Dose-Dependent Effects of Costus speciosus Extract on Growth Performance, Feed Utilization, and Humoral Immune Response in Male Rabbits

Abstract

Costus speciosus is a medicinal plant containing diverse bioactive constituents with potential biological applications. However, experimental evidence regarding its effects on growth performance and humoral immune responses in rabbits remains limited. This study evaluated the effects of graded doses of Costus speciosus extract on growth performance, feed utilization, and humoral immune response in male rabbits. Methods: Male rabbits were allocated to four experimental groups receiving the control treatment or C. speciosus extract at doses of 100, 300, and 600 mg/kg. We evaluated growth performance parameters, including final body weight, total body weight gain, daily weight gain, dry matter intake, and feed conversion ratio. We assessed the humoral immune response using anti-sheep red blood cell (SRBC) antibody titers before immunization and on days 7 and 14 after immunization. Initial body weights were comparable among groups. Final body weight increased from 3.01 ± 0.05 kg in controls to 3.18 ± 0.04, 3.31 ± 0.05, and 3.32 ± 0.04 kg at 100, 300, and 600 mg/kg, respectively (P < 0.05). Total body weight gain increased from 0.86 ± 0.03 kg in controls to 1.04 ± 0.03, 1.15 ± 0.04, and 1.25 ± 0.04 kg, while daily weight gain increased from 15.4 ± 0.6 to 18.6 ± 0.6, 20.5 ± 0.7, and 22.3 ± 0.7 g/day, respectively (P < 0.05). Feed conversion ratio decreased from 4.11 ± 0.09 in controls to 3.49 ± 0.07, 3.25 ± 0.08, and 3.04 ± 0.06, respectively (P < 0.05). Anti-SRBC antibody titers on day 7 increased from 6.8 ± 0.3 log2 in controls to 7.9 ± 0.3, 8.7 ± 0.3, and 9.4 ± 0.3 log2, while day-14 titers increased from 8.1 ± 0.3 to 9.5 ± 0.4, 10.4 ± 0.3, and 11.2 ± 0.3 log2, respectively (P < 0.05). C. speciosus extract was associated with dose-related improvements in growth performance, feed conversion, and anti-SRBC antibody responses in male rabbits. The findings support further investigation of C. speciosus as a botanical candidate for improving productive performance and humoral immune responses in animal production.