Effects Of Dietary L-Arginine Supplementation On Growth Performance, Abdominal Fat Content And Lipid Metabolism In Broiler Chickens

The goals of these experiments were to evaluate the effects of different levels of L-Arginine (L-Arg) on growth performance, plasma lipids, abdominal fat content, intramuscular fat, and gene related to lipid metabolism in broiler chickens from21to42days of age.In the first experiment, a total of192broiler chickens, selected from a group of256Arbor Acres chicks (mixed sex) aged21days, were randomly assigned to four groups (six broilers per replicate and eight replicates per treatment). The control group was fed a basal diet that formulated to contain low energy level (ME=12.48MJ/kg), whereas the treatment groups were fed basal diets supplemented with0.25%,0.50%, or1.00%L-Arg for3weeks. Adding L-Arg in low-energy diets had no effect on growth performance, abdominal fat content, intramuscular fat percentage, plasma triglyceride, total cholesterol, high-density lipoprotein-cholesterol, or thyroid hormone levels and hepatic thyroid hormone responsive spotl4a mRNA expression compared with the control, whereas plasma low density lipoprotein-cholesterol level reduced significantly by supplementing L-Arg, and the lowest value was recorded by inclusion of L-Arg at the level0.25%in the diet.In the second experiment, a total of192broiler chickens, selected from a group of256Cobb500chicks (males) aged21days, were randomly assigned to four groups (six broilers per replicate and eight replicates per treatment). The control group was fed a basal diet that formulated to contain low energy level (ME=12.71MJ/kg), whereas the treatment groups were fed basal diets supplemented with0.25%,0.50%, or1.00%L-Arg for3week. Adding L-Arg in low-energy diets had no effect on growth performance or abdominal fat content compared with the control.In the third experiment, a total of192broiler chickens, selected from a group of256Cobb500chicks (males) aged21days, were randomly assigned to four groups (six broilers per replicate and eight replicates per treatment). The control group was fed a basal diet that formulated to contain ideal energy level (ME=13.27MJ/kg) as reported by NRC (19994), whereas the treatment groups were fed basal diets supplemented with0.25%,0.50%, or1.00%L-Arg for3weeks. Abdominal fat content, plasma triglyceride, total cholesterol concentrations reduced significantly by inclusion of L-Arg at the level of0.25%, whereas low density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, or non-esterified fatty acid, and thyroid hormone levels did not change by inclusion of L-Arg at the level of0.25%compared with the control (control diet prepared to cover and satisfy all nutrient requirements included Arg and metabolisable energy as demonstrated by NRC (1994). Inclusion of L-Arg at the level of0.25%reduced significantly hepatic3-hydroxyl-3-methylglutaryl-CoA reductase, fatty acid synthase (FAS) mRNA expression and enhanced significantly carnitine palmitoyl transferasel (CPT1) and3-hydroxyacyl-CoA dehydrogenase (3HADH) mRNA expression compared with the control.Overall, adding L-Arg in low-energy diets or ideal energy diets had no effect on growth performance or thyroid hormone levels. Supplementing chicken diets (as stated by NRC (1994)) with L-Arg at the level of0.25%can lower abdominal fat deposition by suppressing hepatic FAS mRNA expression and enhancing CPT1and3HADH mRNA expression in the hearts of broiler chickens.