highly significantP < 0.001
2 E, compared with the control group, the bursa of Fabricius indices in the HLP-treated groups exhibited the following dynamic changes: at day 7, the index was elevated in the low-concentration group ( P < 0.01) and peaked in the medium- and high-concentration groups ( P < 0.001); at day 14, the low-concentration group showed a marked increase ( P < 0.01), while the medium- and high-concentration groups had a highly significant increase ( P < 0.001); and at day 21, the high-concentration HLP group still had an elevated index ( P < 0.05).