Genetic variability in terrestrial mammals is essential for understanding population and evolutionary dynamics, as well as for establishing effective strategies in conservation biology. This comprehensive review aimed to critically analyze invasive and non-invasive techniques used to assess genetic variability in wild terrestrial mammals. Using the PICO (Population, Intervention, Comparison, Outcome) format and following PRISMA guidelines, a comprehensive literature search was conducted in Web of Science, Scopus and Science Direct databases, including articles published in English from January 2015 to April 2025. Thirty-one experimental studies were selected that met specific criteria related to genetic evaluation using invasive (direct blood or tissue collection) and non-invasive (stool, hair and saliva collection) techniques. The results indicate that invasive techniques provide samples of high genetic quality, albeit with important ethical and animal welfare considerations. In contrast, non-invasive techniques offer less disruptive methods, although they present significant challenges in terms of quantity and purity of DNA obtained, potentially affecting the accuracy and confidence of genetic analysis. Detailed analysis of selected studies showed diverse patterns of heterozygosity and inbreeding coefficients between different taxonomic orders (Carnivora, Artiodactyla, Proboscidea, Primates and Rodentia). In addition, the main anthropogenic threats and current conservation strategies implemented in different species were identified. An overall genetic variability ranging from high to moderate was observed, with large species being more vulnerable to genetic reduction due to changes in habitat and human activities. Rather than a static comparison, our synthesis traces a clear methodological arc from small short tandem repeats (STR, or microsatellites) panels towards SNP-based approaches enabled by next-generation sequencing, including reduced representation (ddRAD), amplicon panels (GT-seq), and hybridisation capture tailored to degraded DNA from hair, faeces, and environmental substrates. Over 2015–2025, study designs shifted from presence/absence and coarse diversity estimates to robust inference of relatedness, assignment, effective population size, and gene flow using hundreds–thousands of SNPs and genotype-likelihood frameworks tolerant of allelic dropout and low coverage. Laboratory practice converged on multi-tube replication, synthetic blocking oligos, and capture-based enrichment; bioinformatics adopted probabilistic genotype calling, error-aware filtering, and replication-based consensus. This review provides a solid basis for optimizing genetic sampling methods, allowing for more ethical and efficient studies. Furthermore, it contributes to strengthening conservation strategies by underlining the importance of adapting the sampling method to the biological and ecological particularities of each species studied. Ultimately, these findings can significantly improve genetic conservation decision-making, benefiting the sustainability and resilience of wild land mammal populations.

This scientometric review examines the evolution and scope of invasive (blood and tissue) and non-invasive (faeces, hair, and saliva) sampling in terrestrial mammal population genetics, with particular emphasis on the comparability of observed heterozygosity (Ho), expected heterozygosity (He), and the inbreeding coefficient (Fis) between studies published from 1985 to 2026. Searches in Web of Science and Scopus, filtered under PRISMA/PRISMA-S criteria, yielded a compendium of articles analysed with Bibliometrix and VOSviewer 1.6.20 to quantify temporal production, keyword evolution, collaborative networks, and publication outlets. Searches in Web of Science and Scopus, filtered under PRISMA/PRISMA-S criteria, yielded a broad corpus of 145 articles for general scientometric analyses, of which 85 met the eligibility criteria for the focused analysis of Ho, He, and Fis. The field shows steady growth (annual rate ≈ 6.1%), substantial authorship and international collaboration, and increasing thematic diversity. Adoption of non-invasive sampling has accelerated, broadening spatial and taxonomic coverage, but also increasing exposure to DNA degradation and genotyping error when laboratory quality control is insufficient. Across the literature, reporting of quality control practices (e.g., extraction blanks, negative PCR controls, multi-tube replication, and error-rate estimation) has improved over time but remains inconsistent. Comparisons indicate that differences in Ho, He, and Fis between invasive and non-invasive sampling are generally modest once marker system and species are taken into account. These findings indicate that quality control and transparency in reporting, rather than invasiveness per se, are the main factors determining comparability among studies. The scientometric patterns also reveal a methodological transition from microsatellites to SNP-based and reduced representation approaches, with implications for synthesis across marker types. Overall, this review identifies geographic and taxonomic biases in research effort and highlights the need for standardised reporting of DNA quality indicators, inclusion thresholds, and validation protocols to strengthen genetic monitoring in mammalian conservation.

In recent years, brushes have been increasingly implemented on dairy farms to improve animal welfare, health, and productivity. This study presents a narrative review of scientific studies published over the past decade, selected based on their evaluation of brushing effects on behavioral, physiological, and production parameters in dairy cattle. The evidence consistently indicates that access to brushes increases grooming behavior and is associated with reductions in stress-related indicators, supporting improved animal welfare. In addition, brush use has been linked to improved hygiene and may serve as a non-invasive behavioral indicator of health status, as reduced usage has been associated with conditions such as metritis and lameness. In contrast, evidence regarding productive responses remains more variable. Some studies report increases in milk yield and changes in milk composition; however, these effects are not consistently observed and appear to depend on factors such as animal characteristics, management conditions, brush accessibility, and study design. Overall, brushing appears to be a promising enrichment strategy, but further standardized and long-term research is required to better establish its effects on production and reproductive performance.