Raimundo Martins Filho

Herdabilidade para efeitos direto e materno de características de crescimento de bovinos Nelore no Estado da Paraíba

Weight records at 205 (205W), 365 (365W) and 550 (550W) days of age of three Nellore herds raised in Paraiba State from 1975 to 1990, were used in the analyses. Genetic and maternal effects were estimated with the restricted maximum likelihood method, assuming an animal model. There were included the fixed effects of year-month-sex and farm. The linear and quadratic effects of age of dam at calving were included in the model as covariables. The least squares means and respective standard errors for P205, P365 and P550 for three studied farms were, respectively, 149.00 ± 22.28 kg, 198.40 ± 38.84 kg, 256.99 ± 55.65 kg; 145.10 ± 21.31 kg, 182.83 ± 30.38 kg, 247.45 ± 50.57 kg e 162.12 ± 14.23 kg, 246.66 ± 23.11 kg, 332.83 ± 35.02 kg. The heritabilities estimates for genetic direct effect were 0,16 ± 0,05, 0,40 ± 0,11 e 0,76 ± 0,25, for 205W, 365W and 550W, respectively. The heritabilities estimated for the maternal effects of 205W, 365W and 550W were 0,36 ± 0,05, 0,44 ± 0,15 and 0,01 ± 1,10, respectively. The correlations between direct and maternal effect for 205W, 365W and 550W were -0,70, -0,74, and -1,00, respectively. Maternal effects were important only in the pre-weaning phase.

Desempenho reprodutivo de vacas Nelore no Norte e Nordeste do Brasil

The objective of this study was to estimate genetic and phenotypic parameters for reproductive traits of Nelore cows raised in the North and Northeast regions of Brazil. The traits studied were age at first calving (AFC), calving interval (CI), post-partum interval (PPI), number of services per conception (NSC) and gestation length (GL). The statistical analyses were done using the SAS program (Statistical Analysis System) and variance components were estimated by Restricted Maximum Likelihood method using the MTDFREML software. Means and heritability estimates for AFC, CI, PPI, NSC and GL were 45.14±10.83 months; 465.55±128.49 days; 165.76±110.29 days; 1.34±0.67 services and 295.03±5.85 days and 0.21±0.05; 0.05±0.02; 0.32±0.11; 0.05±0.04 e 0.12±0.04, respectively. The repeatability for CI, PPI, NSC and GL were, respectively, 0.05; 0.63; 0.09 and 0.22. The results suggest that despite the small genetic variability for the reproductive traits, AFC and GL must be included in selection programs. The high heritability estimate for PPI is probably associated to the structure of the data, in its majority coming from the same herd. The repeatability estimate for CI suggests that female culling based on first calving interval is not accurate and there is a risk of culling animals with probable good reproductive efficiency.

Efeitos ambientais e genéticos sobre o ganho em peso diário de bovinos Nelore no Estado da Paraíba

Registros de 6.674 pesos de bovinos da raca Nelore nascidos entre 1975 e 1990 em duas fazendas no Estado da Paraiba foram utilizados para estudar efeitos ambientais e estimar parâmetros geneticos das caracteristicas ganhos em peso diario do nascimento aos 205, dos 205 aos 365 e dos 365 aos 550 dias de idade. Os efeitos ambientais foram estudados usando-se o programa SAS®. O modelo incluiu o efeito aleatorio de touro e os efeitos fixos de ano-mes-sexo, fazenda e idade da vaca como covariavel linear e quadratica. Os componentes de (co)variância usados para estimar os coeficientes de herdabilidade direta e materna foram obtidos pelo Metodo da Maxima Verossimilhanca Restrita, usando o programa MTDFREML sob modelo animal. Todos os efeitos incluidos no modelo foram significativos, exceto o efeito de fazenda para o ganho diario do nascimento a desmama. As medias estimadas foram de 0,575 ± 0,089, 0,231 ± 0,114 e 0,283 ± 0,110 kg para ganhos em peso diario do nascimento aos 205, dos 205 aos 365 e dos 365 aos 550 dias de idade, respectivamente. As herdabilidades estimadas para efeito direto foram de 0,12, 042 e 0,21 e, para efeito materno, de 0,29, 0,00 e 0,00, na mesma ordem. Os coeficientes de herdabilidade indicam que a selecao baseada no ganho em peso pos-desmama ate um ano de idade pode proporcionar consideravel ganho genetico.

Análise do desempenho produtivo de diversos grupos genéticos Holandês x Gir no Brasil.

Total milk yield per lactation (PL), milk yield in 305 days (PL305) and lactation length (DL) were estimated based on records of the Brazilian Association of Girolando Breeders (3,574 lactations). Milk production was recorded monthly and 10.8% of the herds were raised under an extensive feeding system, 67.9% under a semi-intensive feeding system and 21.3% under an intensive feeding system. Data were analyzed through the least square method by GLM procedure (SAS, 1996). Preliminary analysis indicated a high interaction between genetic group and feeding system. Thus, the performance of genetic groups was evaluated within each feeding system. Genetic effects of additive difference between (g) Holstein and Gir breeds, dominance (d) and additive x additive epistatic interactions (gg) were also studied. It was observed that, in some cases, the effects of epistatic interactions should be taken into account. Moreover, increasing the proportion of Holstein-Friesian genes did not have any significant effect on milk yield when herds were raised under poor management conditions. However, as such conditions improved, crosses with higher proportion of Holstein tended to show better performance.

Fatores ambientais e genéticos sobre o crescimento ao ano e ao sobreano de bovinos Nelore, criados no Nordeste do Brasil

Data growth records relative to 2004 Nellore breed calves, from Ceara and Piaui states, were used to study the influence of environmental effects and to estimate the heritability of the weight traits at the 365 days (yearling) and 550 days (post-yearling) of age. The variance components were estimated by the restricted maximum likelihood method. In the analysis of variance a model that included the fixed effects of sex, year and season and herd of birth, and the age of dam as covariant and the random effect of sire within the herd, was used. The fixed effects of classification were significant for all evaluated traits. Least square means were 186.16 ± 2.74 kg and 244.06 ± 5.23 kg, for yearling and post-yearling weight respectively. Age of dam at calving influenced only the yearling weights, with estimated maximum weight of 187.29 kg and ages around nine years. Heritability estimates were .56 ± .09 and .64 ± .12, for yearling and post-yearling weight, respectively.

Melhoramento e estrutura populacional em bubalinos da raça Mediterrâneo no Brasil

O objetivo deste trabalho foi avaliar a estrutura populacional e os progressos geneticos, fenotipicos e ambientais de caracteristicas de desenvolvimento ponderal, em bubalinos da raca Mediterrâneo. Foram utilizadas informacoes dos pesos ajustados aos 205, 365 e 550 dias de idade, de 6.243 bubalinos nascidos no periodo de 1974 a 2003, provenientes de quatro fazendas. As estimativas dos coeficientes de herdabilidade foram altas para os pesos ajustados nas tres idades. Os rebanhos apresentaram ganho genetico positivo quanto a essas tres caracteristicas, porem, aquem do possivel, provavelmente em razao da selecao baseada somente no fenotipo, realizada pelos produtores. Para aumento nos ganhos geneticos, sao necessarios a reducao do intervalo de geracao, o aumento do tamanho efetivo, o uso de reprodutores avaliados com base nos valores geneticos preditos pelo BLUP e o controle dos acasalamentos de animais aparentados.

Estudo de Características Quantitativas de Crescimento dos 120 aos 550 Dias de Idade em Gado Nelore

With the aim of a better understanding of quantitative growth traits in Nellore cattle, some parameters were estimated: variance components and heritability coefficients of weight gains between the standardized ages of 120 and 240, 240 and 365, 365 and 455, and 455 and 555 days, and of scrotal circumference gains between the standardized ages of 365 and 455, and 455 and 555 days; and (co)variance components and genetic correlations between weight and scrotal circumference gains. Information from 29,769 records of weight gain and 15,676 records of scrotal circumference gain were analyzed to obtain the (co)variance component estimates. The restricted maximum likelihood, derivative free, under an animal model was the method of choice. The results were the following: 0.32 for the direct genetic heritability and 0.13 for the maternal genetic heritability coefficients for weight gain between 120 and 240 days of age; 0.16, 0.22 and 0.23 for the direct genetic heritability coefficients for weight gain between the ages of 240 and 365, 365 and 455, and 455 and 550 days respectively; 0.24 and 0.18 for the direct genetic heritability coefficients for scrotal circumference gain between the ages of 365 and 455, and 455 and 550 respectively; and genetic correlation of 0.18 between the weight and the scrotal circumference gains.

Efeitos genéticos aditivos e não-aditivos para características produtivas e reprodutivas em vacas mestiças Holandês × Gir

A partir de registros de genealogia e controle leiteiro e reprodutivo fornecidos pela Associacao Brasileira dos Criadores de Girolando, foram estimados os efeitos de diferenca genetica aditiva entres as racas Holandesa e Gir, de dominância e de recombinacao, alem das herdabilidades e repetibilidades, para as caracteristicas producao de leite por lactacao (PL), producao de leite ate os 305 dias de lactacao (PL305), duracao da lactacao (DL), intervalo de partos (IDP), idade ao primeiro parto (IPP) e producao de leite por dia de intervalo de partos (PL/IDP). Foram utilizados 4.805 registros de PL, PL305 e DL e 2.222, 1.408 e 2.363 registros de IDP, IPP e PL/IDP, respectivamente. Analises unicaracteristicas foram realizadas considerando os efeitos de diferenca genetica aditiva entre as racas, de dominância e de recombinacao como covariaveis. As estimativas para a diferenca genetica aditiva entre as duas racas foram significativas para todas as caracteristicas, exceto para o IDP, e foram estimadas em 3.115 ± 273 kg, 2.574 ± 226 kg, 98 ± 13 dias, -236 ± 67 dias e 7,5 ± 0,9 kg/dia para PL, PL305, DL, IPP e PL/IDP, respectivamente. Os efeitos de dominância (heterose) tambem foram significativos para todas as caracteristicas, exceto para a DL. Foi verificada significativa perda por recombinacao para PL e PL305. As estimativas de herdabilidade foram de 0,25 ± 0,05, 0,21 ± 0,04, 0,12 ± 0,04, 0,05 ± 0,05, 0,33 ± 0,09 e 0,21 ± 0,07 para PL, PL305, DL, IDP, IPP e PL/IDP, respectivamente, enquanto as estimativas de repetibilidade foram de 0,49 ± 0,05; 0,47 ± 0,04; 0,18 ± 0,04; 0,09 ± 0,06; e 0,37 ± 0,07 para PL, PL305, DL, IDP e PL/IDP, respectivamente.

The Indubrasil breed in the Brazilian Northeast: breeding and population structure

In order to provide knowledge for breeding, conservation programs and expansion policies of the Indubrasil breed from northeastern Brazil, the evolutionary history, estimates of genetic parameters and the populational structure of the breed were studied. Pedigree information was used from animals born from 1964 to 2006 and the adjusted weights at 205, 365 and 550 days of age of bovines born from 1976 onwards. The heritability coefficient estimates were lower than those reported in the literature for the adjusted weights at the three ages (P205: direct 0.11 ± 0,03 and maternal 0.01 ± 0.03; P365: direct 0.16 ± 0.04 and P550: direct 0.15 ± 0.05) and the genetic gains for the evaluated traits decreased in the sampled period (P205: -0.028 kg/year; P365: -0.030 kg/year and P550: -0.025 kg/year). The low genetic variability and the reduced genetic gains were probably due to a reduction in the effective size and increasing inbreeding within the period. Furthermore, the drastic reduction in the number of births per year and the low use of unrelated sires within the herds make the Indubrasil breed a genetic group potentially threatened by extinction, so that conservationist and expansion programmes should be set up.

Estimativas de herdabilidade de efeitos direto e materno de características de crescimento de bovinos Guzerá, no Estado da Paraíba

Weight data of 205 (205W), 365 (365W) and 550 (550W) days old of Guzera herds raised on Paraiba State from 1975 to 1990 were analysed. Genetic and maternal effects were estimated by Restricted Maximum Likelihood method (REML). It was used an animal model with fixed effects of year-month-sex, farm and age of dam at calving (linear and quadratic). The general means for 205W, 365W and 550W were respectively 141.85 ± 28.67 kg, 199.08 ± 48.43 kg and 252.32 ± 64.90 kg. The heritability of direct genetic effect at 205W, 365 W and 550W days old were: 0.35 ± 0.08, 0.39 ± 0.11 and 0.46 ± 0.16, respectively. The heritability of maternal effect and correlations between direct genetic and maternal effects at 205W, 365W and 550W days old were: 0.26 ± 0.08, 0.28 ± 0.14 and 0.30 ± 0.25 and ¾0.68, -0.48 and ¾0.74, respectively. All effects were significant, except for the age of dam (linear). Direct genetic and maternal effects were antagonic.