Modern Cattle Breeding Research Articles

Milk productivity of first-calf heifers of Holstein breed depending on their genealogical lines origin

Holstein breed, which was bred in the USA and Canada has gained worldwide popularity because it has the most necessary traits for dairy farming on an industrial scale. In our country, this breed has recently been widely used to improve native domestic dairy breeds, for example, Black-and-White and Kholmogory, etc., which are well adapted to local conditions of housing and feeding. One of the widespread breed improvement methods in modern cattle breeding is line breeding. Using this method, breeders and milk producers can increase the productivity of their milking herd in a signifi cantly short period of time, ensuring growth in the economy of milk production. The purpose of the work was to study the milk productivity of fi rst-calf heifers of Holstein breed depending on their genealogical lines origin. The research was carried out at Kaluzhskaya Niva LLC in the Kaluga region, which is a specialized livestock enterprise for breeding dairy cattle. The farm is engaged in breeding cattle of Holstein breed and has the status of a breeding farm for this breed. The fi rst-calf heifers of Holstein breed were the object of the study with completed the first lactation. The total number of experimental animals was 40 animals, which were divided into two groups taking into account their genealogical lines origin. The 1st group included fi rstcalf heifers belonging to the line Wes Back Ideal 1013415 (n=24) and the 2nd group to the line Refl ection Sovereign 198998 (n=16). It was established on base the analysis of the data obtained that fi rst-calf heifers of the line Wes Back Ideal 1013415 with a higher daily milk yield had a minimum milking time and a high intensity of milk ejection. In terms of milk ejection intensity they were ahead of their herdmates from the line Refl ection Sovereign 198998 and the herd average by 0.23 and 0.09 kg/min, respectively (p > 0.05). Thus, to increase milk yield, fat content and protein content of cows Holstein breed, it is necessary to use more widely the sperm of sires of the line Wes Back Ideal 1013415. At the same time, use cows with the most suitable udder (bowl-shaped udder) for robotic milking.

Features of growth and development of young cattle depending on origin

Currently, in modern cattle breeding special importance is attached to improving the methods of using the world’s genetic resources and increasing the potential of domestic breeds. This is due to the wide spread of crossbreds with diff erent portions of blood and the lack of ways to determine the optimal genotype for further breeding. So the question of the relationship between the genotype and the productive traits of animals is always relevant. The purpose of the research was to study the growth and development of heifers of Black-and-White breed of diff erent origin under the conditions of the natural and climatic zone of the Central Caucasus in the Republic of North Ossetia-Alania. In order to carry out the experiment, 3 groups of newborn calves were formed. The 1st control group included purebred heifers of Black-and-White breed, the 2nd experimental group included heifers of Black-and-White breed with a blood ratio of 1/2 of Holstein breed, and the 3rd experimental group included heifers of Black-and-White breed with a blood ratio of 3/4 of Holstein breed. Experimental animals were fed taking into account the planned gains in live weight. The features of growth and development were studied by individual weighing and taking measurements at diff erent age periods. On the basis of weighing the live weight gains were calculated, and according to the measurements the body conformation indices were calculated. Studies have shown that the superiority of heifers of the 3rd experimental group over herdmates of the 1st control group in the fi rst months of life was 6,2 %, and animals of the 2nd experimental group were 2,7 % better than purebred analogues in this indicator. In the future, this diff erence increased and by the age of 18 months the diff erences between the groups were 7,4 and 9,6 %, respectively. In general, it has been established that the use of Holstein breed gene pool contributes to the increase in the growth and development of young animals. Heifers with 3/4 blood portion of Holstein breed were distinguished by the best live weight gains and body conformation indices.

The frequency of somatotropic cascade polymorphic genes appearance and the meatiness and health of Auliekol and Kazakh white-headed cattle

Modern cattle breeding is characterised by the need to select specific animals with extraordinary meat performance, as well as an ability to adapt to the natural environment in order to develop new, improved breeds. As Auliekol and Kazakh white-head races are especially interesting to farmers in Kazakhstan, we chose to study three polymorphs of somatotropic cascade genes: bPit-1, bGH and bGHR in the whole blood of such animals, which are known to have an impact on meatiness and good health. The following polymorphic variations were revealed: bPit-1-HinFI and bPit1-HinF1; bGH-AluIV and bGH-AluIL, as well as bGHR-SspIY and bGHR-SspIF. The agreement of the observed frequencies of genotypes with those theoretically expected according to the Hardy-Weinberg law of balance was also assessed. The final task was to compare the frequency of appearance of polymorphic genes alleles’ with somatotropic cascade distribution in the examined animals. Our studies have shown that the frequency of the genotypes’ occurrence in both races is in compliance with the frequency based on the law of balance. We suggest that the polymorphisms of the cascade network may result from the breeding progress achieved by directional selection, therefore conditioning high values of meat and health characteristics in the examined cattle.

ANALYSIS OF THE QUALITY OF SEXED BULL SEMEN BY COMPUTER-ASSISTED SEMEN ANALYSIS-CASA

The quality of the ejaculate is determined by examination of the macroscopic (volume, density, color, smell) and microscopic properties of the sperm (concentration of spermatozoa in 1 ml and the total number of spermatozoa in the ejaculate, morphology, vitality, mobility of spermatozoa and integrity of the acrosomal membrane). Computer assisted semen analysis (CASA) is an automated system that measures sperm motility, kinetics and concentration. Some systems have modifications for evaluating the morphological characteristics of spermatozoa. The assessment of morphological characteristics of spermatozoa can be performed by microscopic examination (presence of normal and pathological spermatozoa, integrity of sperm cell membrane and acrosome abnormalities). The Blom method, as the method of the staining of the sperm smear with eosin and nigrosine, determines the vitality of the semen. In modern cattle breeding, sexed bull semen (semen from which desired gender of calf will be delivered) is used more and more. The analysis of sexed semen, and especially the comparison of its quality with conventional semen, is an increasingly common requirement on the cattle production market. The aim of the work was to examine the quality of 15 samples of sexed bull semen, originating from imports. The tests included determination of concentration and kinetics using the CASA system, as well as assessment of vitality and morphological characteristics by Blom staining. The average sperm concentration in 15 samples was 19.61x106/ml of ejaculate. The total motility was 39.42%, while the number of immobile spermatozoa in the samples was 60.58%. The number of morphologically normal spermatozoa varied from 2.91x106 to 6.11x106, and the percentage of pathological spermatozoa from 8% to 28%. Taking into account the results obtained and the absence of standards related to sexed semen in the currently valid Regulation on the manner of marking of sperm, the manner of keeping records on sperm production, as well as on the conditions that must be met by animal sperm in terms of quality (Official Gazette of the Republic of Serbia, 38/14), it is necessary to carry out more frequent analyzes of sexed semen using the CASA method in order to obtain values that would become an integral part of the Regulation and thereby facilitate the manipulation of sexed semen on the market.

Long-term artificial selection of Hanwoo (Korean) cattle left genetic signatures for the breeding traits and has altered the genomic structure

Indigenous Korean breeds such as Hanwoo (Korean) cattle have adapted to their local environment during the past 5000 years. In the 1980s, the National Genetic Improvement Program was established to develop a modern economic breed for beef production in Korea through artificial selection. This process is thought to have altered the genomic structure of breeding traits over time. The detection of genetic variants under selection could help to elucidate the genetic mechanism of artificial selection in modern cattle breeds. Indigenous Hanwoo cattle have adapted in response to local natural and artificial selection during a 40-year breeding program. We analyzed genomic changes in the selection signatures of an unselected population (USP; n = 362) and a selected population (KPN; n = 667) of Hanwoo cattle. Genomic changes due to long-term artificial selection were identified using a genome-wide integrated haplotype score (iHS) and a genome-wide association study (GWAS). Signatures of recent selection were detected as positive (piHS > 6) or negative (piHS < –6) iHS scores spanning more than 46 related genes in KPN cattle, but none in USP cattle. A region adjacent to the PLAG1 gene was found to be under strong selection for carcass weight. The GWAS results also showed a selection signature on BTA14, but none on BTA13. Pathway and quantitative trait locus analysis results identified candidate genes related to energy metabolism, feed efficiency, and reproductive traits in Hanwoo cattle. Strong selection significantly altered Hanwoo cattle genome structural properties such as linkage disequilibrium (LD) and haplotypes through causal mutation for target traits. Haplotype changes of genome structure which are changes of ancestral allele to derived alleles due to selection were clearly identified on BTA13 and BTA14; however, the structure of the LD block was not clearly observed except BTA14. Thus, selection based on EBVs would be working very well in Hanwoo cattle breeding program appears to have been highly successful.

Productive longevity and lifelong productivity of daughters of Holstein bulls-producers with different variants of kappa-casein genotype

Reducing age of economic use of cattle is one of the problems of modern cattle breeding. One of the options for increasing productivity in cattle breeding is breeding for productive longevity, through the search and use of genetic markers. We have selected the genotype of the kappa-casein protein as a genetic marker. If the influence of allelic forms of this gene on milk productivity is well studied, then the question of its interaction with lifelong productivity indicators remains open. The purpose of our research was to determine the effect of the kappa-casein genotype of Holstein bulls on the longevity and lifelong productivity of their daughters. The analysis included the indicators of 1,476 animals with at least one completed lactation. Depending on the linear affiliation and genotype of the kappa-casein gene of the breeding bulls, their daughters were divided into 4 groups. The frequency of occurrence of the CSN3A allele in the studied bulls was 81.91%, the CSN3B allele — 18.09%. The highest frequency of occurrence of the desired CSN3B allele was in bulls of the Reflection Sovering line — 20.83%, which is 3.69% more than in bulls of the Vis Back Ideal line. The analysis of the life expectancy of animals showed that it turned out to be the longest in the daughters of bulls from the Reflection Sovering line (2.46 lactation) and especially with the CSN3B genotype — 2.59 lactation. The greatest lifetime milk yield (18,490 kg) was characterized by the daughters of bulls with the CSN3AB genotype in the Reflection Sovering line. Their superiority over animals from the same lineage, but with the CSN3AA genotype, was 1004 kg, the Vis Back Ideal line with the CSN3AA genotype was 1472 kg and with the CSN3AB genotype was 1343 kg. The highest average milk yield in 1 day of a cow’s life was also in animals of the Reflection Sovering line with the CSN3AB genotype — 9.05 kg.

The WC1 γδ T cell pathogen receptor of ruminants is preserved in the genome of ancient extinct auroch.

The work reported here investigated the γδ T cell-specific cell surface receptor known as workshop cluster 1 (WC1) in the extinct Auroch and compared the gene sequences to those in modern cattle breeds. These molecules function as hybrid pattern recognition receptors (PRR), binders of microbial pathogens, and as signaling co-receptors of the T cell antigen receptor (TCR), directing the immune responses by γδ T cell subsets. Sequences in the Auroch genome included both WC1.1 and WC1.2-like a-patterned scavenger receptor cytsteine-rich (SRCR) domains as well as the more conserved b, c, d, and e-patterned SRCR domains. While there was much sequence homology with bovine WC1 genes, there are also unique Auroch genes based on the signature a1 SRCR domain sequences that are used to identify individual WC1 genes. There was also conservation of genes coding for Type I and II intracytoplasmic endodomains although no evidence for gene sequences for Type III endodomains or the extracellular 6 SRCR domains that are associated with this endodomain. This particular WC1 molecule has been proposed to represent the most ancient WC1, and thus, it is particularly interesting that it is apparently missing in the Auroch genome although it could be due to incomplete sequencing. Overall, the results suggest that while WC1 genes have been preserved from Ancient Auroch to modern cattle, they may have co-evolved perhaps as a result of differing pathogen or environmental antigen exposure.

Breed Ancestry, Divergence, Admixture, and Selection Patterns of the Simbra Crossbreed.

In this study, we evaluated an admixed South African Simbra crossbred population, as well as the Brahman (Indicine) and Simmental (Taurine) ancestor populations to understand their genetic architecture and detect genomic regions showing signatures of selection. Animals were genotyped using the Illumina BovineLD v2 BeadChip (7K). Genomic structure analysis confirmed that the South African Simbra cattle have an admixed genome, composed of 5/8 Taurine and 3/8 Indicine, ensuring that the Simbra genome maintains favorable traits from both breeds. Genomic regions that have been targeted by selection were detected using the linkage disequilibrium-based methods iHS and Rsb. These analyses identified 10 candidate regions that are potentially under strong positive selection, containing genes implicated in cattle health and production (e.g., TRIM63, KCNA10, NCAM1, SMIM5, MIER3, and SLC24A4). These adaptive alleles likely contribute to the biological and cellular functions determining phenotype in the Simbra hybrid cattle breed. Our data suggested that these alleles were introgressed from the breed's original indicine and taurine ancestors. The Simbra breed thus possesses derived parental alleles that combine the superior traits of the founder Brahman and Simmental breeds. These regions and genes might represent good targets for ad-hoc physiological studies, selection of breeding material and eventually even gene editing, for improved traits in modern cattle breeds. This study represents an important step toward developing and improving strategies for selection and population breeding to ultimately contribute meaningfully to the beef production industry.

Analyzing the exome heterogeneity of cattle immunity genes with the method of flow-cell sequencing

Toll-like receptors belong to the pattern-recognition receptors (PRRs), which have evolved to recognize conserved features of bacterial and viral molecules. We used the approach developed earlier to screen for the polymorphism in TLR genes in a representative set of historical and modern cattle breeds from Russia. The method pipeline included the steps of obtaining the overlapping amplification products from the coding regions of all ten bovine TLR genes, their subsequent purification and normalization. While the anti-bacterial group included TLR1, -2, -4, -5 and -6, the anti-viral group compressed TLR3, -7, -8, -9 and -10 (in spite of its unclear specificity). Animals from the about seven breeds, both bulls and cows, was used for analysis. The samples from the pooled genomic DNA were sequenced on the PacBio platform. After identification of variations, Bayesian analysis was carried out, followed by filtration on quality of sequencing. The 5–36 structural variants of TLRs were annotated according to their biological significance. Both new and already identified sites of variability, already annotated and documented in dbSNP, have been found. The data are needed for further breeding of local breeds in Russia with respect to their natural resistance to various diseases.

THE RESULTS OF THE EMBRYO TRANSFER TO HEIFERS FROM THE AYRSHIRE BREED

Dairy cattle’s breeding is an important industry, since it is providing milk and meat to population. Modern cows are significantly different from their ancestors in biology, behavior and in productivity. The scientific approach to feeding, condition of content and formation of focused heredity contributed to increasing the cows’ productivity. During the mammary gland formation and sexual cycles manifestation, puberty occurs, which makes it possible to obtain offspring and secretion of milk for feeding calves. The modern cows are capable of producing milk for their calves and for feeding people. The appearance of record cows, giving about 100 kg per day, and during lactation more than 32 tons of milk serves as an example for achieving such indicators of production. There are negative effects in reproduction biology, which takes place in modern cattle breeding. In order to breed highly productive cows, it is important to increase their livestock by intensive selection. Modernity is such that fertility is reduced due to cows’ reproductive functions inhibition. Modern practice shows that it is possible to introduce methods of obtaining several calves from one cow. It is generally accepted for this purpose use new reproduction methods, for example transplantation of embryos with high genetic potential. This technique is widely used in biotechnology of cows breeding. We have tested the method of preparing and conducting embryo transfer to heifers from 13 to 16 months old in the Kuban Agro-Association. The article presents indicators of heifer. It was revealed that not all animals reacted positively to superstimulation. Embryo transplantation showed that 35.1% of embryos survived after embryo transfer. Economic calculations have shown that for the rapid formation of a highly productive herd on the farm, it is advisable to use Ayrshire breed heifers capable of raising embryos and giving birth to healthy calves as recipients.

Genome-wide scan reveals divergent selection among taurine and zebu cattle populations from different regions.

In this study, to identify genomic signatures of divergent selection, we genotyped 10 cattle breeds/populations (n=275), representing eight Ethiopian cattle populations (n=229) and two zebu populations (n=46) adapted to tropical and sub-tropical environments, using the high-density single-nucleotide polymorphisms (SNPs) derived mainly from Bos indicus breeds, and using five reference taurine breeds (n=212). Population genetic differentiation (FST ) values across sliding windows were estimated between zebu and reference combined taurine breeds. The most differentiated regions (FST ≥0.53), representing the top 1% smoothed FST values, were considered to represent regions under diversifying selection. In total, 285 and 317 genes were identified in the comparisons of Ethiopian cattle with taurine and Asian zebu with taurine respectively. Some of these genes are involved in stress responses/thermo-tolerance and DNA damage repair (HSPA4, HSF1, CMPK1 and EIF2AK4), pigmentation (ERBB3 and MYO1A), reproduction/fertility (UBE2D3, ID3 and PSPC1), immune response (PIK3CD and AKIRIN2) and body stature and size (MBP2, LYN and NPM1). Additionally, the candidate genes were associated with functional terms (e.g. cellular response to stress, DNA repair, inflammatory response) important for physiological adaptation to environmental stresses. The results of our study may shed light on the influence of artificial and natural selection in shaping the genomic diversity of modern cattle breeds and also may serve as a basis for further genetic investigation of traits of tropical adaptation in cattle.

English

In modern cattle breeding, assisted reproductive technologies in small ruminants have been used even out-of-season breeding, but in emerging countries these technologies have been mainly used for estrous synchronization and artificial insemination. However, in the last 30 years, significant progress in the matter of transfers of in vivo derived and in vitro produced embryos has been achieved. Currently, eight donor embryos are obtained by goat, due to the physiological knowledge of the presence of dominant follicles; above alter results recovered embryos (4 embryos / donor). Whereas, the goat has the advantage of presenting a shorter interval between generations compared to cow; this promote more research in in vitro fertilization, and overcome the limitations presented in a traditional embryo transfer. However cloning and transgenesis, are two techniques that will begin to have a commercial application, because goats can be used as bioreactors to produce milk with specific proteins to develop drugs. The objective of this study was to establish and describe in a general way the use of these techniques in goats, to promote their use so as to achieve genetic improvement in goats. &nbsp; Key words: Reproductive technologies, goats, estrous synchronization, embryo transfer.

Complete mitochondrial genome of wild aurochs (Bos primigenius) reconstructed from ancient DNA

Extinct aurochs (Bos primigenius), accepted as the ancestor of domestic cattle, was one of the largest wild animals inhabiting Europe, Asia and North Africa. The gradual process of aurochs extinction finished in Poland in 1627, were the last recorded aurochs, a female, died. Some aspects of cattle domestication history and the distribution of aurochs genetic material among modern cattle breeds still remain unclear. Analyses of ancient DNA (aDNA) from bone sample deliver new genetic information about extinct wild aurochs as well as modern cattle phylogeny. DNA was extracted from a fragment of aurochs fossil bone found in the Pisz Forest, Poland. The sample was radiocarbon-dated to about 1500 yBP. The aDNA was used for Whole Genome Amplification in order to form a DNA bank. Auroch mitochondrial DNA sequences were amplified using sets of 41 primers overlapping the whole mtDNA, cloned and sequenced. The sequence of the whole mitochondrial genome was reconstructed and deposed in GenBank [GenBank:JQ437479]. Based on the phylogenetic analyses of the Bovine mitochondrial genomes, a phylogenetic tree was created. As expected, the tree clearly shows that the mtDNA sequence of the analyzed PWA (Polish Wild Aurochs) individual belongs to haplogroup P. In the course of the comparative mtDNA analysis we identified 30 nucleotide marker positions for haplogroup P and nine unique PWA differences compared to the two remaining haplotype P representatives. Our analysis provides the next step to the reconstruction of the demographic history of this extinct but still exciting species.

Bovine Polledness – An Autosomal Dominant Trait with Allelic Heterogeneity

The persistent horns are an important trait of speciation for the family Bovidae with complex morphogenesis taking place briefly after birth. The polledness is highly favourable in modern cattle breeding systems but serious animal welfare issues urge for a solution in the production of hornless cattle other than dehorning. Although the dominant inhibition of horn morphogenesis was discovered more than 70 years ago, and the causative mutation was mapped almost 20 years ago, its molecular nature remained unknown. Here, we report allelic heterogeneity of the POLLED locus. First, we mapped the POLLED locus to a ∼381-kb interval in a multi-breed case-control design. Targeted re-sequencing of an enlarged candidate interval (547 kb) in 16 sires with known POLLED genotype did not detect a common allele associated with polled status. In eight sires of Alpine and Scottish origin (four polled versus four horned), we identified a single candidate mutation, a complex 202 bp insertion-deletion event that showed perfect association to the polled phenotype in various European cattle breeds, except Holstein-Friesian. The analysis of the same candidate interval in eight Holsteins identified five candidate variants which segregate as a 260 kb haplotype also perfectly associated with the POLLED gene without recombination or interference with the 202 bp insertion-deletion. We further identified bulls which are progeny tested as homozygous polled but bearing both, 202 bp insertion-deletion and Friesian haplotype. The distribution of genotypes of the two putative POLLED alleles in large semi-random sample (1,261 animals) supports the hypothesis of two independent mutations.

The global distribution and phylogeography of Mycobacterium bovis clonal complexes

The consequences of the clonality of the Mycobacterium tuberculosis complex are described and, in particular, the identification of clonal complexes. Clonal complexes are groups of strains all descended from a single cell that was the most recent common ancestor (MRCA) of the clonal complex and all bearing characteristics derived from the MRCA. Three clonal complexes of Mycobacterium bovis have been identified and called African 1, African 2 and European 1. Members of each clonal complex have a distinct spoligotype signature and are identified by a unique deletion present in each member of the clonal complex. The African 1 and African 2 clonal complexes are geographically localised to Central-West Africa and East Africa, respectively and have not been found in cattle outside of these regions. However, the European 1 clonal complex is globally distributed and has been identified in the British Isles, former British colonies, The Americas as well as Kazakhstan and Korea. It is suggested that modern cattle breeds, such as Herefords, bred in the UK in the 18th Century, would provide a good vehicle for the global distribution of this closely related group of strains. The phylogeography of M. bovis and M. tuberculosis are compared and in particular the diversity of M. tuberculosis in Africa, compared with the localised dominance of M. bovis clonal complexes, is highlighted. Finally, the practical use of M. bovis clonal complexes is reviewed, however, a more significant use of M. bovis clonal complexes is to generate testable hypotheses to understand the pathogenicity and spread of this important veterinary pathogen. This first look at the phylogeography of M. bovis clonal complexes has shown surprising geographical localisation of molecular types but also hints strongly that much of the worldwide distribution of bovine pathogen resulted from human trade in cattle within the last 200years.

Genomic characteristics of cattle copy number variations

BackgroundCopy number variation (CNV) represents another important source of genetic variation complementary to single nucleotide polymorphism (SNP). High-density SNP array data have been routinely used to detect human CNVs, many of which have significant functional effects on gene expression and human diseases. In the dairy industry, a large quantity of SNP genotyping results are becoming available and can be used for CNV discovery to understand and accelerate genetic improvement for complex traits.ResultsWe performed a systematic analysis of CNV using the Bovine HapMap SNP genotyping data, including 539 animals of 21 modern cattle breeds and 6 outgroups. After correcting genomic waves and considering the pedigree information, we identified 682 candidate CNV regions, which represent 139.8 megabases (~4.60%) of the genome. Selected CNVs were further experimentally validated and we found that copy number "gain" CNVs were predominantly clustered in tandem rather than existing as interspersed duplications. Many CNV regions (~56%) overlap with cattle genes (1,263), which are significantly enriched for immunity, lactation, reproduction and rumination. The overlap of this new dataset and other published CNV studies was less than 40%; however, our discovery of large, high frequency (> 5% of animals surveyed) CNV regions showed 90% agreement with other studies. These results highlight the differences and commonalities between technical platforms.ConclusionsWe present a comprehensive genomic analysis of cattle CNVs derived from SNP data which will be a valuable genomic variation resource. Combined with SNP detection assays, gene-containing CNV regions may help identify genes undergoing artificial selection in domesticated animals.

The Complete Mitochondrial Genome of an 11,450-year-old Aurochsen (Bos primigenius) from Central Italy

BackgroundBos primigenius, the aurochs, is the wild ancestor of modern cattle breeds and was formerly widespread across Eurasia and northern Africa. After a progressive decline, the species became extinct in 1627. The origin of modern taurine breeds in Europe is debated. Archaeological and early genetic evidence point to a single Near Eastern origin and a subsequent spread during the diffusion of herding and farming. More recent genetic data are instead compatible with local domestication events or at least some level of local introgression from the aurochs. Here we present the analysis of the complete mitochondrial genome of a pre-Neolithic Italian aurochs.ResultsIn this study, we applied a combined strategy employing both multiplex PCR amplifications and 454 pyrosequencing technology to sequence the complete mitochondrial genome of an 11,450-year-old aurochs specimen from Central Italy. Phylogenetic analysis of the aurochs mtDNA genome supports the conclusions from previous studies of short mtDNA fragments - namely that Italian aurochsen were genetically very similar to modern cattle breeds, but highly divergent from the North-Central European aurochsen.ConclusionsComplete mitochondrial genome sequences are now available for several modern cattle and two pre-Neolithic mtDNA genomes from very different geographic areas. These data suggest that previously identified sub-groups within the widespread modern cattle mitochondrial T clade are polyphyletic, and they support the hypothesis that modern European breeds have multiple geographic origins.

251 METHYLATION PATTERN OF A DIFFERENTIALLY METHYLATED REGION LOCATED IN THE LAST EXON OF THE Igf2 GENE IN OOCYTES FROM NELLORE COWS

Assisted reproductive technologies are essential in modern cattle breeding. The relevance of in vitro embryo production (IVP) has been increasing around the world, particularly in Brazil. Acknowledging the positive effect of IVP regarding the utilization of female reproductive potential, its productivity can be improved. Methylation pattern of DNA in oocytes is a key factor for the improvement of IVP efficiency because it is related to oocyte competence. The objective of this study was to evaluate the methylation pattern of a differentially methylated region (DMR) located in the exon 10 of the imprint gene IGF2 in immature and in vitro-maturated oocytes from different follicle sizes. Small follicles (1-3 mm in diameter) and large follicles (≥8.1 mm in diameter) were dissected from slaughterhouse ovaries, and the COC were removed. Immature and in vitro-maturated oocytes, presenting the first polar body, were denuded and frozen in PBS at -80°C until DNA extraction. After extraction, DNA was treated with sodium bisulfite using EZ DNA Methylation™ Kit (Zymo Research, Orange, CA, USA). Bisulfite-treated DNA was amplified in a 2-round PCR strategy (nested-PCR), the amplicons purified with Geneclean® III Kit (MP Biomedicals, Irvine, CA, USA), cloned using pGEM®-T Easy Vector System (Promega, Madison, WI, USA), and sequenced. The number of follicles and in vitro maturation data were analyzed with chi-square test, and the methylation status of 27 CpG islands was analyzed with Student (normal distribution) or Mann-Whitney tests in the Prophet software (BBN Systems and Technologies, Cambridge, MA, USA). Cumulus-oocyte complexes from ≥8.1-mm follicles presented greater percentages of viable oocytes (40.5%) and nuclear maturation (60.6%) (P ≤ 0.05). Immature oocytes from 1- to 3-mm follicles were less methylated (33.33%) than those from ≥8.1-mm follicles (83.69%). After in vitro maturation, oocytes from ≥8.1-mm follicles were less methylated (18.51%) than the immature oocytes from ≥8.1-mm follicles (83.69%) and 1- to 3-mm maturated oocytes (49.62%). The less methylated pattern in the oocytes from ≥8.1-mm maturated follicles can be associated with greater competency of those oocytes, because this was the expected pattern. The lower level of methylation in the immature oocytes group (1- to 3-mm follicles) can be associated with the incomplete establishment of imprinting reprogramming pattern. Finally, we concluded that the methylation pattern of DMR, in the last exon of the IGF2 gene, can be used as a molecular marker for epigenetic reprogramming status in oocytes, helping the development of new IVP protocols. Supported by Embrapa Genetic Resources and Biotechnology and CAPES.

Gestation length in first calving Aberdeen Angus x Limousin and Limousin x Aberdeen Angus heifers mated using a synchronised artificial insemination programme

Recent changes to beef production subsidy schemes in the UK has focussed attention on the fertility and reproductive output of suckler beef systems in an attempt to ensure future financial sustainability. Adoption of modern cattle breeding technologies may be more common in the future than they have been in the past as a result of this renewed focus on commercial profitability rather than subsidy reliance. However, relatively little information is available on the biological parameters encountered when modern breeding approaches are employed within commercial crossbred suckler beef management systems in the UK. Previous work (Penny, 2005) has detailed the development of either a triple or double synchronised artificial insemination (AI) programme suitable for use with both multiparous suckler cows and first calving heifers managed as a commercial spring calving suckler herd. The objective of the current report is to detail the effects of breed type and calf sex on average gestation length (GL) in first calving crossbred suckler replacement heifers when mated using a synchronised AI programme.

Cattle domestication in the Near East was followed by hybridization with aurochs bulls in Europe

Domesticated cattle were one of the cornerstones of European Neolithisation and are thought to have been introduced to Europe from areas of aurochs domestication in the Near East. This is consistent with mitochondrial DNA (mtDNA) data, where a clear separation exists between modern European cattle and ancient specimens of British aurochsen. However, we show that Y chromosome haplotypes of north European cattle breeds are more similar to haplotypes from ancient specimens of European aurochsen, than to contemporary cattle breeds from southern Europe and the Near East. There is a sharp north-south gradient across Europe among modern cattle breeds in the frequencies of two distinct Y chromosome haplotypes; the northern haplotype is found in 20 out of 21 European aurochsen or early domestic cattle dated 9500-1000 BC. This indicates that local hybridization with male aurochsen has left a paternal imprint on the genetic composition of modern central and north European breeds. Surreptitious mating between aurochs bulls and domestic cows may have been hard to avoid, or may have occurred intentionally to improve the breeding stock. Rather than originating from a few geographical areas only, as indicated by mtDNA, our data suggest that the origin of domestic cattle may be far more complex than previously thought.