The Later Effects of DHA in Diet on Regulating Transcription of Lipid Genes of Broiler

The effect of docosahexaenoic acid (DHA) on lipid metabolism in broiler were studied in order to provide test results for polyunsaturated fatty acids (PUFA) regulating fatty deposition. 1-wk-old Arbor Acres (AA) broiler were fed with DHA microalgae and slaughtered after 2 wk. The tissues were stored for isolating total RNA. RT-PCR was used to analyze the expression changes of genes. DHA microalgae significantly increased average body gain and feed conversion rates, reduced the levels of total cholesterol (TC), total glycerin (TG), and low-density lipoprotein cholesterol (LDL-C) in serum and increased the content of high-density lipoprotein cholesterol. 1 wk later, the effects were still remained. In liver tissue, DHA microalgae increased the expression of PPARa and carnitine palmitoyltransferase-1 (CPT-1). 1 wk later, it was observed that DHA up-regulated the expression of fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), lipoprotein lipase (LPL) and carnitine palmitoyltransferase-1 (CPT-1). 2 wk later, it still increased the expressions of FAS and CPT-1, but a converse result was observed for ACC and LPL. In adipose tissue, DHA microalgae suppressed the expression of PPARa and LPL, up-regulated the expression of ACC, FAS, and CPT-1. After withdrawal, the expression of genes in test group was significantly lower than that in control group (P<0.01). In the muscle of chest, DHA microalgae significantly inhibited the gene expression (P<0.01). 1 wk later, the expressions of FAS, LPL and CPT-1 in test group were significantly higher than that in control group (P<0.05). 2 wk later, it was shown that DHA significantly inhibited fat synthesis and decomposition. In the leg, there was not any PPARa expression being detected, probably because of the less expression in muscle tissues or the regulation of PPARa had no relation to the case. DHA microalgae promote fat synthesis in the liver and inhibit in adipose and muscle tissues. It still has effects after 1 wk of withdrawal.