Influence of environmental factors on pre-weaning weights of crossed cattle Aberdeen Angus x Nelore / Influência de fatores ambientais sobre pesos pré-desmama de bovinos cruzados Aberdeen Angus x Nelore

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.(AU)

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 a posteriori obtidos 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 heterozigos(AU)

Influence of environmental factors on pre-weaning weights of crossed cattle Aberdeen Angus x Nelore / Influência de fatores ambientais sobre pesos pré-desmama de bovinos cruzados Aberdeen Angus x Nelore

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 a posteriori obtidos 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 heterozigos

Implementation of DNA markers to produce genomically - enhanced EPDs in Nellore cattle

Background: The sequencing and publication of the cattle genome and the identification of single nucleotide polymorphism (SNP) molecular markers have provided new tools for animal genetic evaluation and genomic-enhanced selection. These new tools aim to increase the accuracy and scope of selection while decreasing generation interval. The objective of this study was to evaluate the enhancement of accuracy caused by the use of genomic information (Clarifide® - Pfizer) on genetic evaluation of Brazilian Nellore cattle. Review: The application of genome-wide association studies (GWAS) is recognized as one of the most practical approaches to modern genetic improvement. Genomic selection is perhaps most suited to the improvement of traits with low heritability in zebu cattle. The primary interest in livestock genomics has been to estimate the effects of all the markers on the chip, conduct cross-validation to determine accuracy, and apply the resulting information in GWAS either alone [9] or in combination with bull test and pedigree-based genetic evaluation data. The cost of SNP50K genotyping however limits the commercial application of GWAS based on all the SNPs on the chip. However, reasonable predictability and accuracy can be achieved in GWAS by using an assay that contains an optimally selected predictive subset of markers, as opposed to all the SNPs on the chip. The best way to integrate genomic information into genetic improvement programs is to have it included in traditional genetic evaluations. This approach combines traditional expected progeny differences based on phenotype and pedigree with the genomic breeding values based on the markers. Including the different sources of information into a multiple trait genetic evaluation model, for within breed dairy cattle selection, is working with excellent results. However, given the wide genetic diversity of zebu breeds, the high-density panel used for genomic selection in dairy cattle (Ilumina Bovine SNP50 array) appears insufficient for across-breed genomic predictions and selection in beef cattle. Today there is only one breed-specific targeted SNP panel and genomic predictions developed using animals across the entire population of the Nellore breed (www.pfizersaudeanimal.com), which enables genomically - enhanced selection. Genomic profiles are a way to enhance our current selection tools to achieve more accurate predictions for younger animals. Material and Methods: We analyzed the age at first calving (AFC), accumulated productivity (ACP), stayability (STAY) and heifer pregnancy at 30 months (HP30) in Nellore cattle fitting two different animal models; 1) a traditional single trait model, and 2) a two-trait model where the genomic breeding value or molecular value prediction (MVP) was included as a correlated trait. All mixed model analyses were performed using the statistical software ASREML 3.0. Results: Genetic correlation estimates between AFC, ACP, STAY, HP30 and respective MVPs ranged from 0.29 to 0.46. Results also showed an increase of 56%, 36%, 62% and 19% in estimated accuracy of AFC, ACP, STAY and HP30 when MVP information was included in the animal model. Conclusion: Depending upon the trait, integration of MVP information into genetic evaluation resulted in increased accuracy of 19% to 62% as compared to accuracy from traditional genetic evaluation. GE-EPD will be an effective tool to enable faster genetic improvement through more dependable selection of young animals.

Efeito do mês dentro da estação da monta sobre a fertilidade de éguas inseminadas com sêmen fresco diluído / Effect of month within the breeding season upon fertility of mares inseminated with diluted fresh semen / Efecto del mes de la estación del monta sobre la fertilidad de yeguas inseminadas con semen fresco diluido

Noventa e quatro ciclos, de cinquentas e nova éguas foram analisados com objetivos de estudas o efeito do mês de ovulação sobre a fertilidade de éguas inseminadas com sêmen fresco diluído. As éguas foram rufiadas e inseminadas às segundas, quartas e sextas-feiras, a partir de um folículo de 3,0 a 3,5 cm de diâmetro, com sêmen de apenas um garanhão de fertilidade comprovada, diluído para um volume inseminante de 10 ml com diluidor de mínima contaminação. Os ciclos foram agrupados de acordo com o mês de ovulação (novembro, dezembro, janeiro, fevereiro/março). as taxas de concepção, ao primeiro ciclho, para os grupos novembro, dezembro, janeiro, fevereiro/março foram de 61,11% (11/18); 84,21%(16/19); 55,56%(5/9); 53,85%(7/13), respectivamente, sem que houvesse diferenças entre estas (P>0,05). Após quatro ciclos, as taxas de concepção foram de 61,11% (11/18); 70,37% (19/27); 50,00% (8/16); 42,42% (14/33), respectivamen te, na mesma ordem anterior (P>0,05). Entretanto, foi observada uma menor eficiência de prenhez no mês fevereiro/março. Conclui-se então que o mês de março foi o responsável pela menor fertilidade das éguas.(AU)

Ninety four estral cuycles of fifty nine mares were analyzed to study the effect of ovulation month of mares inseminated with fresh diluted fresh semen. The mares were teased and inseminate on Mondays, Wednesdays and Fridays, from one follicle of 3.0 to 3.5 cm of niameter, with semen from one stallion of proven fertility, extended with minimum contamination extender. The cycles were grouped according the ovulation month (November, December, January, February/Mach). The conception rates for the first cycle for groups November, December, January, Frebuary/March were 61,11% (11/18) 84,21% (16/19); 55,56% (5/9); 53,85% (7/13), respectively, without differences among then (P>0,05). The conception/cicle rates after four cicles were 61,11% (11/18); 70,37% (19/27); 50,00% (8/16); respectively, without differences among then (P>0,05). Homewer, a smaller pregnancy efficiency was observed in the month February/March. It was concluded that the month of March was responsible for the smallest fertility of the mares.(AU)

noventa y cuatro ciclos de cincuenta y nove hembras equinas fueron analizados para estudas el efecto del mes sobre la fertilidad de estas yeaguas inseminadas con semen fresco diluido. Las yeguas fueron inseminadas los lunes, miércoles y viernes, a partir de un folíulo de 3,0 a 3,5 centímetros de diámetro, con semen de un solo garañón de fertilidad comprobada, diluido para un volume inseminante de 10 mL con diluidor de mínima contaminación. Los resultados fuerón agrouped, en del acuerdo con el mes de la ovulación de las yeguas (noviembre, deciembre, enero, febrero/marzo). Las tazas de concepción, al primer ciclo para los grupos fueron del 61,11% (11/18); del 84,21% (16/19); del 55,56% (5/9) y del 53,85% (7/13), respectivamente, sin que hubiera diferencias entre estas (P>0,05). Después de 4 ciclos, las tazas de concepción fuero del 61,11%(11/18); del 70,37%(19/27); del 50,00%(8/16); del 42,42%(14/33), respectivamente, en el mismo orden anterior (P>0,05). Sin embardo, fue una menor eficiencia de la preñez en el mes febrero/marzo. Con base en los resultados obtenidos, el mes de marzo fue responsable por una menor fertilidad de las yeguas.(AU)