Maria Norma Ribeiro

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.

Caracterização genética de raças caprinas nativas brasileiras utilizando-se 27 marcadores microssatélites

Objetivou-se com este trabalho verificar a utilizacao de 27 microssatelites para caracterizacao genetica das racas caprinas nativas do Brasil. Foram coletadas amostras de pelos de 332 animais das racas Moxoto (60), Caninde (50), Serrana Azul (55), Marota (68), Repartida (52) e Grauna (47). Selecionaram-se 27 microssatelites, que foram amplificados mediante a tecnica de reacao em cadeia de polimerase (PCR). Os produtos amplificados foram submetidos a eletroforese em gel de poliacrilamida, em um sequenciador automatico ABI 377XL. Todos os microssatelites analisados mostraram-se polimorficos para o estudo de caracterizacao genetica das racas nativas brasileiras. O numero de alelos variou de 3 (MAF209) a 23 (CSSM66). A heterozigosidade media esperada foi de 0,672 e a observada, de 0,582. Todos os microssatelites analisados foram informativos, a excecao do marcador MAF209 (PIC: 0,042). Os microssatelites analisados mostraram-se polimorficos e os resultados obtidos indicaram a capacidade desses marcadores em identificar a variabilidade genetica em racas caprinas nativas brasileiras.

Genetic characterization of the Moxotó goat breed using RAPD markers

The objective of this study was to verify the genetic diversity between and within seven populations of Moxoto goat (n = 264) from the States of Pernambuco, Paraiba and Rio Grande do Norte, using RAPD (Random Amplified Polymorphic DNA). Moxoto, as well as other naturalized breeds, suffers genetic losses due to the indiscriminate miscegenation with breeds raised in the Northeast Region of Brazil. The genetic characterization of these genetic resources is essential to conservation and breeding programs. DNA was extracted from lymphocytes using a non-organic protocol. The 16 primers used were selected from 120 decamer oligonucleotide primers and generated 56 polymorphic bands. The analysis of molecular variance (AMOVA) showed that the greater part of total genetic variability (71.55%) was due to differences between individuals within populations, while 21.21% was among populations. The analysis of variance among the pairs of populations demonstrated that the populations located in Floresta, PE x Angicos, RN presented a smaller value of intrapopulational differentiation (8.9%), indicating low genetic variability among them. Neis genetic distances varied between 0.0546 and 0.1868 in the populations. The dendrogram generated showed that the Caninde breed, used as outgroup, clustered with the populations of Moxoto, indicating a possible common origin of the naturalized goat breeds.

Efeitos genéticos e ambientais que afetam a produção de leite e duração da lactação de cabras mestiças no estado da Paraíba

Records of 689 lactations of 225 Alpine x Gurgueia goats, progenies of 18 buck, controlled from 1988 to 1996, raised at Carnauba Farm, Taperoa-PB, were analyzed with the objective of study environmental effects and estimate genetics parameters for Milk Production (MP) and Length of Lactation (LL). The environmental effects were analyzed by an statistical model that included buck random effects and the fixed effects of contemporary groups, type of kidding and age of dam at kidding and length lactation as covariate. The genetic parameters were estimated using MTDFREML program, under animal model, including fixed effects and covariates through a described model before. The traits were influenced by contemporary groups. The age of dam at kidding influenced only MP trait. The means for MP and LL were 257.72 ± 54.73 kg and 185.54± 46.87 days, respectively, giving a daily mean production of 1.38 kg of milk/day. The heritability and repeatability estimates were, respectively, 0.23 and 0.35 for MP and 0.20 and 0.24 for LL. The genetic correlation estimate between MP and LL was 0.96. Due to the traits heritability are of average magnitude and sex-limited, it is suggested to use the progeny test as method of more effective selection for bucks.

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.

Drift across the Atlantic: genetic differentiation and population structure in Brazilian and Portuguese native goat breeds

Brazilian goat breeds are believed to derive mainly from animals brought by Portuguese settlers since the 16th century. We used microsatellite markers in a sample of 436 animals to study genetic variability and differentiation of the six Portuguese (PT) and six Brazilian (BR) goat breeds currently recognized in the two countries. These breeds were also compared with an outgroup represented by a sample of Alpine (ALP) goats. The effective number of alleles and allelic richness were slightly higher in PT than in BR breeds. The global F(ST) was nearly 0.11 when PT and BR breeds were considered, with a mean pairwise F(ST) of about 0.03 among PT breeds, 0.07 among BR breeds and 0.15 between PT and BR breeds. The dendrogram illustrating relationships between populations and the correspondence analysis indicate the existence of two very distinct clusters, corresponding to the countries of origin of the breeds studied, which are nearly equidistant from the Alpine outgroup. The analysis with structure confirmed the separation between PT and BR breeds but suggests that some BR breeds, especially Graúna and Canindé, may share a common ancestry with PT breeds. The divergence observed between PT and BR breeds may result from founder effects and genetic drift but could also reflect the introduction in Brazil of goats originating from other regions, e.g., West Africa.

Substituição do milho pela casca de mandioca (Manihot esculenta Crantz) em rações completas para caprinos: consumo, digestibilidade de nutrientes e ganho de peso

The objective of this work was to evaluate the effect of the substitution of corn by cassava peel (CP), in complete rations for growing goats, on the nutrients intake, nutrient digestibility, average daily weight gain and the economical analysis of the rations. Twenty four females Saanen were used, with medium initial weight of 24,20± 2,28 kg and medium age of 10 months. The animals received a complete ration with 59% of hay of Coast-cross (Cynodon dactylon L.) (7,08% PB) and the treatments consisted of the substitution of the corn for the cassava peel, in growing levels (T0 = 0%; T33 = 33%; T66 = 66%; T100 = 100%). The experiment was in randomized block design with four treatments and six replicates. The medium daily intake of dry matter (DM), organic matter (OM), crude protein (CP), carbohydrates no fibrous (FNC) and total carbohydrates (TC) presented a decreasing linear effect, while the acid detergent fiber (ADF) intake presented a quadratic effect, with the substitution of the corn for the CP. Already for neutral detergent fiber (NDF) intake there were not significant differences. The digestibility coefficients of DM, OM, CP, NDF, ADF and gross energy (GE) presented a decreasing linear effect. The medium daily weight gain were: 97,70; 83,33; 45,90 and 23,84 g/animal, respectively, for the treatments T0; T33; T66 and T100. The economical analysis of the experiments rations shows that is economically viable to use until the level of 33% of substitution of the corn for CP.

Estimation models of variance components for farrowing interval in swine

Este trabalho teve como objetivo principal avaliar a importância da inclusao dos efeitos genetico materno, comum de leitegada e de ambiente permanente no modelo de estimacao de componentes de variância para a caracteristica intervalo de parto em femeas suinas. Foram utilizados dados que consistiam de 1.013 observacoes de femeas Dalland (C-40), registradas em dois rebanhos. As estimativas dos componentes de variância foram realizadas pelo metodo da maxima verossimilhanca restrita livre de derivadas. Foram testados oito modelos, que continham os efeitos fixos (grupos de contemporâneo e covariaveis) e os efeitos genetico aditivo direto e residual, mas variavam quanto a inclusao dos efeitos aleatorios genetico materno, ambiental comum de leitegada e ambiental permanente. O teste da razao de verossimilhanca (LR) indicou a nao necessidade da inclusao desses efeitos no modelo. No entanto observou-se que o efeito ambiental permanente causou mudanca nas estimativas de herdabilidade, que variaram de 0,00 a 0,03. Conclui-se que os valores de herdabilidade obtidos indicam que esta caracteristica nao apresentaria ganho genetico como resposta a selecao. O efeito ambiental comum de leitegada e o genetico materno nao apresentaram influencia sobre esta caracteristica. Ja o ambiental permanente, mesmo sem ter sido significativo o seu efeito pelo LR, deve ser considerado nos modelos geneticos para essa caracteristica, pois sua presenca causou mudanca nas estimativas da variância genetica aditiva.

Fatores genéticos e de ambiente sobre o intervalo de partos de cabras leiteiras no semi-árido nordestino

The aims of this study were evaluate influence of the environmental and genetic effects on the kidding interval, using 486 records of kidding crossbred dairy goats obtained from 1988 to 1996 in Paraiba State. The environmental effects were analyzed by means of the procedure GLM of the SAS with a model that included as fixed factors the contemporary group and kidding type, and covariates age of goat at kidding and lactation length. Buck, goat inside of the buck and error were included as random effects. MTDFREML program was used in the analysis with an animal model containing the contemporary group and kidding type, the linear and quadratic effects of age of kidding and lactation length as fixed effects. Animal and permanent environmental and error were included as random effects. The least-square means of kidding interval was 275.55 ± 60.96 days. Kidding interval was affected by the contemporary group and lactation length effects. Estimates of heritability and repeatability were low, 0.09 and 0.09, respectively, showing that smaller kidding intervals would be obtained by better management.

Estrutura populacional e variabilidade genética da raça caprina Marota

espanolA raca caprina Marota e parte do patrimonio genetico do Brasil, formada por animais altamente adaptados ao semi-arido nordestino. Este estudo avaliou a estrutura genetica do nucleo de conservacao da raca Marota, mantida pela Embrapa Meio Norte. Foram estimados os parâmetros populacionais dos dados genealogicos de 663 animais nascidos entre os anos de 1995 a 2003. O coeficiente medio de parentesco (AR) e de consanguinidade (F) para a populacao foi de 0,11% e de 0,84%, respectivamente. O intervalo de geracoes (IEG) foi de 5,28 anos e o tamanho efetivo medio (N e ) por geracao foi de 222 animais, sendo que o numero efetivo de animais fundado- res ( f e ) e de ancestrais ( f a ) foi igual (48). Dentre os 214 ancestrais, apenas 22 foram responsaveis por 50% da variabilidade genetica da populacao, o que indica perda de genes de origem. Observa- se baixa contribuicao dos animais fundadores ao longo das geracoes. Os valores do coeficiente de endogamia de Wright indicam subdivisao da populacao em linhagens. Em geral, a consangui- nidade e os valores medios do coeficiente de parentesco sao baixos para o rebanho avaliado EnglishMarota breed goat is part of the Brazilian genetic patrimony, consisting by animals highly adapted to semi-arid region. This study evaluated genetic structure of Marota breed from Embrapa Meio Norte conservation nucleus. Pedigree records of 663 animals, which were born from 1995 to 2003, were used for population parameters estimation. Inbreeding coefficient (F) and average relationship coefficient (AR) of the population were 0.11% and 0.84% respectively. Generation interval (IEG) was 5.28 years and average effective size (N e ) per generation was 222 animals; being the effective number of founder animals ( f e ) and ancestral ( f a ) was the same (48). Among 214 ancestors evaluated, just 22 of them were responsible for 50% of the population genetic variability, which indicate loss of original genes. This study shows low contribution of the founder animals among the generations. Wright inbreeding coefficient indicates population subdivision in lineages. Inbreeding and average relationship coefficient (AR) are low in the evaluated herd.