The intensification of livestock have increased the emission of pollutants to the environment, leading to a growing interest in seeking strategies that minimise these emissions. Studies have shown that it is possible to manipulate diets by reducing CP levels and thus reducing nitrogen (N) excretion, without compromising performance. However, there is no knowledge of any study that has focused on reducing N excretion and relating this reduction to individual amino acids. This study investigated the effect of dietary methionine + cysteine (MC) and threonine (THR), the two most limiting amino acids for broiler production, on nitrogen excretion (NE) and nitrogen deposition (ND) and determined the efficiency of utilisation of both amino acids for protein deposition. Six trials were conducted to measure the NE and ND in broiler chickens during three rearing phases in response to dietary amino acid. The efficiency of utilisation of the amino acids was calculated by linear regression of body protein deposition and the amino acid intake. Despite the differences between sexes and phases, the efficiency of utilisation was the same, being 0.60 and 0.59 for MC and THR, respectively. The rate of NE behaved exponentially, increasing with amino acid intake, and can exceed 50% of N intake, being higher than ND. On average, for a reduction in intake of each unit of MC or THR (mg) there is a reduction of 0.5% of NE. Although this reduction seems low, considering that it corresponds to changes in one amino acid only, the impact on a large scale would be significant. Knowledge of how animals respond to NE and ND/protein deposition according to amino acid dietary content may represent new efforts towards reducing the impact on environment.Keywords: amino acids, efficiency of utilisation, environmental pollution, nutrition, poultry ImplicationsThis study shows the effect of amino acids on nitrogen excretion and deposition and on their efficiency of utilisation for protein deposition by broilers. The nitrogen originating from the poultry is an environmental pollutant. Provision of higher amounts of amino acids, besides not increasing protein deposition, also causes increased nitrogen excretion. Meeting animal's amino acids requirements, provides greater efficiency of utilisation of these amino acids, without affecting protein deposition in the animals, and thus reduces nitrogen excretion. In this way, the management of amino acids in broilers diets may allow new efforts to reduce the impact of intensification of livestock. IntroductionThe intensification of livestock have significantly increased the emission of pollutants to the environment, leading to a growing interest in seeking alternatives that minimise these emissions. The European Union has already implemented laws regulating environmental pollution, especially in regard to the emission of nitrogen (N) compounds, considered to be a critical pollutants affecting life on earth (European Commission, 2007). N compounds are responsible for pollution of groundwater due to nitrate lea...

-The objective of the present study was to evaluate the influence of a probiotic product (composition:Lactobacillus acidophillus (3.5 × 10 11 CFU), Streptcoccus faecium (3.5 × 10 11 CFU) and Bifidobacterium bifidum (3.5 × 10 11 CFU)) on broiler performance. A total of 1200 one-day-old broilers were reared until 42 days of age, and distributed in a completely randomized experimental design with 3 treatments (antibiotic, probiotic and control) with 10 replicates of 40 birds each. Weight gain, feed intake, feed conversion ratio and mortality were evaluated. Concerning weight gain, in the periods of 0-7 and 0-14 days of age, the group fed the antibiotic product presented higher values as compared with the other treatments. However, in the periods of 0-21, 0-28 and 0-35 days of age, birds fed the antibiotic presented higher weight gain only in relation to the control group. Feed intake differences were detected only in the initial period of 0-7 days of age, with the group fed the antibiotic product presenting higher feed intake as compared with that fed the probiotic product, although these groups were not different from the control group. No statistical difference was detected in feed conversion ratio among treatments in any of the evaluated age intervals. Mortality was different only in the period of 0-14 days of age, which was higher in the control group as compared with that of the birds fed the probiotic product, but it was not different from the group receiving the antibiotic. Treatment with probiotic product containing Lactobacillus acidophillus, Streptococcus faecium and Bifidobacterium bifidum does not affect broiler performance.

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Three experiments were conducted with broiler chickens to evaluate the effects of digestible total sulphur amino acid (TSAA) on their performance at three different phases of starter (1-14 d), grower (15-28 d) and finisher (29-42 d). The measured traits included: average daily gain (ADG), feed intake, feed conversion ratio (FCR), carcass protein, body lipid (BL), feather weight gain, carcass plus feather protein, carcass TSAA deposition and nitrogen excretion (NE). A dilution technique was used to create seven diets (with eight replicates) increasing the TSAA content from 2.5 to 9.04 g/kg of diet for starter, 2.26 to 8.14 g/kg of diet for grower and 2.08 to 7.5 g/kg of diet for finisher. Data measured were imported to neural networks to predict the measured traits in response to dietary and intake levels of TSAA and find the optimal levels of TSAA that lead to the desired responses. Optimization results showed decreases in optimal dietary TSAA values with increasing age for all traits, while reverse was observed for intake values and requirements were increased as birds aged. The highest TSAA requirement (7.95, 7.2 and 6.6 g/kg and 283, 585 and 1150 mg/bird per d for starter, grower and finisher, respectively) were achieved for minimum BL and lowest (5.8, 5.2 and 4.9 g/kg and 201, 444 and 873 mg/bird per d for starter, grower and finisher, respectively) were suggested for minimum NE. Based on intake models, the optimal TSAA values for minimum FCR in phases 1-3 were 283, 585 and 1150 mg/bird per d while maximum ADGs were achieved with 201, 444 and 873 mg/bird per d of TSAA.

The aim of this study was to evaluate carcass characteristics and quality of breast meat after the inclusion of phytase in broiler diets with different levels of apparent metabolizable energy (AMEn) corrected for nitrogen and reduced crude protein (CP) supplemented with essential amino acids following the concept of ideal protein. A total of 1,500 Cobb broilers from 22 to 42 days (initial weight of 833 ± 7 g and final weight of 2741 ± 48 g) were distributed in completely randomized design in a factorial 3x3+1 experiment (three levels of AMEn - 2,950; 3,100 and 3,250 kcal/kg - and three levels of CP - 14, 16 and 18% - and an additional treatment - control without phytase, with 3,100 kcal/kg EMAn, 19.2% PB and 0.4% available phosphorus), in six replications of 25 birds each. At the end of the trial, two birds of each experimental unit were slaughtered in order to measure carcass yield and yields of parts and to determine the chemical composition of the breast meat. The levels of AMEn and CP of diets with phytase influenced (P<0.05) the carcass, breast and abdominal fat yield and humidity, protein and fat percentage in the pectoralis major muscle of the birds. The levels of 3,100 kcal AMEn/kg and 18% CP showed higher carcass and breast yield and lower abdominal fat deposition, although with higher fat percentage in the breast meat. It was concluded that the manipulation of the energy levels of diets with reduced crude protein supplemented with amino acids and phytase influenced the yields of parts of carcass and the breast meat quality of the broilers at 42 days.

Although phytase has been researched, new enzymes have been produced, leading to different animal responses. In this scenario, the present study proposes to evaluate the inclusion of a bacterial phytase produced by Escherichia coli in broiler diets based on corn and soybean meal, with or without nutrient reductions, on the performance, nutrient digestibility, phosphorus bioavailability, and bone minerals of those animals and on the economic viability of this practice. A total of 896 male broiler chickens were distributed into 32 experimental units, each housing 28 broilers. The experiment was set up as a completely randomized design with four treatments (Positive Control (PC)-diet meeting the nutritional requirements of the broiler chickens; Negative Control (NC) with reductions of 100kcal/kg of ME, 0.14% av P and 0.11% t Ca; NC + phytase (500 FTU/kg); PC + phytase (500FTU/kg)) and 8 replicates. Phytase increased (p < 0.05) feed intake and body weight gain and improved feed conversion ratio in starter (1 to 21 days) and total (1 to 42 days) phases, respectively, compared with Negative Control diet without supplementation. The Negative Control + phytase diet also led to a feed intake similar to Positive Control in the starter and total phases. The inclusion of phytase without nutrient reductions improved (p < 0.05) feed conversion ratio in the starter phase, compared to Positive Control diet. There was an increase (p < 0.05) in the digestibility of dry matter, crude protein and phosphorus and in apparent digestible energy in the Negative Control + phytase diet compared to the Negative Control diet. Phytase supplementation increased (p < 0.05) the digestibility of crude protein, calcium and phosphorus, and apparent digestible energy compared to Positive Control diet. Ash, phosphorus, and calcium contents were higher in the Negative Control + phytase diet compared with those observed in the Negative Control diet without enzyme (p < 0.05). The Positive Control + phytase diet provided higher ash contents (p < 0.05), but calcium and phosphorus deposition was similar to those obtained with Positive Control diet. Phytase inclusion allows for a reduction in the diet cost per ton of produced feed. In conclusion, dietary supplementation with bacterial phytase produced from Escherichia coli for broiler chickens is recommended, as it provided increases in production performance, nutrient digestibility, and energy metabolizability and a reduction in the diet cost. ResumoEmbora a fitase tenha sido estudada, novas enzimas foram produzidas, levando a respostas animais diferentes. Nesse sentido, o presente estudo teve como objetivo avaliar a inclusão de fitase bacteriana produzida por Escherichia coli em dietas à base de milho e farelo de soja, com ou sem redução de nutrientes sobre o desempenho, digestibilidade dos nutrientes, biodisponibilidade de fósforo, minerais ósseos e viabilidade econômica. Foram distribuídos 896 frangos de corte machos em 32 unidades experimentais, cada unidade constituída por 28 frangos. O delineamento f...

Um experimento foi conduzido para avaliar o efeito de rações contendo diferentes níveis de cálcio e suplementadas com fitase sobre o desempenho de frangos de corte nas fases inicial (1 a 21 dias), de crescimento (22 a 35 dias) e final (36 a 42 dias). Foram utilizados 2.160 pintos de corte machos da linhagem AG Ross 308, de 1 a 42 dias de idade, distribuídos em 6 tratamentos, cada um com 6 repetições. Foi utilizado um delineamento inteiramente casualizado em esquema fatorial 3 × 2, com 3 níveis de fitase (0, 600 e 1.200 ftu/kg) e 2 de cálcio (0,94 e 0,66%; 0,84 e 0,59%; e 0,78 e 0,54% para as fases inicial, de crescimento e final, respectivamente). As rações experimentais ainda tinham níveis reduzidos de fósforo disponível e níveis mínimos de proteína bruta. Ao final de cada fase, avaliaram-se o ganho de peso, o consumo de ração, a conversão alimentar e a mortalidade. Houve interação entre os níveis de fitase e de cálcio estudados para ganho de peso, consumo de ração e mortalidade nas três fases avaliadas. Os melhores resultados foram obtidos com a suplementação de fitase no nível de 1.200 ftu/kg de ração em associação aos menores níveis de cálcio. Nenhum resultado significativo foi observado para conversão alimentar. Os níveis nutricionais de cálcio podem ser reduzidos em 30% em dietas com baixos níveis de fósforo disponível e níveis mínimos de proteína bruta, desde que as dietas sejam suplementadas com 1.200 ftu/kg de fitase.

ABSTRACT:The objective was to determine the efficiency of utilization of lysine and to describe the responses of pullets to different digestible lysine intakes using three mathematical functions to estimate an optimal intake maximizing body weight gain and feed conversion ratio. The trials were conducted using 2-6-, 8-12-, and 14-18-weekold birds and a completely randomized experimental design with eight treatments and six replicates. The digestible lysine levels ranged 3.20-10.67 g/kg (in 2-6-week-old animals), 2.24-7.48 g/kg (in 8-12-week-old animals), and 1.73-5.78 g/kg (in 14-18-week-old animals) and were obtained using a dilution technique. The efficiency of utilization was determined by a linear regression between lysine deposition and intake for pullets aged 2-4, 8-10, and 14-16 weeks. Three mathematical functions (quadratic polynomial, broken-line, and broken-line with quadratic ascending function) were used to fit the body weight gain and feed conversion responses. The optimal digestible lysine intake was obtained from the first intercept of the quadratic curve with the broken-line plateau. Based on the body weight gain, the responses obtained from the broken-line function and the broken-line with quadratic ascending were similar to those from the quadratic polynomial function. The feed conversion ratio from the first intercept of the quadratic curve with the broken-line plateau was similar to the value obtained from the broken-line with quadratic ascending function only in 2-6-week-old animals. The digestible lysine intakes required to optimize the body weight gain and feed conversion ratio responses were 202, 338, and 300 and 146, 312, and 259 mg/day and the efficiencies were 80, 76, and 80% for 2-6-, 8-12-, and 14-18-week-old animals, respectively.