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Abstract Background Research into the genetic diversity of honey bee (Apis mellifera L.) populations has become increasingly significant in recent decades, primarily due to population declines attributed to human activities and climate change. As a species of great importance, breeding programs that leverage understanding of genomic diversity could offer solutions to mitigate these challenges. The objective of this study was to examine the genomic diversity and population structure of Carniolan honey bees (Apis mellifera carnica) using the Illumina SNP chip on a large honey bee sample collected from Central and South-Eastern European countries. The study also aims to offer recommendations for future breeding programs. Results Our analysis involved Discriminant Analysis of Principal Components (DAPC), heterozygosity, admixture analysis, fixation indices (FST), Neighbour-Joining tree, gene flow and Isolation-by-distance analysis. DAPC indicated distinct separation between the Carniolan and Italian honey bee (Apis mellifera ligustica) populations, whereas the admixture analysis revealed varying levels of gene flow and genetic admixture within the Carniolan honey bee populations, demonstrating closer relationships between specific geographic regions (confirmed by Isolation-by-distance analysis). Furthermore, the research of heterozygosity, genomic inbreeding, pairwise FST values, and Neighbour-Joining tree provided insights into the patterns of genetic differentiation and similarity among the populations of Carniolan honey bee within its natural habitat. We have observed genetic homogeneity of the Carniolan honey bee population when considered in a broader genetic/geographical context. However, the Carniolan honey bee has sufficient genetic diversity in its geographical home range that needs to be carefully monitored and maintained. Conclusions This study provides important insights into the genetic composition, differentiation, and relationships among Carniolan honey bee populations in Central and South-Eastern European countries. The findings are crucial for conservation efforts, breeding programs, and sustainable beekeeping practices. They emphasise the importance of considering genetic factors and population structure in the breeding and management of honey bees. By understanding these genetic relationships, we can develop strategies to preserve genetic diversity, improve breeding outcomes, and ensure the resilience of honey bee populations in the face of environmental changes and challenges. This knowledge can also inform policy makers and stakeholders on best practices to maintain healthy bee populations, which are vital for ecosystem services and agricultural productivity.

Abstract Background The importance of sheep breeding in the Mediterranean part of the eastern Adriatic has a long tradition since its arrival during the Neolithic migrations. Sheep production system is extensive and generally carried out in traditional systems without intensive systematic breeding programmes for high uniform trait production (carcass, wool and milk yield). Therefore, eight indigenous Croatian sheep breeds from eastern Adriatic treated here as metapopulation (EAS), are generally considered as multipurpose breeds (milk, meat and wool), not specialised for a particular type of production, but known for their robustness and resistance to certain environmental conditions. Our objective was to identify genomic regions and genes that exhibit patterns of positive selection signatures, decipher their biological and productive functionality, and provide a "genomic" characterization of EAS adaptation and determine its production type. Results We identified positive selection signatures in EAS using several methods based on reduced local variation, linkage disequilibrium and site frequency spectrum (eROHi, iHS, nSL and CLR). Our analyses identified numerous genomic regions and genes (e.g., desmosomal cadherin and desmoglein gene families) associated with environmental adaptation and economically important traits. Most candidate genes were related to meat/production and health/immune response traits, while some of the candidate genes discovered were important for domestication and evolutionary processes (e.g., HOXa gene family and FSIP2). These results were also confirmed by GO and QTL enrichment analysis. Conclusions Our results contribute to a better understanding of the unique adaptive genetic architecture of EAS and define its productive type, ultimately providing a new opportunity for future breeding programmes. At the same time, the numerous genes identified will improve our understanding of ruminant (sheep) robustness and resistance in the harsh and specific Mediterranean environment.

A recent comprehensive genomic analysis based on 50K SNP profiles has shown that the regional Balkan sheep populations have considerable genetic overlap but are distinctly different from surrounding breeds. All eight Croatian sheep breeds were represented by a small number of individuals per breed. Here, we genotyped 220 individuals representing the native Croatian sheep breeds (Istrian Sheep, Krk Island Sheep, Cres Island Sheep, Rab Island Sheep, Lika Pramenka, Pag Island Sheep, Dalmatian Pramenka, Dubrovnik Sheep) and mouflon using the Ovine Infinium® HD SNP BeadChip (606,006 SNPs). In addition, we included publicly available Balkan Pramenka and other Mediterranean sheep breeds. Our analyses revealed the complex population structure of Croatian sheep breeds and their origin and geographic barriers (island versus mainland). Migration patterns confirmed the historical establishment of breeds and the pathways of gene flow. Inbreeding coefficients (FROH>2 Mb) between sheep populations ranged from 0.025 to 0.070, with lower inbreeding coefficients observed in Dalmatian Pramenka and Pag Island Sheep and higher inbreeding in Dubrovnik sheep. The estimated effective population size ranged from 61 to 1039 for Krk Island Sheep and Dalmatian Pramenka, respectively. Higher inbreeding levels and lower effective population size indicate the need for improved conservation management to maintain genetic diversity in some breeds. Our results will contribute to breeding and conservation strategies of native Croatian sheep breeds.

Sheep are one of the most important livestock species in Croatia, found mainly in the Mediterranean coastal and mountainous regions along the East Adriatic coast, well adapted to the environment and mostly kept extensively. Our main objective was therefore to map the positive selection of the X-chromosome (18,983 SNPs that passed quality control), since nothing is known about the adaptation genes on this chromosome for any of the breeds from the Balkan cluster. Analyses were performed on a sample of eight native Croatian breeds (101 females and 100 males) representing the East Adriatic metapopulation and on 10 mouflons (five females and males), all sampled in Croatia. Three classical within-population approaches (extreme Runs of Homozygosity islands, integrated Haplotype Score, and number of Segregating Sites by Length) were applied along with our new approach called Haplotype Richness Drop (HRiD), which uses only the information contained in male haplotypes. We have also shown that phylogenetic analyses, such as the Median-joining network, can provide additional information when performed with the selection signals identified by HRiD. Our new approach identifies positive selection signals by searching for genomic regions that exhibit a sudden decline in haplotype richness. In total, we identified 14 positive selection signals, 11 using the classical approach and three using the HRiD approach, all together containing 34 annotated genes. The most reliable selection signal was mapped by all four approaches in the same region, overlapping between 13.17 and 13.60 Mb, and assigned to the CA5B, ZRSR2, AP1S2, and GRPR genes. High repeatability (86%) of results was observed, as 12 identified selection signals were also confirmed in other studies with sheep. HRiD offers an interesting possibility to be used complementary to other approaches or when only males are genotyped, which is often the case in genomic breeding value estimations. These results highlight the importance of the X-chromosome in the adaptive architecture of domestic ruminants, while our novel HRiD approach opens new possibilities for research.

The extraction of amplifiable DNA is a crucial step for genetic analysis of farm animals. The aim of present study was to determine the quality and the quantity of DNA extracted from blood, milk, hair and tissue in cattle. It has been shown that milk and hair samples can be used as a reliable source for obtaining good quality and quantity of DNA ready for the next generation sequencing (NGS). Commercially available kit, with several modifications, was included in the evaluation. Raw milk or milk somatic cell pellet storage under -80 °C or -20 °C has shown to be a reliable procedure for preservation when large number of milk samples were collected at once. The quality (purity) and the quantity of extracted DNA were measured using a nanophotometer. The adequacy of the DNA extract was assessed by estimating average read depth of all captured bases of whole NGS mitogenome sequences. Although DNA extracted from different types of samples was suitable for NGS analysis, hair samples showed the largest variation of DNA quantity, low purity and DNA integrity. Non-invasive sampling methods such as milk and hair collection can be used for dairy cattle while sampling from free-range requires handling, capturing and caution. Milk and hair can be used for obtaining optimal DNA concentrations for NGS analysis.

The objective of this study was to compare the psysico-chemical composition and fatty acid (FFA) profile of traditional dry cured bacon Slavonska slanina, produced from the authentic Black Slavonian Pig (BP) and modern pigs (MP), using traditional homemade principles. The samples of Slavonska slanina produced from BP had a significantly (p < 0.05) higher fat content (78.32%) than the samples produced from MP (46.47%), while the samples produced from MP showed significantly higher (p < 0.05) protein and moisture content. The samples produced from BP also showed lower aw and salt content but higher pH. Determination of fatty acid composition was performed at the end of the production process. The composition of fatty acids with respect to the groups of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids was determined, as well as the ratios n-6/n-3 and PUFA/SFA. The results of fatty acid composition determination of Slavonska slanina produced from BP and MP show that oleic acid (C18: 1n9) is the most dominant fatty acid from the MUFA group (47.02 and 46.25%), the most common SFA acid was palmitic acid (C16: 0) (23.44 and 24.96%), and PUFA linoleic acid (C18: 2n-6c) (10.76 and 9.74%). The genotype had a significant (p < 0.05) effect on the SFA and USFA composition of Slavonska slanina. The ratios PUFA/SFA (0.34–0.28) and n-6/n-3 (31.84–27.34) for samples of Slavonska slanina produced from BP and MP are in concordance with previously published data for different dry cured meat products, and do not comply with the nutritionally recommended values of international health organizations (PUFA/SFA > 0.4 and n-6/n-3 < 4).

The majority of the nearly 400 existing local pig breeds are adapted to specific environments and human needs. The demand for large production quantities and the industrialized pig production have caused a rapid decline of many local pig breeds in recent decades. Black Slavonian pig and Turopolje pig, the latter highly threatened, are the two Croatian local indigenous breeds typically grown in extensive or semi-intensive systems. In order to guide a long-term breeding program to prevent the disappearance of these breeds, we analyzed their genetic diversity, inbreeding level and relationship with other local breeds across the world, as well as modern breeds and several wild populations, using high throughput genomic data obtained using the Illumina Infinium PorcineSNP60 v2 BeadChip. Multidimensional scaling analysis positioned Black Slavonian pigs close to the UK/North American breeds, while the Turopolje pig clustered within the Mediterranean breeds. Turopolje pig showed a very high inbreeding level (FROH>4Mb = 0.400 and FROH>8Mb = 0.332) that considerably exceeded the level of full-sib mating, while Black Slavonian pig showed much lower inbreeding (FROH>4Mb = 0.098 and FROH>8Mb = 0.074), indicating a planned mating strategy. In Croatian local breeds we identified several genome regions showing adaptive selection signals that were not present in commercial breeds. The results obtained in this study reflect the current genetic status and breeding management of the two Croatian indigenous local breeds. Given the small populations of both breeds, a controlled management activity has been implemented in Black Slavonian pigs since their commercial value has been recognized. In contrast, the extremely high inbreeding level observed in Turopolje pig argues for an urgent conservation plan with a long-term, diversity-oriented breeding program.

Over many years castration of male pigs has been a common zootechnical practice performed in order to avoid boar taint or offensive odour of pork found in sexually mature boars. As castration of animals in intensive livestock production has been receiving criticism from international organizations for animal protection and welfare in the last decade, male pigs should be castrated with anesthesia in order to perform the procedure in a less painful and stressful way. Along with boar taint, boar production is accompanied by some other important advantages and disadvantages. Hence, there is a need for a detailed research of this kind of production. The main substances accumulated in the fat of male pigs that cause boar taint are androstenone and skatole. In this scientific review, physiological and zootechnical factors responsible for the development of boar taint and the possibilities of its prevention in the Republic of Croatia will be presented.

As Black Slavonian pig was forgotten and replaced by commercial hybrid pigs, after mid 1950s population declined drastically. Today’s population was founded from 46 sows and 6 boars in 1996 while currently consist of 1064 sows and 163 boars. Aim of this study was to evaluate the genetic structure and genetic variability in autochthonous Black Slavonian pig breed using pedigree. The quality of the pedigree information was evaluated by percentage of known ancestors, which was about 35.16%. Increase in pedigree completeness over the years is evident. Number of inbred Black Slavonian animals was 1695. Average inbreeding was 3.2%, with evident growth observed by year. Effective number of founders was 50.8 for males and 51.1 for females. Effective number of ancestors was, 35.8 for male and 34.8 for female animals, respectively. The proportion of the genes contributed to the reference population of males and females by the most important ancestor was 7.1% and 9.1%. The first 15 ancestors for males and 12 for females explained around 50% variability in the gene pool. Average effective population size via number of parents for the last 10 years of Black Slavonian pig is 189.2. In order to perform proper selection decisions, additional work should be done to increase the quality of pedigree data affecting the reliability of estimated parameters and genetic structure of the population.

Genomic predictors offer an opportunity to overcome the limitations of classical selection against boar taint, and this study evaluated different approaches to obtain such predictors. Samples from 941 pigs were included in a design which was dominated by 421 sib pairs, each pair having an animal with a high and a low skatole concentration (>0.3 ¿ug/g). All samples were measured for skatole and androstenone and genotyped using the lllumina SNP 60K porcine lllumina beadchip. The accuracy of predicting phenotypes was assessed by cross-validation using six different genomic evaluation methods, GBLUP and five Bayesian methods. The range of accuracies obtained by different prediction methods was narrow for androstenone, between 0.29 (Bayes Lasso) and 0.31 (Bayes B), and wide for skatole, between 0.21 (GBLUP) and 0.26 (Bayes SSVS). Relative accuracies corrected for h2, were 0.54-0.56 and 0.750.94 for androstenone and skatole, respectively. The whole genome evaluation methods gave greater accuracy than using QTL alone (one SNP for androstenone and one SNP for skatole). Also, the dominance genetic variation was ignored in national evaluations, so we estimated the dominance genetic variance for androstenone and skatole using SNP information. For androstenone, GBLUP with dominance effects included captured substantial ratio of the dominance genetic variances (13%) in total variation. For skatole, more dominance genetic variance was captured by regional chromosomal heritability approach, particularly on chromosome 9, where the proportion of chromosomal dominance genetic variance in total dominance variance was 96%. The results demonstrate that GBLUP for androstenone is the simplest genomic technology to implement and one of the most accurate methods while more specialised models may be preferable for skatole. Dominance genetic effects included could provide additional source of genetic variation for both traits, therefore, it is worthwhile considering in genomic evaluations.