Impact of Milk Thistle (Silybum marianum [L.] Gaertn.) Seeds in Broiler Chicken Diets on Rearing Results, Carcass Composition, and Meat Quality

SIMPLE SUMMARY: This study shows how introducing milk thistle seeds into broiler chicken feed rations affects rearing results (weight gain, intake and conversion of feed), carcass composition and meat quality (pH, color, water holding capacity), the chemical composition (basic components, fatty acids) and organoleptic properties (flavor, tenderness, palatability and juiciness) of meat. Based on the results the use of milk thistle seeds in broiler chicken starter/grower diets can be recommended in the amount of 0/2% or 2/3%, respectively. However, the introduction of Silybum marianum in starter and grower rations (over the whole rearing period) made it possible to obtain the highest body weight at the lowest feed conversion per body weight gain unit, without influencing muscularity and fattening grade, at the same time improving the meat’s value for health. ABSTRACT: The studies aimed to evaluate the impact of milk thistle seeds in broiler chicken feed rations on rearing results, carcass composition and meat quality. The experiment involved 120 broiler chickens randomly allocated to three equinumerous groups (C, MT02, MT23). Each group was divided into five subgroups of eight chickens each. Over the first 21 days of life the birds were fed starter rations, and over the following 21 days received grower rations. Chicken starter/grower diets in groups MT02 and MT23 were supplemented with ground seeds of milk thistle in the amount of 0/2% (MT02) and 2/3% (MT23). It was demonstrated that Silybum marianum added to feed rations over the whole rearing period (group MT23) increased above 3% the birds’ body weight on rearing day 42. (p < 0.05) and decreased about 7% the feed conversion ratio (p < 0.05) in comparison to group C. No effect of feeding on the carcass composition was observed, including on muscularity and fattening grade, although diets containing milk thistle reduced (by 15% and 19% in group MT02 and MT23, respectively) the content of crude fat in chicken leg muscles (p < 0.05). The highest (p < 0.05) content of polyunsaturated fatty acids (PUFA) was determined in the breast (38.06%) and leg (37.63%) muscles of chicken receiving feed rations containing Silybum marianum throughout the rearing period. No effect of nutrition on the evaluated physical properties of muscles was observed, except on the decrease in lightness color (L*) and increase in values a* and C as well as a decrease of water holding capacity of the breast muscles. It was found that Silybum marianum in chicken diets had a positive effect on the evaluated meat flavor characteristics of the muscles. To sum up, based on the study results, including ground seeds of milk thistle in broiler chickens nutrition can be recommended in the amount of 2/3% in starter/grower diets, respectively.