Public concern over drug resistance has led to governmental regulations banning the use of antibiotics as growth promoters, stimulating interest in developing complementary strategies to maintain animal production, mitigate infections, and enhance muscle characteristics and quality parameters, especially in meat-producing animals. Probiotics are recognized as a potential strategy for improving growth, primarily by promoting intestinal homeostasis. These microorganisms are suggested to modulate gut microbiota, preserving their ecosystem and influencing secondary metabolite production, which can directly or indirectly regulate skeletal muscle metabolism by influencing the expression of key muscle-related genes and the activity of various signaling factors. Several studies have documented the potential benefits of various strains of Bacillus, Enterococcus, and members of the Lactobacillaceae family on muscle characteristics. These studies have shown that probiotics not only modulated myogenic factors but also influenced proteins and enzymes involved in signaling pathways related to carbon metabolism, inflammatory response, mitochondrial dynamics, and antioxidant activity. These effects have been associated with improvements in meat quality parameters and enhanced growth performance. This manuscript seeks to present a brief overview of the impact of probiotic supplementation on muscle health and the quality of meat in broiler chickens.

Enterocin (Ent) 4231, produced by non-rabbit origin strain Enterococcus faecium CCM 4231 was used in combination with sage plant extract in rabbits with the aim to check their antimicrobial activity against microbiota, their effect on immunological, biochemical blood parameters, values of volatile fatty acids in caecum, Eimeria sp. oocysts occurrence and selected parameters of rabbits meat. The animals were divided into three experimental groups (EG1-Ent 4231; EG2- sage; EG3- Ent 4231 with sage) and control group (CG); 24 rabbits in each. Natural substances (NS) were administered for 21 days. The experiment lasted for 42 days. The reduction of microbiota in faeces was observed in EG3 at day 21 by a decrease in the numer of coagulase-positive staphylococci (P<0.01) in comparison with that determined in CG. The bacterial counts in the caecum were lower than those found in faeces. A decrease in the numer of Pseudomonas-like sp. in caeca of the experimental groups was observed at days 21 and 42 (difference in range 0.40-1.87 log cycles) comparing with that determined in CG. At day 21, a significant increase in phagocytic activity (PA, P<0.001) was found in blood of rabbits from EG2 comparing with that observed in CG. At day 42, a significant increase in PA (P<0.001) was determined in all experimental groups in comparison with CG. At day 21, in caecal content of EG3 significantly higher values of lactic acid were observed (P<0.05) in comparison with those found in CG. The reduction of Eimeria sp. oocysts was demonstrated after application of each of NS. Addition of NS did not influence biochemical parameters, meat quality of the animals and does not influence negatively the health status of rabbits.

Stored ewe’s milk lump cheese is a local product that can be a source of autochthonous beneficial microbiota, especially lactic acid bacteria. The aim of this study was to show the antimicrobial potential of Lactiplantibacillus plantarum LP17L/1 isolated from stored ewe’s milk lump cheese. Lpb. plantarum LP17L/1 is a non-hemolytic, non-biofilm-forming strain, susceptible to antibiotics. It contains genes for 10 bacteriocins—plantaricins and exerted active bacteriocin with in vitro anti-staphylococcal and anti-listerial effect. It does not produce damaging enzymes, but it produces β-galactosidase. It also sufficiently survives in Balb/c mice without side effects which indicate its safety. Moreover, a reduction in coliforms in mice jejunum was noted. LP17L/1 is supposed to be a promising additive for Slovak local dairy products.

Probiotic bacteria, including the Enterococcus faecium strain, can improve intestinal mucosal health by several mechanisms, including modulation of the immune response, as well as by improving the protective function of the epithelial barrier. In this study, we tested the effect of Enterococcus faecium AL41 on the acute phase proteins response (blood), gene expression of selected molecules of mucosal immunity (immunoglobulin A, mucin-2, insulin-like growth factor 2) and mucus production (all parts of the small intestine) in broilers. Eighty broiler chicks were divided into two groups: a control and E. faecium AL41 (birds were inoculated with AL41 for 7 days) group. The whole experiment lasted 11 days. Our results revealed that the administration of E. faecium AL41 had no substantial effect on the concentrations of acute phase proteins, but we recorded a significant increase in β- and γ-globulin fractions at the end of the experiment, which may indicate an improvement in the immune status. A significant prolonged stimulatory effect of E. faecium AL41 on the relative expression of molecules (immunoglobulin A, mucin-2) as well as on the dynamic of mucus production in the chicken intestine was observed. In addition, AL41 significantly reduced the total number of enterococci in the cecum and faeces.

The mucus layer of the intestinal tract plays an important role of forming the front line of innate host defense. Recent studies have suggested that the involvement of feeding natural additives on protection/prevention/promotion of mucus production in the intestinal environment is beneficial. The goblet cells continually produce mucins for the retention of the mucus barrier under physiological conditions, but different factors (e. g. microorganisms, microbial toxins, viruses, cytokines, and enzymes) can have profound effects on the integrity of the intestinal epithelium covered by a protective mucus. The intestinal mucus forms enterocytes covered by transmembrane mucins and goblet cells produce by the secreted gel-forming mucins (MUC2). The mucus is organized in a single unattached mucus layer in the small intestine and in two mucus layers (inner, outer) in the colon. The main part of the review evaluates the effects of natural additives/substances supplementation to stimulate increased expression of MUC2 mucin in the intestine of animals.

This study was conducted to investigate the effect of the duration of a flaxseed diet on fattening pigs’ antioxidant defence mechanism in blood and tissues. Eighteen 20-week-old Landrace breed fattening pigs (BW 76.61 ± 2.30 kg) were divided into three groups of six animals. The control group was fed a basal diet. The FS3 group was fed the basal diet supplemented with 10% flaxseed for 3 weeks. The FS6 group received the same basal diet with flaxseed for 6 weeks. The total antioxidant capacity of the blood, measured as the total antioxidant status (TAS), total plasma antioxidant capacity (FRAP), reactive oxygen metabolites (dROMs) and total antioxidant capacity (PAT), was not affected by the flaxseed diet. The superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities were significantly decreased in the FS3 pigs in the heart (p < 0.05). However, in the FS3 group, the glutathione-S-transferase (GST) activity significantly increased compared to the control, but in the FS6 group, the activity was inhibited (p < 0.05). In the muscle, the CAT and GST activity was significantly decreased in the FS3 group (p < 0.05). The thiobarbituric acid reactive substance (TBARS) content was significantly reduced in the brain, muscle and heart in the FS3 group(p < 0.05). In FS6, the TBARS content significantly increased in the heart and brain (p < 0.05). Our results showed that the health effect of a flaxseed diet is significantly conditioned by the length of the flaxseed addition.