Genetic Diversity in the Portuguese Mertolenga Cattle Breed Assessed by Pedigree Analysis

The Portuguese mertolenga cattle breed: a review

This review summarizes the state of the art regarding the phylogenetic origins, recent history and present-day main traits and uses of the Mertolenga cattle breed from Southern Portugal, particularly those related to production performances and product quality. Named after the historical city of Mértola, in southern Portugal, the Mertolenga is one of the fifteen autochthonous bovine breeds of Portugal. It is a cattle breed thoroughly adapted to the poor Mediterranean pastures of the southern regions of the Iberian Peninsula. It is used predominantly in an extensive to semi-intensive sylvopastoral production system called montado, where pastures are combined with helm and cork trees. Its productive traits allow for a good adaptation to the intense dry heat and pasture shortage during the summer, and compensatory growth in autumn and spring, when pastures regenerate. They are small to medium sized animals, with well-balanced bodies, roan, red, or, less often, red-spotted coats, and known for their nervous temperament. Although this breed experienced a severe decline in numbers in the 1970s and classified as endangered in the 1990s, the work of a few breeders led to the establishment of larger Mertolenga breed inventories, starting from a limited base. For this reason, the entire breed has today a strong influence from a very few herds and sires. Reproduction is still mostly achieved using natural mating, and the males are often kept with the breeding females all year long. It is a heterogeneous breed both phenotypically and genetically. Recent phylogenetic studies have revealed the Mertolenga as a one of the most genetically diverse breeds in the country and in the Iberian Peninsula and helped classify this breed, once believed to be a variety of the Alentejana breed. These studies also showed genetic relations with other breeds in the Iberian Peninsula. Mertolenga beef currently benefits from several certifications, the most important one being the PDO - Protected Denomination of Origin.

Analysis of Endangered Andalusian Black Cattle (Negra Andaluza) Reveals Genetic Reservoir for Bovine Black Trunk

This comprehensive study on the Andalusian Black cattle breed reveals a substantial population decline, with the average herd size decreasing significantly from 305.54 to 88.28 animals per herd. This decline is primarily attributed to agricultural changes and the introduction of foreign meat-focused breeds. The male-to-female ratio shift is noteworthy, with more cows than bulls, impacting selection intensity for both genders. Inbreeding levels, though relatively low historically (5.94%) and currently (7.23%), raise concerns as 37.08% historically and 48.82% currently of the animals exhibit inbreeding. Positive assortative mating is evident, reflected by the increasing non-random mating coefficient (α). Key ancestors play a crucial role in shaping genetic diversity, with one ancestor significantly influencing the current genetic pool and the top 10 ancestors contributing substantially. Breed maintains a conservation index of 2.75, indicating relatively high genetic diversity. Recent conservation efforts have led to an increase in registered animals. The Cañadas Reales, historical transhumance routes, may have contributed to genetic connections among provinces. Challenges include the historical bottleneck, demographic changes, and potential impacts from reproductive practices. The Andalusian Black breed's conservation necessitates ongoing efforts in genealogical registration, targeted breeding programs, and collaborative initiatives to address the observed demographic shifts and ensure sustainable genetic diversity.

A Genome-Wide Association Study for Resistance to Tropical Theileriosis in Two Bovine Portuguese Autochthonous Breeds

The control of Tropical Theileriosis, a tick-borne disease with a strong impact on cattle breeding, can be facilitated using marker-assisted selection in breeding programs. Genome-wide association studies (GWAS) using high-density arrays are extremely important for the ongoing process of identifying genomic variants associated with resistance to Theileria annulata infection. In this work, single-nucleotide polymorphisms (SNPs) were analyzed in the Portuguese autochthonous cattle breeds Alentejana and Mertolenga. In total, 24 SNPs suggestive of significance (p ≤ 10-4) were identified for Alentejana cattle and 20 SNPs were identified for Mertolenga cattle. The genomic regions around these SNPs were further investigated for annotated genes and quantitative trait loci (QTLs) previously described by other authors. Regarding the Alentejana breed, the MAP3K1, CMTM7, SSFA2, and ATG13 genes are located near suggestive SNPs and appear as candidate genes for resistance to Tropical Theileriosis, considering its action in the immune response and resistance to other diseases. On the other hand, in the Mertolenga breed, the UOX gene is also a candidate gene due to its apparent link to the pathogenesis of the disease. These results may represent a first step toward the possibility of including genetic markers for resistance to Tropical Theileriosis in current breed selection programs.

Evaluation of Chute Exit, Novelty and Human Approach Tests in Mertolenga Beef Cattle

Livestock behavior and welfare are increasingly recognized to be related, not only to the animals' handling, but also with productivity. The present work was carried out at the Mertolenga Breed Testing Center and its objective was to evaluate the behavior of Mertolenga breed young bulls when exiting the chute, the reaction to novelty and human approach tests, as well as to understand if the responses between these tests are related. Twenty-nine Mertolenga-bred young bulls from 16 different farms, aged between 8 and 13 months, entered the study farm from the end of May to the beginning of June 2021. Data was collected on six different days and analyzed with the SAS^® 9.4 software. Older animals showed a tendency to leave the chute more calmly, take longer to touch the novelty ball and to touch the ball less often, with a consequent reduction in the likelihood of playing with it. In the human approach test, animals that came out of the chute more calmly allowed the human to come closer. These behavior tests should be further studied on potential sires, so as to increase docility and manageability of autochthonous beef breeds.

Evaluation of Genetic Diversity in Dog Breeds Using Pedigree and Molecular Analysis: A Review

Domestic dogs are important for many economic and social reasons, and they have become a well-known model species for human disease. According to research, dog breeds exhibit significant levels of inbreeding and genetic diversity loss, decreasing the population’s ability to adapt in certain conditions, and indicating the need of conservation strategies. Before the development of molecular markers, pedigree information was used for genetic diversity management. In recent years, genomic tools are frequently applied for accurate estimation of genetic diversity and improved genetic conservation due to incomplete pedigrees and pedigree errors. The most frequently used molecular markers include PCR-based microsatellite markers (STRs) and DNA sequencing-based single-nucleotide polymorphism markers (SNP). The aim of this review was to highlight genetic diversity studies on dog breeds conducted using pedigree and molecular markers, as well as the importance of genetic diversity conservation in increasing the adaptability and survival of dog breed populations.

Analyses of Genetic Diversity in the Endangered “Berrenda” Spanish Cattle Breeds Using Pedigree Data

Simple Summary

The two “berrenda” cattle breeds are important for the conservation of livestock genetic diversity in Spain. They have a great phenotypic and genotypic uniqueness and both of them are important from the cultural and the tourist perspectives. They also contribute to the conservation of the traditional “Dehesa” ecosystem. Both breeds are considered as endangered ones, but their genealogies have never been used for quantifying the risk status of their populations. The aim of this work was to monitor the structure of the “Berrenda en Negro” and the “Berrenda en Colorado” populations, their inbreeding rate and some other parameters that could be useful to prevent losses in their genetic diversity and to conduct and analyze the effect of the conservation programs developed by ANABE Breeders Association and finally, as a tool to implement some selective measures. We found that both “berrenda” cattle breeds retain a huge genetic variability from their founders’ populations, although they have been affected by a shallow depth in their pedigrees; as a consequence, we suggest increasing exchanges of breeding animals among herds, more specifically in the case of the “Berrenda en Negro” breed.

Abstract

Pedigree analyses of two endangered cattle breeds were performed in order to study the structure and the genetic variability in their populations. Pedigree data were analyzed from 12,057 individuals belonging to the “Berrenda en Negro” cattle breed (BN) and 20,389 individuals belonging to the “Berrenda en Colorado” cattle breed (BC) that were born between 1983 and 2020. BN and BC reference populations (RP) were set up by 2300 and 3988 animals, respectively. The generation interval in BN and BC reference populations was equal to 6.50 and 6.92 years, respectively. The pedigree completeness level was 82.76% in BN and 79.57% in BC. The inbreeding rates were 4.5% in BN and 3.4% in BC, respectively. The relationship among animals when they were born in different herds was 1.8% in BN and 5% in BC; these values increased to 8.5% and 7.7%, respectively when comparing animals that were born in the same herd. The effective number of founding herds was 23.9 in BN and 60.9 in BC. Number of ancestors needed to explain 50% of genes pool in the whole population was 50 and 101, in BN and in BC, respectively. The effective population size based on co-ancestries was 92.28 in BN and 169.92 in BC. The genetic variability has been maintained in both populations over time and the results of this study suggest that measures to promote the conservation of the genetic variability in these two breeds would go through for the exchange of breeding animals among farms and for monitoring the genetic contributions before implementing any selective action.