Nutritional Use of Greek Medicinal Plants as Diet Mixtures for Weaned Pigs and Their Effects on Production, Health and Meat Quality

Current consumer trends for meat production with reduced antibiotic use constitute huge challenges in animal farming. Using indigenous raw materials such as aromatic or medicinal plants or their extracts could positively affect or retain animals’ health. The present study aimed to evaluate the effects of medicinal plant extracts and essential oils on pig performance parameters, health indices and meat quality. A phytobiotic mixture (PM) consisting of oregano (Origanum vulgare subsp. hirtum) essential oil, rock samphire (Crithmum maritimum L.) essential oil, garlic flour (Allium sativum L.) and false flax flour (Camelina sativa L. Crantz) was used in pig diets, containing in the experimental trials two different proportions of the oregano essential oil (200 mL/t of feed vs. 400 mL/t of feed). Three groups of weaned pigs were fed either the control diet (CONT) or one of the enriched diets (PM-A or PM-B, 2 g/kg). After a 43-day feeding period, at 77 days of age, blood was taken from the jugular vein for biochemical and hematological tests, and eight pigs were humanely slaughtered. A microbiological analysis of intestinal digesta from the ileum and caecum was conducted. Additionally, meat tissue cuts (biceps femoris, external abdominal and triceps brachii) were collected for a chemical analysis, fatty acid lipid profile and oxidative stability testing. The statistical analysis revealed no differences (p > 0.05) in the body weights and growth rates among the groups. An increase (p < 0.05) in total aerobic bacteria was detected in the ileum of group PM-A, while Escherichia coli (E. coli) counts were reduced (p < 0.05) in group PM-B. In the caecum, reductions in Enterobacteriaceae and Lactobacillaceae counts were observed in groups PM-A and PM-B. Concentrations of malondialdehyde (MDA) as an indicator of lipid peroxidation were significantly reduced (p < 0.05) in triceps brachii and biceps femoris for both groups PM-A and PM-B (day 0). A reduction (p < 0.05) in MDA was noticed in triceps brachii and external abdominal meat samples (day 7) for groups PM-A and PM-B. In addition, the fatty acid profile of the meat lipids (ΣPUFA, h/H and PUFA/SFA ratios) was positively modified (p < 0.05) in the ham and belly cuts. The addition of the PM significantly (p < 0.05) affected the redness of the ham and shoulder meat (a* value increased), the yellowness of only the ham (b* value decreased) and the lightness of both belly (L* value increased) and ham samples (L* value decreased). The meat proximate analysis, as well as hematological and biochemical parameters, did not identify any differences (p > 0.05) between the groups. In conclusion, the two investigated mixtures could be used in weaned pigs’ diets, with positive results in intestinal microbial modulation, oxidative stability, fatty acid profile and color characteristics of the pork meat produced.