Low‐protein amino acid‐supplemented diets in broiler chickens: effects on performance,carcass characteristics,whole‐body composition and efficiencies of nutrient utilisation

Two concurrent trials were conducted to investigate the influence of low‐protein amino acid‐supplemented diets on the performance, carcass characteristics, whole‐body composition and efficiencies of nutrient utilisation by the male broiler chicken from age 3 to 6 weeks. The first trial comprised five isoenergetic (13.0 MJ kg⁻¹) diets containing 225 (control), 210, 190, 172 or 153 g kg⁻¹ crude protein (CP) supplemented with essential amino acids (EAAs) to meet the minimum National Research Council recommendations. In the second trial a composite mixture of non‐essential amino acids (NEAAs) was added to the lower‐CP diets (ie 210–153 g kg⁻¹) such that they became isoproteinous (N × 6.25) with the 225 g kg⁻¹ control. Neither the lowering of dietary CP nor NEAA supplementation had any significant influence on weight gain or the relative weights of the various carcass cuts. However, chicks fed the lowest‐CP diets consumed more feed (P ≤ 0.05) and had poorer (P ≤ 0.05) feed conversion efficiency (FCE). NEAA supplementation enhanced FCE to the control levels. Whole‐body compositional analysis showed that lowering dietary CP increased (P ≤ 0.01) total body fat in a linear fashion (P ≤ 0.001; r = −0.72). Equalising dietary CP with the control (ie maintaining identical energy/protein ratio) by NEAA supplementation did not correct for the fat deposition. Total body protein (g kg⁻¹) was identical with the control with or without NEAA supplementation. Dietary energy, protein retention efficiency (PRE) and protein efficiency ratio (PER) were more efficient (P ≤ 0.01) in the lower‐protein diets, while NEAA supplementation significantly (P ≤ 0.01) decreased the efficiency of N utilisation. Reducing dietary CP from 225 to 153 g kg⁻¹ decreased N excretion in a highly significant linear fashion (P ≤ 0.001; r = 0.73). The nutritional and environmental implications of the increased body fat deposition on the one hand and the decreased N excretion on the other in the low‐protein‐fed chickens are discussed and the need to harmonise these apparently conflicting interests is emphasised. © 2000 Society of Chemical Industry     

Peripartal metabolism and production of holstein cows fed diets supplemented with fat during the dry period

Previous research from our laboratory demonstrated that cows fed supplemental fat throughout the dry period in an attempt to increase body condition score (BCS) had little hepatic lipid accumulation at d 1 postpartum compared with cows fed an isocaloric high-grain diet or a lower energy control diet. However, results were confounded by lower dry matter intake and loss of BCS by cows fed the fat-supplemented diet. Here, cows were fed a control diet (C) moderately high in nonfiber carbohydrates (NFC) or an isocaloric fat-supplemented, low NFC (F) diet to reassess the effects of supplemental fat throughout the dry period on peripartal lipid accumulation in liver. A more energy-dense, high-NFC diet supplemented with fat (CF) was also fed to test the efficacy of supplemental fat in a diet with similar carbohydrate composition but higher energy density. Intakes of dry matter and net energy for lactation were similar among treatments throughout the experiment, although diet x day interactions during the last 21 d before parturition indicated that cows fed CF decreased intakes more slowly. Cows gained similar amounts of BCS and body weight among diets prepartum, but cows fed C tended to lose more BCS and body weight around parturition. Milk production and milk components did not differ among treatments. Prepartum concentrations of glucose, insulin, total protein, nonesterified fatty acids, and mu-hydroxybutyrate in plasma were similar among treatments. Supplemental fat increased prepartum concentrations of urea and cholesterol in plasma. Postpartum concentrations of metabolites and insulin in plasma were similar among treatments. Concentrations of total lipid and triglyceride in liver increased at parturition, whereas hepatic glycogen concentration decreased, but concentrations were not different among treatments. Supplemental fat fed prepartum did not affect peripartal lipid accumulation in liver tissue and did not benefit postpartum milk production.     

Anti‐obesity effect of Liupao tea extract by modulating lipid metabolism and oxidative stress in high‐fat‐diet‐induced obese mice

Liupao tea (LPT) is traditional dark Chinese tea. The effect of LPT extract on high‐fat‐diet‐induced obese mice was investigated systematically. The results showed that LPT extract could reduce body weight and significantly alleviate liver damage and fat accumulation. LPT could also decrease the levels of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (AKP), total cholesterol (TC), triglycerides (TG), and low‐density lipoprotein cholesterol (LDL‐C) and increase the level of high‐density lipoprotein cholesterol (HDL‐C) in the liver. It also decreased the serum levels of inflammatory cytokines, including tumor necrosis factor alpha (TNF‐α), interferon gamma (IFN‐γ), interleukin (IL)‐1β, and IL‐6 and increased the serum levels of anti‐inflammatory cytokines, including IL‐10 and IL‐4. Moreover, LPT improved the levels of total superoxide dismutase (T‐SOD), glutathione peroxidase (GSH‐Px), and catalase (CAT) and reduced the level of malondialdehyde (MDA) in the liver. Moreover, LPT could upregulate the mRNA and protein expressions of peroxisome proliferator‐activated receptor alpha (PPAR‐α), lipoprotein lipase (LPL), carnitine palmitoyltransferase 1(CPT1), and cholesterol 7 alpha‐hydroxylase (CYP7A1) and downregulate those of PPAR‐γ and CCAAT/enhancer‐binding protein alpha (C/EBP‐α) in the liver. It also increased the mRNA expression of copper/zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), CAT, gamma‐glutamylcysteine synthetase 1 (GSH1), and GSH‐Px. The components of LPT extract include catechin, rutin, taxifolin, and astragalin, which possibly have a wide range of biological activities. In conclusion, our work verified that LPT extract possessed an anti‐obesity effect and alleviated obesity‐related symptoms, including lipid metabolism disorder, chronic low‐grade inflammation, and liver damage, by modulating lipid metabolism and oxidative stress.     

Consumption of barley β‐glucan ameliorates fatty liver and insulin resistance in mice fed a high‐fat diet

Consumption of a diet high in barley β‐glucan (BG) has been shown to prevent insulin resistance. To investigate the mechanism for the effects of barley BG, three groups of male 7‐wk‐old C57BL/6J mice were fed high‐fat diets containing 0, 2, or 4% of barley BG for 12 wk. The 2% BG and 4% BG groups had significantly lower body weights compared with the 0% BG group. The 4% BG group demonstrated improved glucose tolerance and lower levels of insulin‐resistance index and glucose‐dependent insulinotropic polypeptide. Consumption of the BG diet decreased hepatic lipid content. Mice on the BG diet also demonstrated decreased fatty acid synthase and increased cholesterol 7α‐hydroxylase gene expression levels. The BG diet promoted hepatic insulin signaling by decreasing serine phosphorylation of insulin receptor substrate 1 and activating Akt, and it decreased mRNA levels of glucose‐6‐phosphatase and phosphoenolpyruvate carboxykinase. In summary, consumption of BG reduced weight gain, decreased hepatic lipid accumulation, and improved insulin sensitivity in mice fed a high‐fat diet. Insulin signaling enhanced due to the expression changes of glucose and lipid metabolism genes by BG consumption. Consumption of barley BG could be an effective strategy for preventing obesity, insulin resistance, and the metabolic syndrome.     

Beneficial effects of yam on carbon tetrachloride‐induced hepatic fibrosis in rats

BACKGROUND: In a previous study, lyophilised yam reduced brain amyloid β‐protein (Aβ) accumulation and improved the antioxidative defence system in senescence‐accelerated (SAMP8) mice. Therefore, the aim of this study was to investigate the hepatic protection of yam in the carbon tetrachloride‐induced hepatic fibrosis of rats. Hepatic fibrosis was induced in rats via intraperitoneal injections of CCl₄ at a dose of 1 mL kg^?1 body weight (BW) twice weekly for 8 weeks. Three groups of rats were gavaged daily with yams at doses of 0.5, 1 and 2 g kg^?1 BW for 8 weeks, respectively. RESULTS: Yam treatments significantly decreased the ratio of liver/body weight, levels of γ‐glutaminotranspeptidase (GGT), low‐density lipoprotein, and triglyceride in serum when compared with those administered CCl₄ alone. Treatment with yams significantly elevated antioxidant activities of glutathione peroxidase (GSH‐Px) and superoxidase dismutase (SOD) in livers. Microscopically, yam‐treated groups presented with low histoscores of CCl₄‐induced liver injury and fibrosis. Additionally, yam treatment reduced the area of GGT‐positive foci and the index of proliferating cell nuclear antigen (PCNA) in liver. CONCLUSION: Daily administration of yam attenuates CCl₄‐induced hepatic fibrosis in rats in a dose‐dependent manner; this attenuation may be related to the antioxidant properties of yams. Copyright © 2009 Society of Chemical Industry