饲料中花生四烯酸含量对刺参生长性能、抗氧化能力及脂肪酸代谢的影响

为探究饲料中添加花生四烯酸(arachidonic acid,ARA)对刺参(Apostichopus japonicus)生长性能、抗氧化能力及脂肪酸代谢的影响,选用初始体重为(10.78±0.06)g的刺参为研究对象,以鱼粉和发酵豆粕为主要蛋白质源,小麦粉为主要糖源制作基础饲料,通过在基础饲料中添加不同比例的ARA-纯化油,制成ARA含量分别为0.02%(对照组)、0.17%、0.36%、0.51%、0.59%和0.98%(占饲料干重)的6组等氮等脂的实验饲料,在室内循环水养殖系统进行为期56 d的养殖实验。结果表明,随着饲料中ARA含量的升高,刺参增重率(weight gain rate,WGR)呈先上升后降低的趋势,0.36%和0.51%ARA饲料组刺参WGR显著高于其他处理组(P0.05),刺参的特定生长率(specific growth rate,SGR)和饲料效率(feed efficiency,FE)与WGR具有相同的变化趋势;刺参体壁粗脂肪含量随饲料ARA含量升高呈先降低后升高的趋势,在0.51%ARA饲料组含量最低,且显著低于对照组与0.98%ARA饲料组(P0.05);同时,随饲料中ARA含量的提高,刺参体壁中ARA和n-6多不饱和脂肪酸(n-6 polyunsaturated fatty acids,n-6 PUFA)含量呈显著上升趋势,而二十碳五烯酸(eicosapentaenioc acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和n-3多不饱和脂肪酸(n-3 polyunsaturated fatty acids,n-3 PUFA)含量显著降低(P0.05);抗氧化能力方面,0.36%和0.51%ARA饲料组刺参肠道中超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)和总抗氧化能力酶(total antioxidant capacity enzyme,T-AOC)活性均显著高于对照组与0.98%ARA饲料组(P0.05),而肠道丙二醛(malondialdehyde,MDA)含量呈相反的变化趋势(P0.05);刺参肠道中脂肪酸合成酶(fatty acid synthase,FAS)和乙酰辅酶A羧化酶(acetyl-Co A carboxylase,ACC)活性随饲料ARA含量的升高呈显著降低趋势(P0.05);刺参肠道中肉毒碱棕榈酰转移酶-1(carnitine palmitoyltransferase-1,CPT-1)活性随饲料ARA含量升高呈先升高后降低的趋势(P0.05)。研究表明,在本实验条件下,饲料中添加适量ARA(0.36%~0.51%)能够对刺参生长、抗氧化能力起到一定的促进作用,同时结果显示,饲料ARA含量会对刺参肠道内脂肪酸代谢产生一定的影响。

Effects of dietary arachidonic acid on the growth performance, antioxidant capacity, and fatty acid metabolism of sea cucumber (Apostichopus japonicus)

A 56-d feeding experiment in an indoor flowing-through water system was conducted to evaluate the effects of arachidonic acid (ARA) in diets on the growth performance, antioxidant capacity, and body wall fatty acid composition of sea cucumbers (Apostichopus japonicas) with initial weights of (10.78 ±0.06) g. Six isonitrogenous and isoenergetic diets with varying levels of dietary ARA[0.02% (control group), 0.17%, 0.36%, 0.51%, 0.59%, and 0.98%] were formulated. The ARA content had no significant effect on survival rate (87.50%-94.17%; P>0.05). However, both growth rate (WGR) and feed efficiency (FE) increased with increasing ARA content until reaching peak levels at 0.51% dietary ARA, but decreased thereafter (P<0.05). Body wall composition analysis indicated that the whole-body lipid content initially decreased but then increased with increasing dietary ARA, whereas the whole-body protein, ash, and moisture contents were unaffected. Superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity enzyme (T-AOC) activities in the intestinal tract initially increased with increasing ARA content but then decreased (P<0.05), whereas the malondialdehyde (MDA) content of the intestinal tract exhibited a contrasting pattern (P<0.05). Fatty acid synthase (FAS) and acetyl-COA carboxylase (ACC) activities in the intestinal tract were unaffected when dietary ARA content decreased from 0.02% to 0.59% but decreased significantly when the dietary ARA content increased from 0.59% to 0.98% (P<0.05). The ARA and n-6 PUFA contents of the body wall increased with increasing dietary ARA, whereas the EPA and DHA content of the body wall decreased. Therefore, dietary ARA contents of 0.36%-0.51% could be used to promote the growth performance and intestinal antioxidant capacity of sea cucumbers under experimental conditions. The effects of ARA level in diet on the activities of fatty acid synthase, acetyl-CoA carboxylase, and carnitine palmitoyltransferase-1 in the intestinal tract of sea cucumber were also observed in the study.