Genetic parameters for milk yield of Bubalus bubalis using unadjusted and adjusted milk production for days in milk.

The objectives of this study were to estimate genetic parameters for unadjusted and adjusted milk production for 270 and 305 days of lactation and, subsequently, to verify the coincidence of rank of 2%, 5%, 20% and 40% best sires selected based on both models. Complete lactations from 90 or 150 days of lactation to 270 or 350 days of lactation were considered in the analyses. Milk production was adjusted for lactation length by multiplicative correction factors, or by including lactation length as a covariable in the model. Heritabilities, genetic correlations and breeding values were estimated for each trait, and variance and covariance components were estimated by restricted maximum likelihood methodology. Heritability estimates varied from 0.16 to 0.27. Genetic correlations between unadjusted and adjusted milk production for lactation length were higher than 0.64. Heritabilities for adjusted milk production were higher than heritabilities for unadjusted milk production for lactation length. In situations with high selection intensity, probably, modifications will happen in the rank of bulls and/or in the bulls chosen for mating if records are adjusted or unadjusted for 305 days

Partial genetic characterization of Stearoyl Coa-Desaturase´s structural region in Bubalus bubalis

Conjugated Linoleic Acids (CLAs) comprise a family of positional and geometric isomers of linoleic acid. The main form of CLA, cis-9, trans-11-C18:2 show positive effects in cancer prevention and treatment. The major dietary sources of these fatty acids are derived from ruminant animals, in particular dairy products. In these animals, the endogenous synthesis mainly occurs in mammary gland by the action of enzyme Stearoyl CoA Desaturase (SCD). Different levels of expression and activity of SCD in mammary gland can explain partially the variation of CLA levels in fat milk. Considering a great fat concentration in bubaline milk and the benefit of a high and positive correlation between fat milk and CLA production, this study was carried on with the intention of sequencing and characterizing part of the gene that codifies SCD in buffaloes. Genomic DNA was extracted from blood samples of lactating bubaline which begins to the breed Murrah. After the (acho que nao precisa desse the) extractions, PCR (Polymerase Chain Reaction) reactions were made by using primers Z43D1 and E143F1. The fragments obtained in PCR were cloned into “T” vectors and transformed in competent cells DH10B line. After this, three samples of each fragment were sequenced from 5’ and 3’ extremities using a BigDye kit in an automatic sequencer. Sequences were edited in a consensus of each fragment and were submitted to BLAST-n / NCBI for similarity comparisions among other species. The sequence obtained with Z43D1 primers shows 938 bp enclosing exons 1 and 2 and intron 1. The primers E143F1 show 70 bp corresponding to exon 3 of bubaline SCD gene. Similarities were obtained between 85% and 97% among bubaline sequences and sequences of SCD gene described in human, mouse, rat, swine, bovine, caprine and ovine species. This study has permitted the identification and partial characterization of SCD codifing region in Bubalus bubalis specie

Modelos de regressão aleatória para características de crescimento de bovinos da raça Nelore do estado de Mato Groso

Foram utilizados 138.976 registros de informações de pesos corporais variando de 60 a 610 dias de idade, provenientes de 27.327 animais da raça Nelore, oriundos de rebanhos do estado do Mato Grosso, com o objetivo de descrever a variabilidade genética e estimar parâmetros genéticos para o peso corporal em diferentes idades, utilizando-se modelos de regressão aleatória. O modelo empregado incluiu efeitos fixos de grupo de contemporâneos e idade da vaca ao parto como covariáveis, além de efeitos aleatórios genético aditivo direto, genético materno, ambiente permanente de animal, ambiente permanente materno e efeito de ambiente temporário. O modelo de regressão aleatória mais adequado foi o que empregou função de covariância com polinômios de quarta ordem para descrição da variabilidade de todos os efeitos e duas classes de variância residual. As estimativas de variância genética aditiva direta e de ambiente permanente de animal aumentaram com a idade dos animais. As variâncias genética materna e de ambiente permanente materno exibiram comportamento semelhante, com maiores valores na fase de aleitamento. Os coeficientes de herdabilidade estimados variam de 0,25 a 0,43, com maiores valores nas idades mais avançadas na trajetória de crescimento dos animais. Esses resultados indicaram presença de variabilidade genética suficiente para obtenção de ganho genético expressivo por meio da seleção, principalmente após desmama. Os resultados encontrados para a correlação genética aditiva direta exibiram baixas correlações entre pesos nas idades iniciais e finais, porém pesos altamente correlacionados entre idades mais próximas. As correlações genéticas estimadas entre os pesos da desmama com os pesos até 610 dias de idade foram altas e positivas e indicam que os genes responsáveis por maiores pesos nesse período, em sua maioria, são os mesmos