Evolution of inbreeding: a gaze into five Italian beef cattle breeds history

In the last decades, intensive selection programs have led to sustained increases of inbreeding in dairy cattle, a feature that might have adverse consequences on the viability and phenotypic performance of their offspring. This study aimed to determine the evolution of inbreeding of five Italian beef cattle breeds (Marchigiana, Chianina, Romagnola, Maremmana, and Podolica) during a period of almost 20 years (2002–2019). The estimates of Ho, He, Fhat2, and Fped averaged across years (2002–2019) in the studied breeds fluctuated between 0.340–0.401, 0.348–0.392, –0.121–0.072, and 0.000–0.068, respectively. Moreover, annual rates of increase of the estimated inbreeding coefficients have been very low (Fhat2 = 0.01–0.02%; Fped = 0.003–0.004%). The use of a high number of bulls combined with strategies implemented by the Association of Italian Beef Cattle Breeders ANABIC to minimize inbreeding might explain these results. Despite the fact that diversity and inbreeding have remained quite stable during the last two decades, we have detected a sustained decrease of the population effective size of these five breeds. Such results should be interpreted with caution due to the inherent difficulty of estimating Ne from SNPs data in a reliable manner.

TO IMPROVE THE PRODUCTIVITY OF DAIRY AND BEEF CATTLE BREEDS

В статье представлены селекционно-технологические основы улучшения молочно-мясных пород КРС с использованием факторов внешней среды и их скрещивания с мясными породами племенных быков на промышленной основе, а также повышения продуктивности полученного гибридного потомства.

Capitalizing on the Potential of South African Indigenous Beef Cattle Breeds: A Review

Cattle populations arrived in Southern Africa almost 2000 years ago, brought by farming communities migrating southwards. For centuries, cattle have been an integral component of livestock production to meet the animal protein needs of a growing population and they are also important in many cultural and religious events, as repositories of wealth and signifiers of social status. Selection within these cattle populations led to the development of breeds such as the Nguni, Afrikaner and Drakensberger that are well adapted to the local production environment. Genetic information has been generated for most of these populations, providing new insights into their ancestry and indicating moderate levels of diversity and relatively low inbreeding. Indigenous cattle breeds are present in both the well-developed commercial sector as well as the developing South African livestock sector. These breeds have been included in several research studies, mostly focusing on their production and adaptive potential. Genetic improvement of the local cattle populations and breeds, which are often more resilient to local environmental conditions, has the potential to improve the productivity of the small-scale production developing sector and contribute to the alleviation of poverty.

Genetic diversity and population history of eight Italian beef cattle breeds using measures of autozygosity

In the present study, GeneSeek GGP-LDv4 33k single nucleotide polymorphism chip was used to detect runs of homozygosity (ROH) in eight Italian beef cattle breeds; six breeds with distribution limited to Tuscany (Calvana, Mucca Pisana, Pontremolese) or Sardinia (Sarda, Sardo Bruna and Sardo Modicana) and two cosmopolitan breeds (Charolais and Limousine). ROH detection analyses were used to estimate autozygosity and inbreeding and to identify genomic regions with high frequency of ROH, which might reflect selection signatures. Comparative analysis among breeds revealed differences in length and distribution of ROH and inbreeding levels. The Charolais, Limousine, Sarda, and Sardo Bruna breeds were found to have a high frequency of short ROH (30.000); Calvana and Mucca Pisana presented also runs longer than 16 Mbp. The highest level of average genomic inbreeding was observed in Tuscan breeds, around 0.3, while Sardinian and cosmopolitan breeds showed values around 0.2. The population structure and genetic distances were analyzed through principal component analysis and multidimensional scaling analysis, and resulted in a clear separation among the breeds, with clusters related to productive purposes and sample sizes. The frequency of ROH occurrence revealed eight breed-specific genomic regions where genes of potential selective and conservative interest are located (e.g. MYOG, Chitinases (BTA16), TIMELESS, APOF, Olfactory receptors, CACNG2 (BTA5) and Collagens (BTA2)). In all breeds, we found the largest proportion of homozygous by descent segments to be those that represent inbreeding events that occurred around 32 generations ago; with Tuscan breeds also having a significant proportion of segments relating to more recent inbreeding.