Background: To enhance and extend the knowledge about the global historical and phylogenetic relationships between Merino and Merino-derived breeds, 19 populations were genotyped with the OvineSNP50 BeadChip specifically for this study, while an additional 23 populations from the publicly available genotypes were retrieved. Three complementary statistical tests, Rsb (extended haplotype homozygosity between-populations), XP-EHH (cross-population extended haplotype homozygosity), and runs of homozygosity (ROH) islands were applied to identify genomic variants with potential impact on the adaptability of Merino genetic type in two contrasting climate zones. Results: The results indicate that a large part of the Merino’s genetic relatedness and admixture patterns are explained by their genetic background and/or geographic origin, followed by local admixture. Multi-dimensional scaling, Neighbor-Net, Admixture, and TREEMIX analyses consistently provided evidence of the role of Australian, Rambouillet and German strains in the extensive gene introgression into the other Merino and Merino-derived breeds. The close relationship between Iberian Merinos and other South-western European breeds is consistent with the Iberian origin of the Merino genetic type, with traces from previous contributions of other Mediterranean stocks. Using Rsb and XP-EHH approaches, signatures of selection were detected spanning four genomic regions located on Ovis aries chromosomes (OAR) 1, 6 and 16, whereas two genomic regions on OAR6, that partially overlapped with the previous ones, were highlighted by ROH islands. Overall, the three approaches identified 106 candidate genes putatively under selection. Among them, genes related to immune response were identified via the gene interaction network. In addition, several candidate genes were found, such as LEKR1 , LCORL , GHR , RBPJ , BMPR1B , PPARGC1A , and PRKAA1 , related to morphological, growth and reproductive traits, adaptive thermogenesis, and hypoxia responses. Conclusions: To the best of our knowledge, this is the first comprehensive dataset that includes most of the Merino and Merino-derived sheep breeds raised in different regions of the world. The results provide an in-depth picture of the genetic makeup of the current Merino and Merino-derived breeds, highlighting the possible selection pressures associated with the combined effect of anthropic and environmental factors. The study underlines the importance of Merino genetic types as invaluable resources of possible adaptive diversity in the context of the occurring climate changes.

The research carried out on meat from 45 ram lambs of the Polish merino breed allowed to determine the effect of meat aging and muscle type on physicochemical characteristics and oxidative stability of lipids. Analysis of physicochemical traits (pH, meat color, expressed juice, cooking loss, shear force, moisture, protein, fat and total collagen content) was performed on fresh and meat aged for 14 d in the longissimus lumborum (LL) and gluteus medius (GM) muscles. The meat aging determined all physicochemical characteristics except protein and fat content. More changes in pH and meat color parameters were defined in the GM muscle compared to the LL muscle. The increase in the tenderness of meat expressed as a reduction (P < 0.05) of shear force values was observed in both muscles aged for 14 d. A lower value (P < 0.05) of the shear force, despite the higher content of collagen, was determined in the GM muscle compared to LL. The investigated muscles differed in the degree of lipid peroxidation expressed as thiobarbituric acid-reactive substances (TBARS) in both fresh and aged meat. The TBARS value was lower (P < 0.05) in the LL muscle than in GM. In the longissimus lumborum muscle, the significantly lower content of polyunsaturated fatty acids (PUFAs) and PUFA n-6 has been recorded. The oxidation stability was not influenced by the meat aging.

‘Organ-on-a-chip’ technology is a promising and rapidly evolving model in biological research. This innovative microfluidic cell culture device was created using a microchip with continuously perfused chambers, populated by living cells arranged to replicate physiological processes at the tissue and organ levels. By consolidating multicellular structures, tissue–tissue interfaces, and physicochemical microenvironments, these microchips can replicate key organ functions. They also enable the high-resolution, real-time imaging and analysis of the biochemical, genetic, and metabolic activities of living cells in the functional tissue and organ contexts. This technology can accelerate research into tissue development, organ physiology and disease etiology, therapeutic approaches, and drug testing. It enables the replication of entire organ functions (e.g., liver-on-a-chip, hypothalamus–pituitary-on-a-chip) or the creation of disease models (e.g., amyotrophic lateral sclerosis-on-a-chip, Parkinson’s disease-on-a-chip) using specialized microchips and combining them into an integrated functional system. This technology allows for a significant reduction in the number of animals used in experiments, high reproducibility of results, and the possibility of simultaneous use of multiple cell types in a single model. However, its application requires specialized equipment, advanced expertise, and currently incurs high costs. Additionally, achieving the level of standardization needed for commercialization remains a challenge at this stage of development.

Wet brewers grain (WBG) is successfully used in animal nutrition, and due to its high fiber content, especially in ruminants. The low cost of this fodder also has an impact on the economic of production. The aim of this study was to determine the effects of adding WBG to lamb fodder on the body weight gain, slaughter value and meat quality. The experiment was conducted on 40 male lambs of Polish Lowland sheep. The lambs were divided into two feeding groups, the control and the experimental (20 heads in each group), and fattened to their slaughter weight of 40 kg (± 2.5 kg). In the experimental group 35 % WBG was added to the feed. Lambs fed with WBG were characterized by higher daily weight gains (P ≤ 0.01) and reached their slaughter body weight significantly faster (P ≤ 0.01). Furthermore, the carcasses of the WBG group showed better hind leg conformation (P ≤ 0.01) and a higher content of prime cuts (P ≤ 0.05). The meat of lambs fed on WBG also had a lighter color and a lower intramuscular fat content. Additionally, the meat of this group was also characterized by higher PUFA (P ≤ 0.01) and C18 : 2 cis9, trans11 fatty acid (P ≤ 0.01) contents. The results obtained indicate that WBS could be successfully used in slaughter lamb production as a source of readily available, cheap fodder, especially when fattening takes place a short distance from a brewery.

An experiment was conducted to determine the chosen bioactive components and physico-chemical characteristics of lamb meat of different animal genotypes and the muscle types. The 22 ram lambs of Polish Merino (PM) and 22 crossbreeds of Polish Merino × Berrichone du Cher (PMB) were fattened to achieve their slaughter weight of 40 kg. After slaughter, the carcasses were kept at 4 ^∘C for 24 h. Then, the samples of longissimus lumborum (LL) and gluteus medius (GM) muscle were collected to analyse the physico-chemical traits; fatty acid profile; and concentrations of taurine, carnosine, L-carnitine. The GM muscle compared to LL had the higher value (P < 0.05) of L^* and a lower value (P < 0.05) of b^* and H^* both in PM and PMB lambs. The value of expressed juice was lower (P < 0.05) in both LL and GM muscles of PM lambs. A higher amount (P < 0.05) of collagen was found in LL muscle compared to GM both in PM and PMB lambs. The GM muscle of PM lambs showed higher (P < 0.05) conjugated linoleic acid (CLA) content, as well as higher total polyunsaturated acids (PUFAs), PUFA n-6, and PUFA n-3 (P < 0.05). The GM muscle was characterized by a higher (P < 0.05) content of taurine, while in the LL muscle there was a higher amount (P < 0.05) of carnosine. A larger amount (P < 0.05) of L-carnitine was found in GM muscle but only within PMB lambs. The obtained results showed a greater impact of the lamb's genotype on the physical characteristics of meat than on its chemical composition and the content of bioactive components. The muscle type had an effect on meat colour; collagen content; fatty acid profile; and amount of taurine, carnosine, and L-carnitine present.

The aim of the study was to compare the quality of beef in three separate types of muscles – musculus longissimus thoracis, musculus infraspinatus, and musculus longissimus lumborum – obtained from the carcasses of bulls of a local breed of Polish Red and of two lines of Limousin maintained by an extensive production system using year-round pasture and bale grazing. Studies of the lumbar longissimus muscle showed that the Limousin breed (LM FR) was characterised by a higher protein content and the lowest intramuscular fat content. The carnosine content showed significant differences between the types of muscles and breeds; however, the anserine content showed minimal differences. The research showed separate characteristics in terms of the meat composition parameters of Limousin and Polish Red bulls. The beef of the Limousin breed had favourable nutritional value, higher protein content, and reduced fat content, potentially contributing to increased tenderness. The beef of local-breed cattle – although, in every respect, not equal to specialised meat breeds – showed features suitable for the production of meat with unique nutritional value, including a favourable essential fatty acid profile, especially with a higher conjugated linoleic acid (CLA) content.