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Three experiments (Exp) were conducted to determine optimal digestible Ile to Lys ratios for male Yield Plus × Ross 708 broilers from approximately 1.0 to 4.0 kg BW. Broilers were fed dose-response diets with inclusions of blood cells that were formulated to contain a gradient of digestible Ile to Lys ratios (0.46 to 0.83). Treatments for Exp 1 to 3 were fed from 21 to 35, 28 to 42, and 35 to 49 d of age, respectively, to target market weights from 2.5 to 4.0 kg. Experiments utilized positive control (PC) diets that did not contain blood cells and were formulated to the same Ile ratios as Treatment 5. Birds and feed were weighed by pen on the first and last days of the experimental period to determine growth performance. Selected broilers were processed and deboned to determine carcass characteristics. For all Exp, quadratic effects (P ≤ 0.001) were observed with BW gain, feed conversion ratio (FCR), breast meat weight, and breast meat yield (BMY) as digestible Ile to Lys ratios increased. Contrasts between PC and Treatment 5 for each Exp displayed no effect of blood cell inclusion with the exception of FCR in Exp 1 (P = 0.001) and BMY in Exp 3 (P = 0.017). Optimum digestible Ile to Lys ratios for Exp 1 were determined to range from 0.640 to 0.725 for growth from 1.0 to 2.5 kg BW (P ≤ 0.001) and breast meat characteristics. In Exp 2, optimum ratios ranged from 0.664 to 0.682 for growth and breast meat characteristics from 1.6 to 3.1 kg BW (P ≤ 0.001). For growth and breast meat characteristics of broilers in Exp 3, optimum ratios ranged from 0.625 to 0.730, from 2.6 to 3.9 kg BW (P ≤ 0.001). Based on these findings, optimum digestible Ile to Lys ratios were determined to range from 0.63 to 0.73 for broilers from 1.0 to 4.0 kg BW., Competing Interests: DISCLOSURES The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

An experiment (2 trials) was conducted to determine the effects of feeding reduced crude protein (CP) diets to Ross × Ross 708 male broilers while maintaining adequate essential amino acid (AA) concentrations on growth performance, nitrogen excretion, and plasma uric acid (UA) concentration during the starter period. In trial 1, 11 dietary treatments were fed from 1 to 18 d of age containing 1.20% digestible Lys. Diet 1 (23.2% CP) was formulated with DL-Met, L-Lys, and L-Thr to contain 1.70 total Gly + Ser to digestible Lys ratio whereas diets 2 (23.4% CP) to 11 were formulated with additional Gly to contain 1.90 total Gly + Ser to digestible Lys ratio. Free AA were added sequentially in the order of limitation (L-Val, L-Ile, L-Arg, L-Trp, L-His, L-Phe, and L-Leu) from diets 3 to 10 to decrease CP content from 22.6 to 18.8%, respectively. In diet 11, L-Gln was added to increase the CP content to 23.4%. Feed conversion of broilers fed diet 2 was lower (P < 0.05) than those consuming diets 6 to 11 from 1 to 17 d of age. Nitrogen excretion (mg/b/d) decreased (P < 0.001) by 14.1% when broilers were fed diet 4 compared with birds fed diet 2 from 15 to 16 d of age. Broilers fed diet 4 had lower (P = 0.011) plasma UA concentration than birds fed diet 2 at 18 d of age. In trial 2, 8 dietary treatments containing 1.25% digestible Lys and 1.70 total Gly + Ser to digestible Lys ratio were fed from 1 to 21 d of age. Diet 1 (24.0% CP) was supplemented with DL-Met, L-Lys, and L-Thr. Free AA (L-Val, Gly, L-Ile, L-Arg, L-Trp, L-His, and L-Phe) were sequentially supplemented in the order of limitation to decrease CP content in diets 2 to 8 from 23.8 to 20.3%. Broilers fed diet 1 had higher (P < 0.05) body weight gain and lower (P < 0.05) feed conversion when compared with diet 7 or 8. Plasma UA concentration of broiler provided diets 4 to 8 was lower (P < 0.05) compared with diet 1 at 21 d of age. Placing a minimum on dietary CP percentage may not be necessary when proper AA ratios are implemented in diet formulation.

Background: The crude protein (CP) of feedstuffs is important as an indicator of essential and non-essential amino acids for livestock. The protein (P) level needs to be known accurately, to minimize the feeding of excess nitrogen (N) and to reduce N pollution. Laboratory methods for determining N content report N from amino acids, but also N from ammonia and from non-amino acid sources. The determined CP based on 6.25 × N level typically overestimates the true protein of feedstuffs., Results: Determined ingredient-specific N:P conversion factors k(A) , k(P) and k were not equal to the standard 6.25 factor. The k(A) had the highest value in all ingredients, which leads to the estimation of specific crude protein (SCP), which is closer to true protein (the summation of the total amino acid residues from amino acid analyses). The SCP(k(A) ) was lower than CP and true protein in all ingredients, demonstrating that CP might overestimate the actual protein in feedstuffs., Conclusion: Based on data from 677 feedstuff samples from 2009, it is concluded that the mean k(A) should be 5.68 for corn, 5.64 for soybean meal, 5.74 for corn DDGS, 5.45 for poultry by-product meal and 5.37 for meat and bone meal., (Copyright © 2011 Society of Chemical Industry.)

1. Valine (Val) is considered the 4th limiting amino acid for broilers fed on diets containing ingredients from vegetable origin. However, Val and Isoleucine (Ile) may be co-limiting for broilers fed on diets containing animal protein meals. An experiment was conducted to examine growth responses and meat yield of broilers provided diets varying in digestible Val (dVal) and digestible Ile (dIle) concentrations from 28 to 42 d of age. 2. Eight experimental diets varying in dVal (dVal to dLys ratios from 0·66 to 0·76) and dIle (dIle to dLys ratios from 0·57 to 0·67) were studied; digestible Lysine (Lys) was formulated to 9·9 g/kg in all diets. 3. Broilers fed on a negative control (NC) diet supplemented with crystalline Val (L-Val) and crystalline Ile (L-Ile), dVal to dLys = 0·76 and dIle to dLys = 0·67, grew faster and had higher breast meat yield than birds fed on NC + L-Ile (dVal to dLys = 0·66 and dIle to dLys = 0·67), NC + L-Val (dVal to dLys = 0·76 and dIle to dLys = 0·57), and NC + reduced L-Val and L-Ile (dVal to dLys = 0·71 and dIle to dLys = 0·62). 4. Feeding broilers on the NC + L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67) diets gave similar BW gain, carcase weight and yield and total breast meat weight and yield to birds fed on the positive control-fed broilers with no added L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67). 5. These results indicate that Val and Ile are co-limiting in diets containing poultry by-product meal.

The effects of graded levels of corn distillers dried grains with solubles (DDGS) were investigated as a partial replacement for sources of protein, energy, and other nutrients for broilers when the digestible amino acid balance was maintained. Zero, 8, 16, and 24% DDGS were incorporated into isonutritive diets at the expense of corn, soybean meal, and dl-Met. Poultry oil, l-Lys, and l-Thr additions increased with increasing levels of DDGS. Diets were each fed to 36 Cobb 500 straight-run broilers in 6 floor pens in 2 experiments. In experiment 1, broilers fed ≥8% DDGS showed increased BW gain compared with those fed the control diet during the 0- to 18-d starter period (P = 0.0164) but were almost identical in BW at 42 d (P = 0.9395). The only difference at 42 d was in the carcass fat composition of female broilers: percentage of fat pad decreased with increasing DDGS level (P = 0.0133). Corn DDGS reduced the pellet durability index. However, the pellet durability index was not related to growth or feed utilization. In experiment 2 at 42 d, broilers fed all levels of DDGS showed increased BW gain compared with those fed the control diet. Broilers may perform well when fed properly balanced feeds containing up to 24% DDGS despite reduced pellet quality.

Research addressing digestible Lys requirement data of modern broilers from 4 to 6 wk of age is limited. Male broilers (1,632 Ross×Ross TP16 and 3,000 Cobb×Cobb 700) were used in separate experiments to determine the digestible Lys requirements from 28 to 42 d. In each experiment, 2 diets (dilution and summit) consisting of corn, soybean meal, animal protein meal, and peanut meal were formulated to be adequate in all other amino acids. The dilution and summit diets were blended to create 9 titration diets. A control diet formulated to contain corn, soybean meal, and animal protein meal as the primary ingredients was used for comparison with the titration diets. Body weight gain, feed intake, digestible Lys intake, digestible Lys intake:BW gain, feed conversion, mortality, carcass yields, and physiological measurements were assessed during experimentation. Digestible Lys requirements were estimated using a quadratic broken-line model. In experiment 1, the digestible Lys requirement for male Ross×Ross TP16 broilers was determined at 0.988, 1.053, 0.939, and 0.962%, respectively, for BW gain, feed conversion, carcass weight, and total breast meat weight. In experiment 2, the digestible Lys requirement for male Cobb×Cobb 700 broilers ranged from 0.965, 1.012, 1.029, 0.987, and 0.981%, respectively, for 28- to 42-d BW gain, feed conversion, carcass weight, total breast meat weight, and total breast meat yield. Digestible Lys requirements for male Ross×Ross TP16 and Cobb×Cobb 700 broilers were estimated at 1.001 and 0.995%, respectively, based upon averages of live performance and meat yield responses. Both strains required the highest requirement estimate of digestible Lys to optimize feed conversion.

1. The dietary limitation of isoleucine (Ile) and valine (Val) was evaluated in broilers. Common diets were given to all broilers from 0 to 28 d of age. Experimental diets were provided from 28 to 42 d of age. 2. The experimental test diet was based primarily on maize, soybean meal, and meat and bone meal, and formulated to satisfy all nutrient recommendations with the exception of Ile and Val. 3. Diets were supplemented with L-Ile and L-Val at either 0·5 or 1·0 g kg⁻¹ of diet, alone or in combination. A diet composed only of commercially available amino acids and formulated to satisfy all nutrient requirements served as a positive control. 4. Body weight gain was depressed by the test diet, but recovered to a weight similar to birds fed on the positive control when Val was added to the test diet either alone or in combination with Ile. Feed efficiency improved when Val and Ile were simultaneously supplemented. 5. Abdominal fat yield was reduced with the combined supplementation of Val and Ile. Breast meat yield appeared to be more sensitive to Ile supplementation than to Val. 6. The results suggest that live performance may be more sensitive to Val, while breast meat yield was maximised with Ile supplementation. However, their combination is required for optimised growth and meat yield.

There is little research data available on the digestible Lys requirement of broilers from 2 to 4 wk of age. Two experiments were conducted to determine the digestible Lys requirements of male and female Ross x Ross TP16 broilers from 14 to 28 d. Two diets (dilution and summit) consisting of corn, soybean meal, poultry by-product meal, and peanut meal were formulated to be adequate in all other amino acids. The dilution and summit diets were blended to create 9 titration diets. A control diet containing adequate Lys was used for comparison with the titration diets. A true Lys digestibility assay was conducted with cecectomized roosters to determine the values for the dilution (low) and summit (high) diets. True digestible Lys of the low and high dose-response diets were determined to be 0.84 and 1.21%, respectively. Body weight gain, feed intake, digestible Lys intake, digestible Lys intake:BW gain, feed conversion, and mortality were assessed during experimentation. Digestible Lys requirements were estimated using a quadratic broken-line model and a quadratic regression equation based on 95% of the optimum response. In experiment 1, the digestible Lys requirement for male Ross x Ross TP16 broilers was determined to be between 1.07 and 1.09% and 1.10 and 1.15%, for BW gain and feed conversion, respectively. In experiment 2, the digestible Lys requirement for female Ross x Ross TP16 broilers was estimated as 0.98% for BW gain determined with a quadratic broken-line model and 1.03 and 0.99% for feed conversion, respectively, using a quadratic regression equation based on 95% of the optimum response and the quadratic broken-line model. Digestible Lys requirements for male and female Ross x Ross TP16 broilers were estimated at 1.10 and 1.00%, respectively, based upon BW gain and feed conversion averaged for both statistical models.

Two trials were conducted to determine the apparent metabolizable energy (AME) and nitrogen-corrected AME (AMEn) of extruded grain amaranth (Amaranthus cruentus). Procedures for these determinations were the total collection method (TCM) and the use of acid-insoluble ash (AIA) as a marker. The AME and AMEn values for the grain were determined both by regression analysis and by calculations based on differences from the basal diet. Based on standard errors of the predicted values and coefficients of determination of the regression equations, TCM produced more accurate results than did AIA. Using regression analysis, the predicted values from the TCM were 3,382 kcal/kg of AME and 3,267 kcal/kg of AMEn on an as-fed basis. When expressed on a dry-matter basis, these values were 3,646 and 3,522 kcal/kg for AME and AMEn, respectively. When the difference method was used to calculate the ME of the extruded grain on an as-fed basis, the values of 3,295 kcal/kg of AME and 3,164 kcal/kg of AMEn were obtained. When the results were expressed on a dry-matter basis, 3,556 kcal/kg of AME and 3,415 kcal/kg of AMEn were determined.

Apparent amino acid availabilities (AAAA) were determined for grain amaranth in two experiments using broilers. Total collection method (TCM) and acid-insoluble ash (AIA), as a marker, were used for these determinations. Individual amino acid availabilities for the extruded grain were calculated both by regression analysis and by difference from the basal diet. From the linear regression equations, TCM produced more accurate results than did the AIA method, based on standard errors of the intercept and coefficient of determination. Predicted AAAA, based on linear regression equations, from the TCM were 92.4, 79.9, and 89.4% for methionine, lysine, and arginine, respectively. Using the TCM and calculation by difference, average AAAA on an as-fed basis were 85.0, 79.1, and 92.9% for methionine, lysine, and arginine, respectively. The AAAA of 11 other amino acids were also determined.

Six experiments with male broiler chicks were conducted to study responses to dietary supplements of L-methionine, L-cystine, choline, sulfate, and vitamin B12. A corn-soy-poultry oil-based diet calculated to contain .38% methionine, .74% total sulfur containing amino acids, 23% protein, 3,265 kcal metabolizable energy/kg, and 1.39 mg/g of choline was fed. Analysis indicated an average of .38% Methionine (.35 to .45) .77% Methionine + Cysteine (.72 TO .92), and 1.23 mg choline/g feed (.99 to 1.56) in the basal diet. Chicks fed the basal diets gained an average of 508 g in 21 days and had average feed conversion ratios (FCR) of 1.55. Chicks fed diets supplemented with .2% L-methionine gained significantly more (P less than .05) than those fed the basal diet in each experiment (average gain = 551 g; FCR = 1.44). Chicks fed choline-supplemented diets gained as well as those fed L-methionine in five of six experiments (P greater than .05) (average gain = 541 g; FCR = 1.48). Chicks fed sodium sulfate-supplemented diets gained as well as those fed L-methionine in two of four experiments when adequate sodium was fed (average gain = 536; FCR = 1.50). Chicks fed choline and sulfate supplements together did no better than those fed choline supplements only, with adequate sodium levels in the basal diet. The same basal diet was fed in the last two experiments. In one trial, a response to vitamin B12 was observed; in the other there was no response.(ABSTRACT TRUNCATED AT 250 WORDS)

Extruded grain amaranth (Amaranthus cruentus) was incorporated into corn-soybean meal layer rations at 0, 10, 20, or 30%. Diets were each fed to 20 Single Comb White Leghorn laying hens for 6 wk beginning at 65 wk of age. Data collected from the week prior to the test period were used as a covariate. Egg production was significantly higher and egg weights were significantly lower for birds fed the 10 and 20% inclusion levels of amaranth than for those fed the control diet. However, no differences were observed among the diets for daily egg mass. Significantly less feed was consumed at the 10% inclusion level of amaranth while achieving this higher production. Layers fed diets containing amaranth required significantly less feed to produce a dozen eggs or a gram of egg than those fed the control diet. No differences were observed among the treatments for shell strength, shell thickness, number or severity of blood spots, or Haugh units. Yolk color was negatively correlated with increased amaranth inclusion. No yolk or albumen discolorations were observed after 6 wk of storage. Extruded grain amaranth may be effectively used in layer rations without detrimentally altering production characteristics.

Three experiments were conducted to develop a basal diet limiting in the sulfur-containing amino acids and with adequate sodium. Twelve hundred commercial male broiler chicks were grown to 3 weeks of age in battery brooders. Chicks were fed a diet of a corn-soybean meal-poultry oil containing .38% methionine, .74% total sulfur-containing amino acids, and .10% sodium. The first two experiments, pooled for statistical analyses, showed that supplementation with .25% L-methionine significantly increased chick growth over the basal (496 vs. 465 g; P = .034) as did sodium supplementation (518 vs. 465 g; P less than .001). The best growth rate occurred when L-methionine and sodium chloride (NaCl) were supplemented together at .25 and .33%, respectively (579 g gained). The response from NaCl was demonstrated to be due to the sodium and not the chlorine by comparison to responses from potassium chloride (KCl) and sodium carbonate (Na2CO3) supplementation. It is suggested that two "first-limiting" nutrients, methionine and sodium, exist for chicks fed this particular diet. In Experiment 3, a response surface was determined with supplemental sodium (as NaCl) and L-methionine each varying from 0 to .20% (.10 to .30% total sodium and .38 to .58% total methionine). It was concluded that .20% total sodium is adequate to maximize growth and feed efficiency (.20% better than .13%, no different from .27%). Similarly, .17% supplemental methionine (.55% total) appears to be adequate (.17% better than .10%; .20% not better than .17%) with no supplemental choline.

A trial was conducted to determine the effects of feeding extruded grain amaranth (Amaranthus cruentus) on performance of male broilers grown in batteries to 49 days of age. Practical corn-soy rations were supplemented with 0, 10, 20, 30, 40, or 50% amaranth and formulated to meet nutrient requirements for the starter (0 to 21 days), grower (21 to 42 days), and finisher (42 to 49 days) periods. Each diet was fed to six replicate pens of 10 male birds each. No differences were observed for feed utilization (P greater than .05), but at Day 49, birds fed 50% amaranth weighed significantly less and had significantly lighter dressed carcass weights than those fed the control diet. For dressing percentages, no significant differences among diets were observed. Dietary differences in fat pad weights were not detected, but significant differences between diets were observed for fat pad weights expressed as a percentage of the total carcass weight (% OTC). Significant and positive linear responses existed when liver weight, liver weight as % OTC, and fat pad weight as % OTC were regressed upon amaranth inclusion. No treatment differences were observed for heart or pancreas weights or for their weights as % OTC. Gizzard weight and gizzard weight as % OTC decreased linearly with amaranth inclusion. Giblet weights (heart + liver + gizzard) were significantly different among diets, but giblet weight appeared to be unrelated to amaranth level. Birds fed the diet with 50% amaranth had giblets of equal size to birds fed the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)