Arthur da Silva Mariante

Microsatellite based genetic diversity and relationships among ten Creole and commercial cattle breeds raised in Brazil

BackgroundBrazil holds the largest commercial cattle populations worldwide. Local cattle breeds can be classified according to their origin, as exotic or Creole. Exotic breeds imported in the last 100 years, both zebuine and taurine, currently make up the bulk of the intensively managed populations. Locally adapted Creole breeds, originated from cattle introduced by the European conquerors derive from natural selection and events of breed admixture. While historical knowledge exists on the Brazilian Creole breeds very little is known on their genetic composition. The objective of this study was to assess the levels of genetic diversity, phylogenetic relationships and patterns of taurine/zebuine admixture among ten cattle breeds raised in Brazil.ResultsSignificant reduction of heterozygosity exists due both to within-population inbreeding and to breed differentiation in both subspecies (taurine and zebuine). For taurine breeds the number of markers that contribute to breed differentiation is larger than for zebuine. A consistently similar number of alleles was seen in both subspecies for all microsatellites. Four Creole breeds were the most genetically diverse followed by the zebuine breeds, the two specialized taurine breeds and the Creole Caracu. Pairwise genetic differentiation were all significant indicating that all breeds can be considered as genetically independent entities. A STRUCTURE based diagram indicated introgression of indicine genes in the local Creole breeds and suggested that occasional Creole introgression can be detected in some Zebuine animals.ConclusionThis study reports on a comprehensive study of the genetic structure and diversity of cattle breeds in Brazil. A significant amount of genetic variation is maintained in the local cattle populations. The genetic data show that Brazilian Creole breeds constitute an important and diverse reservoir of genetic diversity for bovine breeding and conservation. The genetic data was able to shed light on a number of issues related to the local breeds origin and structure. The Brazilian Creole breeds are all important and viable targets for conservation for they display peculiar traits both phenotypic and of cultural and historical nature that deserve conservation efforts.

Genetic variability of the Brazilian hair sheep breeds

The objectives of this work were to investigate the genetic structure of the Brazilian hair sheep breeds and to determine the origin of the Santa Ines breed. Molecular similarity was determined using Randomly Amplified Polymorphic DNA - Polymerase Chain Reaction markers in 238 individuals from five naturalized sheep breeds: Santa Ines (48 animals), Rabo Largo (48), Somali (48), Morada Nova (48) and Bergamasca (46), collected in Goias, Sergipe, Bahia, and Ceara States as well as in the Federal District. Fifty-four loci were selected from 19 primers, after a pilot test using 140 primers. Qualitative analyses indicate diagnostic markers for all breeds. All breeds were significantly different from each other. Interbreed differences were explained by 14.92% of the total variation. Santa Ines clustered with Bergamasca (97% bootstrap) and with Rabo Largo, composing the third member of the group (81% bootstrap) while Morada Nova and Somali breeds clustered separately. Each breed should be considered as a separate management and conservation unit, and special care should be taken with Rabo Largo, Morada Nova and Somali breeds, represented by small herds in Brazil.

Características corporais associadas com a adaptação ao calor em bovinos naturalizados brasileiros

The aim of this work was to evaluate physical aspects of heat tolerance in cattle. Sixty-four animals from five naturalized breeds were used, including Curraleiro (15 animals), Mocho Nacional (7), Crioulo Lageano (17), Pantaneira (14) and Junqueira (11), as well as twenty-six animals from two commercial breeds: Nellore (15) and Holstein (11). Measurements on shoulder height, girth, body length, cannon bone circumference, skin and hair thickness were analysed as well as hair density and hair and skin pigmentation. Girth in Curraleiro was significantly smaller than in other breeds, especially Mocho Nacional. Crioulo Lageano and Pantaneira had the thickest hair and Mocho Nacional the thickest skin. Curraleiro and Junqueira were shown to be the most heat tolerant of the naturalized breeds.

Fatores genéticos e ambientais que influenciam algumas características de reprodução e produção de leite em cabras no Distrito Federal

This study was carried out in the Federal District of Brazil on two goat farms, using data collected on 772 parturitions. The objective was to evaluate genetic and environmental factors, which influenced the reproduction and milk production of Saanen, Parda Alpine, Toggenburg goats and their crosses, between 1995 and 1997. The data were analysed using SAS (Statistical Analysis System, GLM procedures) and the heritabilities were estimated using MTDFREML with an Individual Animal Model. The studied traits were: age at first kidding (IPP), kidding interval (IP), gestation period (PG), total milk production (PLT) and lactation length (DL). The statistical model included fixed effects [farm, breed, month and year of kidding, type of parturition, sex of the kid (male, female)] and the covariate, dam weight at matting time. The Saanen breed had the lowest IPP and the highest PLT, while the Toggenburg breed had the highest IP. The heritabilities were low and dependent on the breed. The factors as farm, breed, month of kidding and sex of the kid affected the IP. The breed and the type of parturition affected the IPP. The breed only influenced the PLT. The results of this work evidenced that there is a high opportunity to improve the goat performances in Federal District, needing more rigor in herd control and management to reduce the IPP and IP and to increase the production levels.

Genetic diversity and population structure of Brazilian native bovine breeds

Estrategias para conservacao e melhoramento animal devem ser baseadas na associacao de caracteristicas fenotipicas e geneticas. O objetivo deste trabalho foi caracterizar cinco racas nativas brasileiras (Caracu, Crioulo Lageano, Curraleiro, Mocho Nacional e Pantaneiro) e duas comerciais (Holandes e Nelore) pela tecnica de RAPD para estimar a distância genetica e a variabilidade genetica entre e dentro das racas. As relacoes geneticas foram investigadas utilizando-se 22 primers, que geraram 122 bandas polimorficas. A analise de variância molecular revelou que a maior parte da variabilidade genetica total ocorreu em virtude das diferencas de individuos dentro das populacoes. Na comparacao da variabilidade genetica entre os pares de racas, observou-se que todos os valores obtidos foram estatisticamente significativos. A menor divergencia genetica foi observada entre Crioulo Lageano e Curraleiro. A raca Mocho Nacional, apesar de historicamente ser considerada de origem Bos taurus aquitanicus,mesma origem da raca Caracu, agrupou-se com as demais racas nativas consideradas de origem Bos taurus ibericus. Demodo geral, as racas estudadas se agruparam em clustersdistintos, com excecao da Mocho Nacional. A tecnica de RAPD foi capaz de distinguir geneticamente as racas estudadas; Caracu, Crioulo Lageano, Curraleiro e Pantaneiro podem ser consideradas entidades geneticas distintas, comprovando assim, a unicidade de suas populacoes; a Mocho Nacional nao conseguiu se restabelecer, apos seu declinio na decada de 50, perdendo, sua identidade genetica.

Caracterização genética da raça bovina Crioulo Lageano por marcadores moleculares RAPD

The objective of this study was to characterize genetically the Crioulo Lageano cattle breed, using RAPD markers and compare it to the Holstein and Nelore breeds. Forty three primers were selected, and they generated 77 polymorphic bands. Seven groups were studied: 5 subgroups of Crioulo Lageano (I to V) and one each Holstein (VI) and Nellore (VII). Using all groups, the greater part of the genetic variance (65.05%) was due to differences within groups and the rest due to differences between groups. Using five Crioulo Lageano groups (I to V) the results showed 25.28% variation between groups and 74.72% within groups. Genetic diversity has been maintained throughout the generations in this conservation nucleus. The Holstein breed presented the lowest genetic diversity (0.1204) while the Crioulo Lageano herd presented the highest (0.3154). The observed genetic differences were highest between Nellore and Holstein breeds (0.3747), as expected. In general, the Crioulo Lageano groups formed distinct groups and only a few animals from one group were positioned within another group. The RAPD marker technique is adequate to estimate genetic distances between breeds and populations, as well as for use in the choice of individuals for breeding within populations, for conservation of genetic resources.

Avaliação dos Fatores que Influem nas Medidas Lineares do Cavalo Pantaneiro

The objective of this work was to evaluate the effects of sex, sub-region, age at registration and year of registration, on 15 linear measures (withers height, back height, croup height, midback height, head length, neck length, back-loins length, croup length, shoulder bone length, body length, head width, chest width, hip width, thorax perimeter and shin bone perimeter) of the Pantaneiro horse. Data from 1214 animals were used, registered in the Brazilian Pantaneiro Horse Association, from 1972 to 1991, and analyzed using GLM, PRINCOMP and CORR procedures of SAS and grouping procedures of the GENES program. The sex, animal age at registration, sub-region and year of registration were significant sources of variation for most of the characteristics studied. The animals of the Corumba region were in general larger than the animals from the other regions. Morphological measures should be taken on the animals from 4 years of age. Correlations between hip height, back height and shoulder height were high and positive, but between other measures were medium to low. Using the grouping method there are several grouping of animals by type which need to be further investigated.

Parâmetros genéticos das características produtivas e reprodutivas de búfalos na Amazônia brasileira

O objetivo deste trabalho foi estimar componentes de variância e parâmetros geneticos, incluindo correlacoes geneticas, fenotipicas e herdabilidade das caracteristicas produtivas e reprodutivas de bufalos na Amazonia brasileira. As estimativas de herdabilidade (h2) das caracteristicas variaram de 0,04 a 0,05 no primeiro intervalo entre partos, de 0,0 a 0,26 no intervalo entre partos, e de 0,0 a 0,25 no periodo de servico, refletindo grande influencia ambiental. Na idade ao primeiro parto, a herdabilidade variou de 0,12 a 0,38. Em relacao ao peso ao nascer, a raca Murrah foi a que apresentou a mais alta h2 (0,62). As correlacoes geneticas variaram de 1,00 a -1,00. Foram negativas as correlacoes geneticas entre idade ao primeiro parto e peso da femea adulta (-0,12 a -1,00 dependendo da raca), assim como as correlacoes entre periodo de servico, peso ao nascer e peso da femea adulta (0,01 a -1,00). O efeito de ambiente permanente (c2) variou de 0,000 a 0,155. Somente no intervalo entre partos para a raca Jafarabadi pode-se considerar que houve c2 significativo (0,458). O efeito materno (m2) no peso ao nascer variou de baixo a medio, nas racas Carabao, Jafarabadi, Mediterrâneo e Murrah (0,11, 0,17, 0,37, 0,04, respectivamente).

Combining US and Brazilian Microsatellite Data for a Meta-Analysis of Sheep (Ovis aries) Breed Diversity: Facilitating the FAO Global Plan of Action for Conserving Animal Genetic Resources

Microsatellites are commonly used to understand genetic diversity among livestock populations. Nevertheless, most studies have involved the processing of samples in one laboratory or with common standards across laboratories. Our objective was to identify an approach to facilitate the merger of microsatellite data for cross-country comparison of genetic resources when samples were not evaluated in a single laboratory. Eleven microsatellites were included in the analysis of 13 US and 9 Brazilian sheep breeds (N = 706). A Bayesian approach was selected and evaluated with and without a shared set of samples analyzed by each country. All markers had a posterior probability of greater than 0.5, which was higher than predicted as reasonable by the software used. Sensitivity analysis indicated no difference between results with or without shared samples. Cluster analysis showed breeds to be partitioned by functional groups of hair, meat, or wool types (K = 7 and 12 of STRUCTURE). Cross-country comparison of hair breeds indicated substantial genetic distances and within breed variability. The selected approach can facilitate the merger and analysis of microsatellite data for cross-country comparison and extend the utility of previously collected molecular markers. In addition, the result of this type of analysis can be used in new and existing conservation programs.

Produção de populações monossexo macho de tilápia-do-nilo da linhagem Chitralada

The effect of high temperature on sex ratio in the Chitralada strain of Nile tilapia ( Oreochromis niloticus) was tested using two experiments. Primarily, the animals were exposed to a high (35oC) or control (27oC) water temperature for a 28-day-period, beginning ten days after hatching. A significant difference in sex ratio was found. The highest proportion of males was in the high temperature group (72.39%), compared with the control group (62.27%). No differences were found for total length or body weight between the groups. In the second experiment, the effect of exposure times (7, 14, 21 and 28 days starting ten days post hatching) at a constant temperature of 35oC was tested. No differences were found in sex ratio between groups. A significant difference was found between treatments for body weight and total length. In both experiments, the survival rate had a direct relationship with the occurrence of cannibalism, which was significantly higher at 35oC. The significant temperature effect on sex ratio found in the first experiment indicates the thermosensitivity of the Chitralada strain.