Population Structure and Genetic Diversity of Italian Beef Breeds as a Tool for Planning Conservation and Selection Strategies

Evolution of Population Structure, Reproductive Performance, Inbreeding, and Genetic Diversity in Ecuadorian Charolais Cattle

The objective was to evaluate the evolution of the population structure, reproductive performance, inbreeding, and genetic diversity in Charolais cattle. Official genealogical information from the Ecuadorian Charolais Association was divided into five populations: (a) historical (total), (b) 2008-2012 (natural mating period), (c) 2013-2017 (natural mating + artificial insemination period), (d) 2018-2022 (artificial insemination + embryo transfer period), and (e) the reference (known sires and dams) from which the population structure was evaluated using pedigree completeness and the generation interval (GI). Meanwhile, for genetic diversity (GD), inbreeding (F), average relatedness (AR), and the effective population size (Ne) were estimated. The gene origin probability (number of founders, effective number of founders/ancestors, and number of founder genomes) explaining genetic variability, reproductive efficiency, the number of offspring per sire and dam, and the average ages of parents at the birth of their offspring were determined. The database was analyzed using the ENDOG, POPREP, and CFC software programs. The results indicate that pedigree completeness and the GI decreased over time among populations, although the first generation showed higher values. The sire gametic pathway was greater in all populations. F increased over time, although not markedly. Although Ne variations were observed, the levels remained above the recommended limit value. The GD loss increased progressively over time although the most recent population was not significantly affected. Finally, the female reproductive efficiency increased over time as well. In conclusion, the Charolais cattle GI should be reduced. After 2012, the use of Assisted Reproductive Technologies and breeding schemes raised the GD loss. Finally, the F increased over time although it could be reduced using foreign genetic resources in the current Ecuadorian Charolais population.

Pedigree-based analysis of population structure and genetic diversity in high-milch Vrindavani crossbred cattle of India

The present study aimed to elucidate the population structure and genetic diversity along with the estimation of genealogical parameters in Vrindavani cattle using pedigree data. The study was based on pedigree data on 12,718 animals, spread across multiple generations during a 52-year period (between 1971 and 2023). The pedigree data was used to estimate different population genealogical parameters including the generation interval; pedigree completeness; rate and level of inbreeding; effective population size; and parameters characterizing the probabilities of gene origin. The ENDOG program was used for estimation of different parameters while using population after 2010 as reference cohort. The results revealed the maximum number of generations (MG) to be 13, while the numbers of completed (CG) and equivalent generations (EqG) were 3.23 and 1.95, respectively. The mean generation interval for the population was 6.9 years. The average inbreeding coefficient of animals in the whole and reference population was 1.11 and 3.44%, respectively; with 0.68% rate of inbreeding per generation. The average additive relationship among all the animals and those in the reference population was 1.16 and 5.49%, respectively. The average effective population sizes for the maximum, equivalent, and complete generations were 115.56, 56.42, and 46.02, respectively. The effective population size on the basis of regression and log-regression on birth date was 77.40 and 71.24, respectively. The probabilities of gene origin were estimated by the effective number of founders (fe) and ancestors (fa), which was 115 and 78, respectively. The fe/fa ratio in the reference population was 1.20, indicating that occasional bottlenecks may have occurred in the population. The analysis revealed a loss of 5.3% of total heterozygosity as compared to base population, though significant variability exists in the latest generations. The results revealed that considerable genetic variability exists within the population that may be exploited through appropriate breed improvement programs targeting various economic traits.

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.

The Effect of Weaning and Slaughter Age on the Physicochemical and Sensory Characteristics of Arouquesa Beef-A PDO Portuguese Meat

(1) Background: Autochthonous breeds meat is well accepted due to its sensory characteristics, perceived low environmental impact, and animal welfare. We aimed to evaluate the effect of weaning and slaughter age on the physicochemical and sensory characteristics of Arouquesa, a Portuguese Protected Designation of Origin (PDO) meat and to evaluate the psychological effect of knowing the weaning age on the consumer's hedonic evaluation. (2) Methods: Meat from 26 animals was assigned to 4 groups, with combinations of weaning (W) at 9 or 5 months and slaughter (S) at 9 or 12 months: W9-S9, W9-S12, W5-S9, and W5-S12. The meat was analysed for pH24h, colour (L*a*b*), cooking losses and shear force. A Check All that Apply test was made with 70 consumers; they were also asked to punctuate the hedonic appreciation of anonymous and weaning age-identified meat. (3) Results: W9-S9 were more tender, had lower shear force, and was juicier than W5-S9. When animals were slaughtered at 12 months, there were no differences in the physicochemical and sensory characteristics between the weaning ages. The effect of information about the weaning age influences the consumer's hedonic evaluation, as revealed by the comparison between the anonymous and identified samples. (4) Later weaning resulted in more tender meat when the slaughter was at 9 months and positively impacted consumer perception.

Effects of a Ceiling Fan Ventilation System and THI on Young Limousin Bulls' Social Behaviour

The study investigated the relationship between the temperature humidity index (THI) and the behaviour of 24 young fattening Limousin bulls reared in two farms in Tuscany, Italy. In each farm, six animals were undergone to ceiling fans (switched on at THI values up to 72), and six animals represented the control group. The trial lasted three days for two consecutive weeks in August 2020. Behavioural observations were conducted using scan sampling technique and eating, ruminating, drinking, resting and other social activities were registered every 5 min, from 9.30 am to 4.00 pm. Two different microclimatic conditions were evaluated to assess the effect of the ventilation system: normal (THI < 78) and alert (THI ≥ 78) conditions. Results showed that the ventilation system had significant effects increasing inactivity and lying down compared to control groups and decreasing eating and drinking activities. THI alert condition caused a significant decrease in eating and an increase in lying down behaviours. Ventilation system did not influence the animals’ cleanliness. The ceiling fans’ efficiency in changing the behaviour of young fattening bulls was demonstrated but further studies are needed to assess the ventilation system effects, especially during longer heat stress periods.

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.

Genetic Diversity in the Italian Holstein Dairy Cattle Based on Pedigree and SNP Data Prior and After Genomic Selection

Genetic diversity has become an urgent matter not only in small local breeds but also in more specialized ones. While the use of genomic data in livestock breeding programs increased genetic gain, there is increasing evidence that this benefit may be counterbalanced by the potential loss of genetic variability. Thus, in this study, we aimed to investigate the genetic diversity in the Italian Holstein dairy cattle using pedigree and genomic data from cows born between 2002 and 2020. We estimated variation in inbreeding, effective population size, and generation interval and compared those aspects prior to and after the introduction of genomic selection in the breed. The dataset contained 84,443 single-nucleotide polymorphisms (SNPs), and 74,485 cows were analyzed. Pedigree depth based on complete generation equivalent was equal to 10.67. A run of homozygosity (ROH) analysis was adopted to estimate SNP-based inbreeding (F_ROH). The average pedigree inbreeding was 0.07, while the average F_ROH was more than double, being equal to 0.17. The pattern of the effective population size based on pedigree and SNP data was similar although different in scale, with a constant decrease within the last five generations. The overall inbreeding rate (ΔF) per year was equal to +0.27% and +0.44% for F_ped and F_ROH throughout the studied period, which corresponded to about +1.35% and +2.2% per generation, respectively. A significant increase in the ΔF was found since the introduction of genomic selection in the breed. This study in the Italian Holstein dairy cattle showed the importance of controlling the loss of genetic diversity to ensure the long-term sustainability of this breed, as well as to guarantee future market demands.

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 (~ 15.000); 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 and multidimensional scaling analyses, and resulted in a clear separation among the breeds, with clusters related to productive purposes. The frequency of ROH occurrence revealed eight breed-specific genomic regions where genes of potential selective and conservative interest are located (e.g. MYOG, CHI3L1, CHIT1 (BTA16), TIMELESS, APOF, OR10P1, OR6C4, OR2AP1, OR6C2, OR6C68, CACNG2 (BTA5), COL5A2 and COL3A1 (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.

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

Simple Summary

The conservation and maintenance of genetic diversity is one of the priorities of the Convention of Biological Diversity and is included in the United Nations (UN’s) Sustainable Development Goals. The evaluation of the genetic variability of a breed is fundamental for its future use in a sustainable way, being indispensable to outline a successful conservation or improvement strategy. Preserving genetic diversity in a population is one of the main objectives for a breed conservation program. Nevertheless, the correct management of genetic diversity is also essential for the adaptation of a population to a new environment, production system or genetic improvement. For the purpose of population monitoring, assessing changes in genetic variability and genetic erosion in animal populations, many methodologies based on pedigree analyses of inbreeding and relationships, and on the probability of genetic origin from different herds, founders and ancestors, have been used. This study presents several genetic diversity indicators in a Portuguese native cattle breed, Mertolenga, assessed by pedigree analysis, and demonstrates the usefulness of these indicators and how they can be used in the genetic management of a breed.

Abstract

The Mertolenga beef cattle, currently with 27,000 breeding females in Portugal, is the largest Portuguese native breed, despite some variation in the breeding stock over the last years. The purpose of this study was to estimate parameters related to the population structure and genetic diversity and to investigate the major factors affecting genetic erosion in the breed, based on the pedigree herdbook information collected since the 1950s, including records on 221,567 animals from 425 herds. The mean generation intervals were 6.4 years for sires and 7.1 years for dams, respectively. The rate of inbreeding per year was 0.183% ± 0.020% and the correspondent effective population size was 38.83. In the reference population (35,017 calves born between 2015 and 2019), the average inbreeding and relatedness were 8.82% ± 10% and 2.05% ± 1.26%, respectively. The mean relationship among animals from the same and from different herds was 29.25% ± 9.36% and 1.87% ± 1.53%, respectively. The estimates for the effective number of founders, ancestors, founding herds and herds supplying sires were 87.9, 59.4, 21.4 and 73.5, respectively. Although the situation of the Mertolenga breed is not alarming, these results indicate the need to adopt measures to maintain the genetic variability of the population.

Estimation of Linkage Disequilibrium and Effective Population Size in Three Italian Autochthonous Beef Breeds

The objective was to investigate the pattern of linkage disequilibrium (LD) in three local beef breeds, namely, Calvana (n = 174), Mucca Pisana (n = 270), and Pontremolese (n = 44). As a control group, samples of the Italian Limousin breed (n = 100) were used. All cattle were genotyped with the GeneSeek GGP-LDv4 33k SNP chip containing 30,111 SNPs. The genotype quality control for each breed was conducted separately, and SNPs with call rate < 0.95 and minor allele frequency (MAF) > 1% were used for the analysis. LD extent was estimated in PLINK v1.9 using the squared correlation between pairs of loci (r²) across autosomes. Moreover, r² values were used to calculate historical and contemporary effective population size (N_e) in each breed. Average r² was similar in Calvana and Mucca Pisana (~0.14) and higher in Pontremolese (0.17); Limousin presented the lowest LD extent (0.07). LD up to 0.11-0.15 was persistent in the local breeds up to 0.75 Mbp, while in Limousin, it showed a more rapid decay. Variation of different LD levels across autosomes was observed in all the breeds. The results demonstrated a rapid decrease in N_e across generations for local breeds, and the contemporary population size observed in the local breeds, ranging from 41.7 in Calvana to 17 in Pontremolese, underlined the demographic alarming situation.

Genetic Diversity and Signatures of Selection in a Native Italian Horse Breed Based on SNP Data

Simple Summary

The Bardigiano horse is a native Italian breed bred for living in rural areas, traditionally used in agriculture. The breed counts about 3000 horses, and it is nowadays mainly used for recreational purposes. The relatively small size and the closed status of the breed raise the issue of monitoring genetic diversity. We therefore characterized the breed’s genetic diversity based on molecular data. We showed a critical reduction of genetic variability mainly driven by past bottlenecks. We also highlighted homozygous genomic regions that might be the outcome of directional selection in recent years, in line with the conversion of Bardigiano horses from agricultural to riding purposes.

Abstract

Horses are nowadays mainly used for sport and leisure activities, and several local breeds, traditionally used in agriculture, have been exposed to a dramatic loss in population size and genetic diversity. The loss of genetic diversity negatively impacts individual fitness and reduces the potential long-term survivability of a breed. Recent advances in molecular biology and bioinformatics have allowed researchers to explore biodiversity one step further. This study aimed to evaluate the loss of genetic variability and identify genomic regions under selection pressure in the Bardigiano breed based on GGP Equine70k SNP data. The effective population size based on Linkage Disequilibrium (N_e) was equal to 39 horses, and it showed a decline over time. The average inbreeding based on runs of homozygosity (ROH) was equal to 0.17 (SD = 0.03). The majority of the ROH were relatively short (91% were ≤2 Mbp long), highlighting the occurrence of older inbreeding, rather than a more recent occurrence. A total of eight ROH islands, shared among more than 70% of the Bardigiano horses, were found. Four of them mapped to known quantitative trait loci related to morphological traits (e.g., body size and coat color) and disease susceptibility. This study provided the first genome-wide scan of genetic diversity and selection signatures in an Italian native horse breed.

Mitochondrial DNA Survey Reveals the Lack of Accuracy in Maremmano Horse Studbook Records

* Correspondence: andrea [...].

Genetic Variability and Management in Nero di Parma Swine Breed to Preserve Local Diversity

Simple Summary

The Nero di Parma is an Italian pig breed with a peculiar breed history. It originates from a native breed called “Nera Parmigiana”, which, in the beginning of the 20th century, was crossed with highly productive breeds, causing the extinction of the original type in the 1970s. During the 1990s a growing interest for organic products and outdoor farming brought the attention back to the local type and a breed recovery project started to reestablish the original breed. The aim of the study was to investigate the genetic diversity of the Nero di Parma breed to provide further insights for breed conservation and to propose breeding strategies.

Abstract

Nero di Parma is an endangered swine breed reared in the North of Italy which nowadays counts 1603 alive pigs. The aims of this study were (i) to explore the genetic diversity of the breed at pedigree level to determine the actual genetic structure, (ii) to evaluate the effectiveness of the breeding recovery project and (iii) to potentially propose breeding strategies for the coming generations. The pedigree dataset contained 14,485 animals and was used to estimate demographic and genetic parameters. The mean equivalent complete generations was equal to 6.47 in the whole population, and it reached a mean value of 7.94 in the live animals, highlighting the quality of the available data. Average inbreeding was 0.28 in the total population, whereas it reached 0.31 in the alive animals and it decreased to 0.27 if only breeding animals were considered. The rate of inbreeding based on the individual increase in inbreeding was equal to 7%. This study showed the effectiveness of the recovery project of the breed. Nevertheless, we found that inbreeding and genetic diversity have reached alarming levels, therefore novel breeding strategies must be applied to ensure long-term survival of this breed.