Effect of arginine or glutamine supplementation on production, organ weights, interferon gamma, interleukin 6 and antibody titre of broilers

The potential of glutamine supplementation in reduced-crude protein diets for chicken-meat production

This review explores the potential of including glutamine, a so-called non-essential amino acid, in the formulation of reduced-crude protein (CP) diets for broiler chickens. There is a precedent for benefits when including glycine and serine in reduced-CP diets. Fundamentally this is due to decreases in non-essential amino acid concentrations in reduced-CP diets - an unavoidable consequence of reducing CP without amino acid supplementation. The situation for glutamine is complicated because analysed dietary concentrations are very rarely provided as standard assays do not differentiate between glutamine and glutamate and are reported on a combined basis as glutamic acid. The dietary requirement for glutamic acid is approximately 36.3 g/kg but it is increasingly unlikely that this requirement will be met as dietary CP levels are progressively reduced. Glutamine is an abundant and versatile amino acid and constitutes 50.5 mg/g of whole-body chicken protein and is the dominant free amino acid in systemic plasma where it has been shown to provide 22.6% (139.9 of 620.3 μg/mL) of the total in birds offered 215 g/kg CP, wheat-based diets. In addition to dietary intakes, glutamine biosynthesis is derived mainly from the condensation of glutamate and ammonia (NH3) catalysed by glutamine synthetase, a reaction that is pivotal to NH3 detoxification. Glutamate and NH3 are converted to glutamine by phosphate-dependent glutaminase in the reciprocal reaction; thus, glutamine and glutamate are interchangeable amino acids. However, the rate of glutamine biosynthesis may not be adequate in rapidly growing broiler chickens and exogenous and endogenous glutamine levels are probably insufficient in birds offered reduced-CP diets. The many functional roles of glutamine, including NH3 detoxification and maintenance of acid-base homeostasis, then become relevant. Twenty feeding studies were identified where dietary glutamine supplementation, usually 10 g/kg, was evaluated in birds kept under thermoneutral conditions. On balance, the outcomes were positive, but the average dietary CP was 213 g/kg across the twenty feeding studies, which indicates that CP and, in turn, glutamine concentrations would have been adequate. This suggests that glutamine inclusions in reduced-CP diets hold potential and consideration is given to how this may be best confirmed.

Effect of glutamine on the systemic innate immune response in broiler chickens challenged with Salmonella pullorum

BACKGROUND

The objective of this study was to evaluate the effects of glutamine on the growth performance and systemic innate immune response in broiler chickens challenged with Salmonella pullorum. A total of 600 one-day-old Arbor Acres broiler chickens were assigned randomly to 6 dietary treatments with 10 replicates for a 21-day feeding experiment. The experimental treatments were as follows: the control treatment (birds fed the basal diet), the Gln1 treatment, and the Gln 2 treatment (birds fed the basal diet supplemented with 0.5%, and 1.0% Glutamine, respectively). At 3 d of age, half of the birds from each treatment were challenged oral gavage with 2.0 × 104 CFU/mL of S. pullorum suspension (1.0 mL per bird) or an equivalent amount of sterile saline alone, which served as a control.

RESULTS

The results showed that S. pullorum infection had adverse effects on the average daily feed intake, average daily gain, and feed conversion ratio of broiler chickens compared with those of the CON treatment on d 7, decreased the spleen and bursa of fabricius relative weights (except on d 21), serum immunoglobulin A (IgA),immunoglobulin G (IgG), and immunoglobulin M (IgM) concentrations, and spleen melanoma differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology gene 2 (LGP2) mRNA expression levels, and increased the mRNA expression levels of spleen Nodinitib-1 (NOD1), Toll-like receptors 2,4 (TLR2, TLR4), DNA-dependent activator of IFN-regulatory factors (DAI), mitochondrial antiviral-signaling protein (MAVS), P50, P65, and RelB on d 4, 7, 14, and 21. Supplementation with Gln improved the relative weights of the spleen and bursa of Fabricius (except on d 21), increased the serum IgA, IgG, and IgM concentrations and the mRNA expression levels of spleen MDA5 and LGP2, and decreased the mRNA expression levels of spleen NOD1, TLR2, TLR4, DAI, MAVS, P50, P65, and RelB of S. pullorum-challenged broiler chickens.

CONCLUSION

These results indicate that Gln might stimulate the systemic innate immune responses of the spleen in broiler chickens challenged with S. pullorum.

Sensitivity of broiler performance, organ weights and plasma constituents to amino acid supplementation and reused litter exposure using ideal protein-formulated rations

Effects of amino acid supplementation to ideal protein (IP) formulated rations were investigated on growth performance, plasma metabolites and organ weights of broilers placed on 100% recycled (reused) litter. Day-old Ross308 male broilers were raised on either clean or reused litter and fed for three weeks on one of five isoenergetic diets, where an IP-based control diet (C) was compared with diets containing threonine (T) or arginine (A) at 25% above requirements, or with 1% supplemented glutamine (G), or with each amino acid added (TAG). Litter and diet treatments did not strongly interact on outcomes. Reused litter placement resulted in greater weight gain, smaller feed conversion ratio and heavier bursal weights (P < 0.05) compared to clean litter placement. Relative to C and T birds, TAG birds reduced weight gain and feed intake (P < 0.05). Plasma uric acid levels in G birds were greater than in C, T and A birds (P < 0.001). Collectively, since the outcomes of placement on reused litter increased performance and the control diet was IP formulated, the absence of increased growth performance in response to amino acid supplementation would be consistent with amino acids tested being excess to requirements.

Effects of dietary supplementation with glutamine on the lymphocyte proliferation and intestinal immune gene expression in broiler chickens infected with Salmonella Enteritidis

An experiment was conducted to investigate the effects of glutamine (Gln) on the lymphocyte proliferation and intestinal immune relevant gene expression in broilers infected with Salmonella Enteritidis. 240 1-day-old broilers were divided randomly into four groups in a completely randomized design, each of which had 6 replicates. Birds were reared in battery cages for 21 days. The experimental groups were as follows: control group (unchallenged group, CON), basal diet; Salmonella Enteritidis challenged group (challenged with 2.0 × 10⁴ CFU/mL of Salmonella Enteritidis, SCC), basal diet; Gln 1, basal diet plus Salmonella Enteritidis challenged plus Gln at 0.5% diet; Gln 2, basal diet plus Salmonella Enteritidis challenged plus Gln at 1.0% diet. The results showed that Salmonella Enteritidis infection led to some decrease in the relative weight of spleen and bursa (except at 21 d), lymphocyte percentage, number of proliferation peripheral blood T and B lymphocytes, and increased the heterophil percentage, H/L ratio, mRNA expression levels of TNF-α, NF-κB p65, IL-1β, IL-6, and IL-8 in the jejunal and ileal mucosa compared with the measurements of these parameters in the CON group at d 4, 7, 14, and 21 (p < 0.05). On the other hand, chickens fed the Gln showed improved the relative weight of spleen and bursa, increased the lymphocyte percentage, number of proliferation peripheral blood T and B lymphocytes, and decreased the heterophil percentage, H/L ratio, and immune relevant gene expression in the jejunal and ileal mucosa compared with the measurements of these parameters in the SCC group (p < 0.05). These results suggest that Gln as a feed additive could be effective for reducing the detrimental effects of Salmonella Enteritidis infection, and increase the intestinal immune barrier function of broilers.

Response of meat chickens to different sources of arginine in low-protein diets

Arginine activity in broiler diets can be supplied by L-arginine (Arg), guanidinoacetic acid (GAA) and L-citrulline (Cit), all of which are commercially available. This study was conducted to assess the effects of Arg source and level on broiler performance, nutrient digestibility and carcass parameters. Day-old Ross 308 cockerels (n = 768) were assigned to one of eight dietary treatments using a completely randomized design: normal protein (NP), low protein deficient in Arg (LP) and LP with two levels of either Arg (0.238% and 0.476%), GAA (0.309% and 0.618%) or Cit (0.238 and 0.476%). The LP was 5 percentage points lower in protein level than the NP. Wheat, sorghum, soya bean meal, canola meal, and meat and bone meal-based diets were fed over three feeding phases to 6 replicate floor pens with 16 birds each. Compared to NP, birds fed LP had reduced feed intake (FI, p < 0.001), reduced body weight gain (BWG, p < 0.001) and increased feed conversion ratio (FCR, p < 0.001) from day 0 to day 35. Additions of Arg or Cit to the LP at both levels resulted in increased BWG and reduced FCR (p < 0.05). Birds fed LP with GAA added had lower FCR (p < 0.05) but not higher BWG (p > 0.05) compared with the LP observed from day 0 to day 35. Supplementation of Arg, Cit and the low level of GAA to LP resulted in increased carcass yield, bone length, diameter and ash (p < 0.05) but did not increase ileal energy or nitrogen digestibility (p > 0.05). The findings indicate that Cit is an efficacious source of Arg activity in Arg-deficient diets.

An open source physiologically based kinetic model for the chicken (Gallus gallus domesticus): Calibration and validation for the prediction residues in tissues and eggs

Xenobiotics from anthropogenic and natural origin enter animal feed and human food as regulated compounds, environmental contaminants or as part of components of the diet. After dietary exposure, a chemical is absorbed and distributed systematically to a range of organs and tissues, metabolised, and excreted. Physiologically based kinetic (PBK) models have been developed to estimate internal concentrations from external doses. In this study, a generic multi-compartment PBK model was developed for chicken. The PBK model was implemented for seven compounds (with log K_ow range -1.37-6.2) to quantitatively link external dose and internal dose for risk assessment of chemicals. Global sensitivity analysis was performed for a hydrophilic and a lipophilic compound to identify the most sensitive parameters in the PBK model. Model predictions were compared to measured data according to dataset-specific exposure scenarios. Globally, 71% of the model predictions were within a 3-fold change of the measured data for chicken and only 7% of the PBK predictions were outside a 10-fold change. While most model input parameters still rely on in vivo experiments, in vitro data were also used as model input to predict internal concentration of the coccidiostat monensin. Future developments of generic PBK models in chicken and other species of relevance to animal health risk assessment are discussed.

Effects of dietary N-carbamylglutamate supplementation on growth performance, tissue development and blood parameters of yellow-feather broilers

The effects of N-carbamylglutamate (NCG) on the growth performance, tissue development, and blood parameters of broilers are unknown. In this study, 2 linked experiments were conducted to investigate the effects of 4 graded dietary levels and 3 dietary stages of NCG in a Chinese indigenous yellow-feather broiler breed during 2 growth phases: 1 to 18 d and 19 to 36 d. The dietary levels of NCG were 0.05%, 0.10%, 0.15%, and 0.20%, and dietary stages were designed to add NCG during the starter stage or grower stage or throughout the experimental period. At the age of 18 d, graded doses of NCG from 0.05 to 0.20% in the diet produced quadratic (P < 0.05) positive responses in body weight, width of intermuscular fat cingulum, liver weight, serum blood urea nitrogen, and serum low-density lipoprotein as well as linear (P < 0.05) positive responses in albumin serum concentration. The average feed per gain and mortality were unaffected by dietary NCG levels. Among 3 dietary treatments, only NCG dietary treatments throughout the experimental period improved the body weight and daily weight gain linearly (P < 0.05). The daily weight gain under the 3 dietary treatments used indicated that the most fitting dose is 0.1% NCG among the 4 dietary levels of NCG (P < 0.05). At this dose, muscle weight increased, whereas subcutaneous adipose as well as the serum contents of uric acid, triglyceride, and albumin decreased. Considering the growth performance and tissue development under the conditions used in this study, the best-fit model for NCG requirements of Chinese yellow-feather broilers was estimated from regression analysis to be 0.09 to 0.12% dietary NCG treatments during the grower stage. The modified blood parameters indicated that NCG dietary effects on broiler growth may be accompanied by modified homeostasis of arginine metabolism, lipid deposition, protein synthesis, and immune response.

Determination of the optimum arginine : lysine ratio in broiler diets

The study was conducted to determine the optimum dietary concentration of arginine relative to lysine on the basis of the performance, carcass traits and blood characteristics of 1–35-day-old broilers using a randomised complete block design. One-day-old broilers (n = 1200) were allocated to five dietary treatment groups receiving different arginine:lysine (Arg:Lys) ratios, where the proportion of Arg was progressively increased by increments of 10%, and the concentration of lysine was kept constant; the final ratios were 0.85, 0.95, 1.05, 1.16 and 1.26. Each diet treatment was composed of eight replicates (4 males and 4 females), with 30 chickens each replicate. All broilers were fed in three phases, namely starter, grower and finisher, at 1–10, 11–24 and 25–35 days of age respectively. An increase in the Arg:Lys ratio in the diet from 0.85 to 1.26 linearly (P &lt; 0.001) increased bodyweight gain by 7% and improved feed conversion ratio by 6%. Feed intake and mortality were not significantly (P &gt; 0.05) different among the treatments. Increasing the Arg:Lys ratio in the diet linearly (P &lt; 0.0001) and quadratically (P &lt; 0.05) improved the carcass yield and relative chilled carcass weight respectively. The percentages of breast meat and creatinine and insulin-like growth factor-1 concentrations also linearly (P &lt; 0.0001) increased by 5.5%, 23.0% and 18.0% respectively, with an increasing dietary Arg:Lys ratio. The results of the present study indicated that the highest dietary Arg:Lys ratio (1.26) improved bodyweight gain, feed conversion ratio, breast meat, creatinine and insulin-like growth factor-1. However, the optimum dietary Arg:Lys ratio to improve carcass yield and weight gain in the grower phase (Days 11–24 of age) was at 1.05.