Phytogenic Water Additives Improve Broiler Growth Performance via Modulation of Intermediary Metabolism-Related Signaling Pathways

Abstract

A ban on the use of antibiotic growth promoters (AGPs) has fueled and promoted scientific research towards the identification of reliable and effective alternatives. The supplementation of phytogenics AV/SSL12 (AVSSL) and Superliv Gold (SG) in water has been shown to improve broiler feed efficiency (FE) via modulation of hypothalamic neuropeptides. However, their effects on peripheral metabolic pathways are still unknown. The present study was undertaken to determine the effects of AVSSL and SG on lipid and protein metabolism-associated pathways in various tissues. Day-old male Cobb 500 chicks (n = 288) were randomly assigned to 3 treatment groups, with 8 replicates of 12 birds each. The treatment groups were fed a basal diet and supplemented with AVSSL or SG in the drinking water at a rate of 2, 4, and 7 mL/100 birds/d during the starter, grower, and finisher phases, respectively. The control group were fed a basal diet with no additive supplementation. On d 35, liver, adipose, and muscle tissue were collected from one bird per pen (8 birds/group). Data were analyzed using Student's T-test to compare one treatment group to the control using Graph Pad Prism version 6.0 for Windows. In the liver, the levels of phosphorylated acetyl-CoA carboxylase alpha (ACCα) were significantly increased in both the AVSSL and SG groups compared to the control. The hepatic expression of sterol regulatory element-binding protein cleavage-activating protein (SCAP) was significantly downregulated in both treated groups compared to the control. AVSSL supplementation downregulated the hepatic expression of SREBP-2 and adiponectin (AdipoQ), while SG administration upregulated hepatic AdipoR1/R2 mRNA abundances compared to the untreated group. Both AVSSL and SG treatments upregulated hepatic stearoyl-CoA desaturase-1 (SCD-1) gene expression compared to their untreated counterparts. In the adipose tissue, the levels of phosphorylated hormone-sensitive lipase (HSL) at Ser855/554 site were increased in both the AVSSL and SG groups compared to the control. However, ATGL protein expression was decreased in SG compared to the untreated group. In the muscle, the levels of phosphorylated mechanistic target of rapamycin (mTOR) were increased in the AVSSL, but decreased in the SG group compared to the control. Collectively, these data indicate that supplementation of the phytogenics AVSSL and SG in water reduced hepatic lipogenesis-related proteins and increased adipose tissue lipolysis- and muscle protein synthesis-associated targets, which might explain, at least partially, the improvement in FE observed in previous research.

Keywords: broiler chickens; lipogenesis; lipolysis; phytogenic water additives; protein synthesis.

Figure 1

Effect of the phytogenic water additive AVSSL on the expression of lipogenesis-related proteins in liver tissue. Protein levels (a,b) were measured by Western blot and mRNA abundances (c–f) were determined by qPCR using the 2^{− ∆∆Ct} method [21]. Data are presented as the mean ± SEM (n = 8 birds/ group). * Denotes significant difference compared to the control group at p < 0.05. ACCα, phosphorylated-acetyl CoA carboxylase; ACLY, ATP citrate lyase; FASN, fatty acid synthase; ME, malic enzyme.

Figure 2

Effect of the phytogenic water additive SG on the expression of lipogenesis-related proteins in liver tissue. Protein levels (a,b) were measured by Western blot and mRNA abundances (c–f) were determined by qPCR using the 2^−∆∆Ct method [21]. Data are presented as the mean ± SEM (n = 8 birds/ group). * Denotes significant difference compared to the control group at p < 0.05. ACCα, phosphorylated-acetyl CoA carboxylase; ACLY, ATP citrate lyase; FASN, fatty acid synthase; ME, malic enzyme.

Figure 3

Effect of the phytogenic water additive AVSSL on the expression of lipolysis-related proteins and genes in adipose tissue. Protein levels (a,b) were measured by Western blot and mRNA abundances (c–e) were determined by qPCR using the 2^−∆∆Ct method [21]. Data are presented as the mean ± SEM (n = 8 birds/ group). * Denotes significant difference compared to the control group at p < 0.05. ATGL, adipose triglyceride lipase; HSL, hormone-sensitive lipase; LPL, lipoprotein lipase; LIPC, lipase C.

Figure 4

Effect of SG on the expression of lipolysis-related proteins and genes in adipose tissue. Protein levels (a,b) were measured by Western blot and mRNA abundances (c–e) were determined by qPCR using the 2^−∆∆Ct method [21]. Data are presented as the mean ± SEM (n = 8 birds/ group). * Denotes significant difference compared to the control group at p < 0.05. ATGL, adipose triglyceride lipase; HSL, hormone-sensitive lipase; LPL, lipoprotein lipase; LIPC, lipase C.

Figure 5

Effect of the phytogenic water additive AVSSL on the expression of protein metabolism-associated proteins and genes in breast muscle tissue. Protein levels of phosphorylated mTOR, mTOR, and VCL (a,b) were measured by Western blot and mRNA abundances of mTOR and RPS6KB1 (c,d) were determined by qPCR using the 2^−∆∆Ct method [21]. Data are presented as the mean ± SEM (n = 8 birds/ group). * Denotes significant difference compared to the control group at p < 0.05. mTOR, mechanistic target of rapamycin; RPS6KB1, ribosomal protein S6 kinase beta-1.

Figure 6

Effect of the phytogenic water additive SG on the expression of protein metabolism-related proteins and genes in breast muscle tissue. Protein levels of phosphorylated mTOR, mTOR, and VCL (a,b) were measured by Western blot and mRNA abundances of mTOR and RPS6KB1 (c,d) were determined by qPCR using the 2^−∆∆Ct method [21]. Data are presented as the mean ± SEM (n = 8 birds/ group). * Denotes significant difference compared to the control group at p < 0.05. mTOR, mechanistic target of rapamycin; RPS6KB1, ribosomal protein S6 kinase beta-1.