The effect of dietary docosahexaenoic acid on the expression of lipogenic genes in broilers

Abstract

The objectives of this work were to determine the effects of dietary fungal docosahexaenoic acid (DHA) on tissue DHA concentration and lipogenic gene expression in broilers. A fungal (SR-21) meal product containing 31.5% total fat and 32.7% DHA (% of total fatty acids) was fed to chicken broilers at 0, 1, or 3% for 3 weeks. A diet with 1% DHA oil (containing 40% DHA) was also fed to chicken broilers as a positive control. Dietary fungal meal supplementation (3%) improved daily weight gain, food intake, and feed conversion ratio. The fungal meal supplementation increased dietary DHA content and consequently increased the DHA content in plasma, breast muscle (Pectoralis major), and livers in the broilers. The plasma triacylglycerol concentration was decreased by the supplementation of dietary DHA. The data indicate that the dietary DHA treatment modified certain aspects of the lipid metabolism, especially pathways related to triacylglycerol synthesis. Indeed, both the 1% DHA oil and 3% fungal meal treatments decreased the hepatic lipogenic transcription factor sterol regulatory element binding protein 1 (SREBP1) mRNA relative abundance, suggesting that dietary DHA supplementation decreases SREBP1 gene functions. The relative mRNA abundance of the de novo fatty acid synthesis genes, fatty acid synthase and acetyl coenzyme A carboxylase, was reduced by 1% DHA oil and 3% fungal meal treatments, suggesting that dietary DHA supplementation decreases lipogenesis in the livers of the broilers. Taken together, the fungal meal is a suitable dietary supplement to increase tissue DHA content and reduce the expression of hepatic lipogenic genes in broilers.

The effect of feed restriction on expression of hepatic lipogenic genes in broiler chickens and the function of SREBP1

“…The total RNA was digested by DNase I to remove genomic DNA contamination and then reverse transcribed with a SuperScript II kit at 42 °C (Life Technologies, Carlsbad, CA, USA). The real time PCR procedure followed that described by Chin et al (2007). In short, transcribed cDNA was amplified by PCR and DNA products quantitated using the DyNAmo Flash SYBR Green Kit (Finnzymes, Espoo, Finland) and detected by a DNAEngine OPTICOM™ 2 real time PCR Machine (Bio-Rad, Hercules, CA, USA).…”

“…In this procedure, β-actin was used as a house-keeping gene to normalize the gene expression data in the quantitative real time PCR. The same procedure has been validated by Chin et al (2007).…”