Genetic structure of pig breeds from Korea and China using microsatellite loci analysis

To understand molecular genetic characteristics of Korean pigs, the genetic relationships of nine pig breeds including two Korean pigs (Korean native pig and Korean wild pig), three Chinese pigs (Min pig, Xiang pig, and Wuzhishan pig), and four European breeds (Berkshire, Duroc, Landrace, and Yorkshire) were characterized from a 16-microsatellite loci analysis. The mean heterozygosity within breeds ranged from 0.494 to 0.703. Across multiple loci, significant deviation from Hardy-Weinberg equilibrium was observed in most pig breeds, except for two Chinese pigs (Min pig and Wuzhishan pig). This deviation was in the direction of heterozygote deficit. Across population loci, 36 of 144 significantly deviated (P < 0.05) from Hardy-Weinberg equilibrium. The mean FST, a measure of genetic divergence among subpopulations, of all loci indicated that 26.1% of total variation could be attributed to the breed difference. Relationship trees based on the Nei's DA genetic distance and scatter diagram from principal component analysis consistently displayed pronounced genetic differentiation among the Korean wild pig, Xiang pig, and Wuzhishan pig. Individual assignment test using a Bayesian method showed 100% success in assigning Korean and Chinese individual pigs into their correct breeds of origin and 100% exclusion success from all alternative reference populations at P < 0.001. These findings indicate that the Korean native pig has been experiencing progressive interbreeding with Western pig breeds after originating from a North China pig breed with a black coat color. Considering the close genetic relationship of Korean pigs to the Western breeds such as Berkshire and Landrace, our findings can be used as valuable genetic information for the preservation and further genetic improvement of the Korean native pig.     

Analysis of genetic diversity and conservation priorities for six north Ethiopian cattle breeds

Genetic diversity and conservation potential of six indigenous cattle breeds of north Ethiopia was analysed based on 20 microsatellite markers using core set methods. Expected future diversity (assuming assigned extinction probabilities are valid for the next 20-50 years) were 0.988+/-0.011 and 0.980+/-0.010 with expected loss of diversity estimated at 0.02% and 0.74% of current level for the Maximum Variance Total (MVT) and Maximum Variance Offspring (MVO) core sets, respectively. Even though all breeds have contributed to current diversity levels, the Afar and Abergelle breeds only contributed 51% and 62% to the MVT and MVO core sets, respectively, while the Raya breed contributed only 6% and 1.5% to the MVT and MVO core set diversities, respectively. Moreover, prioritizing the six north Ethiopian cattle breeds using the conservation potential obtained from the MVT core set method seems reasonable considering the origin and migration histories of the breeds. Our results suggest that the total current genetic diversity of these breeds can be sufficiently maintained by designing a conservation strategy based on conservation potential of each breed from the MVT core set so that priority is given to lowering the extinction probabilities of breeds with high conservation potential to zero.     

利用微卫星标记对4个肉牛品种进行遗传多样性分析

本研究利用10个微卫星标记分析了鲁西黄牛、布莱凯特肉牛、渤海黑牛和日本和牛4个品种185个个体的品种内遗传变异情况及各品种间的亲缘关系,共检测到58个等位基因,每个位点平均观察等位基因数为5.8个,从4(BM1818)到8个(ETH225和TGLA53)不等;有效等位基因数为2.5417～3.5849个;观察杂合度、期望杂合度和多态信息含量变异范围分别为0.2270～0.5459、0.6082～0.7230和0.5482～0.6791,均属高度多态性位点。群体间遗传分化明显,有34.49%的遗传分化来自群体间的变异。以Nei氏遗传距离(D_A)构建UPGMA系统进化树,聚类结果表明,渤海黑牛与鲁西黄牛首先聚为一类,布莱凯特肉牛和日本和牛聚为一类。布莱凯特肉牛的3个微卫星座位10个克隆的PCR扩增片段测序获得的序列已提交GenBank,登录号分别为：GQ368896、GQ368897、GQ368898、GQ368899、GQ368900、GQ368901、GQ368902、GQ368903、GQ368904、GQ368905。10对微卫星座位可作为有效的遗传标记用于4个肉牛品种的遗传多样性和系统发生关系分析。     

Genetic diversity in native and commercial breeds of pigs in Portugal assessed by microsatellites

Population structure and genetic diversity in the Portuguese native breeds of pigs Alentejano (AL), Bísaro (BI), and Malhado de Alcoba?a (MA) and the exotic breeds Duroc (DU), Landrace (LR), Large White (LW), and Pietrain were analyzed by typing 22 microsatellite markers in 249 individuals. In general, the markers used were greatly polymorphic, with mean total and effective number of alleles per locus of 10.68 and 4.33, respectively, and an expected heterozygosity of 0.667 across loci. The effective number of alleles per locus and expected heterozygosity were greatest in BI, LR, and AL, and least in DU. Private alleles were found in 9 of the 22 markers analyzed, mostly in AL, but also in the other breeds, with the exception of LW. The proportion of loci not in Hardy-Weinberg equilibrium in each breed analyzed ranged between 0.23 (AL) and 0.41 (BI, LW, and Pietrain), mostly because of a less than expected number of heterozygotes in those loci. With the exception of MA, all breeds showed a significant deficit in heterozygosity (F(IS); P < 0.05), which was more pronounced in BI (F(IS) = 0.175) and AL (F(IS) = 0.139), suggesting that inbreeding is a major concern, especially in these breeds that have gone through a genetic bottleneck in the recent past. The analysis of relationships among breeds, assessed by different methods, indicates that DU and AL are the more distanced breeds relative to the others, with the closest relationship being observed between LR and MA. The degree of differentiation between subpopulations (F(ST)) indicates that 0.184 of the total genetic variability can be attributed to differences among breeds. The analysis of individual distances based on allele sharing indicates that animals of the same breed generally cluster together, but subdivision is observed in the BI and LR breeds. Furthermore, the analysis of population structure indicates there is very little admixture among breeds, with each one being identified with a single ancestral population. The results of this study confirm that native breeds of pigs represent a very interesting reservoir of allelic diversity, even though the current levels of inbreeding raise concerns. Therefore, appropriate conservation efforts should be undertaken, such as adopting strategies aimed at minimizing inbreeding, to avoid further losses of genetic diversity.     

A longitudinal study on growth and growth variables in dogs of four large breeds raised in domestic environments

The main objective of this study was to describe the growth patterns of 4 large dog breeds [Newfoundland (NF), Labrador retriever (LR), Leonberger (LEO), and Irish wolfhound (IW)] raised in domestic environments and concomitant changes in 2 growth-related clinical variables: total serum alkaline phosphatase (ALP) and the circumference of the distal radius and ulna (CDRU). The second objective was to investigate whether these measurements were affected by a range of independent variables like age, sex, litter number, and birth weight. Seven hundred dogs were included in the study, and BW data, separated by breed and sex, were fitted to the Gompertz function. Birth weight, adjusted for litter number, differed significantly between sexes for 3 breeds (LEO, P = 0.004; NF, P = 0.02; LR, P = 0.009) and approached significance for IW (P = 0.07). Estimated mean BW increased rapidly during the first 100 d after birth in all 4 breeds, then plateaued, with maturity being reached between 351 (female LR) and 413 d (male NF). Estimated mature BW ranged from 30.8 kg for the female LR up to 65.7 kg for the male IW. Weight gain, as expressed by the derivative of the Gompertz function, reached its peak in the smallest breed (LR) at the youngest age, 89 d for the females and 95 d for males. Log-transformed BW was significantly related to age, breed, and sex, and the age x sex and age x breed interactions. Within breeds, age, birth weight, and litter number had a significant effect on log-transformed BW. The estimated average CDRU increased from 90 d of age toward a peak at 180 d. Thereafter, CDRU declined and stabilized at about 1 yr of age. The estimated total ALP concentrations decreased from 90 to 360 d of age, after which they stabilized, at mean concentrations varying among breeds from 98 to 131 IU/L. Maximum least squares mean total ALP concentrations were found at 3 mo of age in all breeds, with the greatest least squares mean concentration in the IW breed (713 IU/L). In a mixed model analysis of the complete data set, total ALP was affected (P < 0.001) by age, breed, and the interaction of age x breed. This study described the main factors influencing growth and provided reference data for other studies, including those related to nutrition and disorders of growth.     

Genetic diversity and differentiation of five Cuban cattle breeds using 30 microsatellite loci

Conservation and improvement strategies in farm animals should be based on a combination of genetic and phenotypic characteristics. Genotype data from 30 microsatellites were used to assess the genetic diversity and relationships among five Cuban cattle breeds (Siboney de Cuba, Criollo Cubano, Cebú Cubano, Mambí de Cuba and Taíno de Cuba). All microsatellite markers were highly polymorphic in all the breeds. The expected heterozygosity ranged from 0.67 ± 0.02 in the Taíno de Cuba breed to 0.75 ± 0.02 in the Mambí de Cuba breed, and the observed heterozygosity ranged from 0.66 ± 0.03 in the Cebú Cubano breed to 0.73 ± 0.02 in the Siboney de Cuba breed. The genetic differentiation between the breeds was significant (p < 0.01) based on the infinitesimal model (F_ST). The exact test for Hardy‐Weinberg equilibrium within breeds showed a significant deviation in each breed (p < 0.0003) for one or more loci. The genetic distance and structure analysis showed that a significant amount of genetic variation is maintained in the local cattle population and that all breeds studied could be considered genetically distinct. The Siboney de Cuba and Mambí de Cuba breeds seem to be the most genetically related among the studied five breeds.     

Genetic analysis of Mexican Criollo cattle populations

The objective of this study was to evaluate the genetic structure of Mexican Criollo cattle populations using microsatellite genetic markers. DNA samples were collected from 168 animals from four Mexican Criollo cattle populations, geographically isolated in remote areas of Sierra Madre Occidental (West Highlands). Also were included samples from two breeds with Iberian origin: the fighting bull (n = 24) and the milking central American Criollo (n = 24) and one Asiatic breed: Guzerat (n = 32). Genetic analysis consisted of the estimation of the genetic diversity in each population by the allele number and the average expected heterozygosity found in nine microsatellite loci. Furthermore, genetic relationships among the populations were defined by their genetic distances. Our data shows that Mexican cattle populations have a relatively high level of genetic diversity based either on the mean number of alleles (10.2-13.6) and on the expected heterozygosity (0.71-0.85). The degree of observed homozygosity within the Criollo populations was remarkable and probably caused by inbreeding (reduced effective population size) possibly due to reproductive structure within populations. Our data shows that considerable genetic differentiation has been occurred among the Criollo cattle populations in different regions of Mexico.     

Predicting breed composition using breed frequencies of 50,000 markers from the US Meat Animal Research Center 2,000 Bull Project

Knowledge of breed composition can be useful in multiple aspects of cattle production, and can be critical for analyzing the results of whole genome-wide association studies currently being conducted around the world. We examine the feasibility and accuracy of using genotype data from the most prevalent bovine genome-wide association studies platform, the Illumina BovineSNP50 array (Illumina Inc., San Diego, CA), to estimate breed composition for individual breeds of cattle. First, allele frequencies (of Illumina-defined allele B) of SNP on the array for each of 16 beef cattle breeds were defined by genotyping a large set of more than 2,000 bulls selected in cooperation with the respective breed associations to be representative of their breed. With these breed-specific allele frequencies, the breed compositions of approximately 2,000 two-, three-, and four-way cross (of 8 breeds) cattle produced at the US Meat Animal Research Center were predicted by using a simple multiple regression technique or Mendel (http://www.genetics.ucla.edu/software/mendel) and their genotypes from the Illumina BovineSNP50 array, and were then compared with pedigree-based estimates of breed composition. The accuracy of marker-based breed composition estimates was 89% when using either estimation method for all breeds except Angus and Red Angus (averaged 79%), based on comparing estimates with pedigree-based average breed composition. Accuracy increased to approximately 88% when these 2 breeds were combined into an aggregate Angus group. Additionally, we used a subset of these markers, approximately 3,000 that populate the Illumina Bovine3K (Illumina Inc.), to see whether breed composition could be estimated with similar accuracy when using this reduced panel of SNP makers. When breed composition was estimated using only SNP in common with the Bovine 3K array, accuracy was slightly reduced to 83%. These results suggest that SNP data from these arrays could be used to estimate breed composition in most US beef cattle in situations where pedigree is not known (e.g., multiple-sire natural service matings, non-source-verified animals in feedlots or at slaughter). This approach can aid analyses that depend on knowledge of breed composition, including identification and adjustment of breed-based population stratification, when performing genome-wide association studies on populations with incomplete pedigrees. In addition, SNP-based breed composition estimates may facilitate fitting cow germplasm to the environment, managing cattle in the feedlot, and tracing disease cases back to the geographic region or farm of origin.     

Breed comparisons of Angus,Charolais, Hereford,Jersey, Limousin,Simmental, and South Devon for weight,weight adjusted for body condition score,height, and body condition score of cows

Breed means and differences for weight (CW, n = 19,851), height (CH, n = 14,553), and condition scores (CS, n = 19,536) recorded in four seasons per year were evaluated for 881 cows ranging from 2 to 7 yr of age from Cycle I of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center. Cows were straightbred Herefords and Angus and topcrosses from mating of Hereford, Angus, South Devon, Jersey, Simmental, Limousin, and Charolais sires to Hereford and Angus dams. The model included cow age, season of measurement, and their interactions, with year of birth, pregnancy-lactation (PL) code, and breed group as fixed effects for CW and CS. Analyses of weight adjusted for condition score included CS as covariate. Model for CH excluded PL. Random effects were additive genetic and permanent environmental effects. Data were analyzed by REML. Differences due to breeds of sire were significant for all traits. Differences were generally maintained across ages, with few interchanges in ranking through maturity. Rankings were in the following order: Jersey (lightest and shortest), Hereford-Angus (and reciprocal), Limousin, South Devon, Simmental, and Charolais (heaviest and tallest). The only exception was that Limousin-sired cows were heavier than South Devon-sired cows after 5 yr of age. Cows sired by breeds of British origin tended to be lighter than breeds of continental European origin. Adjustment for condition score changed estimates of breed differences. Rankings of breed groups, however, were generally the same for actual weight and weight adjusted for condition score. Results indicated that the part of the differences in weight due to differences in condition were of small magnitude. Differences tended to increase when adjusted for condition score, especially in contrasts of continental vs British breeds. Differences among breed groups for height followed differences for weight closely.     

中国黄牛Y-STRs遗传多样性与起源研究

[目的]研究中国黄牛Y染色体STRs的遗传多样性及父系起源。[方法]利用非变性聚丙烯酰胺凝胶电泳,选择2个牛Y-STRs位点INRA189和BM861,分析16个中国地方黄牛品种284头公牛与4头缅甸黄牛公牛的Y染色体遗传多样性。[结果]在中国16个黄牛品种中,2个Y-STR位点可以区分中国黄牛中的普通牛和瘤牛类型,表明中国黄牛有普通牛和瘤牛两种父系起源。4头缅甸黄牛均为瘤牛类型。在中国16个黄牛品种中,普通牛和瘤牛分布频率分别为57.0%和43.0%,其中普通牛频率在北方黄牛中占优势(98.3%),瘤牛频率在南方黄牛中占优势(76.1%),中原黄牛中普通牛频率较高为63.8%,瘤牛频率为36.2%。[结论]中国黄牛存在普通牛和瘤牛两种父系起源;普通牛频率自北向南逐渐减少,瘤牛频率自北向南逐渐增加,中原地区为普通牛和瘤牛的交汇处。     

Development of a genomic tool for breed assignment by comparison of different classification models: Application to three local cattle breeds

Assignment of individual cattle to a specific breed can often not rely on pedigree information. This is especially the case for local breeds for which the development of genomic assignment tools is required to allow individuals of unknown origin to be included to their herd books. A breed assignment model can be based on two specific stages: (a) the selection of breed-informative markers and (b) the assignment of individuals to a breed with a classification method. However, the performance of combination of methods used in these two stages has been rarely studied until now. In this study, the combination of 16 different SNP panels with four classification methods was developed on 562 reference genotypes from 12 cattle breeds. Based on their performances, best models were validated on three local breeds of interest. In cross-validation, 14 models had a global cross-validation accuracy higher than 90%, with a maximum of 98.22%. In validation, best models used 7,153 or 2,005 SNPs, based on a partial least squares-discriminant analysis (PLS-DA) and assigned individuals to breeds based on nearest shrunken centroids. The average validation sensitivity of the first two best models for the three local breeds of interest were 98.33% and 97.5%. Moreover, results reported in this study suggest that further studies should consider the PLS-DA method when selecting breed-informative SNPs.     

Analysis of factors affecting the electric conductivity of cow's milk--breed, locale, season

The problem was studied in a set of 678 mammary glands of 212 cows - crossbreds between the Holstein-Friesian breed with the Slovak Spotted cattle, crossbreds of the Black-Pied Lowland and Bohemian Spotted breed, and three-way crossbreds of the Black-Pied Lowland, Swedish White and Bohemian Spotted cattle. The confrontation of the confidence intervals of milk conductivity (MC) in healthy mammary glands at alpha = 0.05 showed that in the crossbreds of the Black-Pied Lowland cattle the MC was statistically significantly higher than in the breed types of the Holstein-Friesian cattle. The MC values decrease when there is a larger proportion of the blood of beef-and-dairy cattle (Slovak Spotted and Bohemian Spotted breeds). The locality where the stock was kept was found to act as an important factor underlying MC only in cases when both the geographical conditions and breed proportions were different. In a set homogenized with respect to the breeds, statistically significant differences in MC were demonstrated between the spring and summer season, spring and autumn, summer and autumn, and autumn and winter season.     

Effects of breed proportion and components of heterosis for semen traits in a composite cattle breed

The aim of this study was to estimate the non‐additive genetic effects of the dominance component of heterosis as well as epistatic loss on semen traits in admixed Swiss Fleckvieh, a composite of Simmental (SI) and Red Holstein Friesian (RHF) cattle. Heterosis is the additional gain in productivity or fitness of cross‐bred progeny over the mid‐purebred parental populations. Intralocus gene interaction usually has a positive effect, while epistatic loss generally reduces productivity or fitness due to lack of evolutionarily established interactions of genes from different breeds. Genotypic data on 38,205 SNP of 818 admixed, as well as 148 RHF and 213 SI bulls as the parental breeds were used to predict breed origin of alleles. The genomewide locus‐specific breed ancestries of individuals were used to calculate effects of breed difference as well as the dominance component of heterosis, while proxies for two definitions of epistatic loss were derived from 100,000 random pairs of loci. The average Holstein Friesian ancestry in admixed bulls was estimated 0.82. Results of fitting different linear mixed models showed including the dominance component of heterosis considerably improved the model adequacy for three of the four traits. Inclusion of epistatic loss increased the accuracy of the models only for our new definition of the epistatic effect for two traits, while the other definition was so highly correlated with the dominance component that statistical separation was impossible.     

Genomic polymorphism in Uruguayan Creole cattle using RAPD and microsatellite markers

Uruguayan Creole cattle inhabit areas that cannot sustain conventional farming. They have adapted to fragile environments and are influenced only by natural selection. In this study, random amplified polymorphic DNA (RAPD) and microsatellite (MS) markers were used to analyse Creole cattle genome polymorphism. A comparative analysis using the RAPD technique was performed in pooled DNA of three cattle breeds (Holstein Friesian, Creole and Hereford) in order to evaluate their amplification patterns. A primary screening of RAPD primers allowed us to select and use those with higher percentage of GC base composition. A total of 215 loci ranging between 300 and 2500 bp were amplified. Bandsharing frequency (BSF) among breeds showed that less related fingerprints were observed between Creole and Hereford cattle (0.77), while the highest similarity frequency corresponded to Holstein Friesian compared to Hereford (0.81). Specific RAPD bands were identified in the three DNA pools and they were tested in every individual of each breed. It may be possible to isolate and sequence these bands to create breed-specific molecular markers. The identification of multiple alleles of the MSCYP 21 in Creole cattle with an heterozygosity of He = 0.846 supported the variability of this genetic resource. The use of molecular markers such as RAPD s and microsatellites is proposed to establish genetic distance among American Creole cattle and possibly related ancestral Iberian breeds.     

渤海黑牛种群现状及其保种利用问题

渤海黑牛是肉役兼用的优良品种,被列为我国受保护的地方良种。本文重点介绍了渤海黑牛种群现状及存在的问题,并对渤海黑牛的保种途径与利用措施以及渤海黑牛的杂交改良与开发利用进行了归纳总结,认为以我国优良地方黄牛品种为基础,选育具有中国特色的黄牛肉用新品种,是我国肉牛保种及提高生产效益的必由之路,这对其它地方品种的保护与利用具有一定的借鉴意义。     

日本牛的遗传资源

本文扼要回顾了日本牛种资源的发展历史;介绍了日本牛的遗传资源状况和各主要牛种的特征特性;从日本牛的遗传可变性和遗传距离等方面分析了日本牛品种之间的遗传关系;并展望了日本黑毛和牛、日本褐牛、日本短角牛、日本无角牛、见岛牛、口子岛牛等日本牛种资源的发展前景。     

Genetic diversity and assignment tests among seven French cattle breeds based on microsatellite DNA analysis

Genetic variability and relationships among six native French cattle breeds (Abondance, Tarentaise, Villard de Lans, Montbéliarde, Limousin, and Charolais) and one foreign breed (Holstein) were investigated using 23 microsatellite markers. These breeds were also compared with four Swiss breeds genotyped in a previously published study. Interestingly, the French alpine breeds have smaller population sizes but showed higher genetic variability than the larger Holstein breed. Neighbor-joining trees and PCA (principal components analysis) showed that alpine breeds tend to cluster together. Abondance and Tarentaise breeds were closely related, whereas the Holstein was highly differentiated from all breeds analyzed. Two different assignment tests for determining the breed of origin of individuals were compared: "direct" and "exclusion-simulation" approaches. The exclusion-simulation significance test correctly assigns fewer individuals than the direct approach but provides a confidence level (e.g., P < 0.01) for each individual being assigned. Accurate assignment with high statistical confidence is required for animal traceability. Unfortunately, the accuracy of assignment greatly decreases as the threshold level of confidence of assignment increases (e.g., from P < 0.05 to P < 0.001). Assignment accuracy also greatly declines as the level of population differentiation decreases below the level often found between related breeds (e.g., F(ST) < 0.1).     

4个肉牛品种微卫星多态性分析

本研究探讨了引进牛种（西门塔尔牛、利木赞牛）和山东地方黄牛（鲁西黄牛、利鲁牛）在20个微卫星位点上的多态性。试验从不同地区的种公牛站采集鲁西黄牛、利鲁牛、利木赞牛和西门塔尔牛的血液或精液样本,分别为56、27、31和30个,共计144个样本,血液样本采用Lab-Aid基因组DNA分离试剂盒提取基因组DNA,精液样本采用高盐法提取基因组DNA。利用20个微卫星标记,采用荧光标记毛细管电泳方法,对4个肉牛品种的DNA多态性进行分析,主要研究了每个群体的遗传变异指标（等位基因数、多态信息含量和杂合度）及群体间的遗传关系（F-统计量和基因流）。结果表明,肉牛基因组DNA条带整齐,无拖尾现象,质量较好,可用于本试验。20个微卫星座位中共检测到211个等位基因,平均等位基因数为10.6个。群体的平均观测杂合度在0.6147~0.7176之间,平均期望杂合度在0.6735~0.7862之间。在所有群体中各位点的多态信息含量在0.4853~0.8714之间,平均为0.7284,但在各个群体内的差异较大。近交系数及基因流分析结果表明,4个肉牛品种近交系数较低,群体间平均近交系数为0.085,每个微卫星位点的基因流均>1。总体来看,所选用的20个微卫星座位多态信息含量高,可作为有效遗传标记用于肉牛品种间遗传多样性分析。     

Influence of variations in biological and economical parameters on beef production net returns

Net returns were defined as a function of the monetary returns (revenue) generated by the outputs less the monetary costs generated by the variable inputs. Outputs included total weaning weights of steers and heifers, weight of cull cows and weight of open heifers. Inputs included both feed and nonfeed costs. The net returns equation was incorporated as the objective function in a linear programming model. By maximizing the objective function, the breeding system that generated the highest net returns could be identified considering certain resource constraints. Breeding systems included purebred Herefords; small rotational dual purpose (SR), utilizing the breeds Angus, Pinzgauer, Gelbvieh and Tarentaise; large rotational (LR), a three-way rotational cross with the breeds Charolais, Simmental and Maine-Anjou; and Angus-sired terminal (AL) utilizing Angus as the sire breed and LR heifers as the maternal breed. Large rotational generally produced the greatest net returns, followed by SR and either AL or HE, depending on specific resource constraints (limited feed supply or herd size), calving rates, management systems, environment, beef to feed price ratios and purchased or farm-produced (inexpensive) feed utilized. Only under the conditions of a herd size constraint and farm-produced feed did AL exceed SR in net returns. Hereford had larger net returns than LR only when the two breeding systems were evaluated in an environment assumed to be reproductively stressful to LR. Ranking of breeding systems were dependent on specific conditions and indicated that one must consider each resource constraint and environment in which cattle are expected to produce before making breeding system recommendations.     

The Agersoe cattle: the last remnants of the Danish island cattle (Bos taurus)?

A phenotypically interesting strain of cattle existed on the small island of Agersoe, on the west coast of Zealand, Denmark, in the beginning of the last decade. The cattle share a great resemblance to the extinct Danish breed, the Island cattle. The objective of this study was to genetically characterize the Agersoe cattle, using microsatellites, amplified fragment length polymorphism (AFLP) and mtDNA markers, and analyse the genetic variability within the breed and the genetic relationship to 14 European breeds with focus on the Red Danish and Jutland breed. The results show diversity in nuclear markers comparable to that of modern breeds and that the Agersoe cattle are separable from the two native breeds. The absence of inbreeding and the degree of genetic diversity are taken as a sign of recent admixture. The Agersoe cattle did not exhibit a consistent association with any of the European breeds. Several arguments based on this survey have been put forward in favour of characterizing the Agersoe cattle as being the last remnants of the Danish Island Cattle.