Genetic diversity and population structure of three native cattle populations in Mozambique

The generation interval and season of birth do not affect age at first calving, birth weight and calving interval of Mozambican Angoni cattle

The Angoni cattle breed's contribution to the country's economy is crucial, as it significantly contributes to animal draught power and meat supply, despite not being primarily used for milk production. Despite its importance, there is a lack of comprehensive research conducted to characterize this breed. This study aimed to investigate the impact of the generation interval (GI) and season of birth (SB) on key reproductive parameters, including age at first calving (AFC), birth weight (BW), and calving interval (CI) in angoni cattle. Data sourced from the Angónia Research Station (ARS) included records for 425 heifers' AFC, 1684 calves' BW, and 1272 cows' CI. The study calculated overall averages and explored the relationships between generation intervals, the season of birth, and the aforementioned reproductive traits. The mean values for AFC, BW, and CI were determined as 1475.40 days, 18.49 kg, and 634.62 days, respectively. The analysis revealed that both generation interval and season of birth exhibited weak relationships, and their influence did not yield significant effects on the reproductive traits under investigation (P > 0.05). The observed variability ranged from 0.37 to 0.46% for AFC, 0.10-0.01% for BW, and 0.11-0.26% for CI. In conclusion, this study determined that neither generation interval nor birth season significantly affected the age at first calving, birth weight, or calving interval in Angoni cattle.

Genetic diversity and positive signatures of selection in indigenous cattle breeds of Iran

Animal domestication, climate changes over time, and artificial selection have played significant roles in shaping the genome structure of various animal species, including cattle. These processes have led to the emergence of several indigenous cattle breeds with distinct genetic characteristics. This study focused on unraveling the genetic diversity and identifying candidate genomic regions in eight indigenous cattle breeds of Iran. The data consisted of ∼777 962 single nucleotide polymorphisms (SNPs) of 89 animals from Iranian indigenous cattle scattered throughout the country. We employed various methods, including integrated haplotype score, FST, and cross-population composite likelihood ratio, to conduct a genome scan for detecting selection signals within and between cattle populations. Average observed heterozygosity across the populations was 0.36, with a range of 0.32-0.40. In addition, negative and low rates of inbreeding (FIS) in the populations were observed. The genome-wide analysis revealed several genomic regions that harbored candidate genes associated with production traits (e.g., MFSD1, TYW5, ADRB2, BLK, and CRTC3), adaptation to local environmental constraints (CACNA2D1, CXCL3, and GRO1), and coat color (DYM). Finally, the study of the reported quantitative trait loci (QTL) regions in the cattle genome demonstrated that the identified regions were associated with QTL related to important traits such as milk composition, body weight, daily gain, feed conversion, and residual feed intake. Overall, this study contributes to a better understanding of the genetic diversity and potential candidate genes underlying important traits in Iranian indigenous cattle breeds, which can inform future breeding and conservation efforts.

Genetic Diversity and Population Structure for Resistance and Susceptibility to Mastitis in Braunvieh Cattle

Mastitis is a disease that causes significant economic losses, since resistance to mastitis is a difficult trait to be improved due to its multifactorial occurrence. Therefore, our objective was to characterize a Mexican Braunvieh cattle population for genetic resistance and susceptibility to mastitis. We used 66 SNP markers for 45 candidate genes in 150 animals. The average heterozygosity was 0.445 ± 0.076, a value higher than those reported for some European breeds. The inbreeding coefficient was slightly negative for resistance to subclinical (−0.058 ± 0.055) and clinical (−0.034 ± 0.076) mastitis, possibly due to low selection for the immunological candidate genes that influence these traits. The genotypic profiles for the candidate loci per K-means group were obtained, as well as the group distribution through the graphics of the principal component analysis. The genotypic profiles showed high genetic diversity among groups. Resistance to clinical mastitis had the lowest presence of the heterozygous genotypes. Although the percentage of highly inbred animals (>50%) is up to 13.3%, there are highly heterozygous groups in terms of the studied traits, a favorable indicator of the presence of genetic diversity. The results of this study constitute evidence of the genetic potential of the Mexican Braunvieh population to improve mastitis-related traits.

Meta-Analysis of Mitochondrial DNA Control Region Diversity to Shed Light on Phylogenetic Relationship and Demographic History of African Sheep (Ovis aries) Breeds

To improve sheep breeding and conservation of genetic resources, the mitochondrial DNA control region (mtDNA CR) of 399 sequences of African indigenous sheep breeds from previously published research articles were meta-analyzed to elucidate their phylogenetic relationship, diversity, and demographic history. A total of 272 haplotypes were found, of which 207 were unique and a high level of mtDNA CR variability was observed. Generally, the number of polymorphic sites, nucleotide and haplotype diversity were high (284, 0.254 ± 0.012 and 0.993 ± 0.002, respectively). The median-joining (MJ) network of haplotypes produced three major haplogroups (A, B and C), with haplogroup B being dominant. A mixture of populations suggests a common matrilineal origin and lack of and/or a weak phylogeographic structure. Mismatch analysis showed recent expansion of North African breeds, whereas East African and continental populations exhibited selection pressures for adaptation. A slight historical genetic difference was also observed between the fat tail and thin tail sheep breeds. However, further investigations are required using more samples and long sequence segments to achieve deeper levels of conclusions on the African sheep phylogenetic relationship. The present meta-analysis results contribute to the general understanding of African native sheep populations for improved management of sheep genetic resources.