The main aim of this review is to consolidate the relevant published data examining amino acid requirements of layer hens and to reach a new set of recommendation based on these data. There are inconsistences in lysine, sulphur-containing amino acids, threonine, tryptophan, branched-chain amino acids, and arginine recommendations in data that have surfaced since 1994. This review finds that breed, age, basal diet composition, and assessment method have contributed toward inconsistencies in amino acid recommendations. Presently, the development of reduced-protein diets for layer hens is receiving increasing attention because of the demand for sustainable production. This involves quite radical changes in diet composition with inclusions of nonbound, essential and nonessential amino acids. Increasing inclusions of nonbound amino acids into layer diets modifies protein digestive dynamics, and it may influence amino acid requirements in layer hens. This review considers present amino acid recommendations for layer hens and proposes refinements that may better serve the needs of the layer industry in the future.

The aim of this study was to investigate the effect of dietary emulsifiers and lipase supplementation on growth performance, blood metabolites, intestinal organ weight, gut morphology, nutrient digestibility, carcass measurements, and meat quality in broiler chickens. A total of 384, 1-day-old Ross 308 broiler chicks were randomly allocated to one of eight dietary treatments arranged in a completely randomized design with 6 replications per treatment and 8 birds per cage. Diets were corn-soybean meal-based and formulated to meet the nutritional requirements for Ross 308 specifications. Beef tallow used as the fat source in all diets. Dietary treatments were as follows, (1) positive control (PC; energy sufficient diet); (2) negative control (NC; energy deficient,−100 ME, kcal/kg); (3) NC+POL (0.1%, Polysorbate-20); (4) NC+CET (0.1%, Ceteth-20); (5) NC+POL+TLL (0.1%, Thermomyces lanuginosus lipase); (6) NC+POL+CRL (0.1%, Candida rugosa lipases); (7) NC+CET+CRL and (8) NC+LL (0.05%, Lysolecithin). Growth performances were measured weekly. One bird per pen was selected and sacrificed to collect blood, ileal digesta, jejunum sample, viscera organ weight, and meat samples on day 21 and 35. Results revealed that birds fed NC+POL+CRL diet had higher (P < 0.05) body weight, weight gain, and the improved (P < 0.05) feed efficiency compared to birds fed other low energy diets, and the effect was more prominent at the grower phase from day 21 to 35. Similarly, higher (P < 0.05) villi height and lower (P < 0.05) crypt depth commensurate with higher (P < 0.05) V:C ratio were observed with the broiler chickens fed NC+POL+CRL diet compared to broiler chickens fed NC diet on day 21 and 35. Moreover, broiler chickens fed NC+POL+CRL diet showed improved fat and energy digestibility compared NC diet counterpart on day 35. This study, therefore indicated that Polysorbate-20 together with Candida rugosa lipases had promising ability to improve growth performance of broiler chickens fed with low energy diet and curtail the growth depression without affecting blood metabolites, carcass, and visceral organs weights.

The prime purpose of this review is to explore the pathways whereby progress towards reduced-crude protein (CP) diets and sustainable chicken-meat production may be best achieved. Reduced-CP broiler diets have the potential to attenuate environmental pollution from nitrogen and ammonia emissions; moreover, they have the capacity to diminish the global chicken-meat industry’s dependence on soybean meal to tangible extents. The variable impacts of reduced-CP broiler diets on apparent amino acid digestibility coefficients are addressed. The more accurate identification of amino acid requirements for broiler chickens offered reduced-CP diets is essential as this would diminish amino acid imbalances and the deamination of surplus amino acids. Deamination of amino acids increases the synthesis and excretion of uric acid for which there is a requirement for glycine, this emphasises the value of so-called “non-essential” amino acids. Starch digestive dynamics and their possible impact of glucose on pancreatic secretions of insulin are discussed, although the functions of insulin in avian species require clarification. Maize is probably a superior feed grain to wheat as the basis of reduced-CP diets; if so, the identification of the underlying reasons for this difference should be instructive. Moderating increases in starch concentrations and condensing dietary starch:protein ratios in reduced-CP diets may prove to be advantageous as expanding ratios appear to be aligned to inferior broiler performance. Threonine is specifically examined because elevated free threonine plasma concentrations in birds offered reduced-CP diets may be indicative of compromised performance. If progress in these directions can be realised, then the prospects of reduced-CP diets contributing to sustainable chicken-meat production are promising.

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The present study investigated the effects of supplementing a low protein ( LP ) diet supplemented with key essential amino acids ( AA ) to broilers on growth performance, intestinal tract function, blood metabolites, and nitrogen excretion when the animals were maintained under various sanitary conditions for 35 D after hatching. Three hundred eighty-four one-day-old male broilers (Ross 308) were randomly allotted to groups that received one of 6 dietary treatments in a 2 × 3 factorial arrangement (i.e., 2 environmental conditions and 3 dietary treatments) to give 8 replicates per treatment. Broilers were challenged with 2 environmental conditions (sanitary vs. poor sanitary). The dietary treatments were (1) high protein ( HP ) diet, (2) LP diet, and (3) LP diet with synthetic key essential AA ( LPA ): the LP diet was supplemented with synthetic AA up to the required levels for broilers. On day 14, birds consumed the LP diet impaired growth performance compared with those fed the HP diet, while the average daily weight gain-to-feed conversion ratio of birds fed the LPA diet improved to the level of birds fed the HP diet under poor sanitary conditions ( P < 0.05). Broilers raised under poor sanitary conditions and fed the LP diet displayed higher ( P < 0.05) zonula occludens (ZO-1) expression on day 14 than broilers fed either the HP or LPA diet. Under sanitary conditions, birds fed HP and LPA diets showed higher villus height and crypt depth compared with those of broilers fed the LP diet on day 35. Moreover, broilers raised in the poor sanitary environment had higher ( P < 0.05) serum endotoxins than those raised in the sanitary environment. Broilers fed the LPA diet showed reduced ( P < 0.05) nitrogen excretion on days 14 and 35 compared with those fed the LP and HP diets independent of the environment. In conclusion, the LPA diet did not impair growth performance under poor sanitary conditions for 14 D after hatch while resulting in lower nitrogen excretion in any environment conditions throughout the experiment.

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Objective: To evaluate calcium stearoyl-2 lactylate (CSL) performance as an exogenous emulsifier together with lipase for broiler diets.Methods: In total, 252 one-day-old Ross 308 broiler chickens were allocated in a completely randomized design to give 6 replications per treatment with 7 birds in each cage. There were six dietary treatments representing a 2×3 factorial arrangement consisted of two energy levels (standard energy [positive control, PC] and –100 kcal/kg of the requirement level [negative control, NC]) and three dietary treatments (without additives [CON], CON+CSL [CSL], and CON+CSL+lipase [CSL-Lipase]). Corn and soybean meal-based experimental diets containing vegetable oil were formulated. Growth performance, blood parameters, visceral organ weights, ileal morphology, nutrient digestibility, and cytokine gene expression were measured.Results: Birds fed a diet including CSL increased (p<0.05) lipase level in blood compared to birds fed a diet including CSL-Lipase on day 21. Similarly, higher (p<0.05) liver weight was observed in birds fed a diet including either CSL or CSL-Lipase on day 21. Birds fed NC diet with CSL improved (p<0.05) nutrient digestibility compared to the NC diet on day 21. However, birds fed a diet supplemented with CSL or CSL-Lipase did not affect (p>0.05) the weight gain, feed efficiency, ileal morphology, and cytokine concentrations during the experiment period, regardless of dietary energy levels.Conclusion: Our results indicated that CSL has a role in improving nutrient digestibility in young birds when supplemented to a corn-soybean meal based broiler diet.

Objective: An experiment was conducted to investigate the response of laying hens fed corn distiller' s dried grains with solubles (DDGS) that are naturally contaminated with deoxynivalenol (DON). Methods: One hundred and sixty 52-week-old Lohmann Brown Lite hens were randomly allotted to five dietary treatments with 8 replicates per treatment. The dietary treatments were formulated to provide a range of corn DDGS contaminated with DON from 0% to 20% (i.e., 5% scale of increment). All laying hens were subjected to the same management practices in a controlled environment. Body weight, feed intake and egg production were measured biweekly for the entire 8-week experiment. The egg quality was measured biweekly for 8 weeks. On weeks 4 and 8, visceral organ weights, blood metabolites, intestinal morphology, and blood cytokine concentrations were measured. Results: The inclusion of corn DDGS contaminated with DON in the diet did not alter (p> 0.05) the body weight, feed intake, hen-day egg production, egg mass and feed efficiency of the laying hens. No difference was found (p>0.05) in the egg quality of hens that were fed the dietary treatments. Furthermore, hens that were fed a diet containing corn DDGS contaminated with DON showed no change (p>0.05) in the visceral organ weights, the blood metabolites, and the cytokine concentrations. The crypt depth increased (p<0.05) as the amount of corn DDGS contaminated with DON increased. Proportionately, the villus height to crypt depth ratio of the laying hens decreased (p<0.05) with the increasing level of corn DDGS contaminated with DON in the diet. Conclusion:The inclusion of corn DDGS contaminated with DON up to 20% in layer diets did not cause changes in egg production performance and egg quality, which indicates that DON is less toxic at the concentration of 1.00 mg DON/kg.