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Feed is the most expensive input in any livestock production system including beef cattle, therefore feed efficiency improvements can contribute to cost reduction. Residual feed intake (RFI) is one of the important measures of animal efficiency and can be defined as the difference between actual feed intake (measure at individual or group pens) and predicted feed intake that is required for the observed rate of gain and body weight (BW). The objective here was to evaluate the housing type (individual or group) on variation of traits such as dry matter intake (DMI, kg/d and %BW), average daily gain (ADG), RFI and gain:feed (G:F) in a dataset of Nellore young bulls obtained from performance tests of 83±16 days long after adaptation period, conducted between 2007 and 2013. The animals (273 ± 27 days of age at the beginning of the test) were obtained from selected, traditional and control Nellore lines of Instituto de Zootecnia. The animals were housed in individuals pens (IP) (2007-2012) or group pens (GP) (2012-2013) equipped with the GrowSafe® system (voluntary intake calculated automatically by the system). In IP, animals were fed twice a day and had water available all the time. Voluntary food intake was calculated as the difference between supplied and refused food. Leftovers were collected daily, weighed, and then adjusted to correspond to 10% of the total supplied. A mixed
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The present study aimed to evaluate feed intake and behavior during the efficiency test of Nellore males. Efficiency test was conducted from June to October of 2012, during 119 days. Registers of 85 Nellore males, with initial averages age of 270 ± 23 days and body weight of 239 ± 41 kg were used. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which individual recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI). The first 28 days of test were for adaptation to diet and environment, and the subsequent 91 days were considered as experimental period. Experimental period was divided in three sub periods (28, 28 and 31 days, respectively). Data were analyzed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model period effects (adaptation - 1 and experimental periods - 2, 3 or 4) and animal age as linear covariate. During the adaptation period, low values (P 0.05) were observed of FI, BA and FV (991 ± 40.7 kg/day, 854 ± 33.2 min/day and 1172 ± 49.4 visits/day, respectively) in relation experimental period (1091 ± 18.5 kg/day, 965 ± 15.1 min/day and 1217 ± 22.5 visits/day, respectively). Feeding behavior traits were analyzed in four test periods (Figure 1), and a reduction (P 0.05) in FI (from 1162 ± 39.2 to 984 ± 77.6 kg/day) and BA (from 992 ± 32.1 to 866 ± 63.6 min/day) was observed in the third period. Additionally, FV m
O artigo não apresenta resumo em português.
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This study aimed to evaluate feed intake and behavior during feed efficiency test of Nellore males from different residual feed intake (RFI) classes. Data from 85 Nellore males, with initial average age of 270 ± 23 days and body weight of 239 ± 41 kg were used. The feed efficiency test was performed during 119 days, divided in four periods. The first period (adaptation) had 28 days, and the three subsequent periods had, respectively, 28, 28 and 31 days. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI) individual data. After test end, RFI was calculated by the difference between observed and predicted feed intake, based on average daily gain and metabolic body weight. Then, animals were classified into low ( mean - 0.5 standard deviation-SD), medium (± 0.5 SD from mean) and high (>mean + 0.5 SD) RFI. Statistical analyzes were performed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model effects of test period (1, 2, 3 or 4), RFI classes (low, medium or high) and interaction, being animal age considered as linear covariate. Feeding behavior pattern was not different among the efficiency test periods (P>0.05), however differences were detected among RFI classes inside the periods (P 0.01) (Figure 1). Low RFI animals, when compared to the medium and high RFI
O artigo não apresenta resumo em português.
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Feed efficiency is difficult to evaluate because individual feeding are required. An alternative is selecting animals based on traits easier to obtain and genetically favorably correlated with feed efficiency traits. This study aimed to estimate genetic and phenotypic correlations between feed efficiency traits (residual feed intake RFI, feed efficiency FE and residual BW gain RG) with yearling weight (YW), hip height (HH) and girth circumference (GC) in Nellore cattle. Feed efficiency data set consisted of 887 records of DMI, ADG and BW0.75 obtained during performance tests (83 ± 15 d) to calculate RFI (0.005 ± 0.58 kg DM/d), FE (0.14 ± 0.03) and RG (0.00 ± 0.11 kg/d). FE was calculated as ADG and DMI ratio, RFI was estimated as the error of multiple regression of DMI on ADG and BW0.75, and RG was estimated as the error of multiple regression of ADG on DMI and BW0.75. The YW data set consisted of 7,948 records of males (314.45 ± 45.85 kg) and females (282.68 ± 48.19 kg) adjusted to 378 and 550 d of age, respectively. The HH consisted of 6,418 records of males (131.80 ± 5.40 cm) and females (132.51 ± 5.38 cm), and 3,745 records of GC of males (162.56 ± 8.48 cm) and females (167.72 ± 8.08 cm). Pedigree file contained 9,830 animals. Growth traits were analyzed as unit standard deviation of each sex/age. (Co)variance components were estimated through two-trait animal models
O artigo não apresenta resumo em português.
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Persistency can be dened as the degree to which production is maintained after peak yield is reached. In Gyr cattle, persistency is an obstacle in milk production and profitability. So, persistency is an important trait that must be evaluated with total milk production in Brazilian Gyr cattle. The objective of this study was to calculate genetic tendency for persistency, accumulated 305-day milk yield and partial milk yields in first 100, 200 and 300 days in milk of Brazilian Gyr cows using breeding values predicted (EBV) by random regression models. Data was obtained from ABCZ and included 15052 first lactations from cows with calving year ranged from 1980 to 2006. Fixed effects was contemporary group (milking herd, year and season of milk control) and the days in milk were modeled using Legendre polynomials of order 4 for additive genetic and permanent environmental random effects and a heterogeneous residual variance structure using four classes. To estimate breeding values for 305-day milk yield, the daily EBV were added. To calculate the EBVs for partial periods was made the sum of EBVs daily in the first 100 days (P100), between 100 and 200 days (P200) and between 200 and 300 days (P300) in lactation. Persistency was obtained by the sum of the deviations of EBVs predicted between 30 and 270 days of production in relation to EBV predicted for peak production. The EBV for
O artigo não apresenta resumo em português.
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Several studies have reported relationship between eating behavior and performance in feedlot cattle. The evaluation of behavior traits demands high degree of work and trained manpower, therefore, in recent years has been used an automated feed intake measurement system (GrowSafe System ®), that identify and record individual feeding patterns. The aim of this study was to evaluate the relationship between feeding behavior traits and average daily gain in Nellore calves undergoing feed efficiency test. Date from 85 Nelore males was recorded during the feed efficiency test performed in 2012, at Centro APTA Bovinos de Corte, Instituto de Zootecnia, São Paulo State. Were analyzed the behavioral traits: time at feeder (TF), head down duration (HD), representing the time when the animal is actually eating, frequency of visits (FV) and feed rate (FR) calculated as the amount of dry matter (DM) consumed by time at feeder (g.min-1). The ADG was calculated by linear regression of individual weights on days in test. ADG classes were obtained considering the average ADG and standard deviation (SD) being: high ADG (>mean + 1.0 SD), medium ADG (± 1.0 SD from the mean) and low ADG ( mean - 1.0 SD). Data were analyzed using the PROC MIXED procedure (SAS 9.3). The model included animal and residue as random effects and the fixed effects of ADG class (1, 2 and 3) and age at the middle of t
O artigo não apresenta resumo em português.
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The national herd is predominantly composed by Nelore breed (Bos indicus), being extremely important for beef cattle, even though, it have limitations as aggressive temperament compared to populations of Bos taurus origin. The temperament (TEMP) can be defined as the perception and reaction of the animals when they feel fear or are managed by man. More reactive cattle have lower weight gain, produce beef of lower quality, are more susceptible to diseases and have low reproductive performance. The objective of this research was to obtain the components of (co) variances and genetic parameters of TEMP in order to provide subsidies to farmers and technicians on its use in animal breeding programs. For the TEMP trait, the database used was from the Nelore breeding program Nelore Qualitas. Data was recorded from 2000 to 2009, on 20 farms across six Brazilian states, on 48,879 males and females ranging in age from 450 to 599 days. TEMP trait was performed by visual scores, in 1-5 scale, where higher scores means less reactive animals. The genetic parameters were estimated with univariate animal model and Bayesian inference, using the program GIBBS2F90. The statistical model included fixed effects of contemporary group, age at measurement as a linear covariate, and random effects of additive genetic and residual. The data set included 455 sires, 28,111 dams and 3,153 contemporary gr
O artigo não apresenta resumo em português.
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The objective was to evaluate the interactions of genotype-environment effects on the components of (co)variance estimates and the prediction of breeding values for weaning weight in Nelore cattle, using a Bayesian approach. Records of 16,644 weaning weights were used from cattle distributed in ten ranches across six Brazilian states. The genetic parameters were estimated under an animal model considering Bayesian statistics. To verify genotype-environment interaction effects, we analyzed the following matrix model: without the inclusion of genotype-environment interaction effects, and with the inclusion of genotype-environment interaction effects, which considered the effect of sire-year, sire-herd, and both effects. In general, the results suggest that the inclusion of genotype-environment interaction in genetic analysis for weight at weaning tends to alter the estimates of genetic and environment (co)variances. The Spearman correlations between the breeding values were above 97%, indicating practically no change in the classification of animals evaluated. It can be inferred that the interaction effects of sire-year and sire-herd do not change the animals rank, and if not included in the genetic evaluation, the selection based on predictions of breeding values for weaning weight will not be affected.
Objetivou-se avaliar os efeitos das interações genótipo-ambiente sobre as estimativas de componentes de (co)variâncias e predição dos valores genéticos para o peso ao desmame de bovinos Nelore, sob enfoque bayesiano. Foram utilizados 16.644 registros de pesos ao desmame de bovinos provenientes de dez rebanhos participantes do Programa Nelore Brasil. Os parâmetros genéticos foram estimados sob modelo animal, considerando a estatística bayesiana. Para verificar o efeito da interação genótipo-ambiente, foram analisados os seguintes modelos matriciais: sem a inclusão dos efeitos de interação genótipo-ambiente; com a inclusão dos efeitos de interação genótipo-ambiente, em que se considerou o efeito de touro-ano, touro-rebanho e ambos os efeitos. De modo geral, verifica-se que a inclusão da interação genótipo-ambiente na análise genética para o peso ao desmame, tende a alterar as estimativas de (co)variâncias genéticas e ambientais. As correlações de Spearman entre os valores genéticos foram acima de 97%, indicando que, praticamente, não houve mudança na classificação dos animais avaliados. Pode se inferir que os efeitos de interação touro-ano e touro-rebanho não alteram as classificações dos animais, e a não-inclusão destes efeitos na avaliação genética, não afetam a seleção baseada nas predições dos valores genéticos para o peso ao desmame.
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Among the features of interest to the animal breeding, that can be measured repeatedly throughout an individual"s life, are among other, growth characteristics, which are characteristic features called longitudinal or repeated. It was used 8193 Tabapuã breed records of animal weight raised in 25 farms distributed in the states of Bahia, Alagoas, Sergipe, Minas Gerais and São Paulo and born between the years of 1975 and 2001. Aiming to estimate the (co) variance and genetic parameters for weights at 120 (W120), 365 (W365), 450 (W450) e 550 (W550) days old. Variance components were estimated in a Bayesian context considering a multi-trait animal model with fixed effects for contemporary groups and ages of the mother and the animal. The random effects were considered direct genetic and maternal and maternal permanent environment and error. The effects mothers were included in the model only for W120 and W365. The direct heritability were 0.31, 0.38, 0.33 and 0.29 for W120, W365, W450 and W550, respectively. The fractions of genetic and maternal permanent environment effects on phenotypic variances were 0.06 and 0.01, 0.03 and 0.01 for W120 and W365.
Entre as características de interesse para o melhoramento genético animal que podem ser mensuradas repetidamente ao longo da vida do indivíduo, encontram-se, entre outras, as características de crescimento, que são denominadas características repetidas ou longitudinais. Foram utilizados 8.193 registros de peso de animais da raça Tabapuã criados em 25 fazendas distribuídas nos estados da Bahia, Alagoas, Sergipe, Minas Gerais e São Paulo, nascidos entre os anos de 1975 e 2001, com o objetivo de estimar componentes de (co)variância e parâmetros genéticos para pesos aos 120 (P120), 365 (P365), 450 (P450) e 550 (P550) dias de idade. Os componentes de variância foram mensurados em um contexto bayesiano, considerando um modelo animal multi-característica com efeitos fixos de grupos de contemporâneos e as idades da mãe e do animal. Os efeitos aleatórios considerados foram o genético direto e materno e o de ambiente permanente materno e o erro. Os efeitos maternos foram incluídos no modelo somente para P120 e P365. As herdabilidades diretas foram 0,31; 0,38; 0,33 e 0,29 para P120, P365, P450 e P550, respectivamente. As frações dos efeitos genéticos e de ambiente permanente materno na variância fenotípica foram: 0,06 e 0,01; 0,03 e 0,01 para P120 e P365.
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This work aimed to study the behavior of semi-confined buffaloes, emphasizing the effect of three different supplementation levels with concentrated in daily distribution of activities during the grazing period. Eighteen Murrah buffaloes with approximately 17 months of age and initial average weight of 300kg were observed for 9 days. They remained on pasture from 7 a.m. till 5 p.m. (observation period). In the evenings, animals were put in their individual stalls, and received the concentrate under 3 different treatments: Treatment 1 = 0.6%, Treatment 2 = 0.9% and Treatment 3 = 1.2% of the animal weight. The observed variables were: Grazing time (TP); Standing time (TEP); Lying time (TD); Rumination time (TR); Wallowing time (TCH); and Time in other activities (TOA). The effect of treatment was significant only for TEP and TD. The day influenced significantly (P
Este trabalho teve por objetivo estudar o comportamento de bubalinos semiconfinados, enfocando o efeito de diferentes níveis de suplementação com concentrado na distribuição diária das atividades do período dedicado ao pastejo. Foram observados por 9 dias, 18 búfalos da raça Murrah, com aproximadamente 17 meses de idade e peso médio inicial de 300kg, os quais permaneceram no pasto das 7:00 às 17:00 horas (período de observação), e após serem recolhidos em suas baias individuais, receberam, no período noturno, o concentrado sob 3 diferentes tratamentos: Tratamento 1 = 0,6%, Tratamento 2 = 0,9% e Tratamento 3 = 1,2% do peso vivo. As variáveis observadas foram: Tempo pastejando (TP); Tempo em pé (TEP); Tempo deitado (TD); Tempo de ruminação (TR); e Tempo em outras atividades (TOA). O efeito de tratamento foi significativo apenas para TEP e TD. O dia influenciou significativamente (P
Resumo
Genetic parameters for 50,171 first lactation test-day milk yields and 305 day milk yield (Y305) of 9,281 Holstein cows were estimated, applying uni and bi-trait animal models. The model for Y305 included the additive genetic effect as random and the fixed effects of contemporary group and age of cow at calving as covariable. For TDMY the same animal model described for Y305 was used, including days in milk as covariable. Variance components were estimated by Restricted Maximum Likelihood. Heritability estimates obtained for TDMY ranged from 0.07 to 0.19 and from 0.12 to 0.22 by uni-trait and bi-trait analysis, respectively. Heritability for Y305 was 0.26 by uni-trait and 0.27 by bi-trait analysis. The genetic correlations between TDMY and Y305 were all positive and high, ranging from 0.63 to 1.00. The genetic correlations between TDMY ranged from 0.30 to 1.00. Selection for Y305 seems to be the best selection criterion to be adopted, since it provides larger genetic gain for milk productions in, practically, all test days.
Foram estimados parâmetros genéticos para produção de leite acumulada até 305 dias (P305) e produção de leite no dia do controle (PLDC) de 50.171 controles mensais de 9.281 primeiras lactações de vacas da raça Holandesa. A P305 e as PLDC foram analisadas por meio de modelo animal uni e bicaracterísticas. Para a P305 o modelo incluiu como aleatório, o efeito genético e como efeitos fixos o grupo de contemporâneos e a covariável idade da vaca ao parto. Para as PLDC foi usado o mesmo modelo descrito para a P305, incluindo como covariável o número de dias em lactação. Os componentes de variância foram estimados pelo Método da Máxima Verossimilhança Restrita. As estimativas de herdabilidade (h²) para as PLDC oscilaram entre 0,07 e 0,19 em análises unicaracterísticas e, de 0,12 a 0,22 nas bicaracterísticas. Para a P305, as h² resultantes das análises uni-característica e bicaracterística foram 0,26 e 0,27, respectivamente. As correlações genéticas das PLDC com a P305 foram todas positivas e elevadas, variando de 0,63 a 1,00. As correlações genéticas entre as PLDC variaram de 0,30 a 1,00. A seleção para a P305 parece ser o melhor critério de seleção a ser adotado, uma vez que proporciona maiores ganhos genéticos para as produções de leite em, praticamente, todos os controles da lactação.
Resumo
Genetic parameters for 50,171 first lactation test-day milk yields and 305 day milk yield (Y305) of 9,281 Holstein cows were estimated, applying uni and bi-trait animal models. The model for Y305 included the additive genetic effect as random and the fixed effects of contemporary group and age of cow at calving as covariable. For TDMY the same animal model described for Y305 was used, including days in milk as covariable. Variance components were estimated by Restricted Maximum Likelihood. Heritability estimates obtained for TDMY ranged from 0.07 to 0.19 and from 0.12 to 0.22 by uni-trait and bi-trait analysis, respectively. Heritability for Y305 was 0.26 by uni-trait and 0.27 by bi-trait analysis. The genetic correlations between TDMY and Y305 were all positive and high, ranging from 0.63 to 1.00. The genetic correlations between TDMY ranged from 0.30 to 1.00. Selection for Y305 seems to be the best selection criterion to be adopted, since it provides larger genetic gain for milk productions in, practically, all test days.
Foram estimados parâmetros genéticos para produção de leite acumulada até 305 dias (P305) e produção de leite no dia do controle (PLDC) de 50.171 controles mensais de 9.281 primeiras lactações de vacas da raça Holandesa. A P305 e as PLDC foram analisadas por meio de modelo animal uni e bicaracterísticas. Para a P305 o modelo incluiu como aleatório, o efeito genético e como efeitos fixos o grupo de contemporâneos e a covariável idade da vaca ao parto. Para as PLDC foi usado o mesmo modelo descrito para a P305, incluindo como covariável o número de dias em lactação. Os componentes de variância foram estimados pelo Método da Máxima Verossimilhança Restrita. As estimativas de herdabilidade (h²) para as PLDC oscilaram entre 0,07 e 0,19 em análises unicaracterísticas e, de 0,12 a 0,22 nas bicaracterísticas. Para a P305, as h² resultantes das análises uni-característica e bicaracterística foram 0,26 e 0,27, respectivamente. As correlações genéticas das PLDC com a P305 foram todas positivas e elevadas, variando de 0,63 a 1,00. As correlações genéticas entre as PLDC variaram de 0,30 a 1,00. A seleção para a P305 parece ser o melhor critério de seleção a ser adotado, uma vez que proporciona maiores ganhos genéticos para as produções de leite em, praticamente, todos os controles da lactação.
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The objective of this paper was to study the genetic correlations of the visual scores traits with the growth continuous traits, by applying bayesian statistic methodology, using two-trait analyses under linear-threshold animal models. The morphological categorical traits of musculature, physical structure, conformation and sacrum were studied in animals of the Nelore breed at the age of 8, 15 and 22 months, and also in adult cows; and the growth continuous traits, weights at the age of 210, 365 and 450 days old, as well as the adult weight of the cow. Estimates of genetic correlations between these visual scores (musculature, physical structure and conformation) with the growth traits were favorably positive, indicating that the selection of one of them will bring genetic progress to another. The results achieved in this study also indicated that the physical structure and the conformation are determined, to a large extent, by the same sets of genes as the weight. In the same way, the evaluated visual scores in adult cows presented high genetic correlations with the adult weight of the cow. As concerning the sacrum, the estimates of genetic correlations were low and negative. KEY WORDS: Gibbs sampler, morphological traits, weights, zebu cattle.
O objetivo deste trabalho foi estudar as inter-relações genéticas dos escores visuais com as características de crescimento, por meio da estatística bayesiana, utilizando análises bicaracterísticas sob modelo animal linear-limiar, na obtenção de parâmetros genéticos. Estudaram-se as características categóricas morfológicas de musculosidade, estrutura física, conformação e sacro, aos 8, 15 e 22 meses de idade, em animais da raça Nelore, e também vacas adultas; e as características contínuas de crescimento, pesos aos 210, 365 e 450 dias de idade, além do peso adulto da vaca. Foram obtidas estimativas de correlações genéticas positivas de alta magnitude entre os escores visuais de musculosidade, estrutura física e conformação com as características de crescimento, indicando que a seleção de uma trará progresso genético à outra. Os resultados obtidos neste estudo também indicaram que a estrutura física e a conformação são determinadas, em grande parte, pelos mesmos conjuntos de genes que o peso. Da mesma forma, as características de escores visuais avaliadas em vacas adultas apresentaram altas correlações genéticas com o peso adulto da vaca. Para o sacro, as estimativas de correlações genéticas foram de baixa magnitude e negativas. PALAVRAS-CHAVE: Amostrador de gibbs, características morfológicas, pesos, zebu.
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Bos indicus is the scientific name for humped cattle, synonym of Zebu. These animals are adapted to tropical conditions and are one of the most maternal beef cattle breeds. However, they have high age at puberty, moderate growth rate and adult weight and less tender meat than Bos taurus. Heifer pregnancy close to 14 months of age is the selection criterious indicated to decrease age at puberty. Concerning growth, the challenge is to match the mature cow weight to pasture rearing conditions and the steer carcasses to market demands. Meat tenderness genetic variability exists but, the costs and difficulties of obtaining the phenotypic data for a selection program need to be evaluated. Selection of Zebu cattle is the main point for tropical countries to meet actual World demands for meat produced under animal welfare and food safety. Suche conditions to achied with objective cambe large beef cattle population, genetic variability and technology.
Bos indicus é o nome científico para os bovinos que possuem cupim, sinônimo de Zebu. Estes animais são adaptados às condições tropicais e estão entre as raças de corte mundiais de maior habilidade materna. Entretanto, apresentam alta idade à puberdade, taxa de crescimento e peso adulto médios e carne com menor maciez que os Bos taurus. Para aumentar a precocidade sexual das fêmeas, o critério de seleção indicado é a característica prenhez de novilha, obtida em torno de 14 e 16 meses de idade. Quanto ao crescimento, o desafio é adequar o tamanho adulto da vaca às condições de criação em pastagem e, as carcaças dos novilhos às exigências do mercado. Existe variabilidade genética na maciez da carne, entretanto, os custos e as dificuldades de obten- ção de dados fenotípicos necessários a um programa de seleção, precisam ser avaliados. A seleção das raças Zebu é o ponto fundamental para que os países tropicais possam atender à atual demanda mundial por carne produzida respeitando o bem estar animal e a segurança alimentar. As condições necessárias para isto como, grande efetivo populacional, variabilidade genética e tecnologia, já estão disponíveis.
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The aim of this study was to verify the existence of interaction between age of dam effect and month of birth effect on weaning weight with the studied regions. Records of 333,259 Nelore animals from Brazilian Association of Zebu Breeds (ABCZ) were analysed. The analysis was carried out using the least squares method. Effects of year of birth, sex, farm and interactions between month of birth and region, and age of dam and region were considered. All effects included in the model affected significantly weaning weight. The Northwest, Center-west, Southeast and South regions were compared using Conditional Residual Model to verify differences on month of birth effect and age of dam effect. For all regions, month of birth effect and age of dam effect on weaning weight were statistically significant (P 0,01). The interaction between age of dam and region, and month of birth and region are an important source of variation on weaning weight. To increase the income and to facilitate the handling, breeding seasons should be established for each region.
O objetivo deste trabalho foi verificar a existência de interação entre o efeito da idade da vaca e mês de nascimento sobre o peso à desmama com as regiões estudadas. Foram analisados dados de 333.259 animais da raça Nelore, provenientes da Associação Brasileira de Criadores de Zebu (ABCZ). As análises foram realizadas usando-se a metodologia de quadrados mínimos. Foram considerados os efeitos de ano de nascimento, sexo, fazenda e as interações do efeito da idade da vaca e mês de nascimento com a região. Todos os efeitos incluídos no modelo afetaram significativamente o peso à desmama. Utilizando o método do Modelo do Resíduo Condicional, as regiões Nordeste, Centro-Oeste, Sudeste e Sul, foram comparadas duas a duas para verificar diferenças dos efeitos da idade da vaca ao parto e do mês de nascimento entre elas. Para todas as regiões o efeito da idade da vaca e do mês de nascimento sobre o peso ao desmame foi significativamente diferente (p 0,01). As interações dos efeitos estudados e região são importantes fontes de variação para o peso à desmama. Para aumentar o rendimento e facilitar o manejo, estações de monta devem ser estabelecidas para cada região.
Resumo
The aim of this study was to verify the existence of interaction between age of dam effect and month of birth effect on weaning weight with the studied regions. Records of 333,259 Nelore animals from Brazilian Association of Zebu Breeds (ABCZ) were analysed. The analysis was carried out using the least squares method. Effects of year of birth, sex, farm and interactions between month of birth and region, and age of dam and region were considered. All effects included in the model affected significantly weaning weight. The Northwest, Center-west, Southeast and South regions were compared using Conditional Residual Model to verify differences on month of birth effect and age of dam effect. For all regions, month of birth effect and age of dam effect on weaning weight were statistically significant (P 0,01). The interaction between age of dam and region, and month of birth and region are an important source of variation on weaning weight. To increase the income and to facilitate the handling, breeding seasons should be established for each region.
O objetivo deste trabalho foi verificar a existência de interação entre o efeito da idade da vaca e mês de nascimento sobre o peso à desmama com as regiões estudadas. Foram analisados dados de 333.259 animais da raça Nelore, provenientes da Associação Brasileira de Criadores de Zebu (ABCZ). As análises foram realizadas usando-se a metodologia de quadrados mínimos. Foram considerados os efeitos de ano de nascimento, sexo, fazenda e as interações do efeito da idade da vaca e mês de nascimento com a região. Todos os efeitos incluídos no modelo afetaram significativamente o peso à desmama. Utilizando o método do Modelo do Resíduo Condicional, as regiões Nordeste, Centro-Oeste, Sudeste e Sul, foram comparadas duas a duas para verificar diferenças dos efeitos da idade da vaca ao parto e do mês de nascimento entre elas. Para todas as regiões o efeito da idade da vaca e do mês de nascimento sobre o peso ao desmame foi significativamente diferente (p 0,01). As interações dos efeitos estudados e região são importantes fontes de variação para o peso à desmama. Para aumentar o rendimento e facilitar o manejo, estações de monta devem ser estabelecidas para cada região.
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Bos indicus is the scientific name for humped cattle, synonym of Zebu. These animals are adapted to tropical conditions and are one of the most maternal beef cattle breeds. However, they have high age at puberty, moderate growth rate and adult weight and less tender meat than Bos taurus. Heifer pregnancy close to 14 months of age is the selection criterious indicated to decrease age at puberty. Concerning growth, the challenge is to match the mature cow weight to pasture rearing conditions and the steer carcasses to market demands. Meat tenderness genetic variability exists but, the costs and difficulties of obtaining the phenotypic data for a selection program need to be evaluated. Selection of Zebu cattle is the main point for tropical countries to meet actual World demands for meat produced under animal welfare and food safety. Suche conditions to achied with objective cambe large beef cattle population, genetic variability and technology.
Bos indicus é o nome científico para os bovinos que possuem cupim, sinônimo de Zebu. Estes animais são adaptados às condições tropicais e estão entre as raças de corte mundiais de maior habilidade materna. Entretanto, apresentam alta idade à puberdade, taxa de crescimento e peso adulto médios e carne com menor maciez que os Bos taurus. Para aumentar a precocidade sexual das fêmeas, o critério de seleção indicado é a característica prenhez de novilha, obtida em torno de 14 e 16 meses de idade. Quanto ao crescimento, o desafio é adequar o tamanho adulto da vaca às condições de criação em pastagem e, as carcaças dos novilhos às exigências do mercado. Existe variabilidade genética na maciez da carne, entretanto, os custos e as dificuldades de obten- ção de dados fenotípicos necessários a um programa de seleção, precisam ser avaliados. A seleção das raças Zebu é o ponto fundamental para que os países tropicais possam atender à atual demanda mundial por carne produzida respeitando o bem estar animal e a segurança alimentar. As condições necessárias para isto como, grande efetivo populacional, variabilidade genética e tecnologia, já estão disponíveis.
Resumo
The objective was to evaluate the interactions of genotype-environment effects on the components of (co)variance estimates and the prediction of breeding values for weaning weight in Nelore cattle, using a Bayesian approach. Records of 16,644 weaning weights were used from cattle distributed in ten ranches across six Brazilian states. The genetic parameters were estimated under an animal model considering Bayesian statistics. To verify genotype-environment interaction effects, we analyzed the following matrix model: without the inclusion of genotype-environment interaction effects, and with the inclusion of genotype-environment interaction effects, which considered the effect of sire-year, sire-herd, and both effects. In general, the results suggest that the inclusion of genotype-environment interaction in genetic analysis for weight at weaning tends to alter the estimates of genetic and environment (co)variances. The Spearman correlations between the breeding values were above 97%, indicating practically no change in the classification of animals evaluated. It can be inferred that the interaction effects of sire-year and sire-herd do not change the animals rank, and if not included in the genetic evaluation, the selection based on predictions of breeding values for weaning weight will not be affected.
Objetivou-se avaliar os efeitos das interações genótipo-ambiente sobre as estimativas de componentes de (co)variâncias e predição dos valores genéticos para o peso ao desmame de bovinos Nelore, sob enfoque bayesiano. Foram utilizados 16.644 registros de pesos ao desmame de bovinos provenientes de dez rebanhos participantes do Programa Nelore Brasil. Os parâmetros genéticos foram estimados sob modelo animal, considerando a estatística bayesiana. Para verificar o efeito da interação genótipo-ambiente, foram analisados os seguintes modelos matriciais: sem a inclusão dos efeitos de interação genótipo-ambiente; com a inclusão dos efeitos de interação genótipo-ambiente, em que se considerou o efeito de touro-ano, touro-rebanho e ambos os efeitos. De modo geral, verifica-se que a inclusão da interação genótipo-ambiente na análise genética para o peso ao desmame, tende a alterar as estimativas de (co)variâncias genéticas e ambientais. As correlações de Spearman entre os valores genéticos foram acima de 97%, indicando que, praticamente, não houve mudança na classificação dos animais avaliados. Pode se inferir que os efeitos de interação touro-ano e touro-rebanho não alteram as classificações dos animais, e a não-inclusão destes efeitos na avaliação genética, não afetam a seleção baseada nas predições dos valores genéticos para o peso ao desmame.
Resumo
This work aimed to study the behavior of semi-confined buffaloes, emphasizing the effect of three different supplementation levels with concentrated in daily distribution of activities during the grazing period. Eighteen Murrah buffaloes with approximately 17 months of age and initial average weight of 300kg were observed for 9 days. They remained on pasture from 7 a.m. till 5 p.m. (observation period). In the evenings, animals were put in their individual stalls, and received the concentrate under 3 different treatments: Treatment 1 = 0.6%, Treatment 2 = 0.9% and Treatment 3 = 1.2% of the animal weight. The observed variables were: Grazing time (TP); Standing time (TEP); Lying time (TD); Rumination time (TR); Wallowing time (TCH); and Time in other activities (TOA). The effect of treatment was significant only for TEP and TD. The day influenced significantly (P
Este trabalho teve por objetivo estudar o comportamento de bubalinos semiconfinados, enfocando o efeito de diferentes níveis de suplementação com concentrado na distribuição diária das atividades do período dedicado ao pastejo. Foram observados por 9 dias, 18 búfalos da raça Murrah, com aproximadamente 17 meses de idade e peso médio inicial de 300kg, os quais permaneceram no pasto das 7:00 às 17:00 horas (período de observação), e após serem recolhidos em suas baias individuais, receberam, no período noturno, o concentrado sob 3 diferentes tratamentos: Tratamento 1 = 0,6%, Tratamento 2 = 0,9% e Tratamento 3 = 1,2% do peso vivo. As variáveis observadas foram: Tempo pastejando (TP); Tempo em pé (TEP); Tempo deitado (TD); Tempo de ruminação (TR); e Tempo em outras atividades (TOA). O efeito de tratamento foi significativo apenas para TEP e TD. O dia influenciou significativamente (P
Resumo
The objective of this paper was to study the genetic correlations of the visual scores traits with the growth continuous traits, by applying bayesian statistic methodology, using two-trait analyses under linear-threshold animal models. The morphological categorical traits of musculature, physical structure, conformation and sacrum were studied in animals of the Nelore breed at the age of 8, 15 and 22 months, and also in adult cows; and the growth continuous traits, weights at the age of 210, 365 and 450 days old, as well as the adult weight of the cow. Estimates of genetic correlations between these visual scores (musculature, physical structure and conformation) with the growth traits were favorably positive, indicating that the selection of one of them will bring genetic progress to another. The results achieved in this study also indicated that the physical structure and the conformation are determined, to a large extent, by the same sets of genes as the weight. In the same way, the evaluated visual scores in adult cows presented high genetic correlations with the adult weight of the cow. As concerning the sacrum, the estimates of genetic correlations were low and negative. KEY WORDS: Gibbs sampler, morphological traits, weights, zebu cattle.
O objetivo deste trabalho foi estudar as inter-relações genéticas dos escores visuais com as características de crescimento, por meio da estatística bayesiana, utilizando análises bicaracterísticas sob modelo animal linear-limiar, na obtenção de parâmetros genéticos. Estudaram-se as características categóricas morfológicas de musculosidade, estrutura física, conformação e sacro, aos 8, 15 e 22 meses de idade, em animais da raça Nelore, e também vacas adultas; e as características contínuas de crescimento, pesos aos 210, 365 e 450 dias de idade, além do peso adulto da vaca. Foram obtidas estimativas de correlações genéticas positivas de alta magnitude entre os escores visuais de musculosidade, estrutura física e conformação com as características de crescimento, indicando que a seleção de uma trará progresso genético à outra. Os resultados obtidos neste estudo também indicaram que a estrutura física e a conformação são determinadas, em grande parte, pelos mesmos conjuntos de genes que o peso. Da mesma forma, as características de escores visuais avaliadas em vacas adultas apresentaram altas correlações genéticas com o peso adulto da vaca. Para o sacro, as estimativas de correlações genéticas foram de baixa magnitude e negativas. PALAVRAS-CHAVE: Amostrador de gibbs, características morfológicas, pesos, zebu.