Search Results (4)

The Boerboel dog breed (BBD) is indigenous to South Africa (SA) and plays an important role in safeguarding homes and farms. The Department of Agriculture, Land Reform, and Rural Development (DALRRD) classifies the BBD as a protected species, and it is valued for its intelligence, boldness, and strength, as well as for continually ensuring the safety of its owners. The aim of this study was to investigate genetic diversity within the BBD population using pedigree information. The original BBD data, which contained 87,808 records, were obtained from the Integrated Registration and Genetic Information System (INTERGIS). After editing, the pedigree data included 87,755 records of animals born between 1971 and 2019. Pedigree analyses were performed using PEDIG (Fortran 77 software) to determine the completeness, inbreeding coefficients, and genetic diversity as defined by the genetic contributions of the most important ancestors of the current animals. This study identified 91.2% inbred animals in the BBD population, with an average and maximum inbreeding of 7.5% and 50% of inbred animals, respectively. The estimated inbreeding rate per year was 0.20% with an effective population size of 83.1. The most influential ancestors explained 82.63% and 80.92% of the total genetic variation for males and females in the studied populations, respectively. Only 10 important ancestors explained more than 50% of the entire population’s genetic diversity. The numbers of founders ($f$) were 348 and 356, and the effective numbers of founders ($f_e$) were 57.4 and 60.1, respectively, for males and females. The numbers of founders were higher than the effective numbers of founders, implying a loss of genetic diversity due to unequal founder contributions. The BBD population was not critically endangered based on the inbreeding rates and effective population size; however, the population experienced a significant loss of genetic variability, unequal genetic contributions by founders, and a genetic bottleneck. Future breeding strategies could benefit from using equal proportions of parent stock and including new genetically distant breeds. Full article

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. Full article

Smallholder beef cattle farms in South Africa have had low reproductive performance, which has been associated with management practices. Considering current farm management practices, a multi-stage selection study was conducted to assess reproductive performance as defined by pregnancy rate, fetal and calf losses, calving interval and days open to benchmark reproductive performance. Data were collected twice, in autumn (March–May) for pregnancy diagnosis and in spring (September–November) for monitoring of confirmed pregnancies. Overall, 3694 cow records from 40 smallholder herds were collected during 2018 and 2019 breeding seasons from five provinces. The preferred 25th quartile described target performance and GLIMMIX procedure determined associations between management practices and performance. Smallholder farms on average recorded 50% pregnancy rate and 12% fetal and calf losses with 304 and 608 days open and calving interval, respectively. The derived target benchmarks for pregnancy rate, fetal and calf losses, days open and calving intervals in smallholder farms were 54%, 1.4%, 152 and 425 days, respectively. Reproductive performance was associated with no knowledge of body condition scoring before breeding, culling of old and non-productive cows, record keeping and low bull to cow ratio (p < 0.05). The performance benchmarks implied that industry averages may be improved if sustainable management services are provided through extension and advisory services. Full article

This study aimed to derive additional fertility traits from service data and estimate their genetic parameters for their possible inclusion in the South African Holstein cattle breeding programs. Service records (n = 64,464) were collected from 18 South African Holstein herds using on-farm automated milk recording systems. Using a multivariate model, the data were used to estimate heritabilities and correlations among several fertility traits. The pedigree data consisted of information on 18,592 animals born between 1981 and 2013. Heritability estimates observed were low to moderate (0.02 ± 0.00 to 0.24 ± 0.00), indicating that there is some genetic basis for the explored fertility traits to warrant selection. The genetic correlations observed between fertility traits were generally favorable, with some high correlations between age at first service (AFS) and services per conception for heifers (SPCh) (0.73 ± 0.00) and between days from calving to first service (CFS) and services per conception for cows (SPC) (0.90 ± 0.01). Positive genetic correlations indicate that improvement in one trait is coupled with a correlated genetic increase in another trait. The studied fertility traits could be used in addition to AFC and CI to serve as a basis for the selection of reproduction in dairy cattle to minimize selection bias. Full article