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Ingested starch is a polymer of glucose that consists of α-1,4 and/or α-1,6 bonds. When α-1,4 bonds occur between glucose monomers, the resulting polymer is called amylose, whereas when α-1,6 bonds occur the resulting polymer is referred to as amylopectin. Amylopectin, on the other hand, has a more chaotic macro-structure as the α-1,6 branching points disrupt the helical structure creating amorphous regions often referred to as "waxy." The ratio between amylose and amylopectin in starch determines whether a starch may be categorized as "waxy" or "high amylose" and this varies between and within cereal grain types. Waxy corn may contain as much as 99% amylopectin, whereas high amylose corn starch may be more than 70% amylose. Furthermore, there is considerable heterogeneity in the size of the starch granules in seeds from various plants and in the nature of the crystalline micro- and macro-structure that favors, or not, digestion. Following initial hydrolysis by endogenous amylases, the process of starch digestion is completed by the brush-border enzymes maltase and iso-maltase, and the resulting glucose is absorbed via Na-dependent transport systems for eventual metabolism via the citric acid cycle. As most poultry diets contain 400–500 g/kg starch, successfully converting this ingested starch into glucose is critically important to energetic status and this may be particularly true in older animals with a much greater starch intake. Therefore, factors which delay, impede or interfere with the digestion of starch have a profound effect on the energy value of a given diet. Such factors include the nature of the starch crystals, the extent of starch "damage" during hydrothermal processing of feed or feed ingredients, factors that may inhibit the optimal functioning of endogenous amylases and issues around extraction of glucose from the lumen via Na-dependent transport systems. It was the purpose of this review to discuss such factors and to outline the usefulness of exogenous sources of amylase in monogastric nutrition with emphasis both on direct digestible energy effects. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of dietary iron (Fe) from inorganic and organic sources on breeder hen chicks originated from Pale and Dark eggs. A total of 640 40-wk-old Cobb 500 broiler breeder hens were randomly distributed into 32 floor pens (20 females and 2 males per pen) and fed ferrous sulfate (Fe-S) at 40 ppm Fe; Fe-amino acid complex (Fe-AA) at 40 ppm Fe, or Fe-S and Fe-AA (Fe-S + Fe-AA) at 90 ppm Fe, 50 ppm provided by Fe-S and 40 ppm by Fe-AA. Breeder performance was evaluated from 40 to 67 wk, and laid eggs were separated by color (Pale and Dark) to compose 6 treatments. A total of 600 hatching eggs from each treatment were collected at 65 wk and incubated. Hemoglobin and hematocrit were analyzed from 100 hatched chicks per treatment. In parallel, 1,200 1-day-old male chicks were randomly distributed in a 3 × 2 (Fe fed to hens and eggshell color) factorial arrangement (48 floor pens; 25 birds/pen) and fed common diets. Hens fed the Fe-AA diet produced more eggs per hen housed and had higher fertility compared to hens fed Fe-S whdereas those fed Fe-S + Fe-AA had intermediate results. Chick hemoglobin and hematocrit were not affected by dietary Fe and eggshell color. Breeder hens fed diets with Fe-AA and Dark eggs originated broilers that had improved growth performance and carcass and breast weights. [ABSTRACT FROM AUTHOR]

One-hundred-twenty Cobb 500 hens, 20 wk of age, were randomly allocated into individual cages with the objective of estimating Cu requirements. After being fed a Cu deficient diet for 4 wk, hens were fed diets with graded increments of supplemental Cu (0.0; 3.5; 7.0; 10.5; 14; and 17.5 ppm) from Cu sulfate (CuSO4 5H2O), totaling 2.67; 5.82; 9.38; 12.92; 16.83; and 20.19 ppm analyzed Cu in feeds for 20 weeks. Estimations of Cu requirements were done using exponential asymptotic (EA), broken line quadratic (BLQ), and quadratic polynomial (QP) models. Obtained Cu requirements for hen d egg production and total settable eggs per hen were 6.2, 7.3, and 12.9 ppm and 8.1, 9.0, and 13.4 ppm, respectively, using EA, BLQ, and QP models. The QP model was the only one having a fit for total eggs per hen with 13.1 ppm Cu as a requirement. Hemoglobin, hematocrit, and serum Cu from hens had requirements estimated as 13.9, 11.3, and 18.5, ppm; 14.6, 13.0, and 19.0 ppm; and 16.2, 14.6, and 14.2 ppm, respectively, for EA, BLQ, and QP models. Hatching chick hemoglobin was not affected by dietary Cu, whereas requirements estimated for hatching chick hematocrit and body weight and length were 10.2, 12.3, and 13.3 ppm using EA, BLQ, and QP models; and 6.8 and 7.1 ppm, and 12.9 and 13.9 ppm Cu using EA and BLQ models, respectively. Maximum responses for egg weight, yolk Cu content, and eggshell membrane thickness were 14.9, 12.7, and 15.1 ppm; 15.0, 16.3, and 15.7 ppm; and 7.3, 7.8, and 14.0 ppm Cu, respectively, for EA, BLQ, and QP models. Yolk and albumen percentage were adjusted only with the QP model and had requirements estimated at 11.0 ppm and 11.3 ppm, respectively, whereas eggshell mammillary layer was maximized with 10.6, 10.1, and 14.4 ppm Cu using EA, BLQ, and QP models, respectively. The average of all Cu requirement estimates obtained in the present study was 12.5 ppm Cu. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate growth performance, carcass and breast yields, and the occurrence and severity of white striping (WS) and wooden breast (WB) myopathies of broilers fed diets supplemented with increasing dietary levels of an organic source of selenium (Zn-L-SeMet). Broilers were fed 6 treatments with 12 replications of 26 birds in a 4-phase feeding program from 1 to 42 days. Corn-soy-based diets were supplemented with 0, 0.2, 0.4, 0.6, 0.8, and 1.0 ppm of Zn-L-SeMet. At 42 d, 6 birds were randomly selected from each pen (n = 72) and processed for carcass and breast yields. Breast fillets were scored for WS and WB at 42 days. Increasing Zn-L-SeMet led to quadratic responses (P  < 0.05) for FCR from 1 to 7 d, BWG from 22 to 35 d, and for both responses from 8 to 21 d and 36 to 42 d, as well as in the overall period of 42 days. Carcass and breast yields presented a quadratic improvement (P  < 0.01) with increasing Zn-L-SeMet supplementation and Se requirements were estimated at 0.85 and 0.86 ppm, respectively. In the overall period, estimates of Se requirements were 0.64 ppm for BWG and 0.67 ppm for FCR. White striping and WB scores presented quadratic increases (P  < 0.01), and maximum scores were observed at 0.68 and 0.67 ppm, respectively. Broilers fed diets formulated without Se supplementation had a higher percentage of normal fillets compared to other Se supplementation levels (quadratic, P  < 0.05). In conclusion, increasing Se supplementation to reach maximum growth performance led to higher degrees of severity of WS and WB. Selenium requirements determined in the present study were significantly higher than the present commercial recommendations. [ABSTRACT FROM AUTHOR]

Introduction The present study evaluated the effects of different inocula of Toxoplasma gondii oocysts on the ileal myenteric plexus in rats. Materials and Methods Male Wistar rats, 60 days old, were distributed into four groups: control group (CG; which received saline solution) and groups that were infected with 100 (TG100), 1000 (TG1000), and 5000 (TG5000) T. gondii oocysts. Thirty days after infection, the ratswere sacrificed, and the ileumwas collected tomake whole-mount preparations that were subjected to immunofluorescence staining to observe the general neuronal population (HuC/D), nitrergic neurons (nNOS), and enteric glial cells (S100). Morphometric and quantitative analyses of myenteric neurons were performed. Results The infections with different T. gondii inocula did not cause neuronal or glial loss, but cause neuronal hypertrophy in general population and nitrergic subpopulation in infected groups. Conclusion: Changes in neuronalmorphology were observed in the TG5000 group, including the presence of vacuoles, translocation of Hu protein to the nucleus, and dendritic distortions, suggesting functional alterations in these cells. [ABSTRACT FROM AUTHOR]

A study was conducted to determine the AMEn contents of fat by-products from the soybean oil industry for broiler chickens. A total of 390 slow-feathering Cobb x Cobb 500 male broilers were randomly distributed into 13 treatments having 6 replicates of 5 birds each. Birds were fed a common starter diet from placement to 21 d. Experimental corn-soy diets were composed of four fat sources, added at 3 increasing levels each, and were fed from 21 to 28 d. Fat sources utilized were acidulated soybean soapstock (ASS), glycerol (GLY), lecithin (LEC), and a mixture (MIX) containing 85% ASS, 10% GLY and 5% LEC. A 4 x 3 + 1 factorial arrangement was used with 4 byproducts (ASS, GLY, LEC, or MIX), 3 inclusion levels and 1 basal diet. Each of the four fat by-product sources was included in the diets as follow: 2% of byproducts (98% basal + 2% by-product), 4% (96% basal + 4% by-product), or 6% (94% basal + 6% by-product). Birds were submitted to 94, 96, 98, and 100% of ad libitum feed intake; therefore, the differences in AMEn consumption were only due to the added by-product. Total excreta were collected twice daily for 72 h to determine apparent metabolizable energy contents starting at 25 d. The AMEn intake was regressed against feed intake and the slope was used to estimate AMEn values for each fat source. Linear regression equations (P < 0.05) estimated for each by-product were as follow: 7,153X - 451.9 for ASS; 3,916X - 68.2 for GLY; 7,051X - 448.3 for LEC, and 8,515X - 622.3 for MIX. Values of AMEn were 7,153, 3,916, 7,051, and 8,515 kcal/kg DM for ASS, GLY, LEC, and MIX, respectively. The present study generated AMEn for fat by-products data that can be used in poultry feed formulation. It also provides indications that, by adding the 3 by-products in the proportions present in the MIX, considerable economic advantage can be attained. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate the prevalence and severity of white striping (WS) and wooden breast (WB) in breast fillets from broilers fed diets with increasing digestible Lysine (dLys) from 12 to 28 d (Exp. 1) and from 28 to 42 d (Exp. 2). Trials were sequentially conducted using one-d-old male, slow-feathering Cobb 500 × Cobb broilers, both with 6 treatments and 8 replicates. Increasing dLys levels were equally spaced from 0.77 to 1.17% in Exp. 1 and from 0.68 to 1.07% in Exp. 2. The lowest dLys diet was not supplemented with L-Lysine (L-Lys) in either one of the studies and all other essential amino acid (AA) met or exceeded current commercial recommendations such that their dietary concentrations did not limit broiler growth. Four birds per pen were randomly selected from each replication and processed at 35 and 42 d in Exp. 1 and Exp. 2, respectively. Deboned breast fillets (Pectoralis major) were submitted to a 3 subject panel evaluation to detect the presence of WS and WB, as well as to provide scores of WS (0-normal, 1-moderate, 2-severe) and WB (0-normal, 1-moderate light, 2-moderate, 3-severe). Increasing the level of dLys had a positive effect on BW, carcass, and breast weight, as well as breast yield. White striping and WB prevalences were 32.3 and 85.9% in Exp. 1 and 87.1 and 89.2% in Exp. 2. Birds fed diets not supplemented with L-Lys had the lowest average WS and WB scores (0.22 and 0.78 in Exp. 1 and 0.61 and 0.68 in Exp. 2). White striping and WB presented linear responses to performance variables in Exp. 1, whereas quadratic responses were observed for all variables in Exp. 2. In conclusion, increasing the level of dLys improved growth performance and carcass traits as well as induced the occurrence and severity of WS and WB lesions. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of increased levels of a β-xylanase on energy and nutrient utilization of broiler chickens fed corn-soy diets. A total of 480 slow feathering Cobb × Cobb 500 male broilers were randomly distributed to 10 treatments having 8 replicates of 6 birds each. Birds were fed a common starter diet to d 14 post hatch (3,050 kcal/kg AMEn, 21.7% CP, 1.05% Ca, and 0.53% nPP). The experimental diets were provided afterwards until 25 d. Two experimental diets, a conventional corn/soy-based basal diet (CS) and the basal diet in which 40% of the diet was displaced by corn (CN), were fed as-is or supplemented with 50, 100, 150, or 200 fungal β-xylanase units (FXU)/kg. Dietary treatments were distributed factorially as a 2 × 5 arrangement. Samples of feed, excreta, and ileal digesta were analyzed for determination of ileal digestible energy (IDE), metabolizable energy, and total tract retention of protein and lipid. No interactions between diet and xylanase were observed. The CS diets had higher (P < 0.05) energy utilization and nutrient digestibility when compared to the CN diets. AMEn and IDE were improved (P < 0.05) by 192 and 145 kcal/kg, respectively, when diets were supplemented with 100 FXU/kg xylanase. The xylanase added to the CN diet led to quadratic increases (P < 0.05) in IDE (Y = − 0.014x2 + 2.570x + 3,155; r2 = 0.60) and in AMEn (Y = − 0.016x2 + 3.982x + 3,155; r2 = 0.68). Crude protein digestibility and AMEn were linearly increased (P < 0.05) when xylanase was added to the CN diet. In conclusion, energy utilization and digestibility of crude protein and dry matter increased with xylanase supplementation in corn/soy-based diets. When xylanase was tested in the CS diet, 92 and 124 FXU/kg maximized the energy release effect; however, the maximum energy response in the CN diet or corn was not achieved until 200 FXU/kg. [ABSTRACT FROM AUTHOR]

A study was conducted to determine the ileal digestible energy (IDE), ME, and MEn contents of bakery meal using the regression method and to evaluate whether the energy values are age-dependent in broiler chickens from zero to 21 d post hatching. Seven hundred and eighty male Ross 708 chicks were fed 3 experimental diets in which bakery meal was incorporated into a corn-soybean meal-based reference diet at zero, 100, or 200 g/kg by replacing the energy-yielding ingredients. A 3 x 3 factorial arrangement of 3 ages (1, 2, or 3 wk) and 3 dietary bakery meal levels were used. Birds were fed the same experimental diets in these 3 evaluated ages. Birds were grouped by weight into 10 replicates per treatment in a randomized complete block design. Apparent ileal digestibility and total tract retention of DM, N, and energy were calculated. Expression of mucin (MUC2), sodium-dependent phosphate transporter (NaPi-IIb), solute carrier family 7 (cationic amino acid transporter, Y+ system, SLC7A2), glucose (GLUT2), and sodium-glucose linked transporter (SGLT1) genes were measured at each age in the jejunum by real-time PCR. Addition of bakery meal to the reference diet resulted in a linear decrease in retention of DM, N, and energy, and a quadratic reduction (P < 0.05) in N retention and ME. There was a linear increase in DM, N, and energy as birds' ages increased from 1 to 3 wk. Dietary bakery meal did not affect jejunal gene expression. Expression of genes encoding MUC2, NaPi-IIb, and SLC7A2 linearly increased (P < 0.05) with age. Regression-derived MEn of bakery meal linearly increased (P < 0.05) as the age of birds increased, with values of 2,710, 2,820, and 2,923 kcal/kg DM for 1, 2, and 3 wk, respectively. Based on these results, utilization of energy and nitrogen in the basal diet decreased when bakery meal was included and increased with age of broiler chickens. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of dietary α-amylase and β-xylanase supplementation of corn-soy diets, formulated with or without supplemental phytase, on growth performance, energy utilization, and starch digestibility in broiler chickens. A total of 336 slow-feathering, Cobb × Cobb 500 male broilers were randomly distributed to 6 treatments having 8 replicates of 7 birds each. Birds were fed a common starter diet to d 14 post-hatch (3,050 kcal/kg AMEn, 21.7% CP, 1.05% Ca, and 0.53% nPP). The experimental diets were provided afterwards until d 25. A 2 × 3 factorial arrangement of 2 control diets (basal = corn-soy diet without added phytase or PHY = cornsoy diet formulated with 1,000 phytase units/kg) and 3 carbohydrase supplementations (0, 80 kilo-Novo α-amylase units/kg, or 80 kilo-Novo α-amylase units/kg + 100 fungal β-xylanase units/kg) was used from d 14 to 25. Excreta were collected from 21 to 24 d and all birds were euthanized at 25 d for jejunum and ileum content collection. Samples of feed, excreta, and jejunal and ileal digesta were analyzed for determination of total tract retention and ileal apparent digestibility. No interactions between diet and carbohydrase were observed. Broilers fed diets formulated with phytase or supplemented with amylase + xylanase had higher BW gain (BWG) and lower FCR (P < 0.05) when compared with birds fed diets without carbohydrases. Relative to the basal diet, AMEn was increased (P < 0.01) by 70 kcal/kg and 99 kcal/kg when birds were fed the diet supplemented with amylase and amylase + xylanase, respectively. Starch digestibility in the jejunum and ileum was increased (P < 0.05) by 3.5% and 2.4%, respectively, when birds were fed the diet supplemented with amylase + xylanase. Results from this experiment show that corn-soy diets having phytase and supplemented with amylase and xylanase led to increased growth performance, AMEn, and starch digestibility in broilers. Furthermore, the efficacy of exogenous amylase and xylanase was independent of the presence of microbial phytase. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of phytase supplementation on growth performance, phosphorus availability, and bone mineralization in broilers. Three hundred fifty Cobb × Cobb 500 slow-feathering male broilers were placed in steel battery cages into 7 treatments with 10 replications of 5 chicks each. The treatments were: a positive control (PC) diet [0.42% nonphytate phosphorus (nPP)], 4 diets containing increases in nPP from dicalcium phosphate (0.14, 0.20, 0.26, and 0.32%), and 2 phytase supplemental levels [500 and 1,000 phytase units (FYT)/kg] on the diet having 0.14% nPP. All diets contained 0.8% calcium. Growth performance and bone data were regressed against the 4 diets having increased nPP. The equations generated were replaced by the corresponding performance obtained with 2 phytase levels to estimate their nPP bioequivalence. An overall reduction in performance and bone mineralization was observed associated with a reduction in nPP. Linear fits provided the best adjustments for all responses with the exceptions of BW gain (BWG) and feed intake (FI). Adding phytase to the 0.14% nPP diet improved growth performance and bone mineralization (P < 0.001). Average bioequivalence nPP for each phytase level was dependent on the evaluated response with lowest and highest values at 500 FYT supplementation of 0.077 and 0.145 for toe P and femur Ca, respectively, whereas lowest and highest values at 1,000 FYT of 0.143 and 0.194 for BWG and toe ash. Averaging all values for 500 and 1,000 FYT provided estimations of 0.100 and 0.166 nPP, respectively. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate field performance and economic impacts of feeding diets varying in AME and amino acid (AA) densities to Cobb 500 female broiler grillers (eviscerated carcass averaging 1.0 kg). Corn-soy diets were fed to birds in a factorial arrangement of 3 AME (low, moderate, and high) by 3 AA densities (low, moderate, and high). Differences in AA and AME average values were of 10 and 1.5%, respectively. Treatments had 8 replications of 40 birds allocated in floor pens. Live performance was significantly improved in parallel with increases in AME and AA; however, carcass yield increased and abdominal fat was reduced only when AA was increased (P < 0.05). Gross margins (GM) for each treatment were calculated using scenarios of high and low market costs for corn, soybean meal, as well as for carcass prices. Costs were classified as variable [costs of feeding (CF), fixed farm costs (FFC), and fixed processing costs (FPC)] and their behavior in response to nutritional density was studied. All cost components, (CF, FFC, and FPC) decreased as AME increased, which resulted in the lowest total costs (TC) for the highest AME diets in all scenarios tested, as well as the greatest GM for those dietary programs. In contrast to AME, cost components moved in opposite directions in response to AA density whereby, in 4 out of 7 scenarios, optimizing CF did not result in greater GM. The present study was conducted with low-weight carcasses and, therefore, conclusions made from the presented data are restricted to this type of product. It is concluded that when broiler grillers are objects of study, the use of CF as the sole criteria to choose an optimal feeding program, without considering significant fixed costs present along the production and meat processing chains, tends to underestimate the economic potential of increasing nutrient density. [ABSTRACT FROM AUTHOR]

Comparisons of corn-soy-feeding programs formulated using different protein constraints were done in the present study. A total of 1,800 one-day-old, slow-feathering Cobb × Cobb 500 male broiler chicks were placed in 72 floor pens of 25 birds each with 9 birds/m2. Feeding programs (PRG) were composed of prestarter (PST,1–7 d), starter (ST, 8–21 d), grower (GR, 22–35 d), and finisher (FN, 36–43 d) diets formulated as: PRG 1 = CP restricted to a minimum (22.4, 21.1, 19.8, and 18.4% for PST, ST, GR, and FN, respectively) with amino acid-to-Lys ratios only set for TSAA (0.72) and Thr (0.65); PRG 2 = CP not restricted, whereas ratios of amino acids to Lys were also extended to Val (0.77) and Ile (0.67); PRG 3 and PRG 4 were the same as PRG 2, but with l-Val added in PRG 3 and l-Val and l-Ile in PRG 4. Feeds were formulated to have digestible Lys of 1.324, 1.217, 1.095, and 1.006% for PST, ST, GR, and FN, respectively, or 5% higher. A completely randomized design was used with a 4 × 2 factorial (4 PRG and 2 digestible Lys) design with 9 replications per treatment. Overall, no interactions between PRG and digestible Lys were observed, with 1 exception observed for BW gain and FCR from 36 to 43 d. Birds fed PRG 2 showed improvements in BW gain and FCR when fed the diet 5% higher in digestible Lys. Cumulative BW gain and FCR results at 35 and 43 d, as well as in each individual feeding phase, showed broilers from PRG 2 having the best results, but without mean separation significant differences when compared with PRG 3 and 4. Feeding a dietary program with a 5% increase in digestible Lys resulted in improved cumulative FCR only when cumulatively measured from placement to 43 d. Abdominal fat, as a percentage of the eviscerated carcass at 43 d, was lowest for birds fed PRG 2 diets. Formulation of diets having traditional recommendations of digestible Lys with Val- and Ile-to-Lys ratios of 0.77 and 0.67, without restricting CP, led to the best results overall in performance and fat pad deposition; therefore, if the goal is to reduce CP, similar results should be achieved by adding l-Ile with further reductions in protein if l-Val is also added. Data obtained in this study support the applicability of supplementation with l-Val and l-Ile when ideal AA ratios are followed. [ABSTRACT FROM AUTHOR]

Since it started as an organized economic activity, poultry production has been undergoing an evolution toward the optimization of its feed formulation features. Notably, advances in the knowledge of birds' nutrient requirements have allowed recommendations that are increasingly closer to the needs of the birds. Over time, availability of nutrients and energy has been incorporated into those recommendations, especially to compensate for the variability in the digestibility of nutrients originating from variable feed ingredient sources. Instead of using the total energy and nutrient content, current tables of nutrient recommendations provide an estimate of the digestible fractions of the nutrients in ingredients. For instance, nonphytate P is preferred instead of total P to account for the unavailable phytate P, and digestible amino acids to account for the differences in digestibility of amino acids in different ingredients, whereas energy is usually expressed as a proportion that has been digested and metabolized (AME). With the increasing interest in the use of exogenous enzymes in poultry feeds, special attention is directed to the feed substrates such that an added enzyme can match it, forming an enzyme-substrate complex that will be followed by a chemical reaction within the gastrointestinal tract. As a consequence of a degradation reaction, nutrients released can be absorbed and metabolized. In general, nutritional data banks used in linear feed formulation software have limited data on the proportions of fractions of ingredients that are indigestible. Therefore, estimations of the presence of many substrates in the feeds, and therefore the benefits of adding exogenous enzymes, are frequently limited because of the scarcity of adequate information. The objective of this review paper is to provide insights into the use of expanded nutrient databanks to include all the molecules considered potentially indigestible for poultry such that the inclusion of exogenous enzymes allows the estimation of the values of the product originated by their hydrolysis. [ABSTRACT FROM AUTHOR]

Sources of Zn, Mn, and Cu (IZMC) as sulfates or as amino acid complexes (OZMC) were used to supplement Cobb 500 breeder hen diets. Experimental treatments consisted of diets supplemented with 1) 100, 100, and 10 mg/kg of Zn, Mn, and Cu, respectively, from IZMC (control); 2) 60, 60, and 3 mg/kg of Zn, Mn, and Cu, respectively, from IZMC plus 40, 40, and 7 mg/kg of Zn, Mn, and Cu, respectively, from OZMC (ISO); and 3) a diet with 100, 100, and 10 mg/ kg of Zn, Mn, and Cu, respectively, from IZMC as in control plus 40, 40, and 7 mg/kg of supplemental Zn, Mn, and Cu from OZMC (on top). Ten replications of 20 females and 2 males were used per treatment. Eggs from breeders at 30, 40, 50 and 60 wk of age were incubated, and 5 embryos per replicate were collected at 10 (E10), 14 (E14), and 18 (E18) d of incubation. Midshaft width and calcification were measured for left tibia and femur stained with Alcian Blue and Alizarin Red S. At hatch, the left tibia of 5 chicks per replicate was sampled for histological evaluation of the diaphysis and distal epiphysis. Feeding the ISO treatment compared with the control diet increased the Zn (P < 0.05) but not Mn and Cu content of the yolk and albumen blend. At E14, the ISO and on-top treatments had a trend to increase tibia calcification at the rates of 1.6 and 1%, respectively {P < 0.1). The E18 ISO and on-top treatments had 2% thicker tibia compared with the control, regardless of hen age (P < 0.05). Also, at E18, calcification of tibia and femur was higher from hens fed the on-top treatment (P < 0.05). The chicks from the ISO and on-top groups had increased tibia moment of inertia (P < 0.01) at day of hatch. Broiler breeder hens consuming OZMC associated with IZMC produced embryos and hatching chicks with improvements in selected bone mineralization parameters. [ABSTRACT FROM AUTHOR]

An experiment with 1,440 male Cobb 500 and 1,440 male Ross 308 broilers (14 to 35 d of age) was conducted to investigate the effects of diets having 4 levels of digestible methionine plus cysteine (SAA) on various performance criteria at 2 dietary protein levels (20.5 and 26.0%). Two corn-soybean meal/poultry by-product basal diets were formulated to contain 3,060 kcal/kg MEn and either 20.5 or 26.0% balanced protein, and 1.12 and 1.46% digestible (according to table values) lysine, respectively. Except for SAA, the ratios between essential amino acids were kept identical in both diets according to the ideal protein concept. The ratio between digestible SAA and digestible Lys was 50%. All remaining nutrients met or exceeded NRC (1994) recommendations. Graded levels of SAA were supplemented to obtain digestible SAA to Lys ratios of 62, 69, and 77%, with 77% representing an optimized amino acid balance. Increasing the protein level clearly improved weight gain, feed conversion, breast meat yield, and abdominal fat content. Increasing SAA levels resulted in strong nonlinear or linear dose responses at both protein levels and for both strains. Regression analysis suggested that reducing digestible SAA in a balanced protein (diets with SAA:Lys of 77%) impairs performance, and that optimum SAA:Lys ratio for growing broilers might be higher than 77%, although ANOVA revealed no significant improvement with an SAA:Lys ratio higher than 69%. Responses provide evidence that optimum dietary SAA level depends on dietary protein level and should therefore be related to the protein content. [ABSTRACT FROM AUTHOR]