Strategies for the identification of precocity in zebu beef cattle based on mixed nonlinear models and multivariate approach.

The use of mixed nonlinear models reduces the residual variance by including random effects, thereby improving the estimates in growth curves. Therefore, we tested distinct mixed nonlinear models (Richards, Brody, Gompertz, Logistic, and Von Bertalanffy) to model the growth curves of Zebu cattle herds raised on pasture in Brazil. In addition, we evaluated the diversity among breeds using hierarchical cluster multivariate analysis (full linkage) based on asymptotic weight (A), maturity rate (K), absolute growth rate (AGR), and absolute maturity rate (AMR) adjusted to 205, 365, 550, and 730 days of age. Body weight data from 311,834 males and females of Guzerat, Nellore, Tabapuã, and Polled Nellore breeds provided by the Brazilian Association of Zebu Breeders were used. The Brody model considering breed-sex fixed and animal random effects was the most suitable to describe the growth in the four breeds. The Guzerat and Tabapuã males showed increased precocity (higher K values) when compared to polled Nellore and Nellore males, which were characterized by higher A and AMR values. Females were more precocious than males (high K and low A values), particularly within Tabapuã and Guzerat breeds, respectively. Regardless of sex, the highest AGR values were observed from weaning up to 2 years of age in Tabapuã and Guzerat breeds. The cluster analyses revealed two groups: (1) Polled Nellore and Nellore males with high A, AGR_205, AGR_365, AGR_550, and AGR_730 values, represented by large adult animals, and (2) males and females of Guzerat and Tabapuã, characterized as animals of increased precocity. A subgroup encompassing males of Guzerat and Tabapuã was also observed, with intermediate values ​​for all parameters. This information is useful to help breeders and producers in strategies for feeding management and defining the most precocious beef cattle breed to increase the economic gains in pasture-based raising systems.

Phenotypic differences for growth, feed efficiency, and age of first calving of Brazilian zebu females.

This study investigated phenotypic differences of zebu females from four breeds using variables of growth, feed efficiency, and age at first calving. Weights throughout the life were recorded, and a growth curve was fitted using the Gompertz model. The growth was also evaluated at standardized ages (205, 365, and 550 days) using the body weight and the total and daily weight gains. The Kleiber index and age at first calving were used as measures of feed efficiency and sexual precocity, respectively, totaling 25 variables. New variables were created using the factor analysis and used in new multivariate analyzes. Only six factors explained 95.41% of the total variance and were used for the subsequent analyses. The factors were defined as maturity, precocity, feed efficiency postweaning, feed efficiency post 1 year of age, puberty, and birth weight. There were differences between breeds according to the multivariate analysis of variance. Each breed appeared in a quadrant on the Biplot graph, showing relationship with different factors, demonstrating the diversity of zebu females. There is a difference in growth, feed efficiency, and sexual precocity in Brazilian zebu females, allowing the identification of potentials of the animals and help breeders and decision-makers.

Accuracy and reliability of two body weight estimators based on linear measurements in horses / Acurácia e confiabilidade de dois estimadores de peso corporal baseados em mensurações lineares em equídeos

Estimation methods are routinely used to determine the body weight of a horse when a scale is not available. However, it is important to evaluate the accuracy and reliability of these predictions since nutritional management and drug dosage, among others, require knowledge of the animals weight. The objective of this study was to evaluate the accuracy and reliability of estimated weights of horses using two prediction models, and to discuss the effect of the predictions on animal management. Seventy-one adult male animals (40 mules and 31 horses) were weighed on a precision scale (control weight). Chest circumference and body length were measured and used to estimate body weight using the two models. Accuracy was evaluated by analysis of fit indices, comparison of squared prediction errors, delta Akaikes information criterion, and decomposition of the mean squared error of prediction. For economic evaluation, three production scenarios were established: simple (worming + forage), traditional (worming + forage + concentrate mixture), and traditional with supplementation (worming + forage + concentrate mixture + supplementation). Economic values were collected through a pricing survey carried out in the Midwest region of Brazil and converted to US dollars. Percent differences in costs were evaluated using Fishers exact test. The most suitable model for the morphometric profile of the animals was that using a combination of chest circumference and body length. The differences in economic values between production scenarios were significant (P<0.05). Losses using the inadequate model are 10% higher compared to control; thus, in a facility with 20 equids that uses this model, the losses are ≈ US$ 10,000/year. When investment in a scale is not possible, it is fundamental to evaluate which model is more compatible with the body biotype of the herd since all types of management that depend on the body weight of the animals may result in significant economic losses.(AU)

Estimativas para determinar o peso corporal de um equino são rotineiramente usadas quando uma balança não está disponível. Todavia, é fundamental realizar um diagnóstico da acurácia e confiabilidade das predições destes estimadores, pois o manejo nutricional, dosificação de fármacos, entre outros, exigem o conhecimento do peso. Assim, objetivou-se avaliar a acurácia e confiabilidade de predições de peso estimado de equídeos utilizando dois modelos de cálculos e discutir o reflexo das predições no manejo dos animais. Foram pesados 71 equídeos machos (40 Muares e 31 Equinos) com idade adulta, em balança de precisão (peso controle). Medidas de perímetro torácico e comprimento corporal foram realizadas e utilizadas para estimar o peso corporal usando os modelos. A acurácia foi avaliada via análise do índice de adequação, comparação entre o quadrado do erro de predição, critério de informação Delta Akaike's e decomposição do erro quadrático médio da predição. Para avaliação econômica, criaram-se três cenários de produção: simples (vermifugação + volumoso), tradicional (vermifugação + volumoso + concentrado) e tradicional com suplementação (vermifugação + volumoso + concentrado + suplementação). Valores econômicos foram verificados em pesquisa de preço na região Centro Oeste do Brasil e convertidos em dólar. Avaliou-se as diferenças de percentagem dos custos utilizando teste de Fisher. O modelo mais adequado para o perfil morfométrico dos animais foi o que usa combinação entre perímetro torácico e comprimento corporal. Foram significativas (P<0,05) as diferenças para os valores econômicos nos cenários de produção. Prejuízos usando o modelo inadequado são 10% superiores em relação ao controle, assim em um estabelecimento com 20 equídeos que usa este modelo, os prejuízos são ≈ 10 mil dólares/ano. Na ausência da balança, é fundamental avaliar qual modelo de cálculo será mais compatível com biotipo corporal do rebanho, pois todo tipo de manejo que depende do peso corporal dos animais, pode gerar prejuízos econômicos significativos.(AU)

Comparison of genetic parameters and estimated breeding values for worm resistance in meat sheep obtained using traditional and genomic models.

Gastrointestinal nematode infections have caused expressive losses in sheep production worldwide. The improvement of host genetic resistance to worms has been used as a strategy to mitigate this problem. In this sense, the inclusion of genomic information has shown potential to increase the accuracy of prediction of breeding values and speed up selection. In this study, we aimed to compare estimates of genetic parameters and breeding values for traits that indicate the resistance to gastrointestinal nematode infection in Santa Inês sheep using the pedigree-based BLUP or including genomic information. There were 1478 animals in the pedigree, of which 271 were genotyped using the OvineSNP50 BeadChip (Illumina, Inc.). The host resistance was assessed using the following traits: fecal nematode egg counts (FEC); FAMACHA score (FAMACHA); and resistance to gastrointestinal nematode infection (RGNI) as a combination of FEC, FAMACHA, body condition score, and hematocrit. The genetic parameters and breeding values were estimated using single- and multi-trait analyses. For RGNI, the heritability estimates ranged from 0.25 using the single-trait genomic model (S-H) to 0.54 using the traditional multi-trait model (M-A). The heritability estimates for FEC ranged from 0.06 to 0.36, using the single-trait pedigree-based model (S-A) and the multi-trait genomic model (M-H), respectively. For FAMACHA, the heritability estimates ranged from 0.46 (M-H) to 0.54 (M-A). Estimates of genetic correlation ranged from 0.22 to 0.69. The inclusion of genomic information provided gain in accuracy for all traits. All estimates of predictive ability obtained using genomic data in a multi-trait setting were higher than those obtained using single-trait models. The estimates of predictive ability ranged from 0.03 (S-A) to 0.46 (M-H). The heritability estimates obtained using genomic information showed that all traits evaluated are suitable for genomic selection. Despite the low accuracies obtained, the use of the genomic model provided more accurate estimates of breeding values in comparison to the pedigree-based model.

Genotype by environment interaction for fat and protein yields via reaction norms in Holstein cattle of southern Brazil.

Our objective was to evaluate the genetic merit of Holstein cattle population in southern Brazil in response to variations in the regional temperature by analyzing the genotype by environment interaction using reaction norms. Fat yield (FY) and protein yield (PY) data of 67 360 primiparous cows were obtained from the database of the Paraná Holstein Breeders Association, Brazil (APCBRH). The regional average annual temperature was used as the environmental variable. A random regression model was adopted applying mixed models with Restricted Maximum Likelihood (REML) algorithm using WOMBAT software. The genetic merit of the 15 most representative bulls, depending on the temperature gradient, was evaluated. Heritability ranged from 0.21 to 0.27 for FY and from 0.14 to 0.20 for PY. The genetic correlation observed among the environmental gradients proved to be higher than 0.80 for both traits. Slight reranking of bulls for both traits was detected, demonstrating that non-relevant genotype by environment interaction for FY and PY were observed. Consequently, no inclusion of the temperature effect in the model of genetic evaluation in southern Brazilian Holstein breed is required.

Integration of georeferenced and genetic data for the management of biodiversity in sheep genetic resources in Brazil.

There are few animal germplasm/gene bank collections in Brazil, and basic studies are needed to attend the future internal and external demands from international partners. The aim of this work was to validate a "proof of concept" that integrates spatial (georeferenced data) and genetic data regarding the local of origin from 3518 DNA samples from 17 different genetic groups or breeds of sheep in the Brazilian Germplasm bank. Spatialisation shows that not all genetic groups have samples in the bank, and collection is concentrated in the conservation nuclei spread nationwide. Only 21% of states with a specific breed have samples in the gene bank. The mean number of animals sampled per collection was 32, while the mean distance travelled to collect samples was 262 km from the conservation nuclei. For example, the Brazilian Somali were only collected in the conservation nucleus in Ceará State. No samples were collected to date for the Cariri breed, which is recognised by the Brazilian Ministry of Agriculture. Only two farms and one breed in the bank are from the northern region. Of the 27 states, there are samples in the gene bank of sheep from 13, so several states have no samples, requiring collection from herds outside the official system of conservation to make sure that studies using this germplasm realised are not biased. Significant genetic differences are seen above 332 km, which should guide future sampling efforts. Suggestions are given for improving the quantity, quality and diversity of samples in the gene bank.

Accuracy and reliability of two body weight estimators based on linear measurements in horses / Acurácia e confiabilidade de dois estimadores de peso corporal baseados em mensurações lineares em equídeos

Estimation methods are routinely used to determine the body weight of a horse when a scale is not available. However, it is important to evaluate the accuracy and reliability of these predictions since nutritional management and drug dosage, among others, require knowledge of the animal’s weight. The objective of this study was to evaluate the accuracy and reliability of estimated weights of horses using two prediction models, and to discuss the effect of the predictions on animal management. Seventy-one adult male animals (40 mules and 31 horses) were weighed on a precision scale (control weight). Chest circumference and body length were measured and used to estimate body weight using the two models. Accuracy was evaluated by analysis of fit indices, comparison of squared prediction errors, delta Akaike’s information criterion, and decomposition of the mean squared error of prediction. For economic evaluation, three production scenarios were established: simple (worming + forage), traditional (worming + forage + concentrate mixture), and traditional with supplementation (worming + forage + concentrate mixture + supplementation). Economic values were collected through a pricing survey carried out in the Midwest region of Brazil and converted to US dollars. Percent differences in costs were evaluated using Fisher’s exact test. The most suitable model for the morphometric profile of the animals was that using a combination of chest circumference and body length. The differences in economic values between production scenarios were significant (P<0.05). Losses using the inadequate model are 10% higher compared to control; thus, in a facility with 20 equids that uses this model, the losses are ≈ US$ 10,000/year. When investment in a scale is not possible, it is fundamental to evaluate which model is more compatible with the body biotype of the herd since all types of management that depend on the body weight of the animals may result in significant economic losses.

Estimativas para determinar o peso corporal de um equino são rotineiramente usadas quando uma balança não está disponível. Todavia, é fundamental realizar um diagnóstico da acurácia e confiabilidade das predições destes estimadores, pois o manejo nutricional, dosificação de fármacos, entre outros, exigem o conhecimento do peso. Assim, objetivou-se avaliar a acurácia e confiabilidade de predições de peso estimado de equídeos utilizando dois modelos de cálculos e discutir o reflexo das predições no manejo dos animais. Foram pesados 71 equídeos machos (40 Muares e 31 Equinos) com idade adulta, em balança de precisão (peso controle). Medidas de perímetro torácico e comprimento corporal foram realizadas e utilizadas para estimar o peso corporal usando os modelos. A acurácia foi avaliada via análise do índice de adequação, comparação entre o quadrado do erro de predição, critério de informação Delta Akaike's e decomposição do erro quadrático médio da predição. Para avaliação econômica, criaram-se três cenários de produção: simples (vermifugação + volumoso), tradicional (vermifugação + volumoso + concentrado) e tradicional com suplementação (vermifugação + volumoso + concentrado + suplementação). Valores econômicos foram verificados em pesquisa de preço na região Centro Oeste do Brasil e convertidos em dólar. Avaliou-se as diferenças de percentagem dos custos utilizando teste de Fisher. O modelo mais adequado para o perfil morfométrico dos animais foi o que usa combinação entre perímetro torácico e comprimento corporal. Foram significativas (P<0,05) as diferenças para os valores econômicos nos cenários de produção. Prejuízos usando o modelo inadequado são 10% superiores em relação ao controle, assim em um estabelecimento com 20 equídeos que usa este modelo, os prejuízos são ≈ 10 mil dólares/ano. Na ausência da balança, é fundamental avaliar qual modelo de cálculo será mais compatível com biotipo corporal do rebanho, pois todo tipo de manejo que depende do peso corporal dos animais, pode gerar prejuízos econômicos significativos.

Kleiber ratios and growth curves of African Black and Red Neck ostrich breeds and their crossbreeds / Razão Kleiber e curva de crescimento para raças de avestruzes African Black e Red Neck e seus cruzamentos

The selection of animals with lower production costs can be achieved by using feed efficiency and growth curve information. Kleiber ratio (KR) is an alternative option for discriminating against the animals that have the greatest weight gain about their final weight. Alternative feed efficiency and growth curves for ostriches of the African Black (AB) and Red Neck (RN) breeds and their crossbreeds (CB) were investigated using KR and Gompertz equation. Univariate and multivariate analyses were used. The highest adult weight was identified in the RN and CB. AB was more precocious than the RN and CB individuals. Only AB animals reached 75% of their mature weight at one year of age. At 180 days, AB showed better KR. AB was different from the others, mainly for KR at 90 days and 180 days. Considering multivariate analysis, AB animals were different from the others, regardless of sex, mainly for KR at 90 days and KR at 180 days. Other subgroups separated the animals by sex. In a market preferring animals of minor structure (smaller cuts) and greater precocity, it would be suitable to opt for AB. When animals with greater body structure (larger cuts) are desired, males RN and CR is the best option, however, it will be slaughtered with greater age and lower value for KR (may generate a bigger production cost ). It is possible to obtain animals with precocity and high KR, being well represented by the AB breed.(AU)

A seleção de animais com custos de produção mais baixos pode ser alcançada usando a eficiência alimentar e informações da curva de crescimento. A razão de Kleiber (KR) é uma alternativa para discriminar os animais que apresentam maior ganho de peso em relação ao peso final. Eficiência alimentar alternativa e curvas de crescimento para avestruzes das raças African Black (AB) e Red Neck (RN) e seus cruzamentos (CB) foram investigadas usando a equação de KR e Gompertz. Análises univariadas e multivariadas foram utilizadas. O maior peso adulto foi observado no RN e no CB. AB foi mais precoce do que os indivíduos RN e CB. Apenas animais AB atingiram 75% de seu peso adulto até um ano de idade. Aos 180 dias, AB tem maior KR. AB foi diferente dos demais, principalmente para KR aos 90 dias e 180 dias. Considerando a análise multivariada, os animais AB diferiram dos demais, independente do sexo, principalmente pelos seguintes parâmetros: KR aos 90 dias, KR aos 180 dias. Outros subgrupos separaram os animais por sexo. Em um mercado que prefere animais de menor estrutura corporal (cortes menores) e maior precocidade, seria adequado optar pela AB. Para animais com maior estrutura corporal (cortes maiores), os machos RN e CR são a melhor opção, porém, serão abatidos com maior idade e menor valor para KR (pode gerar um maior custo de produção). É possível obter animais com precocidade e alto KR, sendo bem representados pelo AB.(AU)

Genotype-environment interaction for age at first calving in Holstein cows in Brazil.

Dairy cattle production is distributed throughout the Brazilian regions. However, Brazilian producing regions are different in air temperature and humidity, diet, birth season, and other factors that may alter the reproductive performances of cows. The age of the cow at first calving (AFC) is a good indicator of sexual precocity since it shows the beginning of the female reproductive life and has a great influence on cow replacement costs. Researches on genotype-environment interaction (GEI) show the importance of using specific bulls for the different production systems in Brazil since most semen used in the country is imported. The objective of this work was to evaluate GEI for AFC in Holstein cows in Brazil, using reaction norms. The statistical models used were the standard animal model, which disregards the GEI, and hierarchical reaction norm models with homoscedastic (HRNMHO) and heteroscedastic (HRNMHE) residual variance, and one (HRNMHO1S and HRNMHE1S) and two (HRNMHO2S and HRNMHE2S) steps. HRNMHO1S presented better fit to the data, with lower heritability for environments with lower AFC, and higher heritability for environments with higher AFC. The GEI found was complex, with a reclassification of bulls, denoting the importance of considering GEI for evaluation and selection of bulls for different production levels. The reduction of AFC is possible when using breeding bulls adapted to the tropical and subtropical conditions of Brazil.

Genotype-environment interaction for productive traits of Holstein cows in Brazil described by reaction norms.

Brazil is the world's fourth largest milk producer; this activity extends throughout the national territory, with productions of approximate 34 billion liters of milk per year. The objective of this work was to evaluate the genotype-environment interaction (GEI) in purebred Holstein cows for milk (M), protein (P), and fat (F) yields. The statistical models used were the standard animal model (AM), which disregards the GEI, and hierarchical reaction norm models with homoscedastic (HRNMHO) and heteroscedastic (HRNMHE) residual variance, and one (HRNMHO1S and HRNMHE1S) and two (HRNMHO2S and HRNMHE2S) steps. HRNMHO1S presented a better fit of the data for all traits, with higher heritability for the best environments. Most bulls presented robust phenotypes; however, GEI was found with a reclassification of the bulls in the environmental gradient. Although few, and less used, bulls with plastic phenotypes were found for all traits, and the use of them can optimize genetic gains in specific environments.

Nonlinear mixed effects models for comparing growth curves for Guzerá cattle / Modelos não lineares mistos para comparar curvas de crescimento de bovinos da raça Guzerá

The objective of the present work was to evaluate the accuracy of the fitted Gompertz and von Bertalanffy models for male and female Guzerá cattle, respectively. Four production regions in Northeast Brazil were included in the models as a fixed effect, and the animals were included as a random effect. In addition, the coefficients of the growth models in the production regions were compared. The accuracy of the fit equations was assessed with the Akaike information criterion, Bayesian information criterion, mean absolute deviation, mean squared error, and coefficient of determination. Confidence intervals were used for comparing the production regions. The Guzerá males in the Gado-Algodão and Serra Geral da Bahia production regions were statistically equal in asymptotic weight, and the animals in the Itapetinga-Valadares and Mata-Agreste regions had equivalent maturity rates. The Guzerá females in the Itapetinga-Valadares and Serra Geral da Bahia regions had the same asymptotic weight. The maturity rates in Itapetinga-Valadares were equal to those estimated for Mata-Agreste and Serra Geral da Bahia. The inclusion of the fixed effect of the production region and the random effect of the animals in the models improved the fit quality and increased the possibility of generating growth curves for each region.(AU)

O objetivo do presente trabalho foi avaliar a acurácia dos modelos Gompertz e Von Bertalanffy ajustados, respectivamente, para machos e fêmeas da raça Guzerá, sendo incorporado nos modelos o efeito fixo de quatro regiões de produção do nordeste brasileiro e efeito aleatório de animal, além de comparar os coeficientes dos modelos de crescimento entre regiões de produção. A acurácia das equações ajustadas foi avaliada por meio do critério de informação de Akaike, critério de informação Bayesiano, desvio médio absoluto, erro quadrático médio e o coeficiente de determinação. Para comparar as regiões de produção foram utilizados intervalos de confiança. Verificou-se que machos da raça Guzerá das regiões de produção Gado-Algodão e Serra Geral da Bahia possuem peso assintótico estatisticamente igual, enquanto que a taxa de maturidade é equivalente para animais das regiões Itapetinga-Valadares e Mata-Agreste. As fêmeas da raça Guzerá das regiões de Itapetinga-Valadares e Serra Geral da Bahia possuem o mesmo peso assintótico. A taxa de maturidade em Itapetinga-Valadares é igual a estimada para Mata-Agreste e Serra Geral da Bahia. Ao incluir o efeito fixo de região de produção e aleatório de animal nos modelos, houve melhora na qualidade de ajuste e a possibilidade de gerar curvas de crescimento para cada região.(AU)

Nonlinear mixed effects models for comparing growth curves for Guzerá cattle / Modelos não lineares mistos para comparar curvas de crescimento de bovinos da raça Guzerá

The objective of the present work was to evaluate the accuracy of the fitted Gompertz and von Bertalanffy models for male and female Guzerá cattle, respectively. Four production regions in Northeast Brazil were included in the models as a fixed effect, and the animals were included as a random effect. In addition, the coefficients of the growth models in the production regions were compared. The accuracy of the fit equations was assessed with the Akaike information criterion, Bayesian information criterion, mean absolute deviation, mean squared error, and coefficient of determination. Confidence intervals were used for comparing the production regions. The Guzerá males in the Gado-Algodão and Serra Geral da Bahia production regions were statistically equal in asymptotic weight, and the animals in the Itapetinga-Valadares and Mata-Agreste regions had equivalent maturity rates. The Guzerá females in the Itapetinga-Valadares and Serra Geral da Bahia regions had the same asymptotic weight. The maturity rates in Itapetinga-Valadares were equal to those estimated for Mata-Agreste and Serra Geral da Bahia. The inclusion of the fixed effect of the production region and the random effect of the animals in the models improved the fit quality and increased the possibility of generating growth curves for each region.

O objetivo do presente trabalho foi avaliar a acurácia dos modelos Gompertz e Von Bertalanffy ajustados, respectivamente, para machos e fêmeas da raça Guzerá, sendo incorporado nos modelos o efeito fixo de quatro regiões de produção do nordeste brasileiro e efeito aleatório de animal, além de comparar os coeficientes dos modelos de crescimento entre regiões de produção. A acurácia das equações ajustadas foi avaliada por meio do critério de informação de Akaike, critério de informação Bayesiano, desvio médio absoluto, erro quadrático médio e o coeficiente de determinação. Para comparar as regiões de produção foram utilizados intervalos de confiança. Verificou-se que machos da raça Guzerá das regiões de produção Gado-Algodão e Serra Geral da Bahia possuem peso assintótico estatisticamente igual, enquanto que a taxa de maturidade é equivalente para animais das regiões Itapetinga-Valadares e Mata-Agreste. As fêmeas da raça Guzerá das regiões de Itapetinga-Valadares e Serra Geral da Bahia possuem o mesmo peso assintótico. A taxa de maturidade em Itapetinga-Valadares é igual a estimada para Mata-Agreste e Serra Geral da Bahia. Ao incluir o efeito fixo de região de produção e aleatório de animal nos modelos, houve melhora na qualidade de ajuste e a possibilidade de gerar curvas de crescimento para cada região.

Inbreeding depression in Holstein cattle in Brazil

The objective of this study was to evaluate inbreeding depression in Holstein cows in Brazil, considering their 305-day milk production (MP), age of first calving (AFC), and calving interval (CI). The effects of inbreeding depression on the traits were determined using four regression models (linear, quadratic, exponential, and Michaelis-Menten) about the errors generated by the animal model. The linear model was significant for CI, and the quadratic model was significant for CI and AFC. The Michaelis-Menten and exponential models were significant for MP, AFC, and CI. Inbreeding depression affected MP and CI. Cows with inbreeding coefficient of 15% produced approximately 260 kg less milk than non-inbred cows. A 1% increase in the inbreeding level resulted in an unfavorable increase of CI of 1.88 days. The quadratic and exponential models showed no variations for CI with increasing inbreeding level; however, the Michaelis-Menten model showed a positive effect of inbreeding on CI. Despite of the small number of inbred Holstein cows, the inbreeding negatively affected milk production and calving intervals. Therefore, breeders should monitor their cattle inbreeding levels. The Michaelis-Menten and exponential non-linear models are best suited to fit inbreeding data of Holstein cows.(AU)

Morphofunctional diversity of equine of varied genetic compositions raised in the Pantanal biome of Brazil.

Evaluating phenotypic diversity makes it possible to identify discrepancies in aptitudes among animals of different genetic bases, which is an indicator of adaptive or selective differences between populations. The objective of this work was to evaluate the morphofunctional diversity of 452 male and female adult equines (Arabian, Quarter Mile, Pantaneiro, and Criollo breeds, and undefined crossbreeds of horses and mules) raised in the Pantanal biome (Brazil). Linear measurements were performed to estimate conformation indexes. Initially, a discriminant analysis was performed, regardless of the animal's size, followed by factor analysis. The factors were characterized and used as new variables. The diversity among equines and their relationship with the factors were evaluated using multivariate analysis. The factors were classified according to their decreasing importance: balance, rusticity, and robustness for the measurement factors; and load, ability, conformation, and equilibrium for the index factors. The genetic groups of equines have well-defined morphofunctional characteristics. The main differences are based on the rusticity and ability typologies in relation to those based on performance. Equines introduced to the Pantanal biome presented a more robust and compact body with good conformation. As a result, these horses may have superior athletic performance during equestrian activities when compared to the Pantaneiro local breed. However, this biotype may represent less rusticity (less adaptive capacity). Therefore, the regional breed can be equal or better in equestrian activities than breeds introduced to the Pantanal biome. Thus, breeders may cross horses from local breeds as an alternative to those introduced. Undefined crossbred male equines presented a different profile from the Pantaneiro breed, which may indicate little use of crossbreeds in breeding.

Genetic variability of Leishmania infantum in naturally infected dogs in the state of Bahia, Brazil / Variabilidade genética de Leishmania infantum em cães naturalmente infectados no estado da Bahia, Brasil

Abstract In Brazil, Leishmania infantum mainly affects humans and dogs. The state of Bahia presents many dogs that are positive for this parasite. Despite the importance of epidemiology in this region, there are still very few studies that have assessed the genetic characteristics of L. infantum. The aim of this study is to investigate the genetic variability of L. infantum isolated identified in naturally infected dogs, in order to verify occurrence of subpopulation of this parasite in the different biomes existing in the state of Bahia. Thirty-two samples of L. infantum were analyzed, which were obtained isolated in dogs from the Mata Atlântica (rainforest), Caatinga (semi-arid scrub forest), and Cerrado (a vast tropical savannah eco-region) Bahia municipalities' biomes. All animals presented with clinical changes suggestive of Leishmania spp. and they exhibited positive reactions to serological tests. kDNA analysis with RFLP markers revealed the presence of genetic variability and gene flow in subpopulations of L. infantum; samples from the Mata Atlântica areas were genetically more similar to those from the areas of Caatinga and they were less likely to resemble those of the Cerrado. This data may be used to investigate the dissemination of parasite in the canine population of state of Bahia.

Resumo No Brasil a Leishmania infantum afeta principalmente o homem e os cães. O estado da Bahia apresenta elevado número de cães positivos por este parasito. Apesar da importância epidemiologia para a região, ainda há poucos estudos que avaliam as características genéticas de L. infantum. Objetivou-se com este estudo investigar a variabilidade genética de cepas de L. infantum identificadas em cães naturalmente infectados, a fim de verificar a ocorrência de sobpopulações do parasito nos diferentes biomas existentes no estado da Bahia. Foram analisadas 32 amostras de L. infantum isoladas em cães de municípios baianos distribuídos nos biomas Mata Atlântica, Caatinga e Cerrado. Todos os animais apresentavam alterações clínicas sugestivas de Leishmania spp. e reação positiva em exames sorológicos. A análise do kDNA com marcadores RFLP revelaram a presença de variabilidade genética e fluxo gênico nas subpopulações de L. infantum sendo que as amostras das áreas de Mata Atlântica foram geneticamente mais semelhantes as das áreas de Caatinga e foram mais distantes daquelas oriundas do Cerrado. Estas informações podem auxiliar em investigações de dispersão do parasito na população canino do Estado da Bahia.

Genetic diversity, population structure, and correlations between locally adapted zebu and taurine breeds in Brazil using SNP markers.

Genetic diversity is one of the most important issues in studies on conservation of cattle breeds and endangered species. The objective of this study was to estimate the levels of genetic differentiation between locally adapted taurine (Bos taurus taurus) and zebu (Bos taurus indicus) breeds in Brazil, which were genotyped for more than 777,000 SNPs. The fixation index (F ST), principal component analysis (PCA), and Bayesian clustering were estimated. The F ST highlighted genetic differentiation between taurine and zebu breeds. The taurine lines, Caracu and Caracu Caldeano, had significant genetic differentiation (F ST close to 5%) despite their recent selection for different uses (meat and milk). This genetic variability can be used for conservation of locally adapted animals, as well as for breeding programs on zebu breeds. Introgression of zebu in locally adapted breeds was identified, especially in Curraleiro Pé-Duro breed. The Gyr breed, however, had low breed purity at genomic level due to its very heterogeneous mixing pattern.

Genetic variability of Leishmania infantum in naturally infected dogs in the state of Bahia, Brazil.

In Brazil, Leishmania infantum mainly affects humans and dogs. The state of Bahia presents many dogs that are positive for this parasite. Despite the importance of epidemiology in this region, there are still very few studies that have assessed the genetic characteristics of L. infantum. The aim of this study is to investigate the genetic variability of L. infantum isolated identified in naturally infected dogs, in order to verify occurrence of subpopulation of this parasite in the different biomes existing in the state of Bahia. Thirty-two samples of L. infantum were analyzed, which were obtained isolated in dogs from the Mata Atlântica (rainforest), Caatinga (semi-arid scrub forest), and Cerrado (a vast tropical savannah eco-region) Bahia municipalities' biomes. All animals presented with clinical changes suggestive of Leishmania spp. and they exhibited positive reactions to serological tests. kDNA analysis with RFLP markers revealed the presence of genetic variability and gene flow in subpopulations of L. infantum; samples from the Mata Atlântica areas were genetically more similar to those from the areas of Caatinga and they were less likely to resemble those of the Cerrado. This data may be used to investigate the dissemination of parasite in the canine population of state of Bahia.

Index proposal for Nelore bulls classification using traits groups of weight, carcass and reproductive

Genetic breeding programs generally evaluate animals considering the same objectives, but the indices used in the selection criteria can vary. This can give rise to distinct bull rankings in each program. Thus, we aimed to create alternatives for the referral of bulls for mating through multivariate analyses. We used information from the summaries of two genetic evaluation programs (1 and 2) with Nellore bulls. Characteristics were separated into groups: weight, carcass and reproduction. Groups were formed using the mean Euclidean distance and the Tocher optimization method. The means of each trait among the animals allocated to the same group were used to compose the following subindexes: weight gain (siWG), carcass (siCG) and reproduction (siRG). Based on the mean of the group subindex classification, we calculated the average index of group classification (iAGc). When classifying the best groups by characteristics, we observed an increase (superiority of some bulls) in the estimated breeding values (EBVs) by comparison with the total number of bulls evaluated by the programs, selected animals and best 10 final indexes of the programs. There was a change in bull classification when using the iAGc in relation to the classification using the final indexes of the programs. The coefficient of simple coincidence showed that there was a change in bull classification between programs, both between deciles of the final indexes and groups of characteristics. The subindexes siWG, siCG and siRG are important for correcting specific problems inherds. The iAGc should be used instead of the final index of the programs, providing more options for the selection of bulls for mating.

Growth curve of Repartida goats reared in the Caatinga region, Brazil / Curva de crescimento de caprinos Repartida criados na Caatinga

This work aimed to determine which non-linear model (Brody, Gompertz, logistic, von Bertalanffy or Richards) best represents the average growth curve of goats, in addition to evaluating the effect of the environment. The weight data of 40 Repartida goats reared in the Brazil Caatinga were included in this study. Weight data was collected every 30 days from birth until 270 days of age. The parameters of the models (A, mature body weight; B, constant of integration; k, maturation rate; m, inflection point) were estimated using the NLIN procedure of SAS. The logistic model showed a slightly higher average fit in comparison to the other models. The absolute growth rate suggests that the maximum growth rate was reached early. The effect of the contemporary groups was significant (P 0.05), but only for the estimated k parameter. The estimated correlation between the A and k parameters was significant and negative, indicating a lower probability of a high body weight in adulthood. Goats of the Repartida ecotype are characterized by their high birth weight and low weight at maturity, which combined with the nutritional deficit, suggests that these animals have adapted to the adverse conditions of the Brazilian Caatinga region.(AU)

Objetivou-se neste trabalho verificar dentre os modelos não-lineares seguintes, Brody, Gompertz, Logístico, Von Bertalanffy e Richards, qual representa melhor a curva média de crescimento de caprinos e, também, avaliar a influência do ambiente nos parâmetros estimados. Para a condução deste trabalho foram utilizados registros de peso de 40 caprinos do ecótipo Repartida criados na caatinga, coletados a cada 30 dias entre o nascimento até os 270 dias de idade. Os parâmetros dos modelos (A, peso à idade adulta; B, constante de integração; k, taxa de maturação; e m, ponto de inflexão) foram estimados com o procedimento NLIN do software SAS. O modelo Logístico apresentou ajuste médio ligeiramente superior aos demais modelos. Os resultados obtidos para taxa de crescimento absoluto indicam que a taxa máxima de crescimento foi alcançada precocemente. O efeito de grupos contemporâneos foi significativo (P 0,05) somente para o parâmetro k estimado. A correlação estimada entre os parâmetros A e k foi significativa e negativa, indicando menor probabilidade dos caprinos atingirem pesos elevados à idade adulta. Os caprinos do ecótipo Repartida são de alto peso ao nascimento e baixo peso à maturidade, o que pode indicar, além do déficit nutricional, a adaptação desses animais às condições adversas da caatinga.(AU)

Index proposal for Nelore bulls classification using traits groups of weight, carcass and reproductive

Genetic breeding programs generally evaluate animals considering the same objectives, but the indices used in the selection criteria can vary. This can give rise to distinct bull rankings in each program. Thus, we aimed to create alternatives for the referral of bulls for mating through multivariate analyses. We used information from the summaries of two genetic evaluation programs (1 and 2) with Nellore bulls. Characteristics were separated into groups: weight, carcass and reproduction. Groups were formed using the mean Euclidean distance and the Tocher optimization method. The means of each trait among the animals allocated to the same group were used to compose the following subindexes: weight gain (siWG), carcass (siCG) and reproduction (siRG). Based on the mean of the group subindex classification, we calculated the average index of group classification (iAGc). When classifying the best groups by characteristics, we observed an increase (superiority of some bulls) in the estimated breeding values (EBVs) by comparison with the total number of bulls evaluated by the programs, selected animals and best 10 final indexes of the programs. There was a change in bull classification when using the iAGc in relation to the classification using the final indexes of the programs. The coefficient of simple coincidence showed that there was a change in bull classification between programs, both between deciles of the final indexes and groups of characteristics. The subindexes siWG, siCG and siRG are important for correcting specific problems inherds. The iAGc should be used instead of the final index of the programs, providing more options for the selection of bulls for mating.(AU)