationship between infestation with lice (Bovicola ovis Schrank) and the development of pruritic behaviour and fleece derangement in sheep

Pruritic behaviour and deranged fleece are often used as indicators of sheep louse infestation but the exact relationship between infestation and the observation of signs of pruritis was unclear. Two studies were conducted to examine this association. In the first, 24 castrate Merino sheep were randomly assigned to six pens in groups of four and the sheep in three pens infested with 10 lice each on the right mid-side. Louse numbers were counted, fleece derangement scored and pruritic behaviour assessed periodically on each sheep until 38 weeks after infestation. In the second study a single moderately infested sheep was paddocked for 15 weeks with 32 uninfested sheep and louse numbers and fleece derangement monitored for 41 weeks. In the pen studies, differences between infested and non-infested sheep in fleece derangement and pruritic behaviour first became significant (p<0.05) at 8 and 14 weeks, respectively and at louse densities of 0.06 and 0.27 per 10 cm wool part. Some sheep showed definite signs of deranged fleece as early as 5 weeks after initial infestation. In the paddock studies, it took 37 weeks until lice were detected on all sheep in the flock. The correlation between louse numbers and fleece derangement score first became significant (r=0.44 and p<0.05) at 9 weeks after introduction of the lousy sheep, reached a maximum of r=0.79 (p<0.001) at 22 weeks when 84% of sheep had lice detected and the mean louse density was 0.29 per part, and then declined to r=0.12 (n.s.) at 41 weeks when all sheep were infested and the mean louse density was 3.04 per part. It is concluded that fleece derangement is a powerful early indicator of the presence of lice and that sheep may exhibit signs of pruritis well before lice can be readily found by direct inspection. Fleece derangement may be useful as a basis for establishing economic thresholds for the application of long wool treatments in developing louse infestations but appears to be a poor indicator of louse numbers once the infestation is advanced.     

Critical perspectives of animal agriculture: introduction

The American Society of Animal Science has recently focused its attention on a variety of contentious issues in animal agriculture. This paper deals with critique, a philosophical approach to analyzing and understanding issues. This method has been employed by various contemporary philosophers. For example, feminist theorists have used this approach to critically analyze sexual harassment. Critique involves a critical analysis of the discourse (ideas or language) and practices that define the social reality in which we live. How we think about the world and how we behave in it determines how we humans interact with each other as well as with the rest of nature. This social structure is associated with power structures that benefit some individuals and harm others. In this paper, I demonstrate how critique can be used to better understand the social reality of animal agriculture. By analyzing certain popular texts in this field, I show that a "mechanical view of nature" is dominant in animal agriculture and argue that such a view contributes to a social reality that can be harmful to some humans and other animals. I conclude that various contentious issues can be better addressed when we engage in a critical analysis of this conceptual framework and base our analysis on the experiences of many different people, including those who have been harmed by our current system of animal agriculture.     

A review of morphological characteristics relating to the production and reproduction of fat-tailed sheep breeds

The purpose of this study is to survey the literature pertinent to some morphological traits which are related with the production and reproduction of fat-tailed sheep breeds. The fat-tailed breeds were identified according to Food and Agriculture Organization databases. Articles referring to all these sheep breeds were evaluated. The morphology of udders and their measurable variables were collected and described. The particularities of pelt and fleece features which are important from an economic point of view were summarized. Linear, planar, and spatial parameters of body, slaughter, and carcass factors were compared at various ages of breeding. Testicular dimensions and semen characteristics were recorded. Their relationships with productive and reproductive performance were discussed. The pattern of ovarian follicle development and the involution of the genital tract were assessed from the anatomical point of view in normal and untreated animals. The data presented here provide useful baseline information on the normal morphological aspects which are important in the animal production of these breeds.     

青饲料的卫生与安全饲喂技术研究

青饲料是家畜的重要饲用资源,其适口性好,富含营养素。合理利用青饲料,可以提高家畜养殖生产效益,降低养殖成本。但是,青饲料作物中的一些成分或者在某些条件下的分解、转化产物都会对动物产生毒害作用,从而引起饲料的卫生与安全问题。青饲料中的有毒有害物质包括硝酸盐、亚硝酸盐、生氰糖苷、光敏物质、草酸盐、马铃薯素以及一些牧草中的毒素。对青饲料中所含的有毒有害物质种类及特征进行介绍,对由这些物质引起的动物中毒病的发病机理和救治方法进行综述,在该基础上探讨了青饲料安全饲喂技术,以期为提高青饲料在家畜养殖中的科学饲喂水平提供参考。     

Bovine paramphistomosis in Galicia (Spain): Prevalence,intensity, aetiology and geospatial distribution of the infection

The present study explored various basic aspects of the epidemiology of paramphistomosis in Galicia, the main cattle producing region in Spain. In total, 589 cows from different farms located across the region were selected at random in the slaughterhouse for examination of the rumens and reticula for the presence of Paramphistomidae flukes. Paramphistomes were found in 111 of 589 necropsied cows (18.8%; 95% CI: 15.7–21.9%), with higher prevalences of infection in beef cows than in dairy cows (29.2% vs 13.9%). Although the number of flukes per animal was generally low (median = 266 flukes), some cows harboured large parasite burdens (up to 11,895 flukes), which may have harmful effects on their health or productivity. Cows with higher parasite burdens also excreted greater numbers of fluke eggs in their faeces, which suggests that heavily parasitized mature cows play an important role in the transmission of paramphistomosis. This role may be particularly important in Galicia, where the roe deer, which is the only wild ruminant in the study area, was found not to be a reservoir for the infection. The use of morpho-anatomical and molecular techniques applied to a large number of fluke specimens provided reliable confirmation that Calicophoron daubneyi is the only species of the family Paramphistomidae that parasitizes cattle in Galicia. The environmental data from the farms of origin of the necropsied cows were used in Bayesian geostatistical models to predict the probability of infection by C. daubneyi throughout the region. The results revealed the role of environmental risk factors in explaining the geographical heterogeneity in the probability of infection in beef and dairy cattle. These explanatory factors were used to construct predictive maps showing the areas with the highest predicted risk of infection as well as the uncertainty associated with the predictions.     

高山美利奴羊重要经济性状遗传参数估计

本研究旨在估计高山美利奴羊重要经济性状的遗传参数,为优化高山美利奴羊选育方案、建设品种完整结构、进行遗传评估及实施育种值选种提供理论技术支撑。采用甘肃省绵羊繁育技术推广站2003—2018年高山美利奴羊核心群数据资料,基于ASReml运用单性状个体动物模型和多性状个体动物模型估计高山美利奴羊体重、产羔数、产毛量、净毛量、净毛率、羊毛纤维直径、羊毛纤维直径变异系数、毛丛长度等重要经济性状的遗传参数。结果表明:高山美利奴羊产羔数为低等遗传力,其他所有性状均为中高等遗传力;大部分经济性状间呈正遗传相关,体重、产毛量、羊毛纤维直径与净毛率间呈负遗传相关,羊毛纤维直径变异系数与体重、产毛量、纤维直径呈负遗传相关。