RESUMO
Evaluating traits that allow breeders to increase production efficiency in beef production systems is important. The mouth size (MS) score is a trait easily measured and implemented by breeders. Bite size is related to MS in beef cattle and is a determinant of daily feed intake of pasture-raised animals, influencing their growth. The aim of this study was to estimate genetic parameters for MS, weaning weight (WW) and postweaning weight gain (PWG) of Nelore cattle and to evaluate the influence of the interaction between MS and WW on PWG. Phenotypic records of 134,282 Nelore animals born between 1995 and 2019 were used. Variance components were estimated using multitrait animal model with the Bayesian method. The model included the contemporary group as fixed effect, age at measurement of the trait as linear covariate, and direct additive genetic and residual effects as random effects. For WW, random maternal and maternal permanent environmental effects were added to the model. A Bayesian approach was used to analyze the interaction between WW clusters and MS. The heritability estimates were 0.24, 0.15, and 0.23 for MS, WW, and PWG, respectively. The genetic correlation between variables studied ranged from 0.24 to 0.46. The results suggest that animals with a larger mouth tend to have greater PWG, demonstrating the positive influence of MS score on the postweaning performance of cattle. The direct heritability estimates confirm the possibility of selecting animals for the traits studied.
Evaluating traits that allow breeders to increase production efficiency in beef production systems is important. The mouth size (MS) score is a trait easily measured and implemented by breeders. Our results showed that MS in Nelore cattle is a heritable trait, and it is favorably associated with growth traits, indicating that animals with larger mouth are heavier at weaning and gain more weight after weaning on pasture. MS score should be further explored to evaluate its complexity and inclusion in breeding programs incorporating data collected from cattle raised under pasture conditions.
Assuntos
Boca , Aumento de Peso , Bovinos/genética , Animais , Teorema de Bayes , Fenótipo , Aumento de Peso/genética , Peso Corporal/genética , Desmame , Modelos GenéticosRESUMO
The aim of this study was to estimate the environmental effects (calving age, julian date of birth and weaning age) on the adjusted weights to 120 (P120) and 205 (P205) days of crossbred cattle Angus x Nelore. The database was formed with information from 11,271 animals, borned from 1987 to 2004. Maternal heterozygosity proportions were equal to 0.0, 0.375, 0.4688, 0.5, 0.75 and 1.0. The weights, P120 and P210, were standardized based on the weight daily gain by interpolation of the weighing close to the standardized age and weight measured previously. The (co) variance components and genetic parameters were obtained by Bayesian inference analyzes performed with three statistical models, differing as to the environmental effects. Breeding values were obtained for three models and were compared by Spearman correlations and by percentage of selected bulls in common. Heritability estimates values obtained in the best model was 0.20 for both traits (P120 and P205). Study of genetic values showed changes in the classification of animals according to models. Inclusion of julian date class of birth, age class of the animal in the measurement and interaction of calving age class and maternal heterozygosity in the selection of parents was important to allow greater precision in genetic evaluation of herd.
O objetivo com este trabalho foi estimar efeitos de ambiente (idade da vaca ao parto, data juliana de nascimento e idade do bezerro à desmama) sobre os pesos ajustados aos 120 (P120) e 205 (P205) dias de idade em bovinos mestiços Angus x Nelore. O banco de dados foi formado com informações de 11.271 animais, nascidos no período de 1987 a 2004. Os animais eram filhos de matrizes com proporções de heterozigoses iguais a 0,0; 0,375; 0,4688; 0,5; 0,75 e 1,0. Os pesos, P120 e P210, foram padronizados com base no ganho diário de peso por meio da interpolação da pesagem próxima a idade a ser padronizada e do peso mensurado anteriormente. Para obtenção dos componentes de (co)variância e parâmetros genéticos das características, análises sob inferência bayesiana foram realizadas com três modelos estatísticos, diferindo quanto aos efeitos ambientais. Os valores genéticos foram obtidos para os três modelos e foram comparados por correlações de ordem Spearman e pela porcentagem de touros selecionados em comum. Os valores das estimativas de herdabilidade aposterioriobtidos no melhor modelo foi 0,20 para ambas as características (P120 e P205). O estudo dos valores genéticos mostrou alterações na classificação dos animais de acordo com os modelos. A inclusão de classe de data juliana ao nascimento, classe de idade da mensuração e interação da classe de idade da mãe ao parto e da heterozigose materna no momento da escolha dos reprodutores foi importante de modo a permitir maior precisão na avaliação genética e esquemas de seleção mais acurados.
RESUMO
The aim of this study was to estimate the environmental effects (calving age, julian date of birth and weaning age) on the adjusted weights to 120 (P120) and 205 (P205) days of crossbred cattle Angus x Nelore. The database was formed with information from 11,271 animals, borned from 1987 to 2004. Maternal heterozygosity proportions were equal to 0.0, 0.375, 0.4688, 0.5, 0.75 and 1.0. The weights, P120 and P210, were standardized based on the weight daily gain by interpolation of the weighing close to the standardized age and weight measured previously. The (co) variance components and genetic parameters were obtained by Bayesian inference analyzes performed with three statistical models, differing as to the environmental effects. Breeding values were obtained for three models and were compared by Spearman correlations and by percentage of selected bulls in common. Heritability estimates values obtained in the best model was 0.20 for both traits (P120 and P205). Study of genetic values showed changes in the classification of animals according to models. Inclusion of julian date class of birth, age class of the animal in the measurement and interaction of calving age class and maternal heterozygosity in the selection of parents was important to allow greater precision in genetic evaluation of herd.
O objetivo com este trabalho foi estimar efeitos de ambiente (idade da vaca ao parto, data juliana de nascimento e idade do bezerro à desmama) sobre os pesos ajustados aos 120 (P120) e 205 (P205) dias de idade em bovinos mestiços Angus x Nelore. O banco de dados foi formado com informações de 11.271 animais, nascidos no período de 1987 a 2004. Os animais eram filhos de matrizes com proporções de heterozigoses iguais a 0,0; 0,375; 0,4688; 0,5; 0,75 e 1,0. Os pesos, P120 e P210, foram padronizados com base no ganho diário de peso por meio da interpolação da pesagem próxima a idade a ser padronizada e do peso mensurado anteriormente. Para obtenção dos componentes de (co)variância e parâmetros genéticos das características, análises sob inferência bayesiana foram realizadas com três modelos estatísticos, diferindo quanto aos efeitos ambientais. Os valores genéticos foram obtidos para os três modelos e foram comparados por correlações de ordem Spearman e pela porcentagem de touros selecionados em comum. Os valores das estimativas de herdabilidade aposterioriobtidos no melhor modelo foi 0,20 para ambas as características (P120 e P205). O estudo dos valores genéticos mostrou alterações na classificação dos animais de acordo com os modelos. A inclusão de classe de data juliana ao nascimento, classe de idade da mensuração e interação da classe de idade da mãe ao parto e da heterozigose materna no momento da escolha dos reprodutores foi importante de modo a permitir maior precisão na avaliação genética e esquemas de seleção mais acurados.
RESUMO
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.
RESUMO
This study was conducted to describe the ingestive behavior in Nellore and Bonsmara cattle during the feed efficiency test. The test was performed at the Centro APTA Bovinos de Corte Instituto de Zootecnia, Sertãozinho, São Paulo State. Twenty-three Nellore and 19 Bonsmara calves, aging 276 ± 19.2 and 278 ± 29.2 days and weighing 246 ± 26.7 and 273 ± 30.7 kg, on average, at the beginning of the test, respectively, were used. Animals were randomly located in individual pens, during four periods of 28 days, being the first period a pre-test adjustment period. Calves were fed twice a day, with the same diet. Daily the amount of food offered was adjusted in order to maintain 5 to 10% of refusals. Dry matter intake (DMI) was calculated by the difference between food offered and refusals. Animals were weighed each seven days. Average daily gain (ADG) was obtained by linear regression of weights in days in test. Feed conversion was obtained by the DMI:ADG ratio. Ingestive behavior was measured three times, every 28 days, excluding de pre-test period. Observations lasted 24 hours, with records at intervals of five minutes. The behavioral traits analyzed were: bunk attendance duration (BAD), rumination time (RT) and idle time (IT) expressed in minutes per day. Data were analyzed using the PROC MIXED procedure (SAS 9.3). The model included the fixed effects of period, breed and weight
O artigo não apresenta resumo em português.
RESUMO
This study was conducted to describe the ingestive behavior in Nellore and Bonsmara cattle during the feed efficiency test. The test was performed at the Centro APTA Bovinos de Corte Instituto de Zootecnia, Sertãozinho, São Paulo State. Twenty-three Nellore and 19 Bonsmara calves, aging 276 ± 19.2 and 278 ± 29.2 days and weighing 246 ± 26.7 and 273 ± 30.7 kg, on average, at the beginning of the test, respectively, were used. Animals were randomly located in individual pens, during four periods of 28 days, being the first period a pre-test adjustment period. Calves were fed twice a day, with the same diet. Daily the amount of food offered was adjusted in order to maintain 5 to 10% of refusals. Dry matter intake (DMI) was calculated by the difference between food offered and refusals. Animals were weighed each seven days. Average daily gain (ADG) was obtained by linear regression of weights in days in test. Feed conversion was obtained by the DMI:ADG ratio. Ingestive behavior was measured three times, every 28 days, excluding de pre-test period. Observations lasted 24 hours, with records at intervals of five minutes. The behavioral traits analyzed were: bunk attendance duration (BAD), rumination time (RT) and idle time (IT) expressed in minutes per day. Data were analyzed using the PROC MIXED procedure (SAS 9.3). The model included the fixed effects of period, breed and weight
O artigo não apresenta resumo em português.
RESUMO
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.