This study was conducted to systematically evaluate the regulatory effects of kaempferol (KAE) on lipid metabolism, immune function, inflammatory responses, and antioxidant capacity in late laying hens. A total of 288 49-week-old Jinghong No. 1 laying hens with uniform body weight and consistent laying performance were randomly assigned to four treatment groups, with six replicates per group and 12 hens per replicate. Following a 1-week acclimation period, a formal feeding trial was conducted for 10 weeks. The control group (CON) was fed a basal corn-soybean meal diet, while Experimental Groups I, II, and III received the same basal diet supplemented with 0.2, 0.4, and 0.6 g/kg KAE, respectively. In terms of lipid metabolism, compared with the CON group, dietary KAE supplementation in Groups I, II, and III significantly reduced hepatic vacuole area, with the most pronounced effect observed in Group II; additionally, Groups II and III had significantly lower serum triglyceride (TG) levels and egg yolk total cholesterol content ( p 0.05). For antioxidant function, Groups II and III exhibited a significant increase in serum glutathione peroxidase (GSH-PX) activity relative to the CON group ( p 0.05); Group II showed a tendency toward higher hepatic total antioxidant capacity (T-AOC) activity ( p = 0.072) and elevated relative expression of superoxide dismutase 2 ( SOD2 ) in uterine tissue ( p = 0.07). Furthermore, Groups II and III displayed a significant upregulation in the relative expression of superoxide dismutase 1 ( SOD1 ) in ovarian tissue ( p 0.05). With respect to inflammatory cytokines and humoral immune parameters, Groups II and III had significantly higher serum interleukin-4 (IL-4) levels and significantly lower serum interleukin-1β (IL-1β) levels compared with the CON group ( p 0.05), whereas no significant differences in serum immunoglobulin levels (IgM, IgG, IgA) were found between any of the KAE-supplemented groups and the CON group ( p 0.05). In ovarian tissue, Groups II and III showed a significant decrease in the relative expression of IL-1 β and a significant increase in the relative expression of IL-4 and interleukin-10 ( IL-10 ) ( p 0.05). In uterine tissue, Groups II and III exhibited a significant reduction in the relative expression of IL-1 β and interleukin-6 ( IL-6 ), as well as a significant increase in the relative expression of IL-4 and IL-10 ( p 0.05). In conclusion, dietary kaempferol supplementation can ameliorate hepatic lipid deposition, enhance antioxidant capacity, and modulate the immune-inflammatory balance in late laying hens, thereby effectively alleviating the physiological decline associated with the late laying period.
Fu et al. (Mon,) studied this question.