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B Villanueva

Publications and source records attributed to B Villanueva.

At least 19 recordsLinked to original sources
PubMed2006

Associations of polymorphisms of the ovine prion protein gene with growth, carcass, and computerized tomography traits in Scottish Blackface lambs.

The objective of this study was to investigate and estimate the associations of the ovine prion protein (PrP) genotypes with a wide range of performance traits in Scottish Blackface lambs. Performance records of up to 7,138 sheep of known PrP genotypes born from 1999 to 2004 in 2 experimental farms were utilized. Performance traits studied were BW at birth, marking (when the sheep were identified with permanent ear tags at an average age of 52 d), and weaning (average age of 107 d); slaughter traits (BW at slaughter, slaughter age, carcass weight, and carcass conformation); ultrasonic muscle and fat depths; and computerized tomography-predicted carcass composition and carcass yield at weaning. Different linear mixed models, including random, direct animal effect, and up to 3 maternal effects (genetic, permanent, and temporary environmental) were used for the different traits. The PrP genotype was included in the model as a fixed effect, along with other fixed factors with significant effects (P < 0.05). Five separate analyses were carried out for each trait, differing in the method of PrP genotypic classification. The first analysis was based on classifying the sheep into categories according to all 9 available PrP genotypes. In the other 4 analyses, sheep were categorized according to the number of each PrP allele carried. Results showed that there were no significant differences between PrP genotypes for any of the performance traits studied when all 9 genotypes were compared (first analysis). Similarly, performance of the lambs did not significantly differ between genotypes with different numbers of ARR copies. However, there were significant variations in a few traits with respect to the number of ARQ, AHQ, and VRQ alleles carried. Heterozygous lambs for the AHQ or the ARQ allele were significantly heavier at some ages than lambs of the other genotypes. Lambs carrying the VRQ allele required approximately 10 d longer finishing time (P = 0.01) and yielded carcasses approximately 0.5 kg heavier (P = 0.03) compared with noncarriers. The few significant associations found do not have a negative influence on performance when selecting against the most susceptible PrP allele (VRQ) or in favor of the most resistant one (ARR). Overall, there were no major associations of PrP genotypes with most lamb performance traits in Scottish Blackface sheep.

Alleles↗
PubMed2005

Prediction of accuracy of estimated Mendelian sampling terms.

This study describes a general framework for predicting the accuracy of Mendelian sampling terms when truncation selection is applied on best linear unbiased prediction (BLUP) estimated breeding values. A selection index approach is followed. The pseudo-BLUP index is extended to include terms related to the Mendelian sampling term. Predicted accuracies are compared with those obtained through stochastic computer simulation. Good predictions for the accuracy of the Mendelian sampling term were obtained both at selection time and at convergence of long-term contributions of selected candidates for a range of heritabilities and population structures. The prediction approach developed provides a key tool for obtaining predictions of genetic response from quadratic optimization that maximizes the rate of genetic progress while restricting the rate of inbreeding.

Breeding↗
PubMed2005

Benefits from marker-assisted selection under an additive polygenic genetic model.

This study investigated, through stochastic computer simulation, the extra gains expected from marker-assisted selection (MAS) in an infinitesimal model with linkage. The trait under selection was assumed to be controlled by 2,000 loci of additive small effect and evenly distributed in c chromosomes of one Morgan each (and c = 5, 10, 20, or 30). This approach differs from previous studies on the benefits of MAS that have considered mixed inheritance models. Marker information was used together with pedigree information to compute the relationship matrix used in BLUP genetic evaluations. The MAS schemes were compared with schemes where genetic evaluations were performed using standard BLUP (i.e., the relationship matrix is obtained using pedigree information only). When the number of markers was large enough (approximately one marker every 10 cM), there were increases in the accuracy of selection with MAS, and this led to extra gains compared with standard BLUP for all genome sizes considered. The benefit from MAS increased over generations. At the last generation of selection (Generation 10), the response from MAS was 11, 9, 7, and 5% greater than with standard BLUP for genomes with 5, 10, 20, and 30 chromosomes, respectively. Thus, although small, gains from MAS were nonetheless detectable for genome sizes typical of livestock populations.

Animal Husbandry↗
PubMed2005

Cumulative discounted expressions of sire genotypes for the complex vertebral malformation and beta-casein loci in commercial dairy herds.

Based on discounted gene-flow principles, a set of recursive equations was developed to quantify the value of using sires with a specific genotype for an identified gene in a commercial dairy herd. Two examples were used to demonstrate the usefulness of the method. The first example deals with the implications of using sires that are known carriers of the lethal recessive genetic defect, complex vertebral malformation (CVM). The second example examines the value of using sires homozygous for the A2 allele of beta-casein. Results are presented in terms of cumulative discounted expressions. These are then multiplied by the economic values of specific genotypes to determine the cost or benefit of using these sires. In general, the degree of mortality and the required price reduction for carrier sires increased as the proportion of carrier sires used, the duration of sire use, and the initial frequency in the cow herd increased. A semen discount of 3.10 pound sterling per CVM straw used would be required to offset the expected mortality when 20% of CVM carrier sires are used for 3 yr when 5% of cows are carriers. The cumulative discounted expressions' of using sires homozygous for the A2 allele of beta-casein also increased when the proportion and duration of carrier sire use and the initial frequency of the A2 allele increased. Assuming an A2A2 cow is worth 160 pound sterling more than a non-A2A2 cow, the expected benefit of using A2A2 sires in a 100-cow herd for 5 yr would be 57 pound sterling,120 for a 20-yr planning horizon. The results of this study demonstrate how the starting gene frequency in the herd, and the proportion and duration of use of sires of particular genotypes are critical to the economic implications of using single genes in commercial dairy farms.

Abortion, Veterinary↗
PubMed2004

Mendelian sampling terms as a selective advantage in optimum breeding schemes with restrictions on the rate of inbreeding.

Quadratic indices are a general approach for the joint management of genetic gain and inbreeding in artificial selection programmes. They provide the optimal contributions that selection candidates should have to obtain the maximum gain when the rate of inbreeding is constrained to a predefined value. This study shows that, when using quadratic indices, the selective advantage is a function of the Mendelian sampling terms. That is, at all times, contributions of selected candidates are allocated according to the best available information about their Mendelian sampling terms (i.e. about their superiority over their parental average) and not on their breeding values. By contrast, under standard truncation selection, both estimated breeding values and Mendelian sampling terms play a major role in determining contributions. A measure of the effectiveness of using genetic variation to achieve genetic gain is presented and benchmark values of 0.92 for quadratic optimisation and 0.5 for truncation selection are found for a rate of inbreeding of 0.01 and a heritability of 0.25.

Analysis of Variance↗
PubMed2004

Maximizing genetic gain over multiple generations with quantitative trait locus selection and control of inbreeding.

Stochastic computer simulation was used to investigate the potential extra genetic gains obtained from gene-assisted selection (GAS) by combining 1) optimization of genetic contributions for maximizing gain, while restricting the rate of inbreeding with 2) optimization of the relative emphasis given to the QTL over generations. The genetic model assumed implied a mixed inheritance model in which a single quantitative trait locus (i.e., QTL) is segregating together with polygenes. When compared with standard GAS (i.e., fixed contributions and equal emphasis on the QTL and polygenic EBV), combined optimization of contributions of selection candidates and weights on the QTL across generations allowed substantial increases in gain at a fixed rate of inbreeding and avoided the conflict between short- and long-term responses in GAS schemes. Most of the increase of gain was produced by optimization of selection candidates' contributions. Optimization of the relative emphasis given to the QTL over generations had, however, a greater effect on avoiding the long-term loss usually observed in GAS schemes. Optimized contribution schemes led to lower gametic phase disequilibrium between the QTL and polygenes and to higher selection intensities both on the QTL and polygenes than with standard truncation selection with fixed contributions of selection candidates.

Alleles↗
PubMed2004

Inbreeding trends and application of optimized selection in the UK Holstein population.

Important increases in the rates of inbreeding have recently been observed in dairy cattle populations, and methods have been proposed to address these increases. The aims of this study were to estimate the current level and rates of inbreeding in the UK Holstein population and to investigate the potential of applying optimized selection to manage the rates of inbreeding. Inbreeding coefficients were calculated for the entire UK Holstein population using 1940 as the base year. Rates of inbreeding were obtained for 3 time periods by regressing mean inbreeding coefficients on the year of birth of the animals. The expected average pedigree index and expected inbreeding of offspring using optimized contributions for a given set of selection candidates was compared to the expected pedigree index and inbreeding of offspring for the same set of selection candidates using observed contributions. The rate of inbreeding in the UK Holstein population has increased substantially since 1990 when compared to previous time periods. This increase is most likely due to the large influence of a few related sires on the breed in the mid- to late 1980s. The introduction of the individual animal model in the early 1990s may also have contributed to increased inbreeding. Optimized selection appears to represent a promising selection tool, not only to manage rates of inbreeding, but also to increase genetic gain at the same rate of inbreeding.

Animals↗
PubMed2003

Expected increases in genetic merit from using optimized contributions in two livestock populations of beef cattle and sheep.

The expected benefits from optimized selection in real livestock populations were evaluated by applying dynamic selection algorithms to two livestock populations of sheep (Meatlinc) and beef cattle (Aberdeen Angus). In addition, the effects of introducing BLUP evaluations on the population structure, genetic gain, and inbreeding were investigated. The use of BLUP-EBV accelerated the rates of gain in the Meatlinc, but the effects of BLUP evaluations on Aberdeen Angus are not as evident. Although steady increases in the average coefficient of inbreeding (F) were observed, the inbreeding rates (deltaF) before and after the introduction of BLUP evaluations were not significantly different. The observed deltaF in the last generation was 1.0% for Meatlinc and 0.2% for Aberdeen Angus. The application of the dynamic selection algorithms for maximizing genetic gain at a fixed deltaF led to important expected increases in the rate of genetic gain (deltaG). When deltaF was restricted to the value observed in both populations, increments per year in deltaG of 4.6 (i.e., 17%) index units for Meatlinc and 3.5 (i.e., 30%) index units for Aberdeen Angus were found in comparison to the deltaG expected from conventional truncation BLUP selection. More relaxed constraints on deltaF allowed even higher expected increases in deltaG in both populations. This study demonstrates that the optimization tools constitute a potentially highly effective way of managing gain and inbreeding under a broad range of schemes in terms of scale and inbreeding level. No losses in genetic gain were associated with the use of dynamic optimization selection when schemes were compared at the same deltaF.

Algorithms↗
PubMed2003

[Exoftalmos and palpebral ptosis in the immunocompromised patient].

The mucormycosis is an opportunistic mycosis which has a high rate of global mortality with a bad prognosis. The present clinical case shows a patient attended in the Intensive Care Unit because of a breathing insufficiency secondary to a pneumonia. Among his antecedents there is a larynx carcinoma totally remittent after chemo- and radiotherapy. He develops an infrapalpebral injury which spreads rapidly in a bilateral way acquiring a necrotic look that it did not have initially. Having that evolution, it is implemented a treatment with liposomal amphotericin B and granulocyte colony-stimulating factors after an injury biopsy, whose posterior cultive shows growing of Mucor. This kind of pathology must be initially suspected in all the patients with a neoplasia and its treatment must be early and agressive. At the moment the diagnosis is suspected there is a great tissue destruction and for that reason the patients usually die in spite of the instauration of aggressive therapies

Blepharoptosis↗
PubMed2002

Parental assignment in fish using microsatellite genetic markers with finite numbers of parents and offspring.

Deterministic predictions for the proportion of offspring assigned to different numbers of parent-pairs are developed in order to investigate the power of microsatellite loci for parental assignment in fish species. Comparisons with stochastic simulation results show that predictions based on exclusion probabilities are accurate, provided that the number of parents involved in the crosses is large. Accounting for sampling of parents gave very accurate predictions for a small number of parents and a single biallelic locus. For large numbers of loci or large numbers of alleles per locus stochastic simulations are, however, the only available method to predict the power of assignment of a particular set of loci when the number of parents is small. Nine 5-allele loci or six 10-allele loci with equifrequent alleles, are sufficient for assigning, with certainty, parents to 99% of the fish resulting from either 100 or 400 crosses. Results simulating a set of highly polymorphic microsatellites developed for Atlantic salmon show that the four most informative loci are sufficient to assign at least 99% of the offspring to the correct pair with 100 crosses involving 100 males and 100 females. An additional locus is required for correctly assigning 99% of the offspring when the 100 crosses are produced with 10 males and 10 females.

Animals↗
PubMed2001

Synthesis of direct and maternal genetic components of economically important traits from beef breed-cross evaluations.

Published information on relative performance of beef breed crosses was used to derive combined estimates of purebred breed values for predominant temperate beef breeds. The sources of information were largely from the United States, Canada, and New Zealand, although some European estimates were also included. Emphasis was on maternal traits of potential economic importance to the suckler beef production system, but some postweaning traits were also considered. The estimates were taken from comparison studies undertaken in the 1970s, 1980s and 1990s, each with representative samples of beef breeds used in temperate agriculture. Weighting factors for breed-cross estimates were derived using the number of sires and offspring that contributed to that estimate. These weights were then used in a weighted multiple regression analysis to obtain single purebred breed effects. Both direct additive and maternal additive genetic effects were estimated for preweaning traits. Important genetic differences between the breeds were shown for many of the traits. Significant regression coefficients were estimated for the effect of mature weight on calving ease, both maternal and direct additive genetic, survival to weaning direct, and birth weight direct. The breeds with greater mature weight were found to have greater maternal genetic effects for calving ease but negative direct genetic effects on calving ease. A negative effect of mature weight on the direct genetic effect of survival to weaning was observed. A cluster analysis was done using 17 breeds for which information existed on nine maternal traits. Regression was used to predict breed-cross-specific heterosis using genetic distance. Only five traits, birth weight, survival to weaning, cow fertility, and preweaning and postweaning growth rate had enough breed-cross-specific heterosis estimates to develop a prediction model. The breed biological values estimated provide a basis to predict the biological value of crossbred suckler cows and their offspring.

Animals↗
PubMed1999

Expected genetic contributions and their impact on gene flow and genetic gain.

Long-term genetic contributions (r(i)) measure lasting gene flow from an individual i. By accounting for linkage disequilibrium generated by selection both within and between breeding groups (categories), assuming the infinitesimal model, a general formula was derived for the expected contribution of ancestor i in category q (mu(i)(q)), given its selective advantages (s(i)(q)). Results were applied to overlapping generations and to a variety of modes of inheritance and selection indices. Genetic gain was related to the covariance between r(i) and the Mendelian sampling deviation (a(i)), thereby linking gain to pedigree development. When s(i)(q) includes a(i), gain was related to E[mu(i)(q))a(i)], decomposing it into components attributable to within and between families, within each category, for each element of s(i)(q). The formula for mu(i)(q) was consistent with previous index theory for predicting gain in discrete generations. For overlapping generations, accurate predictions of gene flow were obtained among and within categories in contrast to previous theory that gave qualitative errors among categories and no predictions within. The generation interval was defined as the period for which mu(i)(q), summed over all ancestors born in that period, equaled 1. Predictive accuracy was supported by simulation results for gain and contributions with sib-indices, BLUP selection, and selection with imprinted variation.

Animals↗
PubMed1992

Effect of controlled ovarian hyperstimulation on pregnancy rates after intrauterine insemination.

OBJECTIVE: Our objective was to evaluate the effect of controlled ovarian hyperstimulation on pregnancy rates after intrauterine insemination of washed husband's sperm. STUDY DESIGN: In a private practice setting at the Infertility, Gynecology, and Obstetrics Medical Group in San Diego, 79 treatment programs included intrauterine insemination during natural cycles, 195 included clomiphene stimulation, and 53 had human menopausal gonadotropin stimulation. Pregnancy rates and monthly fecundabilities were calculated by life-table analysis and compared by the Z test. RESULTS: By life-table analysis the cumulative probability of pregnancy after intrauterine insemination with no ovulation induction is 21.0% after six cycles with a monthly fecundability of 3.4%. With clomiphene the pregnancy rate is 32.7% with a monthly fecundability of 6.1%, and with human menopausal gonadotropin the pregnancy rate is 60.7% with a monthly fecundability of 13.0%. The human menopausal gonadotropin group had a significantly higher pregnancy rate and monthly fecundability as compared with the other two groups. There were no differences between the no-stimulation and the clomiphene groups. CONCLUSIONS: Human menopausal gonadotropin stimulation results in a significantly higher pregnancy rate and monthly fecundability after intrauterine insemination as compared with no stimulation or clomiphene use.

Female↗
PubMed1990

Pregnancy rates with fresh versus computer-controlled cryopreserved semen for artificial insemination by donor in a private practice setting.

From late 1970 through December 1987, 580 women began 733 treatment programs (a total of 3405 insemination cycles) with fresh semen for artificial insemination by donor. The unadjusted pregnancy rate was 48.5% and the cumulative pregnancy rate after seven cycles by life-table analysis was 59.6% with a monthly fecundability of 11.9%. From 1988 to the present, 113 women have begun 115 treatment programs (a total of 371 insemination cycles) with cryopreserved semen for artificial insemination by donor. The unadjusted pregnancy rate to date is 18.3% and the cumulative pregnancy rate after seven cycles by life-table analysis is 48.6% with a monthly fecundability of 5.9%. This report shows that using cryopreserved semen for artificial insemination by donor will take somewhat longer to produce a pregnancy but the ultimate pregnancy rate will be similar to that with fresh semen for artificial insemination by donor.

Adult↗
PubMed1986

Results of microsurgical treatment of tubal infertility and early second-look laparoscopy in the post-pelvic inflammatory disease patient: implications for in vitro fertilization.

Sixty-nine patients with tubal infertility secondary to pelvic inflammatory disease were surgically treated by one of three infertility surgeons, who used microsurgery for repair of the tubal pathologic condition and early second-look laparoscopy 6 to 30 days postoperatively for lysis of postoperative adhesions. No patient was included in this group whose disease was thought to have originated from endometriosis or prior abdominal surgery. The average follow-up time was 43.1 months (range 12 to 85.9). Nine patients were excluded from the analysis. Pregnancy outcome by procedure, expressed as the percentage of patients conceiving, was as follows: adhesiolysis, 69% (61% term, 8% ectopic); fimbrioplasty, 35% (25% term, 10% ectopic); salpingostomy, 30% (18% term, 12% ectopic); and cornual implantation, 60% (40% term, 20% ectopic). No added therapeutic value could be attributed to the use of early second-look laparoscopy. Given the relatively poor outcome of fimbrioplasty and salpingostomy, it may be prudent to advise patients with bilateral partial and/or total tubal occlusion against tuboplasty in favor of in vitro fertilization and embryo transfer.

Embryo Transfer↗
PubMed1981

Intravaginal administration of progesterone: enhanced absorption after estrogen treatment.

A progesterone solution was administered by intravaginal instillation, intramuscular injection, and sublingually to estrogen-deficient women, with or without estradiol (E2) replacement, and serum progesterone (P) concentrations were measured by radioimmunoassay. Intravaginal application to postmenopausal subjects receiving E2 gave the highest values of serum P: 10 times baseline at 15 minutes and 30 to 40 times at 1 to 2 hours, with sustained levels, for 7 hours and decline to 10 times baseline at 24 hours. Intravaginal application to hypoestrogenic women gave similar results, but of much lower magnitude (highest value, 20 times baseline). Intramuscular injection, in contradistinction, showed gradually increasing levels over the study period, up to 30 times basal values at 24 hours. It contrast, sublingual application produced very modest serum increases, to approximately 10 times baseline within 2 hours and return to basal value at 24 hours. Since the most rapid and highest levels were observed by vaginal application to postmenopausal women receiving estrogen, and considering that the vagina has been similarly shown to be very effective for estrogen absorption, it is conceived that full hormone replacement could be accomplished in the deficient states by cyclic vaginal application of both steroids.

Absorption↗
PubMed1977

Efficacy of intravaginal and intranasal administration of micronized estradiol-17beta.

Absorption of micronized 17beta-estradiol (E2), after intravaginal administration of 1 mg dose, suspended in saline, is extremely rapid and sustained. A mean peak increment of circulating E2 concentrations of more than 110 times the basal level is achieved at 2 h and remains elevated more than 6 times the basal level even at 24 h. Increments in estrone (E1) are smaller and slower than those of E2 with a mean peak concentration of less than 10% of E2 and remain 3 times the basal level at 24 h. With 0.5 mg dose, the incremental changes in E2 and E1 as well as the degree of gonadotropin suppression are essentially the same. In contrast, intranasal administration of E2 of 1 mg dose induces a rapid but short-lasting increase in both serum E2 and E1 levels. The mean increments of E1 exhibited a higher and sustained elevation with a rise in mean E1/E2 ratio well above unity beginning 1 hr after intranasal application. These findings indicate intravaginal but not intranasal routes of E2 absorption are quantitatively much greater and circumvent the local conversion of E2 to E1 observed after oral administration of E2, and thus represent a practical and highly effective means of delivering E2 into the circulation.

Administration, Intranasal↗