Enriching the captive elephant population genetic pool through artificial insemination with frozen-thawed semen collected in the wild

The first successful AI in an elephant was reported in 1998, using fresh semen. Since then almost 40 calves have been produced through AI in both Asian and African elephants worldwide. Following these successes, with the objective of enriching the captive population with genetic material from the wild, we evaluated the possibility of using frozen-thawed semen collected from wild bulls for AI in captivity. Semen, collected from a 36-yr-old wild African savanna elephant (Loxodonta africana) in South Africa was frozen using the directional freezing technique. This frozen-thawed semen was used for four inseminations over two consecutive days, two before and two after ovulation, in a 26-yr-old female African savanna elephant in Austria. Insemination dose of 1200 × 10⁶ cells per AI with 61% motility resulted in pregnancy, which was confirmed through ultrasound examination 75, 110 and 141 days after the AI procedure. This represents the first successful AI using wild bull frozen-thawed semen in elephants. The incorporation of AI with frozen-thawed semen into the assisted reproduction toolbox opens the way to preserve and transport semen between distant individuals in captivity or, as was done in this study, between wild and captive populations, without the need to transport stressed or potentially disease-carrying animals or to remove animals from the wild. In addition, cryopreserved spermatozoa, in combination with AI, are useful methods to extend the reproductive lifespan of individuals beyond their biological lifespan and an important tool for genetic diversity management and phenotype selection in these endangered mammals.     

Cost comparison of natural service sires and artificial insemination for dairy cattle reproductive management

Despite the widespread popularity of artificial insemination, many dairymen still prefer the use of natural service sires due to a variety of reasons, including a common perception that it is easier to manage and less expensive than AI. Little has been done to estimate the explicit and implicit costs, including the probable loss of genetic progress associated with the use of natural service sires in dairy herds. A partial budget approach was used to stochastically model the expected costs and returns of reproductive management options in large, western, Holstein dairies. Option one was natural service sires managed using currently recommended approaches including breeding soundness evaluations, bull vaccination, and a rotational breeding system. Option two was an AI system using a modified Presync-Ovsynch timed AI program in conjunction with estrus detection and inseminations performed by a commercial route breeder. Stochastic variables in the model included the cost of the lactating ration and purchased bulls, as well as the value received for milk, market bulls, and net merit gains. All other variables were treated deterministically. Under the model's assumptions, the use of natural service sires averaged approximately US dollar 10 more in cost per cow per year as compared to an AI program. Sixty percent of the time, AI was less expensive than using bulls. However, there was wide variation in expected differences in cost between the two systems with net merit estimates having the largest impact, followed by prices received for milk sold and market bulls.     

Impact of genetic selection on management of boar replacement

Boars in an artificial insemination centre have been selected for their superior genetic potential, with 'superior' being defined as having traits the customer wants transmitted to his herd. The ability to meet the customers' needs depends on the heritability of the trait, the geneticist's success in devising a selection scheme for the trait in balance with other economically important traits, and the boar's ability to produce sperm that can fertilise oocytes. Genetic evaluation research over the past 20 years has greatly increased the number of traits for which a boar can be selected: currently in the Canadian national program, these include age at 100 kg, backfat at 100 kg, feed efficiency, lean yield and litter size. In the near future, traits that are very likely to be added to this selection list include piglet survival, marbling, loin eye area and structure traits. In Canada, sires are ranked on two estimated breeding value (EBV) indices; one, focused on development of terminal sire lines, is based on the growth and yield traits and another, primarily focused on maternal line development, de-emphasises these traits and incorporates litter size. Boars that are in Canadian AI centres because of their excellent growth traits are typically in the top 5-10% of the national population for terminal sire line index, but they may be only average or substandard for litter size. Conversely, boars selected to be in the top 5-10% for conveying such reproductive traits as litter size may only be in the top 33% for growth traits. The more offspring from a superior boar in either of these indices, the faster the population average for the trait improves. The original sire gets knocked out of the elite group, is culled and replaced by a higher ranked young boar from the now improved general population. Although genetic superiority should govern an AI centre's selection and culling of boars, decision-making in real life is seldom that simple. Selection criteria may be contradictory as above, or a boar with truly superior traits may be excluded because a newly-developed molecular genetics test determines he carries an undesirable gene such as PSS, RN or others being developed. Selection for terminal sire or maternal line traits can ignore important practical factors that affect an AI centre--boars with superior genetics may not produce good semen because skeletal or penile problems prevent ejaculation, or because sperm production is poor due to a genetic flaw, disease, or some other cause. Interestingly, selection pressure for one trait may inadvertently select for a trait that is linked but whose linkage is unrecognised, and such unintentionally selected genes could benefit, harm, or have no effect on production traits. An AI centre serving a variety of customers must select boars in anticipation of their customers' needs (including new, foreign and niche markets). A centre should also review its genetic evaluation results and progeny records, both to critique its own selection success and to try to detect unexpected linkages. Finally, an AI centre needs to predict its own future, selecting not just for production traits for the swine producer, but also for factors that enhance the centre's efficiency including boar conformation and temperament, and sperm quantity, quality and hardiness. Can we select for efficiency? Our colleagues in dairy cattle AI evaluate bull performance--should the swine industry consider evaluation of male fertility traits?     

Embryo production and possible species preservation by nuclear transfer of somatic cells isolated from bovine semen

Somatic cells in semen are a potential source of nuclei for nuclear transfer to produce genetically identical animals; this is especially important when an animal has died and the only viable genetic material available is frozen semen. Usefulness of somatic cells obtained from fresh (cultured) and frozen (isolated, not cultured) bovine semen for nuclear transfer was evaluated. Twelve ejaculates were collected from nine bulls representing three breeds: Charolais, Brahman, and crossbred Rodeo bull. All samples were processed immediately and cell growth was obtained from seven of the twelve ejaculates (58.3%). Cells from three bulls (with the best growth rates) were evaluated by optical microscopy and used in cloning experiments. In culture, these cells exhibited classic epithelial morphology and expressed cytokeratin and vimentin, indicating they were of epithelial origin. When cells from the three bulls were used as donor cells, 15.9% (18/113), 34.5% (29/84), and 14.4% (13/90) of the fused embryos developed into blastocysts, respectively. Of the blastocyst stage embryos, 38.9% (7/18), 72.4% (21/29), and 61.5% (8/13) hatched, respectively. Somatic cells isolated (not cultured) from frozen bovine semen were also used in the cloning experiments. Although cleavage occurred, no compact morulae or blastocysts were obtained. In conclusion, epithelial cell growth was obtained from fresh bovine ejaculates with relatively high efficiency. Somatic cells from semen can be used as nucleus donors to produce cloned blastocyst-stage embryos.     

Embryo production and possible species preservation by nuclear transfer of somatic cells isolated from bovine semen

Somatic cells in semen are a potential source of nuclei for nuclear transfer to produce genetically identical animals; this is especially important when an animal has died and the only viable genetic material available is frozen semen. Usefulness of somatic cells obtained from fresh (cultured) and frozen (isolated, not cultured) bovine semen for nuclear transfer was evaluated. Twelve ejaculates were collected from nine bulls representing three breeds: Charolais, Brahman, and crossbred Rodeo bull. All samples were processed immediately and cell growth was obtained from seven of the twelve ejaculates (58.3%). Cells from three bulls (with the best growth rates) were evaluated by optical microscopy and used in cloning experiments. In culture, these cells exhibited classic epithelial morphology and expressed cytokeratin and vimentin, indicating they were of epithelial origin. When cells from the three bulls were used as donor cells, 15.9% (18/113), 34.5% (29/84), and 14.4% (13/90) of the fused embryos developed into blastocysts, respectively. Of the blastocyst stage embryos, 38.9% (7/18), 72.4% (21/29), and 61.5% (8/13) hatched, respectively. Somatic cells isolated (not cultured) from frozen bovine semen were also used in the cloning experiments. Although cleavage occurred, no compact morulae or blastocysts were obtained. In conclusion, epithelial cell growth was obtained from fresh bovine ejaculates with relatively high efficiency. Somatic cells from semen can be used as nucleus donors to produce cloned blastocyst-stage embryos.     

Application of Testis Germ Cell Transplantation in Breeding Systems of Food Producing Species: A Review

A major benefit of advanced reproduction technologies (ART) in animal breeding is the ability to produce more progeny per individual parent. This is particularly useful with animals of high genetic merit. Testis germ cell transplantation (TGCT) is emerging as a novel reproductive technology with application in animal breeding systems, including the potential for use as an alternative to artificial insemination (AI), an alternative to transgenesis, part of an approach to reducing generation intervals, or an approach toward development of interspecies hybrids. There is one major difference in TGCT between rodents and some other species associated with immunotolerance in heterologous transplantation. In particular, livestock and aquatic species do not require an immunesuppression procedure to allow donor cell survival in recipient testis. Testicular stem cells from a genetically elite individual transplanted into others can develop and produce a surrogate male—an animal that produces the functional sperm of the original individual.

Spermatozoa produced from testis stem cells are the only cells in the body of males that can transmit genetic information to the offspring. The isolation and genetic manipulation of testis stem cells prior to transplantation has been shown to create transgenic animals. However, the current success rate of the transplantation procedure in livestock and aquatic species is low, with a corresponding small proportion of donor spermatozoa in the recipient's semen. The propagation of donor cells in culture and preparation of recipient animals are the two main factors that limit the commercial application of this technique. The current paper reviews and compares recent progress and examines the difficulties of TGCT in both livestock and aquatic species, thereby providing new insights into the application of TGCT in food producing animals.     

Perspectives for artificial insemination and genomics to improve global swine populations

Civilizations throughout the world continue to depend on pig meat as an important food source. Approximately 40% of the red meat consumed annually worldwide (94 million metric tons) is pig meat. Pig numbers (940 million) and consumption have increased consistent with the increasing world population (FAO 2002). In the past 50 years, research guided genetic selection and nutrition programs have had a major impact on improving carcass composition and efficiency of production in swine. The use of artificial insemination (AI) in Europe has also had a major impact on pig improvement in the past 35 years and more recently in the USA. Several scientific advances in gamete physiology and/or manipulation have been successfully utilized while others are just beginning to be applied at the production level. Semen extenders that permit the use of fresh semen for more than 5 days post-collection are largely responsible for the success of AI in pigs worldwide. Transfer of the best genetics has been enabled by use of AI with fresh semen, and to some extent, by use of AI with frozen semen over the past 25 years. Sexed semen, now a reality, has the potential for increasing the rate of genetic progress in AI programs when used in conjunction with newly developed low sperm number insemination technology. Embryo cryopreservation provides opportunities for international transport of maternal germplasm worldwide; non-surgical transfer of viable embryos in practice is nearing reality. While production of transgenic animals has been successful, the low level of efficiency in producing these animals and lack of information on multigene interactions limit the use of the technology in applied production systems. Technologies based on research in functional genomics, proteomics and cloning have significant potential, but considerable research effort will be required before they can be utilized for AI in pig production. In the past 15 years, there has been a coordinated worldwide scientific effort to develop the genetic linkage map of the pig with the goal of identifying pigs with genetic alleles that result in improved growth rate, carcass quality, and reproductive performance. Molecular genetic tests have been developed to select pigs with improved traits such as removal of the porcine stress (RYR1) syndrome, and selection for specific estrogen receptor (ESR) alleles. Less progress has been made in developing routine tests related to diseases. Major research in genomics is being pursued to improve the efficiency of selection for healthier pigs with disease resistance properties. The sequencing of the genome of the pig to identify new genes and unique regulatory elements holds great promise to provide new information that can be used in pig production. AI, in vitro embryo production and embryo transfer will be the preferred means of implementing these new technologies to enhance efficiency of pig production in the future.     

Genomic prediction of reproduction traits for Merino sheep

Economically important reproduction traits in sheep, such as number of lambs weaned and litter size, are expressed only in females and later in life after most selection decisions are made, which makes them ideal candidates for genomic selection. Accurate genomic predictions would lead to greater genetic gain for these traits by enabling accurate selection of young rams with high genetic merit. The aim of this study was to design and evaluate the accuracy of a genomic prediction method for female reproduction in sheep using daughter trait deviations (DTD) for sires and ewe phenotypes (when individual ewes were genotyped) for three reproduction traits: number of lambs born (NLB), litter size (LSIZE) and number of lambs weaned. Genomic best linear unbiased prediction (GBLUP), BayesR and pedigree BLUP analyses of the three reproduction traits measured on 5340 sheep (4503 ewes and 837 sires) with real and imputed genotypes for 510 174 SNPs were performed. The prediction of breeding values using both sire and ewe trait records was validated in Merino sheep. Prediction accuracy was evaluated by across sire family and random cross‐validations. Accuracies of genomic estimated breeding values (GEBVs) were assessed as the mean Pearson correlation adjusted by the accuracy of the input phenotypes. The addition of sire DTD into the prediction analysis resulted in higher accuracies compared with using only ewe records in genomic predictions or pedigree BLUP. Using GBLUP, the average accuracy based on the combined records (ewes and sire DTD) was 0.43 across traits, but the accuracies varied by trait and type of cross‐validations. The accuracies of GEBVs from random cross‐validations (range 0.17–0.61) were higher than were those from sire family cross‐validations (range 0.00–0.51). The GEBV accuracies of 0.41–0.54 for NLB and LSIZE based on the combined records were amongst the highest in the study. Although BayesR was not significantly different from GBLUP in prediction accuracy, it identified several candidate genes which are known to be associated with NLB and LSIZE. The approach provides a way to make use of all data available in genomic prediction for traits that have limited recording.     

Towards marker assisted selection in livestock

In recent years, genomic tools have become available for most livestock species and are now being used routinely to map quantitative trait loci underlying the genetic variance for numerous economically important traits. Fine-mapping methods are being devised to refine the initially coarse map positions of the quantitative trait loci to the point required for marker assisted selection and, eventually, the positional cloning of the underlying genes. Mapping information on QTL is beginning to be used to increase genetic response by enhancing genetic variance, selection accuracy, selection intensity and by reducing the generation interval. Optimal use of MAS will require the development of more robust methods for the routine genotyping of preimplantation embryos for multiple markers.     

Zootechnical performance of cloned cattle and offspring: preliminary results

This paper presents information on the evolution of sets of cloned heifers of Holstein breed in comparison to that of control heifers derived from artificial insemination (AI) in the same farm, as well as data on a set of cloned bulls and their semen characteristics. Preliminary observations on a group of calves sired by a cloned bull and offspring of cloned females are reported. Mean birth weight in the clone group (50 females) was statistically higher than that of 68 contemporary female controls obtained by AI (49.27 +/- 10.98 vs. 40.57 +/- 5.55 kg, respectively, p < 0.05). Growth rate was within normal values for Holstein heifers (from 0.7 to 0.8 kg/day) and daily gain was not influenced by the high or low birth weight of clones. Within animals of the same clone, variability of daily gain was reduced compared to their control counterparts. Semen production from three cloned bulls was within the parameters expected for young bull of the same age. A direct comparison of morphological analysis was made between the frozen thawed semen of the donor bull and of his three clones collected at the same age. The overall semen picture appeared within acceptable limits and the clones presented similar percentages of sperm abnormalities (80% of morphologically normal spermatozoa) as the donor. These preliminary results suggest no deleterious effect of cloning on the semen picture of cloned sires. Frozen semen from one clone bull was used for an AI trial, resulting in 65% pregnancies, 25 live calves were naturally delivered. Concerning the offspring of both female and male clones, the phenotypical and clinical observation of the calves in the first week of age did not reveal any clinical abnormality, suggesting that the deviations observed in clones are not transmitted to the progeny.     

Genetic markers for stallion fertility--lessons from humans and mice

Our knowledge on the many aspects of mammalian reproduction in general and equine reproduction in particular has greatly increased during the last 15 years. Advances in the understanding of the physiology, cell biology, and biochemistry of reproduction have facilitated genetic analyses of fertility. Currently, there are more than 200 genes known that are involved in the production of fertile sperm cells. The completion of a number of mammalian genome projects will aid in the investigation of these genes in different species. Great progress has been made in the understanding of genetic aberrations that lead to male infertility. Additionally, the first genetic mechanisms are being discovered that contribute to the quantitative variation of fertility traits in fertile male animals. As artificial insemination (AI) represents a widespread technology in horse breeding, semen quality traits may eventually become an additional selection criterion for breeding stallions. Current research activities try to identify genetic markers that correlate to these semen quality traits. Here, we will review the current state of genetic research in male fertility and offer some perspectives for future research in horses.     

A practical approach for minimising inbreeding and maximising genetic gain in dairy cattle

A method that predicts the genetic composition and inbreeding (F) of the future dairy cow population using information on the current cow population, semen use and progeny test bulls is described. This is combined with information on genetic merit of bulls to compare bull selection methods that minimise F and maximise breeding value for profit (called APR in Australia). The genetic composition of the future cow population of Australian Holstein-Friesian (HF) and Jersey up to 6 years into the future was predicted. F in Australian HF and Jersey breeds is likely to increase by about 0.002 and 0.003 per year between 2002 and 2008, respectively. A comparison of bull selection methods showed that a method that selects the best bull from all available bulls for each current or future cow, based on its calf''s APR minus F depression, is better than bull selection methods based on APR alone, APR adjusted for mean F of prospective progeny after random mating and mean APR adjusted for the relationship between the selected bulls. This method reduced F of prospective progeny by about a third to a half compared to the other methods when bulls are mated to current and future cows that will be available 5 to 6 years from now. The method also reduced the relationship between the bulls selected to nearly the same extent as the method that is aimed at maximising genetic gain adjusted for the relationship between bulls. The method achieves this because cows with different pedigree exist in the population and the method selects relatively unrelated bulls to mate to these different cows. Selecting the best bull for each current or future cow so that the calf''s genetic merit minus F depression is maximised can slow the rate of increase in F in the population.     

Genetic differences based on a beef terminal index are reflected in future phenotypic performance differences in commercial beef cattle

The increased demand for animal-derived protein and energy for human consumption will have to be achieved through a combination of improved animal genetic merit and better management strategies. The objective of the present study was to quantify whether differences in genetic merit among animals materialised into phenotypic differences in commercial herds. Carcass phenotypes on 156 864 animals from 7301 finishing herds were used, which included carcass weight (kg), carcass conformation score (scale 1 to 15), carcass fat score (scale 1 to 15) at slaughter as well as carcass price. The price per kilogram and the total carcass value that the producer received for the animal at slaughter was also used. A terminal index, calculated in the national genetic evaluations, was obtained for each animal. The index was based on pedigree index for calving performance, feed intake and carcass traits from the national genetic evaluations. Animals were categorised into four terminal index groups on the basis of genetic merit estimates that were derived before the expression of the phenotypic information by the validation animals. The association between terminal index and phenotypic performance at slaughter was undertaken using mixed models; whether the association differed by gender (i.e. young bulls, steers and heifers) or by early life experiences (animals born in a dairy herd or beef herd) was also investigated. The regression coefficient of phenotypic carcass weight, carcass conformation and carcass fat on their respective estimated breeding values (EBVs) was 0.92 kg, 1.08 units and 0.79 units, respectively, which is close to the expectation of one. Relative to animals in the lowest genetic merit group, animals in the highest genetic merit group had, on average, a 38.7 kg heavier carcass, with 2.21 units greater carcass conformation, and 0.82 units less fat. The superior genetic merit animals were, on average, slaughtered 6 days younger than their inferior genetic merit contemporaries. The superior carcass characteristics of the genetically elite animals materialised in carcasses worth €187 more than those of the lowest genetic merit animals. Although the phenotypic difference in carcass traits of animals divergent in terminal index differed statistically by animal gender and early life experience, the detected interactions were generally biologically small. This study clearly indicates that selection on an appropriate terminal index will produce higher performing animals and this was consistent across all production systems investigated.     

High toxicity,low receptor density,and low integration frequency severely impede the use of adenovirus vectors for production of transgenic mice

Although many methods are available for introducing genes into the mammalian germ line, none is ideal for genetic manipulation of livestock or primates. These organisms produce relatively few offspring in each reproductive cycle and they have long generation times. For these reasons, a recent report that adenovirus vectors can efficiently insert genes into the mouse germ line by embryo infection is of considerable interest. Adenovirus vectors have a high cloning capacity, can be produced in high titers, and can infect a wide variety of cell types. We have investigated in more detail the potential for such vectors to infect embryos and integrate their DNA into the genome. We exposed mouse embryos to adenovirus vectors that express bacterial beta-galactosidase (LacZ), and studied expression in the preimplantation period, toxicity of the vectors, and the frequency with which fetuses and pups integrate vector DNA. Our findings indicate that fully functional adenovirus receptor does not appear until the two-cell stage of development. Successful infection is associated with high toxicity, such that viral titers must be balanced to achieve high infection with tolerable levels of toxicity. Screening of 94 animals after embryo infection revealed a single positive polymerase chain reaction signal, which is indicative of the presence of the lacZ gene. This finding could not be confirmed by Southern blotting, which indicates that the founder animal was a genetic mosaic for the exogenous DNA. We conclude from these experiments that adenovirus gene transfer vectors are not readily usable for germ line gene insertion.     

Influence of interactions between semen extender and number of spermatozoa on nonreturn rate estimates of fertility for individual Holstein bulls

The aim of the present study was to investigate the possibility of adapting sperm cell concentration per insemination unit to the intrinsic fertility of a given bull. For this purpose, split ejaculates of seven proven Holstein sires of unknown fertility were diluted in TRIS or in Laiciphos extenders. TRIS diluted doses contained either 8.12 or 16 million total sperm cells (T8, T12, T16 respectively), while the routinely-used Laiciphos units contained 16 million sperm (L16). A total of 18.068 first artificial inseminations were performed by three different AI centers. No difference in the average fertility occurred between T16 and L16 (69.2 vs 69%), but the individual bull results varied; L16 displayed lower inter-bull variability. The nonreturn rates (60 to 90 days) obtained with T8 and T12 (65.7 and 66.8%, respectively) were significantly lower than with T16 and L16 (P < 0.02). The effect of AI center was also significant (P < 0.05). Despite a highly significant effect of the sire (P < 0.001), no interaction was found between the bull and cell concentration or the AI center. The bull effect indicates that it may be worthwile especially for the bulls of the highest genetic merit to test for the appropriate lowest number of spermatozoa per unit to allow wider commercial and genetic diffusion without compromising the average nonreturn rate of the sire.     

Assessing the impact of natural service bulls and genotype by environment interactions on genetic gain and inbreeding in organic dairy cattle genomic breeding programs

The objective of the present study was to compare genetic gain and inbreeding coefficients of dairy cattle in organic breeding program designs by applying stochastic simulations. Evaluated breeding strategies were: (i) selecting bulls from conventional breeding programs, and taking into account genotype by environment (G×E) interactions, (ii) selecting genotyped bulls within the organic environment for artificial insemination (AI) programs and (iii) selecting genotyped natural service bulls within organic herds. The simulated conventional population comprised 148 800 cows from 2976 herds with an average herd size of 50 cows per herd, and 1200 cows were assigned to 60 organic herds. In a young bull program, selection criteria of young bulls in both production systems (conventional and organic) were either ‘conventional’ estimated breeding values (EBV) or genomic estimated breeding values (GEBV) for two traits with low (h²=0.05) and moderate heritability (h²=0.30). GEBV were calculated for different accuracies (r_mg), and G×E interactions were considered by modifying originally simulated true breeding values in the range from r_g=0.5 to 1.0. For both traits (h²=0.05 and 0.30) and r_mg⩾0.8, genomic selection of bulls directly in the organic population and using selected bulls via AI revealed higher genetic gain than selecting young bulls in the larger conventional population based on EBV; also without the existence of G×E interactions. Only for pronounced G×E interactions (r_g=0.5), and for highly accurate GEBV for natural service bulls (r_mg>0.9), results suggests the use of genotyped organic natural service bulls instead of implementing an AI program. Inbreeding coefficients of selected bulls and their offspring were generally lower when basing selection decisions for young bulls on GEBV compared with selection strategies based on pedigree indices.     

Global gene expression analysis of bovine blastocysts produced by multiple methods

Reproductive efficiency using somatic cell nuclear transfer (SCNT) technology remains suboptimal. Of the various efforts to improve the efficiency, chromatin transfer (CT) and clone-clone aggregation (NTagg) have been reported to produce live cloned animals. To better understand the molecular mechanisms of somatic cell reprogramming during SCNT and assess the various SCNT methods on the molecular level, we performed gene expression analysis on bovine blastocysts produced via standard nuclear transfer (NT), CT, NTagg, in vitro fertilization (IVF), and artificial insemination (AI), as well as on somatic donor cells, using bovine genome arrays. The expression profiles of SCNT (NT, CT, NTagg) embryos were compared with IVF and AI embryos as well as donor cells. NT and CT embryos have indistinguishable gene expression patterns. In comparison to IVF or AI embryos, the number of differentially expressed genes in NTagg embryos is significantly higher than in NT and CT embryos. Genes that were differentially expressed between all the SCNT embryos and IVF or AI embryos are identified. Compared to AI embryos, more than half of the genes found deregulated between SCNT and AI embryos appear to be the result of in vitro culture alone. The results indicate that although SCNT methods have altered differentiated somatic nuclei gene expression to more closely resemble that of embryonic nuclei, combination of insufficient reprogramming and in vitro culture condition compromise the developmental potential of SCNT embryos. This is the first set of comprehensive data for analyzing the molecular impact of various nuclear transfer methods on bovine pre-implantation embryos.     

A definition of unknown parent groups based on bull usage patterns across herds

In genetic evaluations, the definition of unknown parent groups (UPG) is usually based on time periods, selection path and flows of foreign founders. The definition of UPG may be more complex for populations presenting genetic heterogeneity due to both, large national expansion and coexistence of artificial insemination (AI) and natural service (NS). A UPG definition method accounting for beef bull flows was proposed and applied to the French Charolais cattle population. It assumed that, at a given time period, unknown parents belonged to the same UPG when their progeny were bred in herds that used bulls with similar origins (birth region and reproduction way). Thus, the birth period, region and AI rate of a herd were pointed out to be the three criteria reflecting genetic disparities at the national level in a beef cattle population. To deal with regional genetic disparities, 14 regions were identified using a factorial approach combining principal component analysis and Ward clustering. The selection nucleus of the French cattle population was dispersed over three main breeding areas. Flows of NS bulls were mainly carried out within each breeding area. On the contrary, the use and the selection of AI bulls were based on a national pool of candidates. Within a time period, herds of different regions were clustered together when they used bulls coming from the same origin and with an estimated difference of genetic level lower than 20% of genetic standard deviation (σg) for calf muscle and skeleton scores (SS) at weaning. This led to the definition of 16 UPG of sires, which were validated as robust and relevant in a sire model, meaning numerically stable and corresponding to distinct genetic subpopulations. The UPG genetic levels were estimated for muscle and SS under sire and animal models. Whatever the trait, differences between bull UPG estimates within a time period could reach 0.5 σg across regions. For a given time period, bull UPG estimates for muscle and SS were generally larger by 0.30 to 0.75 σg than those of cows. Including genetic groups in the evaluation model increased the estimated genetic trends by 20% to 30%. It also provoked re-ranking in favor of bulls and cows without pedigree.     

Sperm morphology and fertility of progeny-tested AI dairy bulls in Sweden

Use of bull semen with high levels of sperm abnormalities, reflecting genital dysfunction, is not recommended for artificial insemination (AI) since it would most likely lead to subfertility. Sperm quality, including sperm morphology, may deteriorate with increasing age of the bull thus becoming a source of concern when using older, progeny-tested AI bull sires. Although a relationship between sperm morphology and fertility after AI in progeny-tested bull sires has been reported, it is yet unclear which sperm abnormalities are most critical. This constituted the core aim of a 22-month long retrospective study in proven (aged 60-84 months at the start of the study) AI sires of the Swedish Red (SR, n=8) and Swedish Holstein (SLB, n=4) breeds where their semen (107 freezing batches in total, built by a single ejaculate (n=3) or pooling two consecutive ejaculates (n=104) collected at 1-3 months interval), were subjected to detailed morphological examinations on wet- and dry, stained smears. Attention was paid to between- and within-bull variations with regard to presence and level of sperm abnormalities. Sperm morphology differed significantly between sires and ejaculates, with 6/12 sires having ejaculates containing >10% of morphologically deviating sperm head shapes, a commonly used threshold for young AI bulls in Sweden. However, with the exception of pear-shaped or narrow-at-the-base anomalies, the mean values for individual defects were always within the limits expected for a normal bull sire, and were therefore considered acceptable. The percentage of morphologically normal spermatozoa was positively related to fertility, whose output differed significantly among bulls. Among sperm abnormalities, the proportion of morphologically deviating sperm head shapes were negatively correlated with fertility, pear-shaped sperm heads in particular. In conclusion, the relationship between sperm morphology and fertility after AI calls for frequent (2-3 months interval) detailed assessments of sperm morphology in AI stud bull sires.     

Genetic selection of boars

Selection of boars by visual appraisal is the simplest and oldest method used by the swine industry. However, individual performance testing, and later use of computers to incorporate relatives' data and account for environmental variation, resulted in greater rate of improvement for economically important traits. Examples of molecular genetic tools that have increased improvement for some traits are also discussed. Accurate identification of genetic merit is increasingly important with widespread use of AI and resultant greater progeny number per sire. Historically, selection was to produce desirable progeny; however, with the majority of boars now housed in dedicated boar facilities, and the efficiency of sperm production being recorded, boar stud personnel are increasingly interested in selection of boars for fertility traits. Selecting boars that are lean and heavily muscled and have good semen parameters may be problematic, given the genetic relationships among the traits. Whereas conventional animal breeding methods will remain important, use of molecular tools will increase, and identification of a boar's fertility potential at birth will allow earlier and more efficient selection of high-fertility boars. Ability to achieve acceptable female reproduction with frozen semen would facilitate selection for longevity. However, this would lengthen the generation interval and could dilute selection intensity for other traits, as it requires indirect selection for semen freezability.