Effects of lincomycin, sodium butyrate, and probiotic dietary supplementation on growth performance, nutrient digestibility, blood biochemistry, and hepatic expression of growth- and fat metabolism-related genes in broiler chickens

Context Lincomycin is a natural lincosamide antibiotic that originates from Streptomyces lincolnensis and is usually used against intestinal Gram-positive bacterial infections. Sodium butyrate (SB) is a short-chain fatty acid, whereas probiotics are beneficial live microorganisms, which are used in broiler chicken production, as safe alternative to antibiotics, to improve gut health, enhance nutrient utilization, and boost immunity. Aims This experiment was conducted to explore the effects of lincomycin, SB, and probiotic dietary supplementation on broiler growth, nutrient digestibility, blood biochemistry, and selected growth- and fat metabolism-related genes. Methods In total, 2640 1-day-old male Ross broiler chicks were randomly distributed into four treatment groups with six replicates each. The first group received a corn–soybean basal diet (BD) without supplementation. The second, third, and fourth groups received BD containing 100 g/ton lincomycin, 1000 g/ton SB, or 500 g/ton probiotic respectively. Key results After 35 days of dietary supplementation, lincomycin and SB significantly improved the growth performance compared with the control and probiotics-treated groups. Improved growth performance was coupled with increased mRNA copies of growth hormone receptor (GHR) and insulin like growth factor 1 (IGF1). In addition, SB and probiotics resulted in distinct increases in relative carcass weights (%) compared with the lincomycin-treated and control groups. An increase in the digestibility of crude protein in all supplemented groups compared with the control group was observed, without any changes in the digestibility of crude fibers. Both SB and probiotics increased crude fat digestibility compared with that in the lincomycin-treated and control groups. Interesting reductions in cholesterol and low-density lipoprotein concentrations linked with noticeable increases in expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase and fatty acids synthase genes were found without alterations in liver and kidney function enzymes or serum metabolites. Conclusions On the basis of these findings, SB and probiotics improved growth performance and nutrient digestibility in broilers and could therefore be used as effective alternatives to lincomycin in broiler diets. Implications The findings of this study demonstrate that sodium butyrate and probiotics can serve as effective and safe alternatives to antibiotic growth promoters, such as lincomycin, in broiler production. Dietary supplementation with sodium butyrate and probiotics improved growth performance, nutrient digestibility, carcass yield, and lipid metabolism without adverse effects on liver or kidney function. The observed modulation of growth- and fat metabolism–related gene expression suggests that these additives enhance broiler performance through physiological and metabolic mechanisms rather than antimicrobial action alone. From a practical standpoint, the use of sodium butyrate and probiotics may support sustainable poultry production by reducing reliance on antibiotics, improving feed efficiency, and producing healthier carcass traits. These results contribute to strategies aimed at mitigating antimicrobial resistance while maintaining optimal broiler productivity and economic efficiency.