Genetic diversity and patterns of population structure in Creole goats from the Americas.

Biodiversity studies are more efficient when large numbers of breeds belonging to several countries are involved, as they allow for an in-depth analysis of the within- and between-breed components of genetic diversity. A set of 21 microsatellites was used to investigate the genetic composition of 24 Creole goat breeds (910 animals) from 10 countries to estimate levels of genetic variability, infer population structure and understand genetic relationships among populations across the American continent. Three commercial transboundary breeds were included in the analyses to investigate admixture with Creole goats. Overall, the genetic diversity of Creole populations (mean number of alleles = 5.82 ± 1.14, observed heterozygosity = 0.585 ± 0.074) was moderate and slightly lower than what was detected in other studies with breeds from other regions. The Bayesian clustering analysis without prior information on source populations identified 22 breed clusters. Three groups comprised more than one population, namely from Brazil (Azul and Graúna; Moxotó and Repartida) and Argentina (Long and shorthair Chilluda, Pampeana Colorada and Angora-type goat). Substructure was found in Criolla Paraguaya. When prior information on sample origin was considered, 92% of the individuals were assigned to the source population (threshold q ≥ 0.700). Creole breeds are well-differentiated entities (mean coefficient of genetic differentiation = 0.111 ± 0.048, with the exception of isolated island populations). Dilution from admixture with commercial transboundary breeds appears to be negligible. Significant levels of inbreeding were detected (inbreeding coefficient > 0 in most Creole goat populations, P < 0.05). Our results provide a broad perspective on the extant genetic diversity of Creole goats, however further studies are needed to understand whether the observed geographical patterns of population structure may reflect the mode of goat colonization in the Americas.

Carcass characteristics of Neuquén Criollo kids in Patagonia region, Argentina.

Carcass characteristics of 336 kids from the Neuquén Criollo breed were evaluated. Two categories were taken into account: three months and 5 to 7 months kids. Live weight, carcass weights, measurement and indexes of 304 kids were calculated in a study done in a commercial slaughterhouse located in Chos Malal town. Thirty two carcass left sides were dissected into the major components: muscle, bone, fat and remaining tissues. Three months kids were compared with 5 to 7 months kids. The slaughter live weight of the former was 16.3kg and the latter was 22.4kg. Cold carcass weight and dressing percentage differed significantly (p<0.001) between age categories. Three months kids had a higher percentage of bones (26.8 vs. 21.7%; p<0.001) and a lower percentage of fat (10.8 vs. 15%; p<0.01) than those at 5-7 months, but both had similar percentages of muscle (56.4 vs. 57%; p=NS). There were significant differences in the percentages of primal carcass cuts: hind leg (32 vs. 34%; p<0.001), shoulder (22 vs. 20%; p<0.001) and neck, (10 vs. 8%; p<0.01) for three months vs. 5-7 months old kids, respectively.

Dissection of ancestral genetic contributions to Creole goat populations.

Goats have played a key role as source of nourishment for humans in their expansion all over the world in long land and sea trips. This has guaranteed a place for this species in the important and rapid episode of livestock expansion triggered by Columbus' arrival in the Americas in the late 1400s. The aims of this study are to provide a comprehensive perspective on genetic diversity in American goat populations and to assess their origins and evolutionary trajectories. This was achieved by combining data from autosomal neutral genetic markers obtained in more than two thousand samples that encompass a wide range of Iberian, African and Creole goat breeds. In general, even though Creole populations differ clearly from each other, they lack a strong geographical pattern of differentiation, such that populations of different admixed ancestry share relatively close locations throughout the large geographical range included in this study. Important Iberian signatures were detected in most Creole populations studied, and many of them, particularly the Cuban Creole, also revealed an important contribution of African breeds. On the other hand, the Brazilian breeds showed a particular genetic structure and were clearly separated from the other Creole populations, with some influence from Cape Verde goats. These results provide a comprehensive characterisation of the present structure of goat genetic diversity, and a dissection of the Iberian and African influences that gave origin to different Creole caprine breeds, disentangling an important part of their evolutionary history. Creole breeds constitute an important reservoir of genetic diversity that justifies the development of appropriate management systems aimed at improving performance without loss of genomic diversity.