The replacement of some of the soybean meal by the first‐limiting amino acids in practical broiler diets

Amino Acids Supplementation Affects Sustainability of Productive and Meat Quality, Survivability and Nitrogen Pollution of Broiler Chickens during the Early Life

The response to amino acid (AAs) supplementation on broiler production, carcass and meat traits and nitrogen in the excreta during the early growth period was evaluated. Two experiments were performed during 1-28 d (245 birds, experiment 1) and 1-21 d of age (455 birds, experiment 2). In both experiments, the positive control (PC) diet had 22.5% crude protein (CP) and the negative control group (NC) diet had around 18% CP with the same methionine (Met) plus lysine (Lys) concentration as the PC diet. In experiment 1, the NC diet was fed to the other five groups supplemented with synthetic amino acids, such as L-arginine (Arg), L-threonine (Thr), L-valine (Val), L-isoleucine (Ile) or all these AAs, respectively. In experiment 2, the NC diet was formulated to contain 18% CP with either corn-soybean meal and animal protein or with only vegetable protein. Both NC diets were offered to the other ten groups with synthetic amino acids such as L-Arg, L-Thr, L-Val, L-tryptophan (Trp) or a combination of all these AAs plus L-isoleucine (Ile), respectively. In conclusion, broilers fed 18% CP supplemented with DL-Met plus L-Lys showed lower performance and a European production efficiency value (EPEV); Arg, Thr and Val addition improved growth, the feed conversion ratio and EPEV of the diets containing animal protein only, but broiler performance and EPEV was lower than with PC, indicating that DL-Met, L-Lys, L-Arg, L-Thr and L-Val supplementation may be limited in low-protein diets. Furthermore, a low-protein diet supplemented with amino acids did not affect the survivability of broilers up to 28 days of age.

Effects of lysine biomass supplementation on growth performance and clinical indicators in broiler chickens

Production of crystalline amino acids (AA) through microbial fermentation concomitantly provides an AA-enriched biomass that may serve as a cost-effective supplement for broiler chickens. We investigated the effects of feeding a fermentation biomass product containing approximately 62% Lys on growth performance, organ growth, and clinical outcomes of broilers. Beginning at 2 d post-hatch, a total of 360 Ross 308 chicks were randomly assigned to 1 of 5 treatments provided to 12 replicate cages of 6 birds. Practical corn-soybean meal-based dietary treatments included: negative control (NC; no supplementation of L-Lys, 1.01 and 0.86% standardized ileal digestible Lys in starter and grower phases, respectively), NC + 0.23% L-Lys HCl (positive control; PC), and NC supplemented with 0.30, 0.90, or 1.50% Lys biomass (LB) in both phases. Feed and water were provided ad libitum throughout the study. Individual bird and feeder weights were recorded on study day 0, 10, 21, and 35. At study conclusion, birds from each treatment were randomly selected to collect blood and tissue samples. The PC and 0.30% LB diets elicited similar overall (day 0–35) body weight gain and birds were heavier (P < 0.001) than the NC and other LB treatments. The PC, 0.30% LB, and 0.90% LB groups had better (P < 0.001) overall feed conversion ratio than NC. Some LB-supplemented treatments elicited increased (P < 0.001) relative spleen and ileum weight compared with NC and PC. Heterophils were increased (P < 0.001) in LB treatments compared with PC and NC. Lymphocytes were decreased (P < 0.001) in LB treatments compared with NC, and 1.50% LB was similar to PC. This resulted in an increased (P < 0.001) heterophil-to-lymphocyte ratio in some LB treatments, which may have resulted from general AA supplementation or the LB product. Collectively, these results suggest that addition of up to 0.30% LB restored growth performance when added to a Lys-deficient practical diet and elicited results identical to the Lys-adequate PC diet with no negative clinical effects.

Multiple Amino Acid Supplementations to Low-Protein Diets: Effect on Performance, Carcass Yield, Meat Quality and Nitrogen Excretion of Finishing Broilers under Hot Climate Conditions

The objective of this study was to evaluate the effect of low-protein diets with amino acid supplementation on growth performance, carcass yield, meat quality and nitrogen excretion of broilers raised under hot climate conditions during the finisher period. In trial 1, broilers from 28 to 49 days of age were fed 18% crude protein (CP) as a positive control or 15% CP supplemented with (1) DL-methionine (Met) + L-lysine (Lys), (2) Met + Lys + L-Arginine (Arg), or (3) Met + Lys + L-Valine (Val). In trial 2, broilers from 30 to 45 days of age, were fed an 18% CP diet as a positive control or 15% CP supplemented with Met, Lys, Arg, Val, L-Isoleucine (Ile) or combination with glycine (Gly) and/or urea as nitrogen sources: (1) Met + Lys, (2) Met + Lys + Arg, (3) Met + Lys + Val, (4) Met + Lys + Ile, (5) Met + Lys + Arg +Val + Ile + Gly, and (6) Met+ Lys + Arg + Val + Ile + Gly + urea. Protein use was improved by feeding low-protein amino acid-supplemented diets as compared to the high-protein diet. Feeding 15% crude protein diet supplemented with only methionine and lysine had no negative effects on carcass yield, CP, total lipids and moisture% of breast meat while decreasing nitrogen excretion by 21%.

Effect of cellulase supplementation in low-crude protein diets on performance, nitrogen excretion, fat deposition, hepatic lipogenic and lipolytic enzyme activity in broilers

1. Two experiments were conducted to investigate the effect of dietary enzyme supplementation of a low-protein diet on performance, nitrogen excretion, fat deposition, hepatic lipogenic and lipolytic enzyme activity in 7-21- (Experiment 1) and 21-42-d-old (Experiment 2) male broiler chicks. 2. Chicks were given diets containing 210 g (Experiment 1) or 170 g (Experiment 2) crude protein (CP)/kg (Control), amino acid-fortified diets 190 g (Experiment 1) and 150 g (Experiment 2) CP/kg (Low-protein), and a low-protein diet supplemented with 1000 U/kg of cellulase. 3. In Experiment 1, growth performance and abdominal fat deposition were not affected by dietary treatments, and birds given low-protein diets excreted less nitrogen. The activities of hepatic lipogenic and lipolytic enzymes were not different among the three dietary groups. 4. In Experiment 2, the dietary treatment did not affect growth performance or abdominal fat weight. Nitrogen excretion was significantly lower in chicks given the 150 g/kg CP diet than those on the 170 g/kg CP diet; however, nitrogen retention was no different among the treatments. Dietary CP and enzyme supplementation did not significantly affect hepatic enzyme activities. 5. These results suggest that CP content in the broiler diet can be reduced by 20 g/kg without lowering performance by the supplementation of crystalline amino acids, and can reduce nitrogen excretion by about 25%. Cellulase supplementation of a low-CP diet slightly lowered abdominal fat deposition; however, it did not significantly affect hepatic lipogenic and lipolytic enzyme activity.

Moderate excess of dietary protein increases breast meat yield of broiler chicks

Two factorial experiments were carried out to evaluate the effects of dietary protein level, expressed as energy to protein (E:P) ratio, on yields of carcass and breast and on abdominal fat pad weight of male broiler chicks at 43 and 57 d of age. Two diets similar in their energy content and differing markedly in their protein content, in which the E:P ratios were lower and identical to the NRC (1994) recommendations, were used in Experiment 1. Four diets, the combination of two energy and two protein levels, in which the E:P ratios were lower and identical to the recommendations, were used in Experiment 2. There were no differences in feed intake or weight gain until 42 d of age between broilers fed the diets with the low and those fed the recommended E:P ratio. However, feed efficiency of the former was consistently and significantly (P < 0.05) higher. The high-energy diets did not affect feed intake but significantly improved weight gain between 7 and 28 d of age and feed efficiency until 42 d of age. In both experiments, carcass yield was not affected by dietary E:P ratio at 43 d of age; however, at 57 d of age it was increased significantly by the low E:P ratio in Experiment 1 and in birds fed the high energy diet in Experiment 2. On a factorial basis, the effect of the low E:P ratio on increasing yield was significant only in Experiment 1. The high dietary energy level increased carcass yield only at 43 d of age, but on a factorial basis its effect was significant. Carcass yield was significantly (P < 0.001) higher at 57 than at 43 d of age. In both experiments, breast meat yield was negatively correlated with dietary E:P ratio, a significant factorial effect. The difference in this variable between broilers fed the diets containing the low and the recommended E:P ratio was significant, at both ages in Experiment 1, and only at 57 d of age in Experiment 2. Breast meat yield was not affected by dietary energy level, and it was significantly (P < 0.001) higher at 57 than at 43 d of age. Relative abdominal fat pad weight was increased significantly by increasing dietary E:P ratio. Dietary energy level and age did not affect this variable. The relationship between abdominal fat pad weight and breast meat yield within the treatments tended (in most of the cases not significantly) to be negative. However, this negative relationship was significant, at both ages, when the analysis was carried out with the pooled data at each age. It is concluded that the optimal E:P ratio for maximal breast meat yield for broiler chicks, particularly at 57 d of age, may be below the NRC (1994) recommendations.

Effect of a lysine-enriched diet on L-lysine transport by the brush-border membrane of the chicken jejunum

The influx of L-lysine into apical vesicles from the chicken jejunum occurs through two systems, one with low Michaelis constant (K(m)) and features of system b0,+ and the other with relatively high K(m) for L-lysine and with properties of system y+. In the present study the effect of a lysine-enriched diet (Lys, containing 68 g L-lysine/kg dietary protein, control animals 48 g/kg) on L-lysine uptake through both transport systems was investigated. Results show that 1) lysine enrichment had no effect on either body weight or the efficiency of food utilization. 2) In Lys-fed animals, the mediated L-lysine influx was best fitted to the two-system model with y+ and b0,+ activity. 3) In the presence of an Na+ gradient, total L-lysine uptake is significantly higher in Lys-fed animals than in control birds (about 40% increase). 4) Lys diet increases K(m)b0,+ 6-fold (KSCN gradient) and 12-fold (NaSCN gradient) and maximum velocity (Vmax) by 6- and 20-fold, respectively. The effects of Lys enrichment on the y(+)-like system are only observed on the Vmax and in the presence of a Na+ gradient (30% increase). 5) Na+ is involved in the activation of the transport process in the Lys-fed chickens, but there is no correlation between external Na+ concentration and L-lysine influx. In conclusion, both b(0,+)- and y(+)-like transport systems are upregulated by dietary lysine but with different kinetic profiles; the high-capacity y(+)-like carrier shows a Vmax increase without changes in K(m), whereas the low-capacity b(0,+)-like system shows an increase in Vmax as well as in the K(m).

Effect of dietary protein, essential and non-essential amino acids on the performance and carcase composition of male broiler chickens

1. The present study was conducted to determine the possibility of using low-protein broiler diets supplemented with synthetic amino acids. The effects on performance, carcase composition and nitrogen retention were evaluated. 2. A starter diet was given, ad libitum, from 7 to 21 and a finisher diet from 21 to 42 d of age. Body weight, weight gain, food intake and food conversion (FC) were determined at 3 and 6 weeks of age. Abdominal fat deposition (AFD), carcase yield, carcase fat and protein and nitrogen retention were determined at 6 weeks of age. During the starter period chicks were given a 231 g/kg crude protein (CP) diet and a low protein diet supplemented with synthetic amino acid, a: to National Research Council recommendations, b: to the concentration of the control diet, and c: in agreement with the pattern of body composition. Glutamic acid and glycine were added to some diets as sources of non-essential amino acids (NEAA). All diets contained 12.62 MJ metabolisable energy (AMEn)/kg. The diets administered between 3 and 6 weeks were comparable to the starter diets, except that they contained more AMEn (12.85 MJ/kg) and less protein. 3. Performance equal to that of high protein controls was obtained with birds fed a low protein diet supplemented with synthetic essential and NEAA to the amounts in the control diet or based on the amino acid profile of body protein. This was not achieved with low protein diets supplemented with synthetic amino acids to the amounts recommended by NRC. 4. Without altering performances, the efficiency of protein utilisation of birds fed on low protein diets was superior to that of birds fed on the commercial control diet and their nitrogen excretion was reduced by 26%. The percentage carcase yield and protein was unaffected by the dietary regimen but carcase fat content and AFD increased as the protein content of the diet decreased. 5. These results show that it is possible to obtain the same performances with low protein diets supplemented with synthetic amino acids, using an ideal amino acid balance. However, low protein diets result in a higher carcase fat content.

The effect of minimizing amino acid excesses in broiler diets

A series of experiments were conducted to evaluate the performance of 7- to 21-day-old broilers fed diets in which excesses of essential amino acids (EAA) were minimized. A 23% protein diet in which all EAA except TSAA were in excess was reduced in protein in a stepwise manner, keeping the corn; soybean meal ratio constant, to the point where all EAA were at minimum requirement level based on the 1984 National Research Council (NRC) requirements. Crystalline EAA supplemented those EAA that became deficient as dietary protein was reduced. Other test diets included one containing an additional 10% of the particular EAA in question and one with nonessential amino acids (NEAA) added to make the low-protein diet isonitrogenous with the 23% control. Performance of birds fed the low-protein test diets was not significantly different from that of the control birds. All EAA appeared to be adequate at levels recommended by the NRC in 1984 except Trp, which required .25% for optimal performance. A growth response was observed when Gly was used as the NEAA source; however, no response was noted when mixtures of NEAA were used as the NEAA source, suggesting that Gly may have been limiting in these earlier treatments. Total carcass protein of birds fed the low-protein test diets in which all EAA were minimized was equal to that of the control birds. In a final experiment utilizing the EAA-balanced, low-protein diet, dietary energy was allowed to vary by 15%. The EAA intake was constant, indicating that birds were eating to satisfy EAA requirements rather than energy requirements. Increased carcass fat deposition paralleled dietary energy increases.

Dietary protein level and essential amino acid content: influence upon female broiler performance during the grower period

Three experiments were conducted to determine effects of dietary CP level and essential amino acid (EAA) content upon female broiler performance during the grower period (21 to 42 days). In each experiment, the design included a diet containing a conventional CP level (17.8 to 19.0%) and a low CP diet (15.9 to 16.7%) supplemented with several EAA. Regardless of CP content, all diets were formulated to meet National Research Council requirements in 1984 of EAA and to be isocaloric. As additional treatments, modifications of the low CP diet were made in an attempt to improve broiler performance. In Experiments 1 and 2, body weight gain (BWG) and feed efficiency (FE) were significantly impaired by feeding the low CP diet despite various combinations of increased levels of methionine, lysine, arginine, threonine, isoleucine, and tryptophan. In Experiment 3, BWG and FE were not significantly influenced by dietary CP level. Feed intake was unaffected by treatment except when a high level of glutamic acid (GLU) was added; this lowered the intake. The low CP diets increased abdominal fat deposition, which was prevented by 5% GLU supplementation. Breast yield was not affected by diet composition. Plasma free amino acids responded, in some cases, to changes in dietary EAA content.

The amino acid requirements of chicks: experimental validation of model-calculated requirements

The amino acid requirements of broiler chicks, on a weekly or biweekly basis, were calculated according to a model presented previously (Hurwitz et al., 1978). Based on the present results, the model has been somewhat modified. The model requirements provided the basis for computer-designed diets which were fed to chicks of different ages and were composed to others computed on the basis of NRC (1971, 1977) requirements. In all cases the model-based diets, which were considerably lower in protein, supported weight gains equivalent to those obtained on NRC-based diets. The relatively poorer feed efficiency observed in the first trial with chicks fed the model-based diets, could be alleviated by equalizing both energy and lipid concentrations in the experimental diets. Thus, equal growth and feed efficiency were obtained with the model and NRC (1971)-based diets, for 2- to 10-week-old chicks. The possible reasons for the slightly higher abdominal fat content of the chicks fed the model-based diets are discussed.

The sparing action of inorganic sulphate on sulphur amino acids in practical broiler diets: preliminary trials with young chicks

1. In three trials marked responses to Na2SO4 were obtained, both in terms of growth rate and of food/gain ratio. In a fourth trial the chicks responded to graded additions of synthetic methionine but not to inorganic sulphate. 2. The response of the chicks to Na2SO4 depended on the amount of sulphur amino acids in the diets, being absent or difficult to demonstrate in severely deficient diets or in those adequately supplemented, respectively. 3. Sodium sulphate cannot replace more than about 0-05% supplementary methionine. 4. Usually the efficacy of Na2SO4 in improving performance appeared to range from 40% to 60% that of synthetic methionine.