Finishing precocity visual score and genetic associations with growth traits in Angus beef cattle.

Finishing precocity visual score selection was adopted to estimate the time from birth to reach slaughter age. This study estimated (co)variance components and genetic correlations for the finishing precocity score at weaning (WP) and yearling (YP) stages by using daily weight gain (BWG = from birth to weaning; WYG = from weaning to yearling) and speed of weight gain (BWR = from birth to weaning; WYR = from weaning to yearling) as support for a genetic evaluation program for Angus beef cattle. Genetic parameters were estimated using Bayesian inference, considering multi-trait analysis and assuming a nonlinear model for WP and YP and linear model for all other traits. Direct heritability estimates were 0.17 (WP), 0.19 (YP), 0.15 (BWG), 0.16 (WYG), 0.15 (BWR), and 0.16 (WYR). The genetic correlation between the finishing precocity score at two ages (weaning and yearling) was 0.61. Positive and moderate genetic correlations were obtained between WP and BWG (0.47) and WP and BWR (0.46). In contrast, negative and low genetic associations were estimated between WP and yearling growth traits (-0.16, WYG; -0.15, WYR). Genetic correlations between YP and other traits were positive 0.29 (BWG), 0.28 (BWR), 0.48 (WYG), and 0.47 (WYR). The selection response for the finishing precocity score at weaning and yearling ages would be low. Selection to increase WP and YP should result in favorable genetic changes in daily weight gains as a correlated response. Therefore, to obtain animals suited for beef cattle production systems, finishing precocity score and growth traits should be considered as selection criteria.

Avaliação do desempenho na pós-desmama para uma população bovina multirracial Aberdeen Angus x Nelore utilizando-se diferentes modelos genéticos / Post weaning performance evaluation for a multibreed Aberdeen Angus x Nellore population using different genetic models

Com o objetivo de testar modelos genéticos alternativos ao aditivo-dominante em populações multirraciais, foram utilizadas informações do peso ao sobreano (PS) de 35.931 novilhos, filhos de 752 touros e 30.535 vacas das raças Aberdeen Angus (A) e Nelore (N) e de diversos grupos genéticos possíveis por meio do cruzamento entre elas. Foram testados cinco diferentes modelos (M) genéticos: o M1 continha o efeito genético fixo aditivo direto (AD), heterozigótico direto (HD), epistático direto (ED) e aditivo-conjunto direto (ACD); o M2, igual ao M1, menos o efeito ACD; o M3, igual ao M1, menos o efeito ED; o M4, igual ao M1, menos os efeitos ED e ACD; e o M5, igual ao M1, menos os efeitos HD, ED e ACD. Os modelos foram submetidos a três métodos de análise diferentes: método dos quadrados mínimos (MQM), regressão de cumeeira (RC) e máxima verossimilhança restrita (REML). O método de RC produziu estimativas de coeficientes com magnitudes e sinais explicados biologicamente. As estimativas dos efeitos, das (co)variâncias, dos parâmetros e dos valores genéticos diferiram entre os modelos, indicando a importância da correta escolha do modelo de análise, devendo-se ter conhecimento prévio do fenômeno estudado e sua interpretação biológica e sempre preceder à escolha de um modelo de análise genética multirracial o estudo da relação existente entre as variáveis independentes. Importantes efeitos adicionais ao efeito AD foram acrescentados pelas inclusões dos efeitos HD e ED aos modelos de análise. A notação matemática dos efeitos ACD, aplicada atualmente na literatura e testada neste estudo, não foi capaz de explicar a complementaridade entre raças como esperado, havendo problemas com casos de multicolinearidade entre os efeitos estudados.

In order to evaluate alternative genetic models to the additive dominant model, weights at yearling (PS) of 35,931 animals, sired by 752 bulls and 30,535 cows of Aberdeen Angus (A) and Nellore (N) breeds and the genetic groups from their crosses were used. Five different genetic models (M) were tested: M1, containing the direct additive fixed genetic effect (DA), heterozygote direct (HD), epystatic direct (ED), and direct joint additive direct (DJA); M2 was equal to M1, excluding DJA effect; M3 was equal to M1, excluding ED effect; M4 was equal M1, excluding ED and ACD effects, and M5 was equal to M1, excluding HD, ED, and DJA effects. The models were analyzed by different methods: Least Square Means Method (MQM), Ridge Regression Method (RC), and Restricted Maximum Likelihood Method (REML). Estimated coefficients by RC showed magnitude and sign which were biologically explained. The estimates of the covariances, parameters, and genetic values varied among the models, indicating the importance of the correct choice of the model for analysis, being necessary a previous knowledge of the studied phenomenon and its biological interpretation. Besides, it should always be considered the relationship between the independent variables before choosing a multibreed genetic analysis model. Important additional effects to the DA effect were considered by the inclusion of the HD and ED effects to the models for analysis. The DJA math notation, currently used in the literature and tested in the present study, was not able to explain the breed complementarity, due to the multi colinearity among the studied effects.

Associaçäo lidocaína-morfina em raquianestesia / Lidocaine-morphine association in spinal anesthesia

Foram observados os resultados do emprego da associaçäo de lidocaína 5 por cento pesada com 1 mg de morfina e adrenalina, por via intratecal, em 20 pacientes obstétricas. O tempo médio de analgesia pós-operatória foi de 25 h e 15 min. Os efeitos colaterais observados foram náuseas e vômitos, prurido e retençäo urinária. Os recém-nascidos apresentaram índice de Apgar de 7 a 10, ao primeiro minuto, e de 9 a 10 no quinto minuto