Effect of synbiotic dietary supplementation on histological and histopathological parameters of Pectoralis major muscle of broiler chickens

Bioactive substances may constitute an alternative to antibiotics. Probiotics are mixtures of microorganisms that enhance the effectiveness and yield of nutrient absorption by competing for the substrate against pathogens that may cause intestinal infections. Prebiotics are organic substances which include complex carbohydrates and have an influence on the growth and activity of desirable intestinal microflora. Synbiotics are a combination of both of them. The aim of this study was to analyze the impact of synbiotics added to commercial feed on Pectoralis major muscle microstructure in broiler chickens. Research material consisted of 240 one-day-old Ross 308 female chicks. Birds were divided into 2 groups, 12 broilers each (replicated 10 times). The control group (C) was fed a commercial diet, and the SYN group was fed the same diet with added synbiotic: 0.8% of prebiotic RFO (raffinose family oligosaccharides) extracted from lupin seeds and 1% of probiotic Lavipan®. Birds were slaughtered at day 42. Immediately after slaughter, samples of the Pectoralis major muscle for histological analysis were taken and frozen in liquid nitrogen. The staining procedures performed were: hematoxylin and eosin staining to evaluate fibre diameter and histopathological changes, oil red staining to determine intramuscular fat content, NADH-TR (tetrazolium reductase) activity to distinguish muscle fibre types and alkaline phosphatase reaction for counting the number of capillaries. The tendency to reduced muscle fibre diameter in chickens supplemented with synbiotics indicates an increase in muscle fibre density, which gives meat a more delicate structure. When assessing the occurrence of histopathological changes, significantly more fibre splitting was observed in the control group. Moreover, the positive effect of feed supplementation with synbiotics on muscle microvascularization could have an important practical meaning, because low physical activity of chickens during rearing may lead to ischemic muscles, increased changes in the structure of muscle fibres, and reduction of meat quality.