Chicken liver morphology as affected by feed withdrawal time and dietary aflatoxins.

1. An investigation was conducted on the effects of aflatoxin (AFL)-contaminated diets and feed withdrawal periods from 0 to 12 h in broiler chickens at 28 d of age. Both factors can potentially affect liver colour and can cause failure at veterinary inspection in the slaughterhouse.2. A total of 240, one-d-old female Cobb 500 broiler chickens were fed a common corn-soy pre-starters (d 1-7) and then either a non-contaminated control (CON) or feed with 1 ppm AFL (AFL) from d 8 to 28. The inoculum of AFL had 792 ppb of aflatoxin B1, 35 ppb of aflatoxin B2 and 219 ppb of aflatoxin G1. On d 28, all broilers were weighed and euthanised for necropsy following three different feed withdrawal time periods (0, 6 or 12 h), in a 2 × 3 factorial arrangement.3. Body weight gain, liver weight and liver fat content decreased as feed withdrawal lengthened, whereas FCR and gallbladder weight increased (P ≤ 0.05). AFL-fed birds had reduced body weight and proportion of liver fat and increased FCR, liver and gallbladder weights (P ≤ 0.05).4. Livers from fed broilers (0 h withdrawal) showed more lightness (L*) and yellowness (b*) than livers of broilers from 6 or 12 h withdrawal (P ≤ 0.05). The L* and redness (a*) values of livers from broilers fed diets COB were lower than those from AFL fed broilers (P ≤ 0.05).5. Prolonging pre-slaughter feed withdrawal decreased liver L*, whereas feeding AFL increased liver b*. These findings can be used to support veterinary assessment in slaughterhouses as shackled birds move on line through the inspection site. Since chicken liver is a valuable organ and an indicator of animal health, attention must be paid to these differences to ensure consumer safety.

Progressive in vivo detection of wooden breast in broilers as affected by dietary energy and protein.

Wooden breast (WB) myopathy was investigated in broilers fed varying energy and protein at early ages. Correlation analyses were conducted between echogenicity of ultrasound images (US) of breast muscle from live birds and WB after slaughter. A total of 1,000 Cobb 500 one-day-old male chicks were fed on five dietary programs with eight replicates of 25 birds each, in a completely randomized design. Control feeds (commercially used ME and ideally balanced amino acids) or low-density feeds (low EP, with reductions of 50 kcal/kg ME and 0.20% dig. Lys compared to the control) were formulated. Feeds were provided in different periods: 1 to 7 d, 8 to 14 d, 15 to 21 d or 22 to 28 d. All broilers were fed a common basal diet thereafter until 49 d. Images using US were obtained once a week from all individuals and WB scored from one slaughtered bird per replication (0, normal; 1, mild hardening in the upper breast muscle; 2; moderate hardening in the upper and/or lower breast muscle; 3, severe hardening; 4, severe hardening with hemorrhagic lesions and yellow fluid). Blood was collected for enzyme investigation from the weekly slaughtered bird. Broilers had lower BWG and higher FCR when fed low EP feeds, regardless of the period fed when compared to the control (P < 0.001). Growth compensation, however, occurred afterwards such that all birds presented similar performance at the end. At 14, 21, and 28 d, broilers previously fed low EP feeds had lower WB scores (P < 0.001) compared to birds fed the control; however, both groups presented increased WB scores after 28 d. Wooden breast was positively correlated with breast echogenicity at 21 d (r = 0.31), 28 d (r = 0.43), 35 d (r = 0.21) and 42 d (r = 0.39). In conclusion, dietary energy and protein affected the development of WB scores in broilers and breast US images can be used as an early predictor of WB.

Optimizing cost, growth performance, and nutrient absorption with a bio-emulsifier based on lysophospholipids for broiler chickens.

Two experiments (Exp.) were conducted to evaluate effects of a lysophospholipid-based bio-emulsifier (LPL) on growth performance, nutrient digestibility and energy utilization of broilers as well as the return on investment (ROI). In Exp. 1, 392 chicks were housed in battery cages in a completely randomized design with 8 treatments and 7 replicates of 7 birds each from d 0 to 21 posthatch. In Exp. 2, 1,400 chicks were allocated in floor pens and fed the same 8 treatments, with 7 replicates and 25 birds each from d 0 to 43 posthatch. Treatments consisted of 6 degummed soybean oil-based diets: positive control (PC1); PC1 formulated with 500 g/ton LPL (PC1+LPL on top); PC1 formulated with 60 kcal LPL matrix (PC1+LPL60); PC1 formulated with 100 kcal LPL matrix (PC1+LPL100); and two negative controls NC-60 and NC-100 with reductions of 60 and 100 kcal/kg ME, respectively. Two other diets were formulated with acid soybean oil: positive control (PC2) and PC2 formulated with 60 kcal LPL matrix (PC2+LPL60). In Exp. 1, performance was evaluated from d 0 to 21, ME and ileal digestibility of DM, CP and energy were determined on d 21. In Exp. 2, growth performance was evaluated from d 0 to 42, and on d 43 carcass and abdominal fat yields were calculated. There were no effects of soybean oil sources in any parameter. Inclusion of LPL increased (P < 0.05) BW gain and ileal digestibility of DM, fat and CP. Broilers fed the PC1+LPL on top diet had increased (P < 0.05) performance, ileal digestibility and energy utilization as well as decreased abdominal fat compared to NC-60 or NC-100. The use of LPL on top had a ROI of 8:1 vs. PC1, considering the gains in revenue of the slaughtered broilers in relation to the investment with LPL in feed. In conclusion, a lysophospholipid-based bio-emulsifier increased performance, digestibility and return on investment of broilers fed standard or reformulated diets.

An in vivo evaluation of the effects of feed restriction regimens on wooden breast using ultrasound images as a predictive tool.

1. Gradual feed restriction was applied to broilers in order to reduce growth rate and, as a consequence, gradually impacts wooden breast myopathy occurrence. Ultrasound (US) images of breast muscle in live birds were correlated with breast fillets presenting wooden breast characteristics (WB). 2. A total of 1800 Cobb × Cobb 500 slow-feathering male chicks were fed one of the six feed restriction treatments with 12 replicates of 25 birds each, in a completely randomised design. Birds were fed ad libitum or were pair-fed to 50%, 60%, 70%, 80% or 90% of normal ad libitum intakes from 8 to 49 d to provide a gradual reduction in growth rate. Ultrasound images were obtained weekly from all birds and, in parallel, one bird per pen was weekly slaughtered and the major breast muscle was weighed and WB graded as 0 (normal), 1 (mild hardening in the upper), 2 (moderate hardening in the upper and/or lower), 3 (severe hardening) and 4 (severe hardening with haemorrhagic lesions and yellow fluid). Blood was taken for analysis of enzymes related to muscle cell breakdown. 3. Feed restriction applied at 50%, 60%, 70%, 80% and 90% of the ad libitum feed intake (FI) resulted in decreased body weight gain (BWG; P ≤ 0.05). 4. From 21 to 49 d, the increasing feed restriction led to linear increases (P ≤ 0.05) in WB scores, fibre density as well as breast depth and breast echogenicity. Creatine kinase, lactate dehydrogenase and aspartate aminotransferase concentration decreased linearly when broilers were feed restricted (P ≤ 0.05). 5. Wooden breast was positively correlated with echogenicity at 21 d (r = 0.510), 28 (r = 0.531), 35 (r = 0.470), 42 (r = 0.430) and 49 d (r = 0.548) (P ≤ 0.001). The use of breast echogenicity can be an additional tool to early detect alterations related to wooden breast.

Utilization of corn-based diets supplemented with an exogenous α-amylase for broilers.

A study was conducted to evaluate the effects of a supplemental α-amylase on energy and nutrient utilization of broiler chickens fed diets with variable amounts of corn. A total of 480 slow feathering Cobb × Cobb 500 male broilers were randomly distributed into 10 treatments with 8 replicates of 6 birds each. Birds were fed a common starter to 14 D post-hatch. The experimental diets were provided subsequently until 25 D, which were a conventional corn-soy basal diet (CS) and a corn-soy diet displaced with 40% of corn (CN). These were fed as-is or supplemented with 40, 80, 120, or 160 kilo-Novo α-amylase units (KNU)/kg. Dietary treatments were distributed factorially as a 2 × 5 arrangement (diet type vs. amylase). Samples of feed, excreta, and ileal digesta were analyzed for determination of ileal digestible energy (IDE), ME, total tract retention, and digestibility of dry matter, protein, and fat. No interactions between diet type and amylase were observed. The CN diet had lower (P < 0.05) energy utilization and nutrient digestibility when compared to the CS diet. AMEn and IDE increased (P < 0.05) by 110 and 207 kcal/kg, respectively, when CS and CN diets were supplemented with 80 KNU/kg. The amylase added to the CS diet led to quadratic increases (P < 0.05) on growth performance, IDE, AME, and AMEn, as well as in dry matter, protein, and fat digestibility. Energy utilization and crude protein digestibility were linearly increased (P < 0.05) when amylase was added to the CN diet or the extrapolated 100% of corn. In conclusion, energy utilization, digestibility of crude protein, fat, and dry matter increased with amylase supplementation in corn-soy-based diets. When amylase was tested in a complete diet having 53.6% corn, 100 and 105 KNU/kg maximized AMEn and IDE, respectively; however, the maximum energy response in the CN diet or 100% of corn was not achieved until 160 KNU/kg, suggesting an association between amylase dose optimization and dietary starch concentration.

Productive performance, bone characteristics, and intestinal morphology of laying hens fed diets formulated with L-glutamic acid.

This study was conducted to evaluate the effects of L-glutamic acid (Glu) on the productive performance, eggshell quality, bone characteristics, and morphologic parameters of laying hens. Two hundred and forty 53-wk-old Hy-Line W36 laying hens were randomly allocated into 5 treatments, 6 replicates, and 8 birds each. The experimental period was 16 wk. The treatments consisted of a Basal diet (Glu calculated at 2.68%) and 4 L-glutamic acid inclusion levels: 2.88, 3.08, 3.28, and 3.48%. Glu inclusion levels in the hens diet had an increasing linear effect (P < 0.05) on eggshell Ca concentration and bone (tibiotarsus) strength index, and a decreasing linear effect (P < 0.05) on the Seedor index. Serum biochemistry results for total and ionic Ca, inorganic P, and alkaline phosphatase were affected by blood collection time (04:00 Pm, 03:00 Am, and 12:00 Pm) but not by the treatments. Jejunum morphometric variables were not influenced by the treatments except for crypt depth, which demonstrated a quadratic effect (P < 0.05). However, proliferating cell nuclear antigen qualitative immunohistochemical analysis of the jejunum showed more positive nuclei in the villus with the addition of Glu. Both with the basal diet and the lowest Glu inclusion treatment, positive nuclei were observed in the crypts and at the base of the villus, while in the treatments with higher Glu levels, positive cells were common all along the villus mucosa, including its extremity. In conclusion, diets formulated with increased levels of Glu had beneficial effects on eggshell Ca concentration, tibiotarsus structure, and proliferative activity of the jejunum of 69-wk-old laying hens. Therefore, dietary L-glutamic acid can be considered an alternative additive to improve bone characteristics in the productive phase of laying hens.

Broiler responses to increasing selenium supplementation using Zn-L-selenomethionine with special attention to breast myopathies.

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.

Estimation of broiler responses to increased dietary methionine hydroxy analogue [DL-2-hydroxy-(4-methylthio) butanoic acid] using linear and nonlinear regression models.

As the first limiting amino acid in corn-soy broiler diets, methionine (Met) is supplemented using commercial synthetic sources as demanded to obtain economic feed formulations. The Met analogue DL-2-hydroxy-4-(methylthio)-butanoic acid (HMTBA) is largely utilized with that objective. This study intended to obtain responses of broilers fed with increasing levels of HMTBA, from 28 to 42 d, such that economic returns can be calculated. A total of 2,106 Cobb × Cobb 500 one-day-old male broilers was randomly placed in 81 floor pens (2.7 m2 each). Birds were fed conventional starter (zero to 14 d) and grower (14 to 28 d) diets. Starting at 28 d of age, pens of 26 birds were randomly allocated into 9 feed treatments with 9 replications having increasing supplementations with HMTBA (0.00, 0.07, 0.14, 0.21, 0.28, 0.35, 0.42, 0.49 and 0.56%). These were prepared by mixing different proportions of corn-soy dilution and summit diets, which had the same formulated concentration of nutrients and energy [19.7% CP, 0.90% Ca, 0.45% Av. P, 0.95% digestible Lys, and 3,150 kcal/kg AMEn], with the exception of HMTBA [0.56% in the summit but not supplemented in the corn-soy dilution diet (0.52% digestible TSAA)]]. Growth performance was evaluated until 42 d when carcass yield and commercial cuts were evaluated using 6 birds randomly taken from each pen. Body weight gain (BWG), feed conversion ratio (FCR), proportion of breast fillets, and abdominal fat were adjusted using linear broken-line, exponential asymptotic and quadratic polynomial regression models (P < 0.05). Estimations of maximum responses for supplemented HMTBA by the linear broken-line model were 0.17% for BWG, 0.14% for FCR, and 0.29% for breast fillets. Using exponential and quadratic regressions, optimized HMTBA supplementations were obtained at 0.34 and 0.35% for BWG, 0.20 and 0.33% for FCR, and 0.31 and 0.36% for breast fillets, respectively. Supplemental levels of HMTBA that optimize growth performance and breast meat in male broilers from 28 to 42 d, using different regression models, varied from 0.14 to 0.36%.

Apparent metabolizable energy of by-products from the soybean oil industry for broilers: acidulated soapstock, glycerin, lecithin, and their mixture.

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 × 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 × 3 + 1 factorial arrangement was used with 4 by-products (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 by-products (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.

Technical note: Evaluation of urinary purine derivatives in comparison with duodenal purines for estimating rumen microbial protein supply in sheep.

A data set of individual observations was compiled from digestibility trials to examine the relationship between the duodenal purine bases (PB) flow and urinary purine derivatives (PD) excretion and the validity of different equations for estimating rumen microbial N (Nm) supply based on urinary PD in comparison with estimates based on duodenal PB. Trials (8 trials, = 185) were conducted with male sheep fitted with a duodenal T-type cannula, housed in metabolic cages, and fed forage alone or with supplements. The amount of PD excreted in urine was linearly related to the amount of PB flowing to the duodenum ( < 0.05). The intercept of the linear regression was 0.180 mmol/(d·kg), representing the endogenous excretion of PD, and the slope was lower than 1 ( < 0.05), indicating that only 0.43% of the PB in the duodenum was excreted as PD in urine. The Nm supply estimated by either approach was linearly related ( < 0.05) to the digestible OM intake. However, the Nm supply estimated through either of 3 published PD-based equations probably underestimated the Nm supply in sheep.

Age-related energy values of bakery meal for broiler chickens determined using the regression method.

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 × 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.

Energy and nutrient utilization of broiler chickens fed corn-soybean meal and corn-based diets supplemented with xylanase.

A study was conducted to evaluate the effects of increased levels of a ß-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 ß-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 = - 0.014x(2) + 2.570x + 3,155; r(2) = 0.60) and in AMEn (Y = - 0.016x(2) + 3.982x + 3,155; r(2) = 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.

Starch digestibility, energy utilization, and growth performance of broilers fed corn-soybean basal diets supplemented with enzymes.

A study was conducted to evaluate the effects of dietary α-amylase and ß-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 = corn-soy 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 ß-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.

Formulating poultry diets based on their indigestible components.

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.

Productive performance, eggshell quality, and eggshell ultrastructure of laying hens fed diets supplemented with organic trace minerals.

This study was carried out with the purpose of evaluating the effect of supplementing hens' diets with trace minerals from inorganic or organic sources on the productive performance, eggshell quality, and eggshell ultrastructure of laying hens. Three hundred sixty Hy-Line W36 laying hens between 47 to 62 wk of age were used and distributed in a completely randomized experimental design with 9 treatments, 5 replicates, and 8 birds for each experimental unit. The treatments consisted of a control diet without supplementation of the trace minerals Mn, Zn, and Cu; 4 supplementation levels of these trace minerals from an inorganic source; and the same levels of supplementation from an organic source (proteinates). The supplementation levels in milligrams per kilogram for Mn, Zn, and Cu, were, respectively, 35-30-05, 65-60-10, 95-90-15, and 125-120-20. There was no effect of supplementation of trace minerals on the rate of posture, feed intake, feed conversion, specific weight, and Haugh unit of eggs. However, there was a quadratic effect (P < 0.05) of the levels of trace mineral supplementation on average egg weight and egg mass; the results did not differ regarding the source used. The increase in the levels of supplementation of Mn, Zn, and Cu provided a linear increase (P < 0.05) in the breaking strength and the percentage of eggshell. There was a linear decrease (P < 0.05) in the egg loss and the number of mammillary buttons in the shell. The best results were obtained using diets supplemented with trace minerals from an organic source because these diets provided lower egg loss, higher thickness, and increased strength of the shell. Structurally, organic Mn, Zn, and Cu provided higher thickness of the palisade layer and lower mammillary density. The trace mineral supplementation improved the structural characteristics and the quality of the eggshells.

Technical note: Evaluation of markers for estimating duodenal digesta flow and ruminal digestibility: Acid detergent fiber, sulfuric acid detergent lignin, and n-alkanes.

The amount of digesta flowing to the duodenum is a relevant measurement for the evaluation of nutrient supply to ruminants, which is usually estimated in animals fitted with a duodenal T-type cannula using internal or external markers. This study evaluated acid detergent fiber (ADF) compared with external (C32n-alkane) and internal [sulfuric acid lignin (ADL) and n-alkanes C31 and C33] markers for estimating duodenal flow and(or) ruminal digestibility of dry matter (DM) in cattle and sheep. In the first assay, 4 duodenally cannulated Holstein steers housed in metabolism cages, dosed with C32n-alkane, and fed Avena strigosa plus concentrate and increasing levels of tannin extract to reduce ruminal digestibility, were used in a Latin square design. The mobile-bag technique was used to measure the intestinal disappearance of ADL and ADF from forage (Avena strigosa, Pennisetum purpureum, Cynodon dactylon, and Medicago sativa) and concentrate (corn grain, soybean meal, and sunflower meal) samples that were previously incubated in the rumen of additional fistulated steer for 12, 24, 36, or 48 h. The ADF concentration in residues recovered in the feces was strongly related to the ADF concentration in residues at the duodenum (R(2)=0.93, standard deviation=30.0, n=901). This relationship showed a lower precision for ADL fraction (R(2)=0.88, standard deviation=12.6, n=590). In a second assay, duodenal flow and ruminal DM digestibility were calculated from the duodenal and fecal concentration of either marker. We observed a significant effect of marker type on ruminal DM digestibility values, and the effect of tannin treatments was observed only when ADF or ADL was used as the marker. The lowest residual error was obtained for ADF. Ruminal DM digestibility was, on average, higher for C31 and C(33)n-alkanes, and the use of dosed C(32)n-alkane resulted in a negative value. In the third assay, a data set of 235 individual observations was compiled from digestibility trials to compare ADF and ADL as markers for estimating duodenal digesta flow in wethers (n=204) and cattle (n=31). We observed a strong relationship between markers (R(2)=0.84 in sheep and R(2)=0.88 in cattle), but variance analysis within trials indicated that ADF was more precise than ADL. In conclusion, in digestibility trials in which fecal output was measured and spot samples of the duodenal digesta were obtained, duodenal flow and ruminal digestibility of the DM may be estimated from the relationship between the ADF concentration in feces and that in the duodenal digesta of ruminants.