Inferência bayesiana na predição de valores genéticos do peso aos 365 dias de bovinos de corte

Data from purebred Simmental, Nellore and Canchim cattle breeds obtained from the respective Brazilian Associations of Breeders were used to estimate variance components and to predict genetic values for 365 days weight. The results obtained by Bayesian inference were compared to those from Restricted Maximum Likelihood (REML) and Best Linear Unbiased Prediction (BLUP), which are the most commonly used methods of estimation and prediction in animal breeding. The two methods presented similar point estimates but the study of the marginal posterior distributions in the Bayesian approach yields more detailed information about the parameters and other unknowns in the model.

Relações materno-filiais e sua influência no peso pré-desmama de animais Nelore da Bahia

The aim of this study was to investigate the maternal-offspring relationships in the bovine breeds Nellore PO (Pure Breed) and Nellore CL (Cara Limpa) in Bahia State. The genetic composition of breeds did not affect LP (latency time to stand); this variable showed mean values of 71 min and 52 min, respectively, for Nellore PO and Nellore CL. The variable LPTM (latency time to begin suckling after standing) was significantly higher for Nellore PO (mean values of 39 min) tham for Nellore CL (18 min). The variable TCC (time in contact with the calf) was classified as class 4 (60 to 80% of the time was spent with the calves). The P120 (weight at 120 days) had mean values of 122.3 kg and 122.7 kg respectively, for Nellore PO and Nellore CL. In conclusion, the maternal-offspring behaviour had little influence of the genetic composition of the breeds. These results suggest that more studies are necessary to define technological parameters for cattle raising in Bahia State.

Physiological bases for understanding estrous cycle differences between bos taurus and bos indicus

Background: Although there is some information in the literature discussing differences of the estrous cycle of Bos taurus and Bos indicus cattle, most of the data derive from studies performed in temperate climate countries, under environmental and nutritional conditions very different than those found in tropical countries. Moreover, the physiological basis for understanding the differences between Bos taurus and Bos indicus estrous cycles are still unknown. This review explores the physiological and metabolic bases for understanding the key differences between the Bos taurus and Bos indicus estrous cycle. Moreover, it presents recent results of studies that have directly compared reproductive variables between Zebu and European cattle. Review: The knowledge of reproductive physiology, especially the differences between Bos taurus and Bos indicus, is important for the development and application of different techniques of reproductive management in cattle. In this regard, overall, Bos indicus have a greater number of small ovarian follicles and ovulatory follicles are smaller as compared to Bos taurus. Consequently, Zebu cattle also have smaller corpus luteum (CL). Nevertheless, circulating concentrations of steroid and metabolic hormones are not necessarily higher in European cattle. In fact, some studies have shown that despite ovulating smaller follicles and having smaller CL, Bos indicus cows or heifers have higher circulating concentrations of estradiol, progesterone, insulin and IGF-I compared to Bos taurus females. In addition, there are also substantial differences between Bos indicus and Bos taurus cattle in relation to follicle size at the time of selection of the dominant follicle. Conclusion: Data from very recent studies performed in Brazil have corroborated results from previous reports that have observed substantial differences in the estrous cycle variables of Bos indicus versus Bos taurus cattle. Those differences are probably related to distinct metabolism and metabolic hormone concentrations between Zebu and European cattle. This increased knowledge will allow for the establishment of more adequate reproductive management protocols in both breeds of cattle.

Influência da raça do touro (Bos indicus x Bos taurus) na tolerância ao estresse térmico calórico de embriões bovinos produzidos in vitro

To better understand the differences related to HS resistance between Bos indicus and Bos taurus, we aim to verify if the HS tolerance is due mostly to the genetic contribution from the oocyte, spermatozoa or both. Oocytes from Nelore and crossbreed Holstein cows (cHST) were collected, matured and fertilized with semen from Nelore (N), Angus (An), Brahman (Bra) and Gir (Gir) bulls. Nine six hours post insemination (hpi), ≥ 16 cells embryos were separated in two groups: control and HS. In control group, embryos were cultured at 39°C, whereas in the HS group, embryos were subjected to 41°C for 12 h, and then returned to 39°C. There was no effect of HS on blastocyst and hatched blastocyst rates in all breeds analyzed. The percentage of oocytes that cleaved and reached morula stage was significantly lower (p < 0.05) in cHST x Gir as compared to the other breeds. Additionally, blastocyst rates was higher in cHST x N than in cHST x An and cHST x Gir (p < 0.05). It was concluded that the oocyte is more important than the spermatozoa for the development of thermotolerance, since the breed of the bull did not influence embryo development after HS.

Implementation of DNA markers to produce genomically - Enhanced EPDs in nellore cattle

Background: The sequencing and publication of the cattle genome and the identification of single nucleotide polymorphism (SNP) molecular markers have provided new tools for animal genetic evaluation and genomic-enhanced selection. These new tools aim to increase the accuracy and scope of selection while decreasing generation interval. The objective of this study was to evaluate the enhancement of accuracy caused by the use of genomic information (Clarifide® - Pfizer) on genetic evaluation of Brazilian Nellore cattle. Review: The application of genome-wide association studies (GWAS) is recognized as one of the most practical approaches to modern genetic improvement. Genomic selection is perhaps most suited to the improvement of traits with low heritability in zebu cattle. The primary interest in livestock genomics has been to estimate the effects of all the markers on the chip, conduct cross-validation to determine accuracy, and apply the resulting information in GWAS either alone [9] or in combination with bull test and pedigree-based genetic evaluation data. The cost of SNP50K genotyping however limits the commercial application of GWAS based on all the SNPs on the chip. However, reasonable predictability and accuracy can be achieved in GWAS by using an assay that contains an optimally selected predictive subset of markers, as opposed to all the SNPs on the chip. The best way to integrate genomic information into genetic improvement programs is to have it included in traditional genetic evaluations. This approach combines traditional expected progeny differences based on phenotype and pedigree with the genomic breeding values based on the markers. Including the different sources of information into a multiple trait genetic evaluation model, for within breed dairy cattle selection, is working with excellent results. However, given the wide genetic diversity of zebu breeds, the high-density panel used for genomic selection in dairy cattle (Ilumina Bovine SNP50 array) appears insufficient for across-breed genomic predictions and selection in beef cattle. Today there is only one breed-specific targeted SNP panel and genomic predictions developed using animals across the entire population of the Nellore breed (www.pfizersaudeanimal.com), which enables genomically - enhanced selection. Genomic profiles are a way to enhance our current selection tools to achieve more accurate predictions for younger animals. Material and Methods: We analyzed the age at first calving (AFC), accumulated productivity (ACP), stayability (STAY) and heifer pregnancy at 30 months (HP30) in Nellore cattle fitting two different animal models; 1) a traditional single trait model, and 2) a two-trait model where the genomic breeding value or molecular value prediction (MVP) was included as a correlated trait. All mixed model analyses were performed using the statistical software ASREML 3.0. Results: Genetic correlation estimates between AFC, ACP, STAY, HP30 and respective MVPs ranged from 0.29 to 0.46. Results also showed an increase of 56%, 36%, 62% and 19% in estimated accuracy of AFC, ACP, STAY and HP30 when MVP information was included in the animal model. Conclusion: Depending upon the trait, integration of MVP information into genetic evaluation resulted in increased accuracy of 19% to 62% as compared to accuracy from traditional genetic evaluation. GE-EPD will be an effective tool to enable faster genetic improvement through more dependable selection of young animals.

How bioinformatics enables livestock applied sciences in the genomic era

This review paper presents the three main approaches currently used in livestock genomic sciences where the bioinfomatics plays a critical role. They are named as Genomic Selection (GS), Genome Wide Association Study (GWAS) and Signatures of Selection (SS). The subsides for the construction of this article were generated in a current project (started in 2011), so called Zebu Genome Consortium (ZGC), which joins researchers from different institutions and countries, aiming to scientifically explore genomic information of Bos taurus indicus cattle breeds and deliver useful information to breeders and academic community, specially from the tropical regions of the world. © 2012 Springer-Verlag.

Differentially transcribed genes in skeletal muscle of lambs

The objective of this study was to compare gene transcription profiles in Longissimus dorsi muscle of the following four hair sheep genetic groups, Morada Nova (MO), Brazilian Somali (SO), Santa Inĉs (SI) and 1/2 Dorper×1/2 Morada Nova (F1). These groups all display different postnatal muscle growth. The transcriptomes of the skeletal muscle of the lambs (at 200 days of age) were profiled by using oligonucleotide microarrays and reverse transcription-quantitative real-time PCR (RT-qPCR). The microarray experiment identified 262 transcripts that were differentially expressed when transcription levels were compared between the different breeds. A total of 23 transcripts among which those involved in skeletal muscle development (MyoD1 and IGFBP4), lipogenesis and adipogenesis (C/EBPδ, PPARγ and PGDS) were differentially expressed in at least in one comparison. Clustering analysis showed that there is greater similarity in gene expression between the MO and SI breeds and between F1 and SO genetic groups. The SO breed has the most distinct expression pattern. The RT-qPCR results confirmed the findings from the microarray study. A positive correlation was observed between the expression of MyoD1 and the cold carcass yield. The negative correlations between the weight and yield of cold carcass with the expression of C/EBPδ mean that the selection for adipogenesis could lead to a lower carcass weight. The GLUT3 and PYGL gene transcripts were negatively correlated with fat thickness, but ATP5G1 was positively correlated with this trait. Interestingly, many genes negatively correlated with PUFA were positively correlated with cold carcass yield. In conclusion, the present work demonstrated that there are breed-specific expression patterns in Brazilian hair sheep genetic groups. The differences in gene expression among genetic groups were consistent with their phenotypic differences. The positive correlation of the MyoD1 expression with the cold carcass yield suggests that this gene is important for tissue growth in sheep. The positive correlation of the C/EBPδ expression with PUFA provides an opportunity to select for lipid deposition in meat animals. © 2012 Elsevier B.V.

Effect of superstimulatory treatments on the expression of genes related to ovulatory capacity, oocyte competence and embryo development in cattle.

Multiple ovulation (superovulation) and embryo transfer has been used extensively in cattle. In the past decade, superstimulatory treatment protocols that synchronise follicle growth and ovulation, allowing for improved donor management and fixed-time AI (FTAI), have been developed for zebu (Bos indicus) and European (Bos taurus) breeds of cattle. There is evidence that additional stimulus with LH (through the administration of exogenous LH or equine chorionic gonadotrophin (eCG)) on the last day of the superstimulatory treatment protocol, called the 'P-36 protocol' for FTAI, can increase embryo yield compared with conventional protocols that are based on the detection of oestrus. However, inconsistent results with the use of hormones that stimulate LH receptors (LHR) have prompted further studies on the roles of LH and its receptors in ovulatory capacity (acquisition of LHR in granulosa cells), oocyte competence and embryo quality in superstimulated cattle. Recent experiments have shown that superstimulation with FSH increases mRNA expression of LHR and angiotensin AT(2) receptors in granulosa cells of follicles >8 mm in diameter. In addition, FSH decreases mRNA expression of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) in oocytes, but increases the expression of both in cumulus cells, without diminishing the capacity of cumulus-oocyte complexes to generate blastocysts. Although these results indicate that superstimulation with FSH is not detrimental to oocyte competence, supplementary studies are warranted to investigate the effects of superstimulation on embryo quality and viability. In addition, experiments comparing the cellular and/or molecular effects of adding eCG to the P-36 treatment protocol are being conducted to elucidate the effects of superstimulatory protocols on the yield of viable embryos.

Effects of heat stress on development, quality and survival of Bos indicus and Bos taurus embryos produced in vitro

Heat stress is an important cause of poor development and low survival rates in bovine embryos. Experiments were conducted to test the hypothesis that Bos indicus embryos are more resistant to heat stress than are Bos taurus embryos. In experiment 1, Nelore and Jersey embryos from oocyte pick-up-derived oocytes were submitted to heat stress (96 hours post-insemination, 41 °C, 6 hours), developmental ratios were assessed at Day 7 (Day 0 = day of fertilization), and blastocysts were frozen for RNA extraction. Experiment 2 evaluated expression of COX2, CDX2, HSF1, and PLAC8 in previously frozen blastocysts. In experiment 3, Nellore and Angus embryos from oocyte pick-up-derived oocytes were submitted to heat stress (96 hours post-insemination, 41 °C, 12 hours) and transferred to recipients on Day 7. In experiment 4, embryos developed as in experiment 3 were fixed for Terminal deoxynucleotidyl transferase dUTP nick end labeling labeling and total cell counting. In experiment 1, heat stress decreased the percentage of Jersey oocytes that became blastocysts, but had no effect on Nellore embryos (34.6%, 25.0%, 39.5%, and 33.0% for Jersey control, Jersey heat-stressed, Nellore control, and Nellore heat-stressed oocytes, respectively; P < 0.05). In experiment 2, heat stress decreased (P < 0.05) expression of CDX2 and PLAC8, with higher expression of these genes in Nellore embryos than in Jersey embryos. Heat stress also decreased (P < 0.05) expression of COX2 in Jersey embryos, but had no effect on Nellore embryos. Expression of HSF1 was decreased (P < 0.05) by heat stress in both breeds, with a greater effect in Nellore embryos. In experiment 3, heat stress tended (P = 0.1) to decrease the percentage of pregnancies among cows (Day 30 to 35) that received Angus embryos. In experiment 4, heat stress increased (P < 0.05) the percentage of apoptotic blastomeres, but had no breed-specific effects. In addition, Nellore embryos had fewer (P < 0.05) Terminal deoxynucleotidyl transferase dUTP nick end labeling- positive blastomeres than did Angus embryos. We concluded that the detrimental effects of heat stress were dependent upon embryo breed and were more evident in Bos taurus embryos than in Bos indicus embryos. © 2013 Elsevier Inc.

Comparison of random regression models to estimate genetic parameters for milk production in Guzerat (Bos indicus) cows

Random regression models have been widely used to estimate genetic parameters that influence milk production in Bos taurus breeds, and more recently in B. indicus breeds. With the aim of finding appropriate random regression model to analyze milk yield, different parametric functions were compared, applied to 20,524 test-day milk yield records of 2816 first-lactation Guzerat (B. indicus) cows in Brazilian herds. The records were analyzed by random regression models whose random effects were additive genetic, permanent environmental and residual, and whose fixed effects were contemporary group, the covariable cow age at calving (linear and quadratic effects), and the herd lactation curve. The additive genetic and permanent environmental effects were modeled by the Wilmink function, a modified Wilmink function (with the second term divided by 100), a function that combined third-order Legendre polynomials with the last term of the Wilmink function, and the Ali and Schaeffer function. The residual variances were modeled by means of 1, 4, 6, or 10 heterogeneous classes, with the exception of the last term of the Wilmink function, for which there were 1, from 0.20 to 0.33. Genetic correlations between adjacent records were high values (0.83-0.99), but they declined when the interval between the test-day records increased, and were negative between the first and last records. The model employing the Ali and Schaeffer function with six residual variance classes was the most suitable for fitting the data. © FUNPEC-RP.

Genetic Diversity in the Modern Horse Illustrated from Genome-Wide SNP Data

Horses were domesticated from the Eurasian steppes 5,000-6,000 years ago. Since then, the use of horses for transportation, warfare, and agriculture, as well as selection for desired traits and fitness, has resulted in diverse populations distributed across the world, many of which have become or are in the process of becoming formally organized into closed, breeding populations (breeds). This report describes the use of a genome-wide set of autosomal SNPs and 814 horses from 36 breeds to provide the first detailed description of equine breed diversity. FST calculations, parsimony, and distance analysis demonstrated relationships among the breeds that largely reflect geographic origins and known breed histories. Low levels of population divergence were observed between breeds that are relatively early on in the process of breed development, and between those with high levels of within-breed diversity, whether due to large population size, ongoing outcrossing, or large within-breed phenotypic diversity. Populations with low within-breed diversity included those which have experienced population bottlenecks, have been under intense selective pressure, or are closed populations with long breed histories. These results provide new insights into the relationships among and the diversity within breeds of horses. In addition these results will facilitate future genome-wide association studies and investigations into genomic targets of selection. © 2013 Petersen et al.

Resistance against gastrointestinal nematodes in Crioulo Lageano and crossbred Angus cattle in southern Brazil

Gastrointestinal nematode (GIN) infection is a major cause of production losses in cattle. This study was carried out to evaluate the natural resistance against nematode infection in Crioulo Lageano and crossbred Angus male calves. Crioulo Lageano is a local cattle breed in the state of Santa Catarina, in southern Brazil. Ten weaned calves of each breed were grazed together on pasture and naturally infected with nematodes between July 2009 and December 2010. Once every 28 days, we collected fecal and blood samples for parasitological and immunological tests, as well as recording body weights. After 19 samplings, all animals were slaughtered for quantification and identification of GINs. We found that the animals had been infected with the following nematode species, in decreasing order by the mean number of specimens: Trichostrongylus axei, Cooperia punctata, Ostertagia ostertagi, Haemonchus placei, Oesophagostomum radiatum, and Trichuris spp. There were no significant differences between the Crioulo Lageano and crossbred Angus groups in terms of worm burden or nematode fecal egg count, nor in terms of the mean levels of immunoglobulin (G and A) against C. punctata and H. placei antigens, except in IgA mean level in abomasal mucus against H. placei adult worms that was significantly higher in crossbred Angus cattle (p<0.05). At the end of the study, the crossbred Angus cattle were heavier than were the Crioulo Lageano cattle (mean live weight, 507.35 and 390.3. kg, respectively). Comparative parasitological and immunological evaluation revealed no difference between two breeds in terms of their natural resistance against GINs. © 2012 Elsevier B.V.

Effect of Storage Time and Temperature of Equine Epididymis on the Viability, Motion Parameters, and Freezability of Epididymal Sperm

The recovery of sperm from the epididymal cauda may be the last chance to obtain genetic material when sudden death or serious injuries occur in valuable stallions. However, the lack of technical knowledge regarding the storage and transportation of the epididymis often prevents the preservation of the sperm. Therefore, the aim of this study was to compare sperm parameters of sperm obtained immediately after orchiectomy with sperm recovered from epididymal cauda at different times after storage at 5°C and at room temperature (RT). For that, 48 stallions of different breeds were used. In group 1 (control group), eight stallions were used, and the harvest of the epididymal sperm was performed immediately after orchiectomy. In group 2, 40 stallions were used, which were divided into five groups according to the storage time of the epididymis after orchiectomy (6, 12, 18, 24, or 30 hours), making a total of eight stallions per group. One epididymis of each stallion was stored at 5°C, and the contralateral epididymis was stored at RT, both for the same period. The sperm parameters of total motility, progressive motility, progressive linear velocity, curvilinear velocity, percentage of rapid sperm, and plasma membrane integrity were evaluated in all the groups after sperm recovery, resuspension in a sperm freezing diluent, and thawing. In conclusion, the storage of the testis-epididymis complex at 5°C provided better preservation of epididymal sperm than the storage at RT, and regardless of the temperature, the progressive motility is the sperm parameter that is most sensitive to storage time. © 2013 Elsevier Inc.

Physiology and endocrinology symposium: Influence of cattle genotype (Bos indicus vs. Bos taurus) on oocyte and preimplantation embryo resistance to increased temperature

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic parameters for test-day milk yield, 305-day milk yield, and lactation length in Guzerat cows

Milk production in tropical environments requires the use of crossbreeding systems including breeds well adapted to harsh conditions, but with lower productivities when compared to specialized breeds. Besides the genetic improvement for milk production, lactation lengths also need to be studied for most of these breeds. Accordingly, genetic parameters were estimated for 305-day cumulative milk yield (MY305), test-day milk yield (TDMY), and lactation length (LL) using information from the first lactations of 2816 Guzerat cows selected for milk production in 28 herds in Brazil. Contemporary groups were defined as herd, year and season of the test for TDMY, and as herd, year and season of calving for MY305 and LL. Variance components were estimated with the restricted maximum likelihood method under a multi-trait animal model. Heritabilities estimated for TDMY ranged from 0.16 to 0.24, and were 0.24 and 0.12 for MY305 and LL, respectively. Genetic correlations were high and positive, ranging from 0.51 to 0.99 among TDMY records, from 0.81 to 0.98 between each TDMY and MY305, and from 0.71 to 0.94 between each TDMY and LL. Genetic parameters obtained in this study indicated the possibility of using test-day records for the prediction of breeding values for milk yield in this population of the Guzerat breed. The use of TDMY as selection criteria would result in indirect gains in MY305 and LL. However, the highest response to selection for MY305 would be obtained by direct selection for this trait. © 2012 Elsevier B.V.