Diet Supplementation of Silymarin Increased the Antioxidantive Capacity in Cumene Hydroperoxide-Challenged Ducks

Use of Milk Thistle in Farm and Companion Animals: A Review

Milk thistle, Silybum marianum, is a medicinal plant grown for its bioactive compounds with well-documented antioxidant and hepatoprotective properties. Milk thistle has a well-established pharmacological reputation for treatments of human liver disease, but it is also used in animals. This review summarizes the experimental evidence of milk thistle's effects on animals when administered as silymarin extract (feed additive) or a feed ingredient, if administered as seed or expeller/cake with the seed residue still containing the bioactive components. The use as a feed additive or feed ingredient is motivated by the complexity of silymarin registration as a veterinary drug. In farm animals, the drug improves the animals' performance and product quality and oxidative stability, supports liver function during the productive life-cycle, improves gut-health and morphology, and can reduce intestinal pathogens. In dogs and cats, the treatment is focused on acute and chronic liver diseases including the detoxification processes and support of drug treatments including chemotherapy. In equine athletes, milk seed cake showed positive effects and a faster return of cortisol to the resting values before exercise occurred. In aquaculture, it confirms its usefulness in supporting animal health and performance. In certain studies it is not clear what has been administered, and the composition and doses are not always clearly reported. A few studies reported no effects, but none reported problems connected to milk thistle administration. However, the overall picture shows that the use of milk thistle results in improved or restored health parameters or better animal performance.

Hepatic fatty acids profile, oxidative stability and egg quality traits ameliorated by supplementation of alternative lipid sources and milk thistle meal

This study assessed the effects of different levels of milk thistle (Silybum marianum) meal (MTM) on egg quality traits, oxidative stability, blood biochemical parameters and liver health indices in laying hens receiving diets supplemented with lipid from different sources. For this purpose, Leghorn laying hens (Hy-Line W-36) were randomly assigned to 12 experimental treatments with eight replicates of five birds each. Dietary treatments consisted of four dietary fat sources (fish oil, sunflower oil, poultry oil and fat powder, each with different fatty acid profiles) and three levels of MTM (0.0, 15 and 30 g/kg) offered through 10 days of adaptation and 70 days of main recording. Results showed that dietary inclusion of polyunsaturated fatty acids, including fish or sunflower oils, reduced serum cholesterol content but increased blood malondialdehyde (MDA) concentration (p < 0.05). While fish oil improved the yolk colour index and Haugh unit (p < 0.05), it decreased yolk cholesterol concentration (p < 0.01). The highest hepatic glycogen content and tissue integrity as well as the lowest liver lipid percentage and MDA content were observed in birds fed diets supplemented with poultry oil. On the other hand, feeding 30 g/kg of MTM reduced not only hepatic lipid percentage but also aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities (p < 0.01), while it improved eggshell strength and thickness (p < 0.05). Supplementation of fat powder enhanced hepatic C16:0 content, while addition of poultry, sunflower or fish oil increased C18:1, C18:2 or C20:5 concentrations respectively (p < 0.01); nonetheless, feeding the highest level of MTM reduced hepatic ΣSFA but increased Σn-3 fatty acids (p < 0.01). The interaction effects indicated that fish or sunflower oil supplementation increased the MTM level required to reduce not only serum or egg cholesterol concentrations (p < 0.05) but also blood or hepatic MDA content (p < 0.01). It was concluded that fish oil and MTM (30 g/kg) supplements might improve internal egg quality traits and eggshell quality respectively. The hepatic fatty acid profile was also found strongly correlated with dietary fatty acids. Finally, the best hepatic health indices and the highest oxidative stability were achieved when the birds were fed diets supplemented with poultry oil and 30 g/kg of MTM.

Effects of milk thistle meal on performance, ileal bacterial enumeration, jejunal morphology and blood lipid peroxidation in laying hens fed diets with different levels of metabolizable energy

This study was conducted to evaluate the effects of different levels of milk thistle meal on performance, blood biochemical indices, ileal bacterial counts and intestinal histology in laying hens fed diets containing different levels of metabolizable energy. A total number of 200 Leghorn laying hens (Hy-Line W-36) were randomly assigned to eight experimental treatments with five cage replicates of five birds each. Dietary treatments consisted of four levels of milk thistle meal (0%, 15%, 30% and 60%) and two levels of AMEn (11.09 and 12.34 MJ/kg) fed over a period of 80 days. In vitro studies revealed that the total phenolic component of milk thistle meal was 470.64 mg gallic acid equivalent/g of the sample, and its antioxidant activity for inhibiting the 2-2-diphenyl-1-picrichydrazyl free radical and reducing ferric ions was about 21% higher than that of butylated hydroxyltoluene (p < .05). Diets containing high level of AMEn led to improved egg production (p < .05), egg weight (p < .05), egg mass (p < .01) and feed conversion ratio (p < .01). In addition, offering diets containing high energy significantly enhanced (p < .01) serum triglyceride and malondialdehyde (MDA) concentrations as well as jejunal villus height. Dietary supplementation of 3% milk thistle meal resulted in the best feed conversion ratio (p < .05), reduction of ileal Escherichia coli enumeration (p < .01) and an enhancement in the villus height-to-crypt depth ratio (p < .05). Furthermore, feeding incremental levels of this meal led to remarkable decrease in serum cholesterol, triglyceride and MDA (p < .01) concentrations while significant increase in blood high-density lipoprotein content and goblet cell numbers (p < .05). The present findings indicate that milk thistle meal with high antioxidant and antibacterial properties in laying hen diets may improve health indices and productive performance.