Abstract The use of morphological traits assessed using visual scores as indirect selection criteria in cattle has the advantage of evaluating young animals regarding potential productive and reproductive performance. This enables breeders to make earlier decisions compared to later measurements, such as scrotal circumference at 450 days (SC450) and stayability (STAY). The aim of this study was to estimate the genetic parameters for visual score traits and their associations with reproductive traits: scrotal circumference at 365 days of age (SC365), SC450, STAY, probability of precocious calving (PPC30) and age at first calving (AFC) in Nellore cattle. Visual score data from 4,175 Nellore cattle, with an average age of 22 months, and reproductive data from 3,075 cattle belonging to the HoRa Genetics Provada herd were used. The morphological traits were evaluated by the MERCOS methodology. The heritability estimates obtained ranged from 0.15 to 0.28 for visual scores and 0.10 to 0.54 for reproductive traits. Genetic correlations between visual scores and reproductive traits were generally low, except between: muscularity and PPC30; structure and STAY; racial and SC450; conformation and SC365, SC450, STAY, and AFC; navel and STAY and AFC; and sacrum and SC365, STAY, and AFC, which were moderate to high. The identification of animals with flat sacral bone (not protruding or sloping) can also be an efficient characteristic in the identification for early pregnancy, and together with the musculature score, they can be related to animals with lower age at the first calving.

Resumo A utilização de características morfológicas de bovinos, pelo uso de escores visuais como critério de seleção indireta tem como vantagem a avaliação em animais jovens quanto ao potencial desempenho produtivo e reprodutivo, antecipando a tomada de decisão em comparação a medidas tomadas de forma tardia, como perímetro escrotal aos 450 dias (PE450) e stayability (STAY). Objetivou-se estimar os parâmetros genéticos para características de escores visuais e a associação dessas com características reprodutivas, perímetro escrotal aos 365 (PE365) dias de idade, PE450, STAY, probabilidade de parto precoce (3P) e idade ao primeiro parto (IPP) em bovinos Nelore. Foram utilizadas informações de escores visuais e de reprodução de 4.175 e 3.075 bovinos, respectivamente, com idade média de 22 meses, pertencentes a fazenda HoRa Genética Provada. As características morfológicas foram avaliadas pela metodologia MERCOS. As estimativas de herdabilidade obtidas apresentam grande amplitude, variando de 0,15 a 0,28 para escores visuais e 0,10 a 0,54 para características reprodutivas. As correlações genéticas entre característica de escores visuais e reprodução foram, de maneira geral baixas (0.03-0.66), com exceção entre a musculosidade e 3P, estrutura e STAY, racial e PE450, conformação com PE365, PE450, STAY e IPP, ônfalo com STAY e IPP, e sacro com PE365, STAY e IPP, que foram moderadas a altas. A identificação de animais com melhor osso sacro (mesmo nível das ancas), ou seja, não saliente ou inclinado pode ser uma característica eficiente na identificação para prenhez precoce, e juntamente ao escore de musculatura poderão ser relacionados a animais com menor idade ao primeiro parto.

Abstract The aim was to evaluate the association between growth, carcass and visual scores traits with precocious calving in Nellore cattle. Birth weight (BW), weight at 120, 210, 365 and 450 days of age, pre and post-weaning average daily gain, rib eye area, backfat thickness (BF), rump fat thickness and visual scores obtained at 18 months were used for the analysis. Records from 700 females born between 2009 and 2015, exposed to mating starting at 11 months of age were analyzed. Discriminant analyzes were performed with the software Statistica. BW and BF showed the highest (P>0.01) discrimination value for early heifer pregnancy (EP). Extreme intrauterine growth retardation can result in slower growth, which reflects in the worst reproductive performance, confirmed by the variation in BW between precocious and conventional heifers. The results also demonstrate that the level of body fat affects begin of puberty. Bone structure, musculature, depth, tail insertion and rump scores presented the highest discrimination value for EP. These traits can be used as selection tools to improve sexual precocity in female Nellore cattle. The results obtained in this study would support farmers to guide the heifer management and decisions in order to enhance the EP.

ABSTRACT The objective was to evaluate the existence of heterogeneity of variances and its impact on the genetic evaluation of ponderal performance in sires of the Nellore breed. We used records of adjusted body weights at 210 (W210), 365 (W365), and 450 (W450) days of age. Both W365 and W450 were combined by principal component analyses using the first component (PC). Average daily gain (ADG) was obtained by difference between W450 and W210. The classes of standard deviations (SD) for W210, PC, and ADG were obtained by the standardization of means of herd-year means subclasses, with positive values composing the high SD and values equal and less than zero composing the SD. The model included the fixed effects of contemporary group and age at calving as a covariate, random genetic additive, and maternal genetic (except for PC) effects, and the permanent maternal environment. Variance components were obtained by Gibbs sampling. Posterior means of heritability in analyses without considering heterogeneity of variances ranged from 0.15±0.01 to 0.31±0.01. Posterior means of genetic correlations between the two classes of SD for W210, PC, and ADG were equal to 0.85±0.04, 0.83±0.03, and 0.71±0.08, respectively. Spearman correlation to breeding values of sires for ADG as the selection intensity increased in them, and the correlations between breeding values in general analyses were more correlated with those predicted in the high DP. Therefore, when there is a higher selection intensity on the sires only for the ADG criterion, there is a significant presence of the heterogeneity of variances and impact on the genetic evaluation of the sires. Thus, for ADG, the predictions of breeding values obtained by the genetic evaluation model in which the heterogeneity of variances are not considered are more weighted by the class of greater heterogeneity.

ABSTRACT The aim of this study was to evaluate genomic information inclusion in genetic parameter estimation of standardized body weight at birth and at 240, 365, and 450 days of age, and visual scores for body structure, precocity, and body muscularity, measured as yearlings in Nelore cattle. We compared genetic parameters, (co)variance components (estimated from Bayesian inference and Gibbs sampling), breeding value accuracies, genetic trends, and principal component analysis (PCA) obtained through traditional GBLUP and ssGBLUP methods. For all traits analyzed, part of the phenotypic variation was explained by the additive genetic effect, thus indicating the capacity of traits to respond to the selection process. Estimates of genetic correlation, in both methodologies, between body weights and visual scores were, in general, high and positive, showing that the selection for visual scores can lead to heavier animals. Genetic trends showed genetic progress, both when estimated breeding values and genomic estimated breeding values were used. The PCA, genetic trends, and accuracy estimates on breeding values showed that inclusion of single nucleotide polymorphism information contributed towards slightly better estimates of the genetic variability of evaluated traits. Genomic information did not bring greater gains in genetic estimates, due to redundancy of kinship information from the pedigree, which already had complete animal kinship data.

RESUMO Objetivo: O objetivo do presente estudo foi avaliar o efeito da aplicação do laser Yd:YAG sobre a superfície metálica da base de braquetes ortodônticos, a resistência da colagem ao cisalhamento (RU) e os locais das falhas nas interfaces adesivas. Métodos: Os braquetes foram divididos em dois grupos, de acordo com o tipo de base: OP (One Piece - monobloco, base jateada) e OPL (One Piece - monobloco, base irradiada a laser). Foram selecionados 40 incisivos bovinos hígidos para a colagem de braquetes na superfície do esmalte. Os testes de RU foram realizados por meio de uma máquina de ensaio universal EMIC DL1000. O Índice de Adesivo Remanescente (ARI) e a caracterização das superfícies foram realizados empregando-se estereomicroscópio e microscópio eletrônico de varredura (MEV). O teste t de Student foi aplicado para comparar a RU entre os dois grupos (p< 0,05). O ARI foi avaliado por meio da análise de Frequência e teste do Qui-quadrado. Resultados: O grupo OPL obteve maiores valores de RU (p<0,001) do que o grupo OP (43,95 MPa e 34,81 MPa, respectivamente), e o ARI obteve diferença significativa (p<0,001) entre os grupos OPL (ARI 0 = 100%) e OP (ARI 0 = 15%). A análise proveniente do MEV mostrou alta interação adesiva entre a resina e a superfície metálica da base irradiada pelo feixe de laser. Conclusões: A irradiação com laser Yd:YAG sobre a superfície da base de braquetes metálicos aumentou os valores da RU, demonstrando que as falhas adesivas ocorreram na interface esmalte/adesivo. O uso de braquetes modificados com irradiação a laser pode ser adotado como alternativa aos braquetes com bases convencionais nos casos em que uma maior retentividade for requerida para reduzir as falhas de adesividade.

ABSTRACT Objective: The purpose of this study was to evaluate the effect of the Yd:YAG laser irradiation on orthodontic bracket base surface. Shear bond strength (SBS) values and sites of the bonding failure interfaces were quantified. Methods: Brackets were divided into two groups: OP (One Piece - integral sandblast base) and OPL (One Piece - laser irradiation). The brackets were randomly bonded on an intact enamel surface of 40 bovine incisors. The SBS tests were carry out using a universal test machine. A stereomicroscopy was used to evaluate the adhesive remnant index (ARI), and surface characterization was performed by scanning electron microscopy (SEM). Student’s t-test was used to compare the SBS between the two groups (p< 0.05). Frequencies and chi-square analysis were applied to evaluate the ARI scores. Results: OPL group showed higher value (p< 0.001) of SBS than OP group (43.95 MPa and 34.81 MPa, respectively). ARI showed significant difference (p< 0.001) between OPL group (ARI 0 = 100%) and OP group (ARI 0 = 15%). SEM showed a higher affinity between the adhesive and the irradiated laser base surface. Conclusions: Yd:YAG laser irradiation on bracket base increased SBS values, showing that bonding failure occurs at the enamel/adhesive interface. Laser-etched bracket base may be used instead of conventional bases in cases where higher adhesion is required, reducing bracket-bonding failure.

RESUMO Objetivou-se avaliar três tipos de silagem de grão úmido de sorgo (alto tanino, baixo tanino e branco), na forma de silagem de grão úmido, combinados com duas formas de fornecimento da ração (volumoso e concentrado fornecidos de forma separada ou misturada), sobre o consumo de matéria seca, evolução do peso vivo, ganho de peso médio diário, conversão alimentar e principais características de carcaça (área de olho de lombo, espessura de gordura subcutânea e marmorização in vivo e post mortem) e carne (cor, maciez e pH) de novilhos cruzados Hereford-Angus. Foram utilizados 48 bovinos machos, castrados, cruzados Hereford-Angus, com idade média de 20 meses, divididos em blocos casualizados, em fatorial 3 × 2. A regressão do ganho de peso de cada tratamento foi comparada utilizando-se contrastes ortogonais. Para consumo de matéria seca relativo, houve efeito do tipo de sorgo (P=0,002) e forma de fornecimento da ração (P=0,0005). A forma de fornecimento da ração pode interferir sobre o consumo de matéria seca absoluto e peso vivo médio (P=0,0001). Para a conversão alimentar foi observado efeito do tipo de sorgo (P=0,04. Observou-se efeito da forma de fornecimento da ração para a marmorização (P=0,04) post mortem. Não houve efeito do tipo de sorgo e da forma de fornecimento da ração sobre as características de carcaça e pesos dos cortes cárneos. O fornecimento do volumoso separado do concentrado na alimentação de bovinos confinados é viável do ponto de vista operacional e nutricional.

SUMMARY This work aimed to evaluate three varieties of sorghum as wet grain silage (high, low and white tannin), combined with two form of food supply (concentrated with roughage separated or mixed) on dry matter intake, body weight evolution, average daily growth, feed conversion, main meat and carcass traits (rib eye area, fat thickness and marbling in vivo and post mortem) in Hereford-Angus crossbred steers. Forty eight males castrated with 20 months of age were used, divided into randomized blocks, arranged in a 3 × 2 factorial. The regression coefficients for the weight gain of each treatment was compared using orthogonal contrasts. Dry matter intake was affected by the type of sorghum (P=0.002) and the form of food supply (P=0.0005). The form of food supply can interfere with the dry matter intake (P=0.0001) and weight (P=0.0001). Feed conversion and marbling, was affected by the type of sorghum (P=0.04). Meat marbling measured at deboning was affected by the form of food supply (P=0.04). The type of sorghum and form of food supply did not influence carcass characteristics and weights of meat cuts. The concentrated with roughage separated supply is nutritionally and operationally preferable.

The objective of this study was to evaluate the characteristics of ruminal fermentation and enteric methane production in beef cattle subjected to different supplementation frequencies while grazing on Brachiaria brizanthacv. Marandu pastures. Nine cattle (325±65.7 kg BW) fitted with ruminal and duodenal cannulas were used in the ruminal fermentation study, and 12 cattle (399±32.6 kg BW) were used in the enteric methane production study. The treatments included supplementation once daily, supplementation once daily except Saturdays and Sundays, or supplementation on alternate days. The supplementation was equivalent to 10 g kg−1 BW day−1 for all treatments. The design employed was completely randomized with three treatments and three replications. When all supplements were provided (day 1), no effects of supplementation frequency were observed on ruminal pH; concentration of NH3-N; concentration of acetic, propionic, or butyric acids; or total volatile fatty acids (VFA), but there were month effects. During the day on which only daily supplements were provided (day 2), significant differences were observed only on the molar concentration of acetic acid and total VFA; and month effects were noted on all variables. No significant differences were observed in ruminal fluid volume, dilution rate, N intake, bacterial N synthesis and enteric methane production among the studied supplementation frequencies. Differences were observed in the enteric methane production in the different months, with 85 g kg−1 of gross energy intake observed in September and 123 g kg−1 of gross energy intake observed in November. Lower supplementation frequency is a good option to lower labor costs with little or no consequences on ruminal fermentation characteristics and enteric methane production.

O objetivo deste trabalho foi estimar as frequências de polimorfismos alélicos em genes de bovinos Nelore e associá-los às características de carcaça e qualidade da carne. Seiscentos machos foram genotipados quanto aos seguintes polimorfismos: DGAT1 (VNTR com 18 nucleotídeos na região promotora); ANK1, novo polimorfismo, identificado no presente estudo e mapeado na região gênica regulatória NW_001494427.3; TCAP (AY428575.1:g.346G>A); e MYOG (NW_001501985:g.511G>C). No estudo de associação, foram utilizados os dados fenotípicos de massa da carcaça quente, área de olho do lombo, espessura de gordura subcutânea, percentagem de gordura intramuscular, força de cisalhamento, índice de fragmentação miofibrilar, coloração da carne (L*, a*, b*) e perdas por cocção. O alelo B do gene ANK1 foi associado ao aumento da coloração vermelha (a*) da carne. No gene DGAT1, os alelos 5R, 6R e 7R foram associados ao aumento de gordura intramuscular, à redução das perdas por cocção e ao aumento da área de olho de lombo, respectivamente. O SNP (polimorfismo de nucleotídeo único) do gene TCAP não apresentou polimorfismo, e os alelos do gene MYOG não foram associados a nenhuma das características avaliadas. Os resultados indicam que os genes ANK1 e DGAT1 podem ser utilizados na seleção de animais Nelore quanto à qualidade de carne e carcaça.

The objective of this work was to estimate the allele polymorphism frequencies of genes in Nellore cattle and associate them with meat quality and carcass traits. Six hundred males were genotyped for the following polymorphisms: DGAT1 (VNTR with 18 nucleotides at the promoter region); ANK1, a new polymorphism, identified and mapped here at the gene regulatory region NW_001494427.3; TCAP (AY428575.1:g.346G>A); and MYOG (NW_001501985:g.511G>C). In the association study, phenotype data of hot carcass weight, ribeye area, backfat thickness, percentage of intramuscular fat, shear force, myofibrillar fragmentation index, meat color (L*, a*, b*), and cooking losses were used. Allele B from the ANK1 gene was associated with greater redness (a*). Alleles 5R, 6R, and 7R from the DGAT1 VNTR gene were associated with increased intramuscular fat, reduced cooking losses and increased ribeye area, respectively. The single nucleotide polymorphism (SNP) of the TCAP gene was not polymorphic, and MYOG alleles were not associated with any of the evaluated characteristics. These results indicate that ANK1 and DGAT1 genes can be used in the selection of Nellore cattle for carcass and meat quality.

Reduced supplementation frequency is a broadly applied management practice. Ruminants consuming low quality forages/pastures, supplemented less than once daily are able to maintain body weight gain (BWG), efficiency of use of dry matter, nitrogen and other nutrients, as compared with animals supplemented once daily. We evaluated the feeding behavior, dry matter intake (DMI), dry matter and organic matter digestibility (DMD and OMD), BWG, Longissimus muscle area and backfat depth of Nellore steers raised on Brachiaria brizantha cv. Marandu pastures during the dry season, with different supplementation patterns. Thirty six animals (338 ± 40.7 kg) were distributed over nine paddocks according to a completely randomized design. Treatments were based on supplementation frequency: once daily (OD), once daily except Saturdays and Sundays (SS), or on alternate days (AD), at 1.0 %, 1.4 % and 2.0 % BW, respectively. Average total DMI accounted for 1.6 % BW day-1, with no effect of supplementation frequency. Supplementation frequency had no effect on BWG or grazing time during the day. There was no difference in Longissimus muscle area animals supplemented daily, SS and AD. The backfat depth was thinner in animals supplemented AD, but even in this case, it was within the standards considered satisfactory for a finishing steer. Reducing supplementation frequency seems a good option to lower labor costs without affecting feed efficiency or carcass quality in beef cattle grazing tropical pastures.

Apesar de Baum e Dutton (1996) terem chamado atenção há mais de uma década para a imersão da estratégia, os trabalhos sobre estratégia mantêm-se mais influenciados pelos teóricos da economia do que pelos teóricos da sociologia. A concepção atomizada revela-se tanto no nível de análise como no conceito de ambiente. Oliver (1996) afirma que teóricos de estratégia explicam as vantagens diferenciadas das firmas e sua capacidade de obtenção de lucro a partir das ineficiências de mercado. Explicações da ineficiência dos mercados e da heterogeneidade das firmas centram-se exclusivamente nas características da firma e dos mercados. Este artigo vai ao encontro do argumento desses autores de que diferenças sustentáveis da firma e retornos acima do normal não são somente uma função da sua capacidade e das características da indústria e do mercado. A imersão das organizações e dos mercados em um contexto institucional tem um profundo impacto sobre o seu desempenho. Este artigo enfatiza a estratégia como contexto interfirma, combinando a perspectiva da imersão social e a teoria institucional para uma análise do setor de carcinicultura norte-rio-grandense. Consiste em um estudo qualitativo, histórico, baseado na análise de documentos e na análise de entrevistas realizadas com dirigentes empresariais e de associações do setor. O objetivo foi evidenciar como a estratégia adotada pelas organizações do setor pode ser explicada pela dinâmica do contexto social. Assim, desenvolveu-se uma análise que combina os impedimentos institucionais e econômicos para a eficiência dos mercados para explicar a estratégia adotada. Para isso, realizou-se uma reconstrução histórica da sua formação, evidenciando os principais momentos e fatos, bem como o papel assumido pelos diferentes atores. Os resultados indicaram que abordagens dominantes no estudo da estratégia como economic costs theory (ECT), RBV e posicionamento estratégico, pelo caráter descontextualizado, não são suficientes para explicar a postura estratégica das empresas, sendo necessário combiná-las com perspectivas que levem em consideração a natureza socialmente construída dos processos organizacionais e seu caráter, muitas vezes, não reflexivo.

Baum and Dutton (1996) pointed out that although the embeddedness of strategy have been highlighted a decade ago, strategy research still maintain more influenced by theorists of economic than theorists of sociology. The atomized conception is identified in the level of analysis and at the concept of environment. This paper stresses the strategy as context inter-firm. It grasps the institutional theory and embeddedness perspective for analyzing the shrimp farming sector at Rio Grande do Norte. It consists on a qualitative, historical study, based on archive analysis as well interview in deep with CEOs and associations representatives of the sector. The aim was to appoint how the strategy adopted by the set of sector's companies can be explained considering the social context dynamic. Thus, it was developed an analysis that integrated both the institutional and economic impediments for the market efficiency for explaining the sector's strategy. It was carried on a historical account of its formation, stressing the main moments and facts, as well the role played by different actors. The results indicated that the dominant approaches in the strategy field such as Economic Costs Theory, Resource Based-View and strategic management were not able to explain the strategic action of the sector's companies. It is necessary put together this economic perspective with sociological perspectives, which take in count the socially constructed nature of the organizational processes, as well its non reflexive character.

A pesar de que Baum y Dutton (1996) han llamado la atención, hace más de una década, para la inmersión de la estrategia, los trabajos sobre estrategia se mantienen más influenciados por los teóricos de la economía que por los teóricos de la sociología. La concepción atomizada se identifica en el nivel de análisis y en el concepto de ambiente. En este trabajo se hace hincapié en la estrategia como marco entre empresas. Se agarra la teoría institucional y la perspectiva de arraigo para analizar el sector de la cría de camarones en Rio Grande do Norte. Consiste en un estudio cualitativo, histórico, basado en el análisis de archivo y entrevistas en profundidad con los representantes de los CEOs y asociaciones del sector. El objetivo fue nombrar como la estrategia adoptada por el conjunto de las empresas del sector puede explicarse teniendo en cuenta la dinámica del contexto social. Por lo tanto, se desarrolló un análisis que integra tanto los impedimentos institucionales y económicos para la eficiencia del mercado para explicar la estrategia del sector. Que se llevó a cabo un recuento histórico de su formación, haciendo hincapié en los principales momentos y hechos, así como el papel desempeñado por los diferentes actores. Los resultados indicaron que los enfoques dominantes en el ámbito de la estrategia, tales como costos de transacción, visión basada en los recursos y la gestión estratégica no fueron capaces de explicar la acción estratégica de las empresas del sector. Es necesario armar este punto de vista económico con perspectivas sociológicas, que tengan en cuenta el carácter socialmente construido de los procesos de organización, así como su carácter no reflexivo.

Este trabalho foi desenvolvido com o objetivo de estudar a evolução das características de crescimento e carcaça em função da idade em bovinos da raça Hereford, utilizando modelos não-lineares. Foram utilizados dados de 240 bovinos machos (castrados) da raça Hereford, pertencentes à fazenda Experimental "La Estanzuela" do INIA, Colonia, Uruguai. As características começaram a ser mensuradas a partir da desmama de animais com aproximadamente seis meses de idade, até o abate (dois anos de idade). As medições de peso foram realizadas a cada 15±3 dias durante todo o período e sem jejum prévio. As mensurações de área de olho de lombo, obtidas por ultrassom, e altura dos animais foram obtidas a cada 90 dias, sendo que as medidas de ultrassom foram tomadas entre a 12ª e 13ª costelas. Os modelos não-lineares utilizados foram os modelos de Brody, Gompertz, Logístico e Von Bertalanffy. Para as características peso, altura e área de olho de lombo, todos os modelos avaliados atingiram a convergência. Para descrever a evolução dos dados de peso e área de olho de lombo em função da idade, o modelo de Von Bertalanffy foi o mais indicado, e os modelos de Brody e Logístico mostraram o pior ajuste, respectivamente. A evolução da altura dos animais desde o desmame até os dois anos de idade pode ser modelada através de qualquer um dos modelos não-lineares considerados neste estudo.

The objective of this research was to study the evolution of growth and carcass traits as a function of age in Hereford cattle using nonlinear models. Records from 240 Hereford steers (castrated), belonging to the experimental station "La Estanzuela" of INIA Uruguay, were utilized. The animals were measured from weaning, approximately at 6 months of age, to slaughter (two years of age). The animals were weighed, without fasting, every 15±3 days throughout the period. The measurements of ribeye loin area (between the 12th and 13th rib) were obtained by ultrasound every 90 days. The height of the animals was obtained every 90 days. The Brody, Gompertz, Logistic and Von Bertalanffy nonlinear models were applied to describe the trajectory of weight, height and ribeye loin area along the age. For height, weight and ribeye loin area, all the models reached the convergence. To describe the evolution of weight and ribeye loin area, the Von Bertalanffy nonlinear model was the most suitable. For weight and ribeye loin area, the Brody and Logistic nonlinear models have shown the worst fit, respectively. The height trajectory from weaning until two years of age can be modeled by any of the nonlinear models considered in this research.

Objetivou-se com este trabalho estimar parâmetros genéticos para a produção de leite acumulada até os 305 dias (P305) de cabras das raças Saanen e Alpina. Foram utilizadas as duas primeiras parições de cabras pertencentes a rebanhos participantes do programa de controle produtivo e reprodutivo de caprinos (PROCAPRI) da UNESP-FCAV-Jaboticabal-SP. A P305 foi analisada por meio de modelos de repetibilidade e bicaracterísticas. Para verificar a influência dos efeitos fixos sobre a característica analisada foram realizadas análises preliminares, pelo método de quadrados mínimos. Os componentes de covariâncias foram estimados pelo método da máxima verossimilhança restrita (REML), utilizando o programa Wombat. A duração da lactação, a idade da cabra ao parto, o rebanho, o ano de parto e a estação de parto foram importantes fontes de variação para a P305. Não houve diferença significativa entre as raças estudadas. As estimativas de herdabilidade e repetibilidade para a P305, obtidas com o modelo de repetibilidade, foram de 0,29 e 0,36, respectivamente. As estimativas de herdabilidade, obtidas pelos modelos de repetibilidade e bicaracterísticas foram semelhantes. Sendo assim, um modelo de repetibilidade poderia ser indicado para avaliar a P305 pela sua simplicidade.

The objective of this study was to estimate genetic parameters for 305 days milk yield (M305) in Saanen and Alpina breed goats. Data consisted of records from first to second lactations of goats belonging to herds participating in the program control productive and reproductive goats (PROCAPRI) from UNESP-FCAV-Jaboticabal-SP. The M305 was analyzed by repeatability and bi-trait models. The influence of fixed effects on the traits was analyzed preliminary analysis by the method of least squares. Variance components were estimated by restricted maximum likelihood method (REML), using the package Wombat. The duration of lactation, age of dam at calving, the herd, calving year and season of birth were important sources of variation for the M305. There was no significant difference between the breeds. Heritability and repeatability estimates obtained by repeatability model were 0.29 and 0.36, respectively. The repeatability estimate was 0.32. The heritability estimates obtained by the bi-trait models were similar and repeatability. Thus, a repeatability model might be indicated for its simplicity.

O objetivo deste trabalho foi estimar parâmetros genéticos para idades ao primeiro (IPP) e segundo partos (ISP), idades ao primeiro (IPP PEN) e segundo partos penalizadas (ISP PEN), e a ocorrência de parto até os 38 meses de idade (PP38), em bovinos da raça Canchim, bem como estimar as relações genéticas entre essas características e o peso (PE420) de machos e femêas e a circunferência escrotal (CE420) de novilhos, medidos aos 420 dias de idade. Foram estimados parâmetros genéticos em análises bicaracterísticas, por meio de inferência bayesiana. As análises foram realizadas entre CE420 e PE420 e as características reprodutivas medidas em fêmeas. As características reprodutivas das fêmeas devem apresentar baixa resposta à seleção, e mudanças no manejo e nas condições ambientais melhoram tais características. A seleção quanto ao maior peso aos 420 dias de idade não deve provocar mudanças nas características reprodutivas em fêmeas, enquanto a seleção para o aumento da circunferência escrotal, na mesma idade, contribui para melhorar tais características.

The objective of this work was to estimate genetic parameters for age at first (AFC) and at second (ASC) calvings, penalized age at first (AFC PEN) and at second (ASC PEN) calvings, and occurrence of calving until 38 months of age (PP38) in Canchim breed, as well as to estimate the genetic correlations between these traits with weight (PE420) of males and females, and scrotal circumference (CE420) measured at 420 days of age. Genetic parameters were estimated by two-trait analyses using the Bayesian inference. The analyses were performed between CE420 and PE420, and the reproductive traits measured in the females. The female reproductive traits should show low response to selection, and changes in the management and environmental conditions improve these traits. Selection for the higher weight at 420 days of age does not change female reproductive traits, while selection to increase scrotal circumference, at the same age, contributes to improve such traits.

The objectives of this study were to estimate the genetic parameters for milk yield unadjusted and adjusted for days in milk and, subsequently, to assess the influence of adjusting for days in milk on sire rank. Complete lactations from 90 or 150 days of lactation to 270 or 350 days in milk were considered in these analyses. Milk yield was adjusted for days in milk by multiplicative correction factors, or by including lactation length as a covariable in the model. Milk yields adjusted by different procedures were considered as different traits. Heritability estimates varied from 0.17 to 0.28. Genetic correlation estimates between milk yields unadjusted and adjusted for days in milk were greater than 0.82. Adjusting for days in milk affected the parameter estimates. Multiplicative correction factors produced the highest heritability estimates. More reliable breeding value estimates can be expected by including short length lactation records in the analyses and adjusting the milk yields for days in milk, regardless of the method used for the adjustment. High selection intensity coupled to the inclusion of short length lactations and adjustment with multiplicative factors can change the sire rank..

Records from 106,212 Nellore animals, born between 1998 and 2006, were used to estimate (co)variance components and genetic parameters for birth weight (BW), average weight gains from birth to weaning (GBW), average weight gains from weaning to after yearling (GWAY), weaning hip height (WHH), postweaning hip height (PHH) and scrotal circumferences at 9 (SC9), 12 (SC12) and 15 (SC15) months of age. (Co)variance components were estimated by an animal model using multi-trait analysis. Heritability estimates for BW, GBW, GWAY, WHH, PHH, SC9, SC12 and SC15 were 0.31 ± 0.01; 0.25 ± 0.02; 0.30 ± 0.04; 0.51 ± 0.04; 0.54 ± 0.04; 0.39 ± 0.01; 0.41 ± 0.01 and 0.44 ± 0.02, respectively. Genetic correlations between growth traits ranged from 0.09 ± 0.01 to 0.88 ± 0.01, thereby implying that, at any age, selection to increase average weight gains will also increase stature. Genetic correlations between BW and average weight gains with scrotal circumferences were all positive and moderate (0.15 ± 0.03 to 0.38 ± 0.01). On the other hand, positive and low genetic associations were estimated between hip height and scrotal circumference at different ages (0.09 ± 0.01 to 0.17 ± 0.02). The results of this study pointed out that selection to larger scrotal circumferences in males will promote changes in average weight gains. In order to obtain Nellore cattle with the stature and size suitable for the production system, both weight gain and hip height should be included in a selection index.