Effects of Dietary Bile Acids on Growth Performance, Lipid Deposition, and Intestinal Health of Rice Field Eel (Monopterus albus) Fed with High-Lipid Diets
Wei Lei, Jiamin Li, Peng Fang, Shanshan Wu, Yao Deng, Ao Luo, Zhengwei He, Mo Peng
Abstract
The purpose of this trial was to study the positive effects of bile acids (BAs) on growth performance and intestinal health of rice field eel fed with high-lipid diets (HLDs). Rice field eels (initial weight 17.00 ± 0.10 g) were divided into four groups, each group containing four repetitions and feeding with different isonitrogenous diet: control diet containing 7% lipid content, HLDs containing the lipid content increased to 13%, HLDs supplementing with 0.025% BAs and 0.05% BAs, respectively. After 8 weeks, compared control group, the fish fed HLDs had no significant effect on weight gain rate and specific growth rate ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"><a:mi>P</a:mi><a:mo>></a:mo><a:mn>0.05</a:mn></a:math> ), but increased the lipid deposition in tissues and intestinal lipase activity, and damaged to intestinal oxidative stress, inflammatory response, physical barrier, and structural integrity ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"><c:mi>P</c:mi><c:mo><</c:mo><c:mn>0.05</c:mn></c:math> ). Dietary BAs significantly increased weight gain rate and specific growth rate in fish fed with HL diets ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"><e:mi>P</e:mi><e:mo><</e:mo><e:mn>0.05</e:mn></e:math> ) and reduced feed conversation rate ( <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M4"><g:mi>P</g:mi><g:mo><</g:mo><g:mn>0.05</g:mn></g:math> ). Further, the eels fed with BAs reduced the total lipid content in liver, muscle, and whole body ( <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" id="M5"><i:mi>P</i:mi><i:mo><</i:mo><i:mn>0.05</i:mn></i:math> ). Dietary BAs decreased the activity of intestinal lipase ( <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" id="M6"><k:mi>P</k:mi><k:mo><</k:mo><k:mn>0.05</k:mn></k:math> ). Meanwhile, BAs supplemented in HLDs improved intestinal antioxidant capacity through increasing the activities of T-SOD (total superoxide dismutase), GSH-PX (glutathione peroxidase), CAT (catalase), T-AOC (total antioxidant capacity), whereas reducing MDA (malondialdehyde) content ( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" id="M7"><m:mi>P</m:mi><m:mo><</m:mo><m:mn>0.05</m:mn></m:math> ). Moreover, dietary BAs regulated the mRNA expression related to inflammatory response, oxidative stress, and physical barrier in intestine, such as tnf-α, il-8, tlr-8, il-10, nrf2, keap1, claudin12, and claudin15 ( <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" id="M8"><o:mi>P</o:mi><o:mo><</o:mo><o:mn>0.05</o:mn></o:math> ). Dietary BAs supplementation also enhanced the intestinal structural integrity characterized by increased fold height and lamina propria width ( <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" id="M9"><q:mi>P</q:mi><q:mo><</q:mo><q:mn>0.05</q:mn></q:math> ). This study showed that dietary BAs supplemented in HLDs (13% lipid) could increase the growth performance of rice field eel, reduce lipid deposition in tissues and whole body, and enhance intestinal health.