Dietary metabolizable energy and crude protein levels affect pectoral muscle composition and gut microbiota in native growing chickens

The experiment aimed to study effects of dietary metabolizable energy (ME) and crude protein (CP) levels alone and in interaction on performance, pectoral muscle composition and gut microbiota in native growing chickens. A total of 648 10-wks-old Beijing-You Chicken (BYC) female chickens were randomly allocated to 9 groups with 6 replicates per group and 12 chickens per replicate, and the chickens were fed with a 3 × 3 factorial diets (3 levels of dietary ME: 11.31 MJ/kg, 11.51 MJ/kg, 11.71 MJ/kg; and 3 levels of dietary CP: 14%, 15%, 16%). The results showed that dietary ME and CP levels didn't affect average feed intake (AFI), body weight gain, feed gain ratio (P > 0.05), but ME level significantly affected the AFI (P < 0.05); mortality rate of 11.31 MJ/kg group was the highest (P < 0.05). Dietary ME, CP levels, and the interaction significantly affected pectoral CP and crude fat (CF) content of the growing chickens (P < 0.01). Dietary CP level had opposite effects on pectoral CP and CF content (P < 0.01). The 16% CP increased the pectoral CF content, which may have a negative impact on meat flavor. Dietary ME level affected 11 types of pectoral free amino acids (FAA) contents, including aspartic acid, L-threonine (P < 0.05), also amino acid classification, for example, total amino acid (TAA) and essential amino acid (EAA) content (P < 0.05). The 11.51 MJ/kg group had the highest TAA, EAA, delicious amino acid (DAA) content and EAA percentage (P < 0.05), while 11.31 MJ/kg group had the lowest bitter amino acid (BAA) content and BAA percentage and the highest fresh and sweet amino acid (FSAA) percentage (P < 0.05). Dietary CP level significantly affected glutamine and tyrosine content (P < 0.05). The interaction of dietary ME and CP level affected C20:3n6 content, saturated fatty acid (SFA), and unsaturated fatty acid (UFA) percentage (P < 0.05). The CP level significantly affected SFA percentage (P < 0.05). The 16% CP level increased the diversity of gut microbiota, but at the same time increased the relative abundance of Proteobacteria (P < 0.05), which is a sign of microbiota disorder. The increase of dietary ME level resulted in a gradual decrease in the diversity and relative abundance of gut microbiota. In conclusion, the present study suggested that the medium dietary ME (11.51 MJ/kg) and low CP (14-15%) levels can be helpful for enhancing pectoral muscle composition, increase meat quality such as flavor and nutritional value, and benefit for gut microbiota in native growing chickens.

Hepatoprotective effects of Lactobacillus plantarum 299v supplemented via drinking water against aflatoxin-induced liver damage

The aim of this study was to examine the impact of intake of a lactic acid bacterium, Lactobacillus plantarum 299v (Lp299v) on aflatoxin-induced hepatotoxicity in broilers. For this, broilers were intoxicated with dietary aflatoxins and simultaneously treated with live Lp299v in drinking water. One-day-old male broilers were divided into eight groups (n = 10/group) as follows. Aflatoxin groups fed basal diet contaminated with aflatoxins (200 or 2000 ppb). The probiotic groups received drinking water enriched with live (Lp299v) (10⁸ CFU/ml). A group of birds was given a commercial mycotoxin binder (2.5 g/kg feed). Control groups received basal diet without probiotic or aflatoxin binder. The growth performance was calculated for the entire period (0-42 days), and blood and liver specimens were processed for histology and determination of liver damage markers. Results showed extensive damage including bile duct hyperplasia, hepatocellular ballooning, and necrosis in chickens fed aflatoxin alone. However, liver lesions were limited to lobular inflammation and pyknosis in broilers treated with aflatoxins along with Lp299v. The histology of the liver tissues from the birds on aflatoxin-free diet + probiotic appeared to be normal when compared to the respective controls. Histopathological indices in different experimental groups were corroborated with the liver damage markers namely, serum ALT, AST, LD, and γ-GT. It is concluded that the improvement in the growth performance and prevention of aflatoxin-related liver lesions could be mainly assigned to the probiotic therapy for the entire period of breeding, although the aflatoxin-binding ability of the Lp299v in inactivation of aflatoxins cannot be ruled out.RESEARCH HIGHLIGHTS Aflatoxin-related liver damage progression was inhibited by probiotics in broilers.Aflatoxin inactivation by probiotics can be assessed by liver histopathology.Growth performance in broilers was improved following the intake of probiotics.

Improving the Reliability of Optimal In-Feed Amino Acid Ratios Based on Individual Amino Acid Efficiency Data from N Balance Studies in Growing Chicken

Three consecutive nitrogen balance experiments with fast-growing male broiler chickens (ROSS 308), both during starter and grower periods, were conducted to determine the ideal ratios of several indispensable amino acids relative to lysine. The control diets based on corn, wheat, fishmeal, field peas, wheat gluten and soybean oil were formulated by computer optimizing to meet the assumed ideal amino acid ratios and to fulfill both the energy and nutrient requirements of growing chicken. According to principles of the diet dilution technique, balanced control diets were diluted by wheat starch and refilled by crystalline amino acids and remaining feed ingredients, except the amino acid under study. The lysine, threonine, tryptophan, arginine, isoleucine and valine diluted diets resulted in significantly lower protein quality as compared to control diet, especially following increased dietary lysine supply (experiments II and III) and stronger amino acid dilution (experiment III). Accordingly, the limiting position of individual amino acids was confirmed, and the derived amino acid efficiency data were utilized to derive ideal amino acid ratios for the starter period: Lys (100): Thr (60): Trp (19): Arg (105): Ile (55): Val (63); and the grower period: Lys (100): Thr (62): Trp (17): Arg (105): Ile (65): Val (79).