Effects of lysine deficiency or excess on growth and the expression of lipid metabolism genes in slow-growing broilers. (9th February 2019) - Tian, D L
ABSTRACT: This experiment was conducted to evaluate the effects of lysine deficiency or excess on growth and the expression of lipid metabolism genes in slow-growing birds. A total of 360 one-day-old chicks were randomly divided into 3 groups, with 6 replicates of 20 birds each. The birds fed the basal diet with a total lysine 0.60% (LL), 1.00% (ML), or 1.40% (HL). The amount of lysine (ML) as the control group, LL and HL as the experimental group, the trial period last 3 wk. The results showed that compared with ML, LL significantly decreased average daily gain and average daily feed intake and remarkably increased feed conversion ratio of birds at 21 day old ( P < 0.01), while the above indices in HL had no significant effects ( P > 0.05). Besides, LL reduced the pectoral muscle rate ( P < 0.01) and decreased the percentage of abdominal fat significantly ( P < 0.05). In addition, compared with ML, the expression of fatty acid binding protein 1 ( FABP1 ), acetyl-CoA carboxylase ( ACC ), malic enzyme ( ME ), and sterol regulatory element binding protein 1 ( SREBP1c ) mRNA of liver in LL was significantly decreased ( P < 0.05), and the expression of cholesteryl ester transfer protein ( CETP ) mRNA was significantly increased ( P < 0.01), whereas LL had no significant effects on the expression of peroxisome proliferator activated receptor alpha ( PPARα ) mRNA ( P > 0.05). Moreover, compared with ML, HL significantly reduced the expression of FABP1, ACC, ME, SREBP-1c, and PPARα mRNA in the liver ( P < 0.05), and had no significant effects on the expression of CETP mRNA ( P > 0.05). The results of current research suggest that dietary lysine deficiency could reduce the growth and fat deposition of slow-growing broilers mainly by downregulating the expression of lipid synthesis genes.