Hu, Jiaying, Hui Chen, and Heng-Wei Cheng. “Effect of Direct-Fed Microbials, Bacillus Subtilis, on Production Performance, Serotonin Concentrations and Behavioral Parameters in a Selected Dominant Strain of White Leghorn Hens”. International Journal of Poultry Science 17, no. 3 (February 15, 2018): 106–115. Accessed September 22, 2025. https://ijpsjournal.org/index.php/ijps/article/view/2394.