ABSTRACT. The aim of the study was to detect polymorphisms in the leptin gene and to determine the association of these polymorphisms with growth and carcass traits in Nellore cattle. The single nucleotide polymorphisms (SNPs) -1457 (AJ571671:g.-1457A>G) and A59V (AF536174.1:g. 321C>T), as well as the microsatellite BM1500 (3.9 kb downstream), were genotyped. The measures of body weight and ultrasound examinations (rib eye area, back, and rump fat thickness) were performed in 3 different periods of animal management. During the first period, the animals were fed with grass and mineralized salt ad libitum. In the second period, they received grass and concentrate, and in the third, only concentrate. After the slaughter of animals, data were collected for classification and typification of carcasses. No significant association was found between the variables assessed and SNP -1457. Conversely, SNP A59V was associated with rump fat thickness and muscle color post-slaughter. BM1500 was associated with rump fat thickness in the first period (pre-slaughter), subcutaneous fat thickness 3003 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 13 (2): 3002-3012 (2014) Leptin gene variations in Nellore cattle in the second, weight of the animals in the third, and length of the carcass after slaughter. These results suggest that SNP A59V and the microsatellite BM1500 might be useful for marker-assisted selection in Nellore cattle.

ABSTRACT. Sheep of the Pantaneiro breed and seven other breeds, raised in the State of Mato Grosso do Sul, Brazil, were genotyped using eight microsatellite loci. The aim of the present study was to determine the genetic variability, phylogenetic relationship, and patterns of gene introgression and miscegenation among the animals surveyed, to obtain information about the genetic structure of locally adapted sheep in Mato Grosso do Sul. A total of 195 animals were used for genetic analysis. The Pantaneiro breed had the largest average number of alleles/locus (9.25), and higher allelic richness (6.95), while the Dorper population had the lowest values for these parameters (4.88 and 3.86, respectively). Analysis of genetic distance values and genetic structure between populations made it possible to characterize these animals with regard to distinct genetic groups. Average expected heterozygosity ranged from 0.72 (Pantaneiro) to 0.55 (Dorper), while average observed heterozygosity ranged from 0.63 (White Dorper) to 0.54 (Dorper). On the basis of the statistical parameters evaluated, it 5459 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (4): 5458-5466 (2013) Genetic diversity in Pantaneiro sheep was possible to demonstrate that when compared to other populations, the Pantaneiro breed represented a reservoir of genetic diversity with rare and useful alleles for genetic improvement, emphasizing the importance of preserving the breed.

Brazil has several breeds of sheep, including animals that developed from breeds brought by settlers soon after their discovery. Over the years, these animals were under the process of natural selection, resulting in breeds that are considered naturalized. The Pantaneiro sheep shows rusticity and ability of adaptation to tropical climate regions and tolerance or resistance to disease and parasites. Molecular tools have marked the discovery of the origin and domestication processes of a wide variety of species, using both nuclear and mitochondrial molecular markers. These tools have aided in the understanding of evolutionary relationships, taxonomies, and demographics of various species and provided support to identify the most important areas for conservation programs, in addition to assisting in the analysis of genetic diversity in domestic, wildlife and endangered species. Researches using these tools show the importance of exploiting the potential of the genetic diversity found in locally adapted livestock. So far, a few studies were performed to observe that Pantaneiro sheep served as maternal basis for the origin of other breeds reared. Moreover, it is possible to suggest an European origin for the sheep populations studied; therefore, more studies using more markers are needed, so that it is possible to prove their origin.