Interactive effect of dietary vitamin D3 and zinc (Zn) on growth performance, Zn metabolism, and intestinal health of yellow catfish Pelteobagrus fulvidraco

Abstract

Both vitamin D3 (VD3) and zinc (Zn) are essential micronutrients to fish, and VD3 can regulate Zn uptake and metabolism in various animals. However, the interactive effect of VD3 and Zn on growth performance, Zn metabolism, and intestinal health remains largely unknown in fish. The study formulated four experimental diets to culture yellow catfish, i.e., basic VD3 addition without extra Zn addition (control), basic VD3 addition with extra Zn addition (Zn group), high VD3 addition without extra Zn addition (VD3 group), and high VD3 and Zn addition (Zn + VD3 group). Four experimental groups contain Zn and VD3 contents at 41.15 mg/kg + 1027 IU/kg (control), 94.77 mg/kg + 1033 IU/kg (Zn group), 41.04 mg/kg + 16,047 IU/kg (VD3 group), and 94.89 mg/kg + 16,109 IU/kg (Zn + VD3 group), respectively. The experiment continued for 10 weeks. Dietary Zn and VD3 interacted to affect specific growth rate (SGR), Zn content and mRNA expression of Zn metabolism (zip4, zip9, zip14, znt1, znt2, mtf-1, and mt), SUMOylation-relevant genes (sae1, ubc9, pias1, sumo1, senp2, and senp5), tight junction-relevant genes (claudin-4, zo1, zo2, zo3, and jam2a), antioxidant (nrf2 and cat) and inflammatory genes (il1b and il8). Compared to the control, high dietary Zn addition increased intestinal mRNA expression of zip4, znt1, znt2, mt, sae1, ubc9, pias1, sumo1, claudin4, zo1, zo2, and jam2a and il1b, and Zn contents, but decreased mRNA expression of zip9, senp2, senp5, nrf2 and cat. Compared to high Zn addition in the diets, Zn and VD3 co-addition increased SGR, Zn contents, and mRNA expression of zip4, znt1, znt2, mt, mtf-1, senp2, senp5, claudin4, zo1, zo2, zo3, jam2a, nrf2 and cat, but decreased mRNA expression of zip9, zip14, sae1, ubc9, pias1, sumo1 and il1b. Dietary Zn and VD3 co-addition interacted to influence Cu/Zn-SOD, CAT and GPx activities, T-AOC, MDA content. Compared to control, high dietary Zn addition decreased intestinal Cu/Zn-SOD, CAT, GPx activities and T-AOC but increased MDA content. Compared to extra Zn addition in the diets, Zn and VD3 co-addition increased Cu/Zn-SOD, CAT and GPx activities as well as T-AOC but decreased MDA content. Based on these observations, our study indicated that high dietary Zn addition influenced Zn metabolism and SUMOylation modification, damaged the tight junction, induced oxidative stress and inflammatory responses in the intestine, and dietary vitamin D3 addition promoted growth performance and alleviated high dietary Zn-induced negative effects on the intestine of yellow catfish. Significance of relevanceOur study elucidated the innovative insights into the interaction of Zn and VD3 in fish, which provided the important references for dietary Zn and VD3 addition in aquafeeds.