The effect of fermented and raw sesame meal, with probiotic supplementation, on performance, carcass characteristics, gastrointestinal microbial population, and meat quality in broiler chickens

Introduction
 
Feed represents the major proportion of production expenses in poultry farming, accounting for nearly 70% of total costs. Among feed ingredients, soybean meal is considered the primary protein source in broiler diets; however, its high price and limited availability have encouraged the search for alternative protein sources. Therefore locally available feed ingredients with suitable nutritional characteristics is important for reducing feed costs and improving the sustainability of poultry production. Sesame (Sesamum indicum L.) is an oilseed crop with high tolerance to drought and adaptability to various environmental conditions. Sesame meal, obtained after oil extraction, is a valuable protein-rich by-product containing more than 44% crude protein and considerable levels of essential amino acids. Nevertheless, the presence of anti-nutritional compounds, particularly phytic acid and tannins, restricts its efficient utilization in poultry diets by reducing nutrient digestibility and mineral availability. Different processing methods have been investigated to improve the nutritional value of plant-derived feed ingredients. Among these approaches, solid-state fermentation has gained attention as an effective biological process for reducing anti-nutritional factors and enhancing nutrient availability. Fermentation by beneficial microorganisms, including lactic acid bacteria, Bacillus species, fungi, and yeasts, can improve the nutritional quality of feed materials through the degradation of undesirable compounds and the production of bioactive metabolites. In parallel, probiotics have been widely studied as functional feed additives in poultry nutrition. Their beneficial effects are associated with modulation of intestinal microbial populations, improvement of gut health, enhancement of immune function, and positive effects on growth performance and meat quality. These effects are mainly related to the production of organic acids, enzymes, vitamins, and antimicrobial substances. Although fermented plant-based ingredients have shown promising results in animal nutrition, information regarding the application of fermented sesame meal in broiler diets remains limited. Moreover, the potential of combining raw sesame meal with probiotic supplementation as an alternative strategy has not been fully investigated. Therefore, this study was conducted to evaluate and compare the effects of raw sesame meal, fermented sesame meal, and raw sesame meal supplemented with probiotics on growth performance, carcass characteristics, gastrointestinal microbial populations, and meat quality in broiler chickens.
Method
Sesame meal was fermented with Lactobacillus plantarum for 25 days. A total of 240 male Ross 308 broiler chickens were used in a completely randomized design with 4 treatments and 4 replicates (15 birds per replicate) for 42 days. Experimental treatments included: 1) control diet  (Corn-Soybean meal), 2) diet containing 50% raw sesame meal replacing soybean meal, 3) diet containing 50% fermented sesame meal replacing soybean meal, and 4) diet containing 50% raw sesame meal with probiotics replacing soybean meal.
Results
Fermentation of raw sesame meal with Lactobacillus plantarum significantly reduced pH, phytic acid, and tannin contents, while increasing lactic acid bacteria counts compared with the raw substrate. The reduction in pH is mainly attributed to organic acid production during carbohydrate fermentation, whereas decreases in anti-nutritional factors may result from enzymatic degradation during microbial activity. Replacing soybean meal with 50% raw sesame meal negatively affected growth performance, whereas fermented sesame meal and probiotic-supplemented diets improved body weight gain and feed conversion ratio, with values comparable to the control group. These improvements are associated with enhanced nutrient availability, reduced anti-nutritional factors, and improved intestinal microbial balance. Carcass traits were adversely affected by high inclusion of raw sesame meal, leading to reduced carcass, breast, and thigh yields. In contrast, fermented and probiotic treatments reduced abdominal fat deposition. Increased liver weight in fermented treatments may be linked to enhanced bile acid turnover and hepatic metabolic activity, while other organs were unaffected. Dietary treatments significantly improved gut microbiota by reducing coliform counts and pH and increasing lactic acid bacteria populations in the crop and ileum. These changes indicate a more favorable intestinal environment, likely resulting from organic acid production and competitive exclusion of pathogenic bacteria. Meat quality analysis showed no differences in lipid oxidation (MDA) or pH at 1 day post-slaughter; however, after 30 days of storage, fermented and probiotic treatments significantly reduced MDA and improved pH stability. These effects suggest improved oxidative stability, potentially related to reduced fat deposition and enhanced gut-derived metabolic health. Overall, fermentation and probiotic supplementation mitigated the negative effects of high inclusion levels of raw sesame meal and improved growth performance, carcass characteristics, gut health, and meat quality in broiler chickens.
Conclusions
Overall, the results of the present study demonstrated that microbial fermentation is an effective strategy for reducing phytic acid and tannin contents in sesame meal. Replacing soybean meal with a diet containing 50% fermented sesame meal or 50% raw sesame meal supplemented with probiotics improved broiler performance, as evidenced by higher body weight gain and better feed conversion ratio. In addition, these dietary treatments enhanced carcass characteristics, including increased carcass, breast, and thigh yields, along with a reduction in abdominal fat deposition. Furthermore, fermented and probiotic-supplemented diets positively modulated gut microbiota by increasing lactic acid bacteria populations while reducing coliform counts and pH in both the crop and ileum. A significant reduction in malondialdehyde (MDA) in birds fed raw sesame meal supplemented with probiotics indicates improved oxidative stability of meat during storage. In conclusion, fermented sesame meal and probiotic supplementation can successfully replace up to 50% of soybean meal in broiler diets and may serve as suitable alternative protein sources in poultry nutrition.