ABSTRACT The use of enzymes is a concrete fact in broiler feeding. The global economic situation has been undergoing major changes, especially in the cost of agricultural commodities such as corn and soybean meal, the main ingredients in broiler diets in many parts of the world. This study aimed to assess the effect of increasing doses of phytase by assigning an optimized non-linear increasing nutritional matrix to the diet of broilers from 1 to 42 days of age, using economic production indicators as response variables. 900 one-day-old chicks were distributed in a randomized block design with six treatments and ten replications. Different nutritional matrices were studied: a positive control diet without phytase; diets with increasing levels of this enzyme (350, 500, 1,000, 1,500 FTU); and a negative control diet (-100 kcal/kg EMA) without phytase supplementation. Performance from 1 to 42 days of age and economic viability were assessed. It was observed that the negative control and the overdose (1,500 FTU) of phytase showed worse feed conversion than the positive control diet. In the economic analysis, there was a reduction in feed costs with increasing doses of the enzyme, as well as lower production costs per carcass kilo. The data found in this study shows that performance indicators do not always reflect economic efficiency responses. Specifically, the production cost was lower in broiler diets (1 to 42 d) formulated with increasing doses of phytase (up to 1,500 FTU kg-1). feeding changes meal world nonlinear non linear 4 variables 90 onedayold one day old replications studied 350, 350 (350 500 1000 000 1,000 1500 1,50 100 (-10 kcalkg kcal kg EMA supplementation assessed (1,50 analysis kilo responses Specifically ( d up kg1. kg1 . kg-1) 9 35 (35 50 00 1,00 150 1,5 10 (-1 (1,5 kg-1 3 (3 5 0 1,0 15 1, (- (1, kg-

ABSTRACT The objective of this study was to evaluate different strategies for the oxidative stabilization of rice bran (RB) in the diet of broiler chickens using natural antioxidant additives, synthetic antioxidant additives and heat treatment on performance, breast meat quality and liver fat content and the nutrient digestibility coefficients. Furthermore, the study aimed to evaluate the effects of heat treatment and antioxidants, antioxidant additive treatments, without antioxidants, natural, and synthetic, and to three heat treatments, without heat, dry-heat and moist-heat, after the rice bran was stored for 90 days and then incorporated into the experimental diets. 1080 broilers were arranged in a 3 x 3-factorial randomized design with 10 replicates per treatments. The wet heat treatment of the meal resulted in a higher daily feed intake and body weight at 28 days and better feed conversion than did the meal without heat treatment. No significant interactions were observed between the tested factors on the apparent digestibility of dry matter and ether extract as well as the values of apparent metabolizable energy and apparent metabolizable energy corrected for nitrogen. However, there was significant interaction between the tested factors on the nitrogen retention coefficient; the natural antioxidant and dry heat-treated meal combination presented a lower crude protein digestibility coefficient than those without heat treatment. In conclusion, thermal treatment of this bran proved to be more effective as demonstrated by the performance responses of the birds. Broiler chickens reared up to 28 days of age consuming diets containing 6.5% RB stabilized by heat treatment showed better performance, and the use of antioxidants was not necessary.

ABSTRACT Broiler energy nutrition has attracted attention due to its economic importance, particularly during the rearing period of 22-42 days of age. There are many evidences that broilers changed their feed intake capacity due to genetic selection, especially when good quality pellets are fed, which suggests that modern broiler strains may achieve good performance when fed low metabolizable energy levels. The objective was to evaluate the energy efficiency, performance parameters, bone parameters, and carcass yield of 22- to 42-d-old broilers fed diets with energy levels below or above their requirements, while maintaining the density of all other nutrients. In total, 900 male broilers were distributed in a randomized block design, with five treatments consisting of five ME levels (2850, 2950, 3050, 3150 and 3250 kcal/kg). As expected, increasing dietary metabolizable energy reduced feed intake, feed conversion ratio, and energy efficiency. Interestingly, body weight, carcass and cut yields, and bone quality were not affected (p>0.05) by dietary ME levels. In conclusion, 22- to 42-d-old broilers fed pelleted and crumbled diets containing 2,850 to 3,250 kcal ME/kg (14% difference) achieved the same body weight and carcass yield at slaughter. The results show that energy efficiency may provide a more accurate interpretation of broiler performance than feed conversion ratio, and that broilers are able to change their feed intake, indicating an opportunity to improve their nutritional management.

Seven hundred and twenty Ross 308 chicks were raised in a controlled environment room, distributed in a factorial design with 3 hatching chick weights (37, 40 and 44 g), 3 geometric mean diameter (GMD) (0.561; 0.783 and 0.997 mm) and 4 total sodium levels (Na) (0.12; 0.24; 0.36 and 0.48%) in the pre-starter diet (1 to 7 days). From 8 to 21 days (d) one single basal diet was used for all treatments. The thirty seven-gram chicks had the smallest yolk sack weight at 4d, smallest body weight (BW) and feed intake (FI) at 7d and 21d, but the same feed conversion (FC) than the other groups of hatching weight. Chicks receiving diet with intermediate GMD had the greatest BW and FI at 7d, but at 21d this effect was no longer seen. The diet with finest particle size resulted in birds with the smallest gizzard weight at 7d. The 0.12%Na diet was statistically different from the other Na levels, resulting in chicks at 7d with the worst FC and lowest body weights. At 21d, BW still was the lowest for this group of chicks. Birds with 0.48%Na produced more watery excreta and less dry matter in the carcass at 7d. Water consumption (C H2O) was influenced linearly by chick weight up to 0.36%Na level. In the 0.48%Na level, 40 and 44 g chicks had similar C H2O, which was different from 37-g chicks. For best performance, Na values were set from 0.31 to 0.48%. The three studied factors influenced quality of pre-starter diet and consequently chick performance.

Esse experimento foi realizado com o objetivo de avaliar a ação de produto de exclusão competitiva (EC) sobre os efeitos da ocratoxina A (OA). As aves alimentadas com 2 ppm de OA na dieta reduziram significativamente o consumo de ração e ganho de peso, além de apresentarem pior conversão alimentar quando comparadas às aves não expostas à OA na dieta. O emprego da EC no primeiro dia de vida não minimizou esses efeitos, bem como não afetou os parâmetros zootécnicos estudados. Aves alimentadas com OA apresentaram diminuição nos títulos vacinais contra o vírus da doença de Newcastle, evidenciando-se assim a interferência dessa micotoxina na resposta imune humoral de frangos de corte. De outra forma, a EC não interferiu na resposta imune humoral de frangos de corte vacinados contra a doença de Newcastle. Tanto a AO como a EC não alteraram os dados de altura de vilo, profundidade de cripta e relação vilo:cripta nas aves aos sete dias de idade quando comparados àqueles do grupo controle na mesma idade

This experiment aimed at evaluating the action of competitive exclusion (CE) on the effects of ochratoxin A (OA). Birds fed 2ppm OA in the diet had significant lower feed intake, weight gain, and feed conversion than birds not exposed to OA in the diet. The use of CE on the first day of age did not minimize these effects nor the performance parameters studied. Birds fed OA has lower vaccinal titers of Newcastle disease virus, showing the interference of this mycotoxin on the humoral immune response of broilers. CE did not interfere in the humoral immune response of broilers vaccinated for Newcastle disease. OA and CE did not influence villus height, crypt depth, nor villus:crypt ratio in seven-day-old birds as compared to control broilers of the same age.

Dois experimentos (EXP 1 e 2) foram conduzidos para avaliar relações energia metabolizável:proteína bruta (EM:PB) e a adição de treonina (Thr) em dietas com alta (A) (3.200kcal EM/kg) e baixa (B) (2.900kcal EM/kg) energia, sobre desempenho e composição de carcaças de frangos de corte machos. As relações energia:proteína foram 139 e 160 kcal/%, para as dietas iniciais (1 a 21 dias) (EXP 1) e 160 e 181kcal/%, para as de crescimento (22 a 40 dias) (EXP 2), nos dois níveis de energia. As dietas com ampla relação EM:PB foram suplementadas, ou não, com Thr a fim de iguala-las às dietas com menor EM:PB. Os níveis de Met+Cys e de Lys foram constantes. As aves receberam uma dieta única após (EXP1), ou antes (EXP2) do fornecimento das dietas experimentais. Nos dois EXP as dietas A proporcionaram melhor desempenho: ganho de peso (GP),consumo de ração e conversão alimentar (CA) (p<0,01), ao final de cada período experimental. Porém, no EXP 1, as aves que receberam dietas B tiveram melhor conversão calórica (CC, kcal/kg,) (p<0,01) no período total (1 a 40 dias), indicando um período de crescimento acelerado. Os níveis de Thr (0,74 e 0,69% para A e B respectivamente) das dietas com relação EM:PB ampla não foram limitantes no desempenho das aves. No EXP 2, a EM:PB 181 deprimiu o GP (p<0,08) e piorou a CA (p<0,01), nas energias A e B. Portanto, em dietas práticas iniciais, Thr não foi um aminoácido (AA) limitante. Porém, de 22 a 40 dias, a adição de Thr foi necessária, em dietas com EM:PB 181kcal/%(EXP 2). A suplementação de Thr não influenciou a composição das carcaças nos dois EXP.

Two experiments (EXP) were carried out to investigate the metabolizable energy:crude protein ratios (ME:CP) and threonine addition (Thr) in high-energy (H) (3.200kcal ME/kg) and low-energy (L) (2.900kcal ME/kg) diets, on the performance and carcass composition of male broiler chickens. The ME:CP ratios were: 139 and 160kcal/% for starter diets (1 to 21 days of age) (EXP 1) and 160 and 181kcal/% for grower diets (22 to 40 days)(EXP 2), in both energy levels, keeping Met + Cys and Lys constant. Thr was supplemented to equalize its level to the lower EM:PB ratio. All birds received a unique diet after (EXP 1) or before (EXP 2) been fed with the experimental diets. In both EXP feeding H diets resulted in better performance -weight gain (WG), feed intake (FI) and feed conversion (FC) (p<0,01) at the end of each experimental period. However, in EXP 1, birds fed with L diets during the starter period had better caloric conversion (kcal/kg) (CC) in the total period (1 to 40 days), as an indicative of accelerated growth. The lower levels of Thr (0.74 and 0.69% for H and L diets, respectively) were not limiting for birds' performance. On EXP 2, the 181 ME:CP decreased WG (p<0.08) and increased FC (p<0.01) in both energy levels. Thr was not a limiting amino acid in initial practical diets (1 to 21 days of age). On the other hand, Thr supplementation improved performance of birds at 181 E:CP (22 to 40 days) (EXP2). Thr addition did not influence carcass composition in both EXP.

Dois experimentos (EXP) avaliaram os efeitos da redução de proteína bruta (PB) em dietas com alta (A) (3.200kcal EM/kg) e baixa (B) (2.900kcal EM/kg) energia, sobre o desempenho e composição de carcaças de frangos de corte machos. Os níveis de PB foram reduzidos para obter as relações energia: proteína (E:PB) 139, 146, 153 e 160 (kcal/%) para as dietas iniciais (EXP 1), e 160, 167, 174 e 181(kcal/%) para as dietas de crescimento (EXP 2), em ambos os níveis de energia, mantendo constantes os níveis de MET+CIS e LIS. Todas as aves receberam uma mesma dieta antes (EXP 2) ou após (EXP 1) o fornecimento das dietas experimentais. O fornecimento das dietas A proporcionou melhor desempenho, no entanto resultou em maior deposição de gordura nas carcaças. No EXP 1, as aves alimentadas com as dietas B apresentaram ganho de peso (GP) similar àquelas alimentadas com as dietas A no período total (1 a 42 dias), porém melhor conversão calórica (CC) (kcal/kg) (p<0,01). Foi observada também melhor CC, com relação E:PB 139. Menores níveis de PB dietética resultaram, algumas vezes, em um menor GP, porém sempre foi verificada uma pior CC nas relações mais amplas E:PB. Em ambos os Experimentos (EXP), o maior nível de energia e a redução da PB dietética melhoraram a utilização da PB consumida.

Two experiments (EXP) were carried out to investigate the effects of crude protein (CP) levels reduction in high-energy (H) (3.200kcal ME/kg) and low-energy (L) (2.900kcal ME/kg) diets, on the performance and carcass composition of male broiler chickens. The CP levels were decreased to meet the following energy: protein (E:PB) ratios: 139, 146, 153 and 160 (kcal/%) for starter diets (EXP 1) and 160, 167, 174 and 181 (kcal/%) for grower diets (EXP 2), in both energy levels, keeping MET + CIS and LYS levels at the same concentration. All birds received a same diet before (EXP 2) or after (EXP 1) feeding the experimental diets. Feeding H diets resulted in better performance, but also in higher carcass fat deposition. In EXP 1, birds fed with L diets during the starter period had similar body weight gain (BWG), in the total period (1 to 42 days), than those H diets, however with better caloric conversion (kcal/kg) (CC). Also, the best CC was obtained with E:PB of 139. Lower BWG, sometimes occurred with lower levels of dietary CP, but in all experiments the CC was decreased with wider E:PB ration. In both EXP, protein utilization was improved with higher levels of dietary energy and with lower levels of dietary CP.