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A study was conducted to evaluate the effects of dietary α-amylase and β-xylanase, in single or combined supplementation, on growth performance of broiler chickens fed maize-soy diets. A total of 1800 slow feathering, Cobb × Cobb 500 male broilers were randomly distributed to 8 treatments with 9 replicates of 25 birds each. Broilers were fed starter and finisher diets respectively from 1 to 21 and 22 to 40 d Broilers were fed starter and finisher diets respectively from 1 to 21 and 22 to 40 d. A negative control (NC) diet was formulated to contain 12.35 MJ/kg and 12.85 MJ/kg in the starter and finisher phases, respectively. A further four control diets were formulated with orthogonal energy density increases in increments of 0.21 MJ/kg to a maximum of 13.17 MJ/kg (starter) and 13.67 MJ/kg (finisher). All control diets were formulated to be equivalent in amino acids and minerals. The NC diet was supplemented with α-amylase (80 kilo-Novo α-amylase units/kg), β-xylanase (100 fungal β-xylanase units/kg), or both enzymes combined at the same supplementation levels. Increasing AME n resulted in a linear increase (P < 0.01) in BWG and a linear decrease (P < 0.01) in FCR from 1 to 40 d. Corresponding AME n estimates for BWG and FCR from 1 to 40 d were, respectively 0.41, 0.35, and 0.57 and 0.18, 0.11, and 0.21 MJ/kg for amylase, β-xylanase and amylase + β-xylanase. In conclusion, supplementing maize-soy diets with α-amylase and β-xylanase led to increased estimated energy yields. A marked difference occurred in favor of α-amylase when compared to β-xylanase supplementation whereas adding both enzymes in the same feed generated similar AME n to the single addition of α-amylase. Growth performance responses corresponded to findings in the AME n assay. [ABSTRACT FROM AUTHOR]

Responses of broilers to dietary amino acids (AA) have been extensively studied especially after their synthetic and crystalline forms became available. Synthetic (DL-Met and Met analogue) as well as crystalline ( l -Lys and l -Thr) AA are now widely used in commercial production diets to reduce crude protein (CP) levels to allow competitive bird performance. In parallel, birds diets formulated without excess CP have reduced nitrogen excretion as well as lower costs. Diet composition affects the order of limiting AA after Thr and this has led to some debate on the feasibility of including the next limiting AA, which would be the fourth, in most of the scenarios. Using maize-soy type diets, the literature suggests that Val is the fourth AA limiting. As the commercial cost of l -Val is progressively reduced, concerns have been raised on the effectiveness of its supplementation to produce broiler responses that are similar compared with feed that does not contain this AA. Antagonisms between branched-chain amino acids (BCAA) have been reported in the past; however, their use in the current maize-soy diet commercial setting is unlikely. Formulation of diets with crystalline l -Val can potentially modify the ratio between BCAA as it is supplemented in diets that are further reduced in CP. Increased availability of AA can also be achieved when diets are supplemented with exogenous proteases; however, the resulting impact in the total profile of AA is different because a wider group of AA becomes simultaneously available when compared to diets receiving addition of synthetic/crystalline AA one by one. A scenario of CP reduction in diets seems clear with the increasing use of supplemental AA along with protease in broiler diets. The knowledge of CP reduction strategies, such as protease and synthetic AA supplementation, can be a valuable asset due to the competitive nature of broiler meat production business. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of an exogenous protease added to diets having soybean meal (SBM) from two geographic areas in Brazil (South or North). Evaluation was conducted on energy utilisation and nutrient digestibility using 224 slow feathering Cobb × Cobb 500 male broilers. Birds were fed a common starter diet to d 15. Semi-purified experimental diets containing 555 g/kg SBM and 408 g/kg maize starch plus minerals and vitamins were provided afterwards until 24 d. Diets had 0.1 g/kg phytase and 10 g/kg Celite (indigestible marker). Birds were randomly distributed in a 2 × 2 factorial arrangement of the two SBM with or without protease supplementations (0 or 15,000 protease units/kg) from 17 to 24 d. Excreta were collected from 21 to 23 d and ileal content was collected from all birds. Samples of feed, excreta, and ileal content were analysed for determination of total tract retention and ileal apparent digestibility. No interactions between SBM and protease were observed. Broilers fed semi-purified diets formulated with South SBM had lower (P < 0.05) ileal digestibility of crude protein and also from most amino acids (AA) when compared with birds fed North SBM. Ileal digestible energy was increased (P < 0.01) by 0.51 MJ/kg when birds were fed the diet supplemented with protease. Indispensable and dispensable AA digestibility also increased (P < 0.05) with protease supplementation. Ileal digestibility coefficients of Met, Lys, Thr and Val were increased (P < 0.05) by 3.1%, 3.1%, 4.8%, and 3.3%, respectively when birds were fed the diet supplemented with protease. Results from this experiment show that utilisation of energy and AA from SBM depends on its origin, but protease supplementation improved their utilisation regardless of the SBM source. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of supplementing maize-soy diets with a commercial xylanase-β-glucanase complex [β-xylanase, 1,3(4)-β-glucanase, and 1,4-β-glucanase] on growth performance, energy and amino acid utilisation of broiler chickens. A total of 2016 Cobb × Cobb 500 1-d-old male chicks were distributed into 9 treatments with 8 replicates of 28 birds each in a completely randomised design. Treatments consisted of a Control diet formulated with AME and nutrients as commercially used by the Brazilian integrators without enzyme supplementation as well as 8 other diets having reductions in formulated AME (−0.33 and −0.50 MJ/kg) and digestible amino acids (dig. AA; −3 and −6%). These diets were supplemented or not with 50 mg/kg of the enzyme complex. Ileal contents were collected at 21 and 42 d to determine ileal digestible energy (IDE), dry matter and AA digestibilities. Broilers fed diets with AME and dig. AA reductions without enzyme had higher FCR and these diets had lower IDE (P < 0.05). The supplemental enzyme increased total AA digestibility at 21 d; however, no effects were observed at 42 d. The highest total AA digestibility (P < 0.05) was observed when broilers were fed the Control diet whereas the supplemental enzyme compensated the nutrient and energy reductions. The addition of 50 mg/kg of the xylanase-β-glucanase complex in maize-soy diets led to improvements on FCR, IDE and ileal digestibility of dry matter in broilers at 21 and 42 d. The highest energy improvement provided by the supplemental enzyme was observed at 21 d on broilers fed diets with −0.50 MJ/kg AME and −6% dig. AA, being 5.8% higher when compared to those fed the analogous diet without enzyme. [ABSTRACT FROM AUTHOR]

A total of 4,800 one day (d) old Cobb 500 male broilers was used in a study with the objective of evaluating dietary programs formulated with different degrees of restriction in crude protein (CP) and the supplementation of L-valine and L-isoleucine. Four feeding programs (PRG) reflecting different strategies to deliver amino acids (AA) to broilers were used, respectively from d 1 to 7, 8 to 21, 22 to 35 and 36 to 42, as follow: PRG 1, CP restricted to 224, 211, 198 and 184 g/kg with minimum digestible AA to lysine (Lys) ratios only set for total sulfur AA (TSAA) (0.72) and threonine (Thr) (0.65); PRG 2, as PRG 1 without CP restriction with AA ratios to Lys extended to valine (Val) (0.77) and isoleucine (Ile) (0.67); PRG 3, as PRG 2 supplemented with L-Val and PRG 4, as PRG 3 supplemented with L-Ile. Replications of the 4 PRG provided from 1 to 21 d were further divided into the 4 respective PRG given from 22 to 42 d for total of 16 treatments. The study was conducted as a completely randomized block design with 2 time blocks and 24 replications per treatment per block from 1 to 21 d and 12 replications from 22 to 42 d. Overall, there were no effects for time block or interaction between PRG fed from 1 to 21 and 22 to 42 d of age. Performance and processing data demonstrated benefits of formulating diets using minimum ratios of Val and Ile. Body weight gain was higher when both AA were supplemented together (PRG 4). On the other hand, feed conversion ratio (FCR) was improved when the ratios Val and Ile to Lys were obtained without the use of synthetic sources. Carcass yield data was not affected by PRG with the exception of the proportion of abdominal fat that was reduced (P<0.05) when broilers were fed diets with minimum ratios of Val and Ile without using synthetic sources. In conclusion, formulation of diets for broilers without minimum CP level but using AA to Lys ratios as in PRG 2, 3 and 4, allowed competitive growth performance and carcass yield results. Using L-Val and L-Ile led to improved FCR and, therefore, this possibility should be explored to maintain the efficiency of broiler meat production. [ABSTRACT FROM AUTHOR]