Meat quality and sensory traits in rabbits fed with two different percentages of bovine colostrum.

The nutritional, antimicrobial, and antioxidant properties of bovine colostrum (BC) have encouraged its use in animal nutrition as a functional food in recent years. Nonetheless, the potential implications of BC supplementation on meat quality remain to be thoroughly assessed. To address this, thirty-nine New Zealand White rabbits (n = 13/group) were fed different dietary regimens until slaughter.: commercial standard diet for the control group (C) and C with 2.5% and 5% w/w of BC for BC-2.5 and BC-5 groups, respectively. Rabbits were slaughtered at 91 days of age and meat quality, and sensory characteristics were evaluated at days 2 (48 h after slaughter), 5, and 10 of refrigerated storage at 4 °C. The addition of colostrum in the diet resulted in a reduction of the total viable count, albeit only at the highest concentration and at the final detection, whereas for Lactobacillus spp. and Pseudomonas spp., there was little or no effect. The colour coordinates showed no differences between the groups, but they varied over time according to diet. Some differences between groups emerged in the definition of sensory attributes but did not affect the overall liking and overall scores of individual descriptors. These results indicate that the use of colostrum in rabbit feeding does not significantly impart meat quality and sensory attributes, but the potential of this valuable by-product for the food industry needs further investigation.

Age and anatomical region-related differences in vascularization of the porcine meniscus using microcomputed tomography imaging.

Meniscal lesions in vascularized regions are known to regenerate while lack of vascular supply leads to poor healing. Here, we developed and validated a novel methodology for three-dimensional structural analysis of meniscal vascular structures with high-resolution microcomputed tomography (µCT). We collected porcine medial menisci from 10 neonatal (not-developed meniscus, n-) and 10 adults (fully developed meniscus, a-). The menisci were cut into anatomical regions (anterior horn (n-AH and a-AH), central body (n-CB and a-CB), and posterior horn (n-PH and a-PH). Specimens were cut in half, fixed, and one specimen underwent critical point drying and µCT imaging, while other specimen underwent immunohistochemistry and vascularity biomarker CD31 staining for validation of µCT. Parameters describing vascular structures were calculated from µCT. The vascular network in neonatal spread throughout meniscus, while in adult was limited to a few vessels in outer region, mostly on femoral side. n-AH, n-CB, and n-PH had 20, 17, and 11 times greater vascular volume fraction than adult, respectively. Moreover, thickness of blood vessels, in three regions, was six times higher in adults than in neonatal. a-PH appeared to have higher vascular fraction, longer and thicker blood vessels than both a-AH and a-CB. Overall, neonatal regions had a higher number of blood vessels, more branching, and higher tortuosity compared to adult regions. For the first time, critical point drying-based µCT imaging allowed detailed three-dimensional visualization and quantitative analysis of vascularized meniscal structures. We showed more vascularity in neonatal menisci, while adult menisci had fewer and thicker vascularity especially limited to the femoral surface.

Bovine Colostrum Supplementation in Rabbit Diet Modulates Gene Expression of Cytokines, Gut-Vascular Barrier, and Red-Ox-Related Molecules in the Gut Wall.

Rabbits, pivotal in the EU as livestock, pets, and experimental animals, face bacterial infection challenges, prompting a quest for alternatives to curb antibiotic resistance. Bovine colostrum (BC), rich in immunoregulatory compounds, antimicrobial peptides, and growth factors, is explored for disease treatment and prevention. This study assesses BC diet supplementation effects on rabbit intestines, examining gene expression. Thirty female New Zealand White rabbits at weaning (35 days) were divided into three experimental groups: control (commercial feed), 2.5% BC, and 5% BC. The diets were administered until slaughtering (81 days). BC-upregulated genes in the jejunum included IL-8, TGF-ß, and CTNN-ß1 at 5% BC, while PLVAP at 2.5% BC. Antioxidant-related genes (SOD1, GSR) were downregulated in the cecum and colon with 2.5% BC. BC 5% promoted IL-8 in the jejunum, fostering inflammation and immune cell migration. It also induced genes regulating inflammatory responses (TGF-ß) and gastrointestinal permeability (CTNN-ß1). BC 5% enhanced antioxidant activity in the cecum and colon, but no significant impact on anti-myxo antibody production was observed. These results suggest that BC has significant effects on the rabbit gastrointestinal tract's inflammatory and antioxidant response, but further research is required to fully understand its histological and physiological impact.

Intestine Health and Barrier Function in Fattening Rabbits Fed Bovine Colostrum.

The permeability of the immature intestine is higher in newborns than in adults; a damaged gut barrier in young animals increases the susceptibility to digestive and infectious diseases later in life. It is therefore of major importance to avoid impairment of the intestinal barrier, specifically in a delicate phase of development, such as weaning. This study aimed to evaluate the effects of bovine colostrum supplementation on the intestinal barrier, such as the intestinal morphology and proliferation level and tight junctions expression (zonulin) and enteric nervous system (ENS) inflammation status (through the expression of PGP9.5 and GFAP) in fattening rabbits. Rabbits of 35 days of age were randomly divided into three groups (n = 13) based on the dietary administration: commercial feed (control group, CTR) and commercial feed supplemented with 2.5% and 5% bovine colostrum (BC1 and BC2 groups, respectively). Rabbits receiving the BC1 diet showed a tendency to have better duodenum morphology and higher proliferation rates (p < 0.001) than the control group. An evaluation of the zonulin expression showed that it was higher in the BC2 group, suggesting increased permeability, which was partially confirmed by the expression of GFAP. Our results suggest that adding 2.5% BC into the diet could be a good compromise between intestinal morphology and permeability, since rabbits fed the highest inclusion level of BC showed signs of higher intestinal permeability.

In Vitro and In Vivo Biocompatibility Assessment of a Thermosensitive Injectable Chitosan-Based Hydrogel for Musculoskeletal Tissue Engineering.

Musculoskeletal impairments, especially cartilage and meniscus lesions, are some of the major contributors to disabilities. Thus, novel tissue engineering strategies are being developed to overcome these issues. In this study, the aim was to investigate the biocompatibility, in vitro and in vivo, of a thermosensitive, injectable chitosan-based hydrogel loaded with three different primary mesenchymal stromal cells. The cell types were human adipose-derived mesenchymal stromal cells (hASCs), human bone marrow stem cells (hBMSCs), and neonatal porcine infrapatellar fat-derived cells (IFPCs). For the in vitro study, the cells were encapsulated in sol-phase hydrogel, and then, analyzed via live/dead assay at 1, 4, 7, and 14 days to compare their capacity to survive in the hydrogel. To assess biocompatibility in vivo, cellularized scaffolds were subcutaneously implanted in the dorsal pouches of nude mice and analyzed at 4 and 12 weeks. Our data showed that all the different cell types survived (the live cell percentages were between 60 and 80 at all time points in vitro) and proliferated in the hydrogel (from very few at 4 weeks to up to 30% at 12 weeks in vivo); moreover, the cell-laden hydrogels did not trigger an immune response in vivo. Hence, our hydrogel formulation showed a favorable profile in terms of safety and biocompatibility, and it may be applied in tissue engineering strategies for cartilage and meniscus repair.

Postnatal morpho-functional development of a dog's meniscus.

This study evaluates the morpho-functional modifications that characterize meniscal development from neonatal to adult dogs. Even if menisci are recognized as essential structures for the knee joint, poor information is available about their morphogenesis, in particular in dog models. Menisci from a group of Dobermann Pinchers aged 0, 10, 30 days, and 4 years (T0, T10, T30, adult, respectively) were analyzed by SEM, histochemistry (Safranin O and Picro Sirius Red Staining analyzed under a polarized light microscope), immunofluorescences (collagen type I and II), biomechanical (compression) and biochemical analyses (glycosaminoglycans, GAGs, and DNA content). SEM analyses revealed that the T0 meniscus is a bulgy structure that during growth tends to flatten, firstly in the inner zone (T10) and then even in the outer zone (T30), until the achievement of the completely smooth adult final shape. These results were further supported by the histochemistry analyses in which the deposition of GAGs started from T30, and the presence of type I birefringent collagen fibers was observed from T0 to T30, while poorly refringent type III collagen fibers were observed in the adult dogs. Double immunofluorescence analyses also evidenced that the neonatal meniscus contains mainly type I collagen fibers, as well as the T10 meniscus, and demonstrated a more evident regionalization and crimping in the T30 and adult meniscus. Young's elastic modulus of the meniscus in T0 and T10 animals was lower than the T30 animals, and this last group was also lower than adult ones (T0-T10 vs T30 vs adult). Biochemical analysis confirmed that cellularity decreases over time from neonatal to adult (p < 0.01). The same decreasing trend was observed in GAGs deposition. These results may suggest that the postnatal development of canine meniscus may be related to the progressive functional locomotory development: after birth, the meniscus acquires its functionality over time, through movement, load, and growth itself.

How Do Alternative Protein Resources Affect the Intestine Morphology and Microbiota of Atlantic Salmon?

The availability and cost of fishmeal constitute a bottleneck in Atlantic salmon production expansion. Fishmeal is produced from wild fish species and constitutes the major feed ingredient in carnivorous species such as the Atlantic salmon. These natural stocks are at risk of depletion and it is therefore of major importance to find alternative protein sources that meet the nutritional requirements of the Atlantic salmon, without compromising the animals' health. Terrestrial animal by-products have been used in aquaculture feed, but their use is limited by the lack of several essential amino acids and consumer acceptance. In the case of plant ingredients, it is necessary to take into account both their concentration and the extraction methodologies, since, if not dosed correctly, they can cause macro- and microscopic alterations of the structure of the gastrointestinal tract and can also negatively modulate the microbiota composition. These alterations may compromise the digestive functions, growth of the animal, and, ultimately, its well-being. An updated revision of alternative protein sources is provided, with the respective impact on the intestine health in terms of both morphology and microbiota composition. Such information may constitute the premise for the choice and development of Atlantic salmon feeds that guarantee fish health and growth performance without having a significant impact on the surrounding environment, both in terms of depletion of the fish's natural stocks and in terms of pressure on the terrestrial agriculture. The sustainability of aquaculture should be a priority when choosing next-generation ingredients.

Towards a More Realistic In Vitro Meat: The Cross Talk between Adipose and Muscle Cells.

According to statistics and future predictions, meat consumption will increase in the coming years. Considering both the environmental impact of intensive livestock farming and the importance of protecting animal welfare, the necessity of finding alternative strategies to satisfy the growing meat demand is compelling. Biotechnologies are responding to this demand by developing new strategies for producing meat in vitro. The manufacturing of cultured meat has faced criticism concerning, above all, the practical issues of culturing together different cell types typical of meat that are partly responsible for meat's organoleptic characteristics. Indeed, the existence of a cross talk between adipose and muscle cells has critical effects on the outcome of the co-culture, leading to a general inhibition of myogenesis in favor of adipogenic differentiation. This review aims to clarify the main mechanisms and the key molecules involved in this cross talk and provide an overview of the most recent and successful meat culture 3D strategies for overcoming this challenge, focusing on the approaches based on farm-animal-derived cells.

Bovine Colostrum Supplementation Modulates the Intestinal Microbial Community in Rabbits.

BC is a nutraceutical that can modulate intestinal microbiota. This study investigates the effects of BC diet supplementation on luminal and mucosa-associated microbiota in the jejunum, caecum, and colon of rabbits. Twenty-one New Zealand White female rabbits were divided into three experimental groups (n = 7) receiving a commercial feed (CTRL group) and the same diet supplemented with 2.5% and 5% BC (2.5% BC and 5% BC groups, respectively), from 35 (weaning) to 90 days of age (slaughtering). At slaughter, the digestive tract was removed from each animal, then both content and mucosa-associated microbiota of jejunum, caecum, and colon were collected and analysed by Next Generation 16SrRNA Gene Sequencing. Significant differences were found in the microbial composition of the three groups (i.e., beta-diversity: p < 0.01), especially in the caecum and colon of the 2.5% BC group. The relative abundance analysis showed that the families most affected by the BC administration were Clostridia UCG-014, Barnesiellaceae, and Eggerthellaceae. A trend was also found for Lachnospiraceae, Akkermansiaceae, and Bacteroidaceae. A functional prediction has revealed several altered pathways in BC groups, with particular reference to amino acids and lactose metabolism. Firmicutes:Bacteroidetes ratio decreased in caecum luminal samples of the 2.5% BC group. These findings suggest that BC supplementation could positively affect the intestinal microbiota. However, further research is needed to establish the optimal administration dose.

Antioxidant Activity of Different Tissues from Rabbits Fed Dietary Bovine Colostrum Supplementation.

Recent advances in animal nutrition have indicated that bovine colostrum (BC), due to its content of macronutrients, micronutrients and bioactive compounds, is an excellent health supplement. To the best of our knowledge, no studies on the effect of BC on antioxidant status have been performed in rabbits. This study aimed to investigate the effect of two BC concentrations on antioxidant status and gene expression of antioxidant enzymes in some tissues of rabbits. Thirty New Zealand White male rabbits were randomly divided into three experimental diets, containing 0% (CON), 2.5%, and 5% of BC (BC-2.5 and BC-5, respectively). The activity of antioxidant enzymes in plasma (catalase: CAT; glutathione peroxidase: GPx; superoxide dismutase: SOD), and the enzymes' gene expression in the liver and longissimus dorsi muscle, were determined. Results showed no significant differences, neither in plasma nor in tissues. A significant tissue-related effect has been observed regarding the mRNA levels of SOD and GPx, which were higher in the LD (p = 0.022) and liver (p = 0.001), respectively. Further studies, considering modifications of the length and dosage of dietary BC supplementation, are required to update the current state of knowledge in rabbits, as well as to fully understand the potential value of BC for possible application in farming use.

Effect of Bovine Colostrum Dietary Supplementation on Rabbit Meat Quality.

Bovine colostrum (BC) is rich in nutrients, antimicrobial, and antioxidant factors; for these reasons, it has been used as supplement in animal nutrition. However, its possible effects on meat quality have not been studied yet. Thirty-nine New Zealand White rabbits (n = 13/group) were assigned to three groups and fed until slaughter with a commercial standard diet, control group (C), and C supplemented with 2.5% and 5% (w/w) of BC (BC-2.5 and BC-5 groups, respectively). After slaughtering, the effect of dietary supplementation on microbiological and chemical characteristics of the rabbit loins was evaluated at 48 h postmortem (D0) and after 3 (D3) and 8 (D8) days of refrigerated storage. Results showed no difference in the microbiological parameters. In the supplemented groups, TBARS and TVBN values were lower and higher than in the C group, respectively (p < 0.01), and their fatty-acid profile was increased in SFA and decreased in MUFA (p < 0.05). In conclusion, research must continue to examine in depth the possible effects of BC byproduct reuse in animal nutrition on meat quality (e.g., antioxidant power, and physical and sensory characteristics).

Endostatin in 3D Fibrin Hydrogel Scaffolds Promotes Chondrogenic Differentiation in Swine Neonatal Meniscal Cells.

The success of cell-based approaches for the treatment of cartilage or fibro-cartilaginous tissue defects requires an optimal cell source with chondrogenic differentiation ability that maintains its differentiated properties and stability following implantation. For this purpose, the aim of this study was to evaluate the use of endostatin (COL18A1), an anti-angiogenic factor, which is physiologically involved in cell differentiation during meniscus development. Swine neonatal meniscal cells not yet subjected to mechanical stimuli were extracted, cultured in fibrin hydrogel scaffolds, and treated at two different time points (T1 = 9 days and T2 = 21 days) with different concentrations of COL18A1 (10 ng/mL; 100 ng/mL; 200 ng/mL). At the end of the treatments, the scaffolds were examined through biochemical, molecular, and histochemical analyses. The results showed that the higher concentration of COL18A1 promotes a fibro-chondrogenic phenotype and improves cellularity index (DNA content, p < 0.001) and cell efficiency (GAGs/DNA ratio, p < 0.01) after 21 days. These data are supported by the molecular analysis of collagen type I (COL1A1, a marker of fibrous-like tissue, p < 0.001), collagen type II (COL2A1, a marker of cartilaginous-like tissue, p < 0.001) and SRY-Box Transcription Factor 9 (SOX9, an early marker of chondrogenicity, p < 0.001), as well as by histological analysis (Safranin-O staining), laying the foundations for future studies evaluating the involvement of 3D endostatin hydrogel scaffolds in the differentiation of avascular tissues.

Rearing Environment during the Endogenous Feeding Stage of Acipenser baerii.

The aim of this study was to evaluate behaviour, growth, lipid composition, muscle development, and stress status of Siberian sturgeon larvae reared with two types of substrate: Bioballs1 (BB1) and Bioballs2 (BB2), when compared to no substrate (CTR). Sampling points were: hatching (T0), schooling (T1), and yolk-sac full absorption (T2). BB1 larvae were less active and showed no schooling behaviour. At T1 and at T2, BB1 larvae showed a significantly higher weight and total length than larvae reared in either CTR or BB2 (p < 0.05). The lipid content of larvae decreased over time, with little relevant differences between groups. At T2, total muscle area, slow muscle area and fast muscle area were significantly higher in larvae reared in BB1 (p < 0.05). No significant differences in muscle proliferation were found between groups. Real Time PCR was used for evaluating the relative expression of a pool of genes: myod, myog, mrf4, igf2, hsp70, hsp90a, hsp90b, and glut2. The expression of these genes did not seem to be much affected by the type of rearing substrate, except for myog and hsp70 at T1, which was greater in BB2 larvae. Our data suggest that the presence of a substrate during this developmental period seems to have positive effects but further studies would be necessary during the exogenous feeding stage.

Meniscus Matrix Structural and Biomechanical Evaluation: Age-Dependent Properties in a Swine Model.

The analysis of the morphological, structural, biochemical, and mechanical changes of the Extracellular Matrix (ECM), which occur during meniscus development, represents the goal of the present study. Medial fully developed menisci (FD, 9-month-old pigs), partially developed menisci (PD, 1-month-old piglets), and not developed menisci (ND, from stillbirths) were collected. Cellularity and glycosaminoglycans (GAGs) deposition were evaluated by ELISA, while Collagen 1 and aggrecan were investigated by immunohistochemistry and Western blot analyses in order to be compared to the biomechanical properties of traction and compression tensile forces, respectively. Cellularity decreased from ND to FD and GAGs showed the opposite trend (p < 0.01 both). Collagen 1 decreased from ND to FD, as well as the ability to resist to tensile traction forces (p < 0.01), while aggrecan showed the opposite trend, in accordance with the biomechanics: compression test showed that FD meniscus greatly resists to deformation (p < 0.01). This study demonstrated that in swine meniscus, clear morphological and biomechanical changes follow the meniscal maturation and specialization during growth, starting with an immature pattern (ND) to the mature organized meniscus of the FD, and they could be useful to understand the behavior of this structure in the light of its tissue bioengineering.

Could Dietary Supplementation with Different Sources of N-3 Polyunsaturated Fatty Acids Modify the Rabbit Gut Microbiota?

The present study evaluated the effects of feed supplemented with two dietary sources of n-3 polyunsaturated fatty acids (PUFAs; fish oil and extruded flaxseed) on the gut microbiota, caecal fermentations, gastrointestinal histology, and histochemistry in rabbits. Fifteen male New Zealand White rabbits were divided into three groups (n = 5/group) and fed with different diets from weaning (35 days of age) until slaughtering (90 days of age): C group, fed with a commercial diet; F group, supplemented with 10% of extruded flaxseed; and O group, supplemented with 3.5% of fish oil. At slaughter, the content of the stomach, duodenum, jejunum, ileum, caecum, and colon was collected and analyzed by Next Generation 16S rRNA gene sequencing. Tissue samples of the same tracts were evaluated with histological and histochemical analysis. Ammonia and lactic acid in the caecum were also quantified. Twenty-nine operational taxonomic units (OTUs) were significantly different between groups. Groups receiving n-3 PUFAs supplementation showed an increase in Bacteroidetes and Lachnospiraceae in several gastrointestinal tracts, while Bacilli abundance, as well as Firmicutes/Bacteroidetes ratio, were reduced compared to the control group (for all p < 0.05). Caecal ammonia was lower in the F than C group (p < 0.032), whereas no difference was found for lactic acid. Finally, histological evaluations revealed a mild hemorrhagic infiltration and vessels ectasia in the stomach mucosa of both F and O groups, but no effect of nutritional treatment was evidenced by the histochemical analyses. In conclusion, n-3 PUFAs supplementation could modify the rabbit gut microbiota and fermentation. The increase in beneficial bacterial populations may, at least partially, explain the positive effects of n-3 PUFAs diet supplementation on human and animals' health, although the appropriate dosage should be established.

Testing Hypoxia in Pig Meniscal Culture: Biological Role of the Vascular-Related Factors in the Differentiation and Viability of Neonatal Meniscus.

Menisci play an essential role in shock absorption, joint stability, load resistance and its transmission thanks to their conformation. Adult menisci can be divided in three zones based on the vascularization: an avascular inner zone with no blood supply, a fully vascularized outer zone, and an intermediate zone. This organization, in addition to the incomplete knowledge about meniscal biology, composition, and gene expression, makes meniscal regeneration still one of the major challenges both in orthopedics and in tissue engineering. To overcome this issue, we aimed to investigate the role of hypoxia in the differentiation of the three anatomical areas of newborn piglet menisci (anterior horn (A), central body (C), and posterior horn (P)) and its effects on vascular factors. After sample collection, menisci were divided in A, C, P, and they were cultured in vitro under hypoxic (1% O2) and normoxic (21% O2) conditions at four different experimental time points (T0 = day of explant; T7 = day 7; T10 = day 10; T14 = day 14); samples were then evaluated through immune, histological, and molecular analyses, cell morpho-functional characteristics; with particular focus on matrix composition and expression of vascular factors. It was observed that hypoxia retained the initial phenotype of cells and induced extracellular matrix production resembling a mature tissue. Hypoxia also modulated the expression of angiogenic factors, especially in the early phase of the study. Thus, we observed that hypoxia contributes to the fibro-chondrogenic differentiation with the involvement of angiogenic factors, especially in the posterior horn, which corresponds to the predominant weight-bearing portion.

Hypoxia as a Stimulus for the Maturation of Meniscal Cells: Highway to Novel Tissue Engineering Strategies?

The meniscus possesses low self-healing properties. A perfect regenerative technique for this tissue has not yet been developed. This work aims to evaluate the role of hypoxia in meniscal development in vitro. Menisci from neonatal pigs (day 0) were harvested and cultured under two different atmospheric conditions: hypoxia (1% O2) and normoxia (21% O2) for up to 14 days. Samples were analysed at 0, 7 and 14 days by histochemical (Safranin-O staining), immunofluorescence and RT-PCR (in both methods for SOX-9, HIF-1α, collagen I and II), and biochemical (DNA, GAGs, DNA/GAGs ratio) techniques to record any possible differences in the maturation of meniscal cells. Safranin-O staining showed increments in matrix deposition and round-shape "fibro-chondrocytic" cells in hypoxia-cultured menisci compared with controls under normal atmospheric conditions. The same maturation shifting was observed by immunofluorescence and RT-PCR analysis: SOX-9 and collagen II increased from day zero up to 14 days under a hypoxic environment. An increment of DNA/GAGs ratio typical of mature meniscal tissue (characterized by fewer cells and more GAGs) was observed by biochemical analysis. This study shows that hypoxia can be considered as a booster to achieve meniscal cell maturation, and opens new opportunities in the field of meniscus tissue engineering.

Prebiotic Effects of Seaweed Polysaccharides in Pigs.

To ensure environmental sustainability, according to the European Green Deal and to boost the One Health concept, it is essential to improve animals' health and adopt sustainable and natural feed ingredients. Over the past decade, prebiotics have been used as an alternative approach in order to reduce the use of antimicrobials, by positively affecting the gut microbiota and decreasing the onset of several enteric diseases in pig. However, dietary supplementation with seaweed polysaccharides as prebiotics has gained attention in recent years. Seaweeds or marine macroalgae contain several polysaccharides: laminarin, fucoidan, and alginates are found in brown seaweeds, carrageenan in red seaweeds, and ulvan in green seaweeds. The present review focuses on studies evaluating dietary seaweed polysaccharide supplementation in pig used as prebiotics to positively modulate gut health and microbiota composition.

Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study.

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress-relaxation tests comprised of increasing strains followed by stress-relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.