Amino acid requirements for laying hens: a comprehensive review

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.

Graded concentrations of digestible lysine on performance of White Leghorn laying hens fed sub-optimal levels of protein

Objective

An experiment was conducted to study the effect of graded concentration of digestible lysine (dLys) on performance of layers fed diets containing sub-optimal level of protein.

Methods

Five diets were formulated to contain graded concentrations of dLys (0.700%, 0.665%, 0.630%, 0.593%, and 0.563%), but similar levels of crude protein (15% CP), energy (10.25 MJ ME/kg) and other nutrients. A total of 3,520 hens (26 wk of age) with mean body weight of 1,215+12.65 g were randomly divided into 40 replicate groups of 88 birds in each and housed in an open sided colony cage house. Each diet was offered ad libitum to eight replicates from 27 to 74 wk of age. The performance was compiled at every 28 d and the data for each parameter were grouped into three phases, that is early laying phase (27 to 38 wk), mid laying phase (39 to 58 wk), and late laying phase (59 to 74 wk of age) for statistical analysis.

Results

Egg production, egg mass and feed efficiency (feed required to produce an egg) were significantly improved by the dLys level during the early and mid laying phases but not during the late phase. Whereas feed intake was significantly reduced by dLys concentration during mid and late laying phases but not during early laying phase. The egg weight was not affected by dLys concentration in any of the three phases.

Conclusion

Based on best fitted statistical models, dietary requirements of dLys worked out to be 0.685%, 0.640%, and 0.586% during early phase, mid phase, and late egg laying phase, respectively. The calculated requirement of dLys for the respective production phases are 727 mg/b/d during the early and mid laying phases and 684 mg/b/d during the late laying phase in diets containing 15% CP.

Effect of incremental levels of dietary total sulfur amino acids on performance of white leghorn laying hens fed diets containing guar (Cyamopsis tetragonoloba) meal

BACKGROUND

The present study evaluated the potential of increasing dietary levels of the most limiting amino acids such as total sulfur amino acids (TSAA) with respect to mitigating the adverse effects of the inclusion of guar meal (GM) in the diet of WL layers on egg production, feed efficiency and egg weight. In total, 4928 WL (Lohmann L) hens (32 week of age) were randomly allotted to eight treatments with seven replicates of 88 birds. The dietary treatments were a set of four maize-soybean meal based diets containing four graded concentrations of TSAA (5.85, 6.18, 6.51 and 6.84 g kg^-1 ) and another set of four diets containing 100 g kg^-1 guar meal (GM) with similar concentrations of TSAA.

RESULTS

The inclusion of 100 g kg^-1 GM in the diet caused a 20%, 23%, 35.5% and 6.7% reduction in egg production, daily egg mass, feed efficiency and egg weight, respectively, when the diet contained 5.85 g kg^-1 TSAA. Increasing TSAA levels in GM groups reduced the adverse effects on egg production and feed efficiency 50%, with no effect on egg weight. The TSAA requirement of WL birds fed 10% GM was estimated as 6.28-7.39 g kg^-1 diet at different ages.

CONCLUSION

Increasing dietary TSAA to 7.39, 6.28, 6.53 and 6.37 g kg^-1 or dTSAA (digestible TSAA) to 6.53, 5.32, 5.80 and 5.63 g kg^-1 during 33-36, 37-40, 41-44 and 45-48 weeks of age, respectively, may be an effective and practical strategy for reducing the adverse effects of inclusion of 100 g kg^-1 GM in the diet of WL layers. © 2018 Society of Chemical Industry.

Effect of supplementation of lysine producing microbes vis-a-vis source and level of dietary protein on performance and egg quality characteristics of post-peak layers

Aim:

The aim was to study the effect of supplementation of lysine producing microbes (LPM) as an in vivo source of lysine on performance and egg quality characters of post-peak layers.

Materials and Methods:

BIS (1992) specified diets (except crude protein [CP] and lysine) were prepared using either soybean meal (SBM) or groundnut extractions (GNE) or sunflower extractions (SFE) with 16 and 15% CP resulting in six control diets. Further, each control diet was fortified with either synthetic lysine or LPM to meet BIS (1992) specified lysine requirement resulting in the set of 12 test diets. Each of the eighteen diets was offered to quadruplets groups of 4 post-peak (52 weeks) commercial laying hens in each. The trial lasted for 119 days.

Result:

The results revealed that the feed consumption and body weight changes and Roche yolk color and yolk index were significantly (p ≤ 0.05) different among different treatments. However, egg production, feed efficiency, egg weight, egg shape index, Haugh unit score, albumen index and shell thickness, and net returns remained non-significant (p ≤ 0.05) among different treatments. Among main factors, protein level (16% and 15% CP) made a significant (p ≤ 0.05) difference in egg production (79.6 and 75.1%) and feed efficiency (2.64 and 2.81 kg feed/kg egg mass, respectively). Among protein source GNE- and SFE-based diet fed groups showed significantly (p < 0.0%) higher feed consumption and body weight gain than SBM based diets fed birds. Yolk color (7.0, 7.3 and 7.3, respectively) and yolk index (0.40, 0.38 and 0.43, respectively) were significantly (p ≤ 0.05) different from the protein sources. CP level and Protein source interaction effects showed significant differences in albumen index and Haugh unit score.

Conclusion:

Optimum level of protein (16% CP) and GNE as a source of protein tended to be superior in increasing the performance and egg characteristics of post-peak layers and supplementation of lysine in either synthetic or LPM form found to be beneficial in optimizing their performance.

Effects of metabolizable energy and crude protein levels on laying performance, egg quality and serum biochemical indices of Fengda-1 layers

This study was conducted to investigate the effects of dietary ME and CP levels on laying performance, egg quality and serum biochemical indices of Fengda-1 layers. In a 2 × 3 factorial arrangement, 2,400 Fengda-1 layers (32 wk of age) were randomly assigned to 6 experimental diets with 2,650 and 2,750 kcal of ME/kg of diet, each containing 14.50%, 15.00% and 15.50% CP, respectively. Each dietary treatment was replicated 5 times, and feed and water were provided ad libitum. The trial lasted for 10 wk, including a 2-week acclimation period and an 8-week experimental period. Our results showed that ADFI decreased as the ME level of diet increased from 2,650 to 2,750 kcal/kg (P < 0.05). Layers fed diets with 2,750 kcal/kg ME exhibited higher mortality than those fed with 2,650 kcal/kg ME (P < 0.05). Birds fed with 14.50% and 15.00% CP had higher egg production (EP) and egg mass (EM) than those fed with 15.50% CP (P < 0.05). Yolk color increased as the ME level of the diet increased from 2,650 to 2,750 kcal/kg, however, the eggshell thickness decreased (P < 0.05). Serum concentrations of uric acid and triglyceride in layers fed diets with 2,750 kcal/kg ME were higher than those fed diets with 2,650 kcal/kg ME (P < 0.05). There was no significant interaction between ME and CP on laying performance, egg quality, or serum biochemical indices (P > 0.05). Based on the data under the experimental conditions, the optimal dietary ME and CP levels of Fengda-1 layers are 2,650 kcal/kg and 15.00% (33 to 41 wk of age).

Effect of supplementation of crystalline lysine on the performance of WL layers in tropics during summer

A trial was conducted to evaluate the effect of lysine concentration in the diet of WL layers with constant ratio of other essential amino acids to lysine. Pullets (528) aged 25 to 36 weeks were fed with test diet containing two protein levels (13.36 and 15.78%) each with 5% concentration of lysine (0.50, 0.55, 0.60, 0.65, and 0.70) and a control with 17% CP and 0.70%, lysine. Each test diet was fed ad libitum to six replicates of eight birds for a period of 12 weeks. Egg production (EP), egg weight (EW), egg mass (EM), feed efficiency (g/g) (FE), body weight gain (BWG), Haugh unit (HU) and yolk colour (YC) were measured. Increased (P ≤ 0.05) EP, EW, EM, FE and BWG were obtained with increasing lysine concentration in diets. Whereas, feed intake/h/day, feed intake/egg, egg shell defects (ESD), mortality and shell thickness were not affected (P ≥ 0.05) by the concentration of lysine in diet. However, higher (P ≤ 0.05) HU score and YC were noticed at low lysine (0.50 %) concentrations. Based on this, it was concluded that WL layers (25-36 weeks) reared in open-sided houses in the tropics require approximately 0.70 % lysine (597.90 vs. 584.39 mg/h/day) in low (13.36% CP) and high (15.78% CP) protein groups in diets containing approximately 2700 kcal of ME/kg in summer.

Dietary Protein Sources Affect Internal Quality of Raw and Cooked Shell Eggs under Refrigerated Conditions

This study was conducted to evaluate the effects of various protein sources (soybean meal, SBM; cottonseed protein, CSP; double-zero rapeseed meal, DRM) on the internal quality of refrigerated eggs. A total of 360 laying hens (32 wk of age) were randomly allotted to six treatment groups (five replicates per treatment) and fed diets containing SBM, CSP, or DRM individually or in combination with equal crude protein content (SBM-CSP, SBM-DRM, and CSP-DRM) as the protein ingredient(s). A 6×3 factorial arrangement was employed with dietary types and storage time (0 d, 2 wk, and 4 wk) as the main effects. After 12 wk of diet feeding, a total of 270 eggs were collected for egg quality determination. The egg Haugh unit (HU) in the CSP, SBM-DRM, and DRM groups were significantly lower than those in the SBM and SBM-CSP groups. The hardness and springiness of the cooked yolk in the CSP group were significantly higher than those in the other treatment groups. A lower HU, lower yolk index and higher albumen pH were observed in the DRM group compared to the SBM and SBM-CSP groups when the eggs were stored to 4 wk, and the HU was improved in the CSP-DRM group compared to the DRM group (p<0.05). Higher yolk hardness was observed in the CSP group compared to the other groups during storage (p<0.05), but the hardness of the cooked yolk in the SBM-CSP and CSP-DRM groups showed no difference in comparison to the SBM group. In conclusion, CSP may ameliorate the negative effects of DRM on the HU of refrigerated eggs, and SBM or DRM may alleviate the adverse effects of CSP on yolk hardness.

Effects of balanced dietary protein levels on egg production and egg quality parameters of individual commercial layers

The effects of a series of balanced dietary protein levels on egg production and egg quality parameters of laying hens from 18 through 74 wk of age were investigated. One hundred forty-four pullets (Bovans) were randomly assigned to individual cages with separate feeders including 3 different protein level series of isocaloric diets. Diets were separated into 4 phases of 18-22, 23-32, 33-44, and 45-74 wk of age. The high protein (H) series contained 21.62, 19.05, 16.32, and 16.05% CP, respectively. Medium protein (M) and low protein (L) series were 2 and 4% lower in balanced dietary protein. The results clearly demonstrated that the balanced dietary protein level was a limiting factor for BW, ADFI, egg weight, hen day egg production (HDEP), and feed per kilogram of eggs. Feeding with the L series resulted in lower ADFI and HDEP (90.33% peak production) and more feed per kilogram of eggs compared with the H or M series (HDEP; 93.23 and 95.68% peak production, monthly basis). Egg weight responded in a linear manner to balanced dietary protein level (58.78, 55.94, and 52.73 g for H, M, and L, respectively). Feed intake of all hens, but especially those in the L series, increased considerably after wk 54 when the temperature of the house decreased due to winter conditions. Thus, hens fed the L series seemed particularly dependent on house temperature to maintain BW, ADFI, and HDEP. For egg quality parameters, percent yolk, Haugh units, and egg specific gravity were similar regardless of diets. Haugh units were found to be greatly affected by the variation of housing temperature (P = 0.025). Maximum performance cannot always be expected to lead to maximum profits. Contrary to the idea of a daily amino acid requirement for maximum performance, these results may be used to determine profit-maximizing levels of balanced dietary protein based on the cost of protein and returns from different possible protein levels that may be fed.

Effect of three protein levels and an enzyme blend on egg quality of laying hens

One approach to enhance the Crude Protein (CP) value of laying hens diets it is the use of enzymes. The objective of this experiment was to evaluate different CP levels and an enzyme blend (Avizyme; AZ) in laying hens diets on egg quality. Two hundred and eighty eight ISA Babcock B-300 hens were used. The diets were: (A) 18.8% CP, (B) 18.8% CP+AZ, (C) 16.6% CP, (D) 16.6% CP+AZ, (E) 16.0% CP and(F) 15.4% CP. Data were analyzed using analyses of variance for factorial designs (Diets A, B, C and D) and a complete randomized design (Diets C, E and F). CP or AZ had no effect on egg quality (p>0.05). Reduction of CP in laying hen diets tended (p<0.08) to increase feed intake (90.8, 93.6 and 96.5 g day(-1)) and feed conversion (p<0.05) (2.1, 2.2 and 2.3) for 16.6, 16.0 y 15.4% of CP, respectively. Reduction of CP in laying diets increased (p<0.05) albumen height (11.4, 11.9 y 11.9 mm). Significant (p<0.05) reductions of feed intake (96.2 vs 89.9 g day(-1)) and feed conversion (2.1 versus 2.0) in diets supplemented AZ were observed. Significant (p<0.05) interactions of PC and AZ on feed intake and feed conversion were found. The reduction of CP in the diets did not affect egg quality, but has an effect on feed intake and feed conversion. Avizyme supplementation reduced feed intake and improve feed efficiency in high CP diets.

Influence of different concentrations of metabolisable energy at constant ratio to dietary protein, lysine, methionine, calcium and phosphorus on the performance of White Leghorn layers in the tropics

An experiment was conducted to study the effect of nutrient density on the performance (21–72 weeks of age) of White Leghorn layers reared in an open-sided poultry house in the tropics. Six diets with graded levels (9.62–11.72 MJ/kg) of metabolisable energy (ME) with an increment of 0.42 MJ were formulated. Concentrations of crude protein, lysine, methionine, calcium and non-phytate phosphorus were kept constant to ME in all diets (15.9, 0.73, 0.35, 3.19 and 0.31 g/MJ ME, respectively). At 21 weeks of age, a total of 5280 birds was distributed randomly in 4-bird colony cages and 22 such cages in a row constituted one replicate. Each diet was fed ad libitum to 10 replicates from 21 to 72 weeks of age and performance parameters were recorded at 28-day intervals (period, 1–13). Egg production (EP) increased (P < 0.05) with increasing dietary ME and maximum response in EP was observed when dietary ME levels ranged between 10.93 and 11.69 MJ/kg during the majority of periods, while in periods 6, 7 and 8 (summer, 28−37°C), maximum EP was observed at higher ME levels in diet (11.64–11.69 MJ/kg diet). Feed intake (P < 0.01) decreased, feed efficiency (P < 0.01), egg mass (P < 0.01) and weight gain (P < 0.05) improved quadratically with increase in dietary ME concentration. Maximum feed efficiency was observed at 11.36 MJ ME/kg diet during 21–72 weeks of age. Egg shell defects were not influenced (P > 0.05) by dietary nutrient density. Mortality reduced quadratically with increase in dietary ME concentration and mortality was minimum at 11.64 MJ ME/kg diet. Based on results from the experiment it was concluded that White Leghorn layers (21–72 weeks of age) require 11.36 MJ ME/kg diet for maximum egg production, feed efficiency and egg mass with better liveability. The calculated intake of metabolisable energy, crude protein, lysine, methionine, calcium and non-phytate phosphorus in layers fed 11.30 MJ ME/kg diet was 1.157 MJ, 18.42 g, 865 mg, 409 mg, 3.68 g and 358 mg per bird per day, respectively.