Dietary Crataegus sinaica leaves enhance growth performance, antioxidant status, intestinal integrity, and regulate inflammation-related genes in Nile tilapia under melamine exposure

IntroductionDietary exposure to melamine (MELA) adversely affects growth performance and intestinal health in Nile tilapia. This study evaluated the protective effects of Crataegus sinaica leaf extract (CSL) against MELA-induced toxicity.MethodsIn this study, a total of 240 fish (26.39 ± 0.22) were randomly assigned to four groups (60 fish/group; four replicates of 15 fish each). The control group received a basal diet, the CSL group received 1% CSL, the MELA group received 10 g/kg MELA, and the CSL+MELA group received both CSL (1%) and MELA (10 g/kg) for 60 days. ResultsMELA exposure significantly reduced growth performance, including final body weight (−26.78%), weight gain (−50.59%), specific growth rate (−41.41%), and feed intake (−20.50%) compared to the control, and increased feed conversion ratio (FCR). Conversely, CSL supplementation enhanced growth parameters, with increases in weight gain (33.88%), specific growth rate (21.88%), and FCR reduced by (20.57%). Co-administration of CSL with MELA partially restored growth, with final body weight, weight gain, and FCR approaching control values. MELA also suppressed digestive enzyme activities (lipase −21.38%, α-amylase −34.72%, protease −32.42%) and impaired intestinal antioxidant defenses (SOD −43.73%, CAT −37.88%, GPx −38.01%, GST −50%; MDA increased by 128.58%). CSL supplementation increased antioxidant enzyme activities (SOD + 17.20%, CAT + 57.58%, GPx +13.43%, GST + 28.95%) and restored digestive enzyme activity (lipase: +10.11%, α- amylase: +11.50%, and protease: +8.82%). At the molecular level, MELA significantly upregulated inflammatory genes (tnf-α: 5.22 ± 0.35, tlr-4: 3.01 ± 0.34, il-6: 2.66 ± 0.11, il-8: 2.65 ± 0.15) while CSL co-administration downregulated these genes and normalized il-10 expression (2.67 ± 0.15). Histopathological analysis confirmed that CSL mitigated MELA-induced intestinal damage, including epithelial denudation, inflammatory infiltration, hemorrhage, and goblet cell hyperplasia.ConclusionThese findings showed that dietary CSL markedly promotes growth, enhances antioxidant defenses, modulates inflammatory responses, and protects intestinal integrity, demonstrating its potential as a natural dietary strategy to counteract MELA toxicity in Oreochromis niloticus.