S.E.F. Guimarães

Bayesian GWAS and network analysis revealed new candidate genes for number of teats in pigs

The genetic improvement of reproductive traits such as the number of teats is essential to the success of the pig industry. As opposite to most SNP association studies that consider continuous phenotypes under Gaussian assumptions, this trait is characterized as a discrete variable, which could potentially follow other distributions, such as the Poisson. Therefore, in order to access the complexity of a counting random regression considering all SNPs simultaneously as covariate under a GWAS modeling, the Bayesian inference tools become necessary. Currently, another point that deserves to be highlighted in GWAS is the genetic dissection of complex phenotypes through candidate genes network derived from significant SNPs. We present a full Bayesian treatment of SNP association analysis for number of teats assuming alternatively Gaussian and Poisson distributions for this trait. Under this framework, significant SNP effects were identified by hypothesis tests using 95xa0% highest posterior density intervals. These SNPs were used to construct associated candidate genes network aiming to explain the genetic mechanism behind this reproductive trait. The Bayesian model comparisons based on deviance posterior distribution indicated the superiority of Gaussian model. In general, our results suggest the presence of 19 significant SNPs, which mapped 13 genes. Besides, we predicted gene interactions through networks that are consistent with the mammals known breast biology (e.g., development of prolactin receptor signaling, and cell proliferation), captured known regulation binding sites, and provided candidate genes for that trait (e.g., TINAGL1 and ICK).

Heritability Estimate and Genetic Correlations of Reproductive Features in Nellore Bulls, Offspring of Super Precocious, Precocious and Normal Cows Under Extensive Farming Conditions

The present work aimed to estimate heritability and genetic correlations of reproductive features of Nellore bulls, offspring of mothers classified as superprecocious (M1), precocious (M2) and normal (M3). Twenty one thousand hundred and eighty-six animals with average age of 21.29 months were used, evaluated through the breeding soundness evaluation from 1999 to 2008. The breeding soundness features included physical semen evaluation (progressive sperm motility and sperm vigour), semen morphology (major, minor and total sperm defects), scrotal circumference (SC), testicular volume (TV) and SC at 18 months of age (SC18). The components of variance, heritability and genetic correlations for and between the features were estimated simultaneously by restricted maximum likelihood, with the use of the vce software system vs 6. The heritability estimates were high for SC18, SC and TV (0.43, 0.63 and 0.54; 0.45, 0.45 and 0.44; 0.42, 0.45 and 0.41, respectively for the categories of mothers M1, M2 and M3) and low for physical and morphological semen aspects. The genetic correlations between SC18 and SC were high, as well as between these variables with TV. High and positive genetic correlations were recorded among SC18, SC and TV with the physical aspects of the semen, although no favourable association was verified with the morphological aspects, for the three categories of mothers. It can be concluded that the mothers sexual precocity did not affect the heritability of their offspring reproduction features.

Seleção de variáveis de desempenho de suínos por meio da análise de componentes principais

Dados de 435 animais de uma populacao F2 de suinos foram utilizados para avaliar a possibilidade de reducao da dimensao do espaco multivariado, por meio da tecnica de componentes principais. Foram avaliadas as seguintes caracteristicas de desempenho: tamanho da leitegada ao nascer (TLN), tamanho da leitegada a desmama (TLD), numero de tetos (NT), pesos ao nascer (PN), aos 21 (P21), aos 42 (P42), aos 63 (P63) e aos 77 (P77) dias de idade e ganho medio de peso diario (GPD), consumo de racao (CR) e conversao alimentar (CA) dos 77 aos 105 dias de idade. Seis componentes principais, obtidos a partir da matriz de correlacao, apresentaram variância inferior a 0,7 (autovalores inferiores a 0,7), o que sugere seis variaveis para descarte, por apresentarem maiores coeficientes, em valor absoluto, a partir do ultimo componente principal. As variaveis descartadas apresentaram correlacao linear simples significativa com as demais. Em razao do grande numero de variaveis redundantes, 54,5% delas podem ser eliminadas, sendo recomendada a avaliacao de apenas TLN, NT, P77, CR e CA, sem que haja perda consideravel da informacao.

Estimativas de herdabilidades e correlações genéticas entre características reprodutivas em touros da raça Nelore

Estimates of phenotypic, genetics and residual variances for reproductive traits in 5903 Nellore bulls were obtained. The experimental model used was multiple trait derivative-free restricted maximum likelihood. The values obtained for heritability were 0.24±0.05 for scrotal circumference at 450 days of age and 0.37±0.05 at 21 months for age at the time of the breeding soundness evaluation; 0.24±0.05 and 0.26±0.05 for left and right testicle length; 0.29±0.05 and 0.31±0.05 for left and right testicle width; 0.12±0.04 for testicle format; 0.33±0.06 for testicle volume; 0.11±0.03 for gross motility; 0.08±0.03 for individual motility and 0.05±0.02 for spermatic vigor; 0.20±0.04, 0.03±0.02 and 0.19±0.04 for larger defects, smaller defects and total defects, respectively. The values for heritability for testicular biometric characteristics were moderate to high while the seminal characteristics, presented low values. Genetic correlations between scrotal circumference with all the reproductive traits were favorable, suggesting the scrotal circumference as a feature of choice in the selection of bulls.

The effect of heat stress on GHR, IGF-I, ANT, UCP and COXIII mRNA expression in the liver and muscle of high and low feed efficiency female quail

Abstract 1. A study was conducted to test the hypothesis that feed efficiency (FE) correlated with the expression of genes from the somatotropic axis and mitochondrial genes involved in energy production, and that the environment to which the birds are exposed influenced the expression of such genes. 2. Quails were divided into High-FE and low-FE groups and maintained in a comfortable or heat stress (HS) (38°C for 24 h) environment to evaluate changes in insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), adenine nucleotide translocator (ANT), uncoupling protein (UCP) and cytochrome oxidase subunit III (COX III) messenger ribonucleic acid (mRNA) expression in liver and muscle tissues. 3. High-FE quails (0.28 g/g) presented a higher final body weight, greater weight gain and a better feed conversion ratio than low-FE birds (0.18 g/g). High-FE birds showed greater IGF-I mRNA expression in the liver and muscle and greater GHR mRNA expression in the muscle. 4. Environmental effects only affected GHR expression in the liver, with quails under comfortable conditions exhibiting greater GHR expression than quails subjected to HS. 5. There was a significant interaction between FE and environmental temperature on ANT mRNA expression in the liver. The greatest ANT mRNA expression was observed for high FE-birds that remained under comfortable conditions. 6. In the liver, UCP mRNA expression did not differ among the quails and was not affected by environment or efficiency. However, comparisons of the low- and high-FE birds revealed higher levels of UCP mRNA in the muscle of low-FE birds. 7. COX III mRNA expression in the liver was dependent on environmental temperature and FE. Higher COX III mRNA expression was observed in animals that remained under comfortable conditions, and high-FE birds exhibited higher expression levels compared to low-FE birds. 8. These results suggest a correlation between IGF-I, GHR, ANT, UCP and COX III gene expression and FE and that environmental temperature could affect the expression of some of these genes.

Using pedigree analysis to monitor the local Piau pig breed conservation program

portuguesA raca local brasileira Piau e um suino tipo banha a qual passou por um processo de selecao realizado pelo medico veterinario Antonio Teixeira Vianna em 1939, com o intuito de desenvolver um animal de dupla aptidao, em outras palavras que fosse adequado para a producao de carne e gordura. As principais caracteristicas da raca sao rusticidade, adaptabilidade e resistencia a doencas. O status de conservacao da raca e ameacado e em 1998 a Granja de Melhoramento de Suinos da Universidade Federal de Vicosa (UFV, Vicosa, MG, Brazil) iniciou uma criacao de suinos da raca Piau com o objetivo de conserva- la e utiliza-la em estudos geneticos. O objetivo do presente estudo e descrever o programa de conservacao da raca Piau da UFV e avaliar uma serie de parâmetros populacionais, a fim de gerar informacoes que possibilitem o monitoramento e a melhoria do programa. Para a analise da estrutura populacional foi utilizado arquivo de pedigree com 1349 individuos por meio do software ENDOG v. 4.8. O programa de conservacao da raca possui boa estrutura com registro de dados zootecnicos e pedigree desde a introducao dos primeiros animais na granja de melhoramento de suinos, juntamente com o controle de acasalamentos, o qual e baseado no acasalamento de animais com menor coancestralidade e na manutencao das familias fundadoras. A populacao de Piau avaliada possui numero efetivo de fundadores e ancestrais iguais a 9 e 8, respectivamente. O coeficiente de endogamia medio, coeficiente de relacao medio e tamanho efetivo da populacao sao 6,55 %, 19,74 % e 18,59, respectivamente. De acordo com os parâmetros avaliados e recomendado aumentar o tamanho efetivo da populacao, por meio da introducao de animais de outra populacao, uma vez que o pequeno numero de fundadores torna dificil o controle da endogamia. portuguesThe local Brazilian pig breed Piau is a lard-type pig that has undergone a breeding and selection process devised by the veterinarian Antonio Teixeira Vianna in 1939. The objective of the program was to develop a dual purpose animal, that is an animal suitable for the production of both fat and meat. The main characteristics of the Piau breed are rusticity, adaptability and high disease resistance. The conservation status of the breed is threatened, and in 1998, the Pig Breeding Farm at Universidade Federal de Vicosa (UFV, Vicosa, MG, Brazil) started a Piau herd for the purposes of conservation and use in genetic studies. The objectives of the present study were to describe the Piau genetic conservation program of the Universidade Federal de Vicosa (UFV) and to evaluate a range of population parameters to generate information for monitoring and improving the program. Population genetic structure analysis was performed using a pedigree file of 1349 animals and ENDOG v 4.8 software. The Piau conservation program has data and a collection of pedigree registers going back to the introduction of the first animals to the Pig Breeding Farm. The program used mating control, which is based on the mating of animals with the lowest pedigree- based relationships and on the maintenance of all the population’s founding families. The effective numbers of founders and ancestors in the studied Piau population are 9 and 8 animals, respectively. The average inbreeding coefficient (F), the avera- ge relatedness coefficient (AR) and the effective population size are 6.55 %, 19.74 % and 18.59, respectively. The findings support an increase in the effective population size of this population through the introduction of animals from other populations, as the small number of founders makes inbreeding control difficult.

Detecção de locos de características quantitativas nos cromossomos 1, 2, 3, 12, 14, 15 e X de suínos: características de desempenho

The accomplishment of the present study had the objective of mapping Quantitative Trait Loci (QTL) related to performance traits in a F2 pig population developed by mating two Brazilian Piau breed sires with 18 dams from a commercial line (Landrace × Large White × Pietrain). The linkage map for this population was constructed after genotyping the animals for 35 microsatellite markers. Estimates of polymorphic information content indicated that the microsatellite markers were appropriate for QTL analyses. The genotypes were analyzed by interval mapping using the GridQTL program. A total of six QTL were found, of which the QTL for slaughter age (days) was significant at the 5% genome-wise level. The information of the significant QTL detected in this study is useful for future fine-mapping studies for the identification of genes. Such information can be used together with traditional methods in breeding programs or even for a better understanding of the phenotypes of swine production.

Immotile short-tail sperm defect in Nelore (Bos taurus indicus) breed bulls.

This case study reported the presence of short tail sperm defect in the semen of three Nelore breed bulls. The sperm presented 0% of motility in the three animals evaluated and a total of 70%, 61% and 34% of pathologies of the intermediate piece of the tail respectively for animals 1, 2 and 3. It was identified that animals 2 and 3 had high degree of inbreeding, although no relationship was found with animal 1. Animal 2 was the only one that presented inbreeding coefficient (6.25%). His half-sib (animal 3) and animal 1, from the same herd, had shown no inbreeding, showing that inheritance is not the only determinant factor for its incidence on Nelore males.

Testosterone serum profile, semen characteristics and testicular biometry of Mangalarga Marchador stallions in a tropical environment

This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14xa0days along a year. Blood samples were collected once at the middle of each season, in a 20-min interval during 24xa0hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations along the day were higher at the beginning of the afternoon (from 12:00 to 15:00xa0hr), but a circadian secretion was not clearly observed. Mean testosterone concentrations did not differ among seasons (pxa0>xa0.05), but a pattern of secretion along the day showed variations with higher concentrations in the afternoon during the winter. Ejaculate volume was higher during summer; however, sperm motility decreased in summer and spring. Total sperm in ejaculate, sperm morphology and testicular biometry kept constant along the year showing no differences among the seasons. The results demonstrated that in a tropical region, reproductive aspects of stallions did not show a clearly defined seasonal variation, and months of autumn and winter were not unsuitable for reproduction of the males.

The use of ultrasonography in the reproductive evaluation of boars

The objective was to study the use of ultrasound as a complementary test in the breeding soundness evaluation in male pigs and study the pattern of echogenicity of the testicular parenchyma in boars of different racial groups. Twenty-six adult boars from four different racial groups were used, 10 from the Piau breed (group 1), four from the commercial and finishing group (group 2), six Pietrain breed (group 3) and six from the Duroc breed (group 4). All animals were evaluated for breeding soundness evaluation and the ultrasound examination of the testicles. The groups of animals that were evaluated showed no difference in the main semen parameters that were evaluated, except for the sperm volume, concentration of the ejaculated sperm and the supravital staining; the lowest figures were for the animals from the Piau breed (group 1). In relation to the testicular biometrics, Duroc animals (group 4) had a greater scrotal width compared to the other groups. But when we assessed the intensity of pixels of the testicles, there was a difference between groups. The groups 2 (finishing animals), 3 (Pietrain) and 4 had no difference between themselves. Group 3 had greater pixel intensity in relation to group 1. Of the 26 animals studied, five showed an abnormality during ultrasound evaluation, like hydrocele, hyperechoic mass in the testicular parenchyma, cyst in the head of the epididymis and the presence of fluid in the head and tail of the epididymis. The various animal groups studied did not differ in the principal reproductive parameters evaluated, showing that despite the great variability of reproductive traits between breeds and within the same breed, the breeding soundness evaluation, the more complete it is, is essential for the selection of breeders and the ultrasonography of the reproductive system becomes an important addition in this examination.