ABSTRACT This study aimed to impute the genetic makeup of individual fishes of Serrasalmidae family on the basis of body weight and morphometric measurements. Eighty-three juveniles, belonging to the genetic groups Pacu, Pirapitinga, Tambaqui, Tambacu, Tambatinga, Patinga, Paqui and Piraqui, were separated into 16 water tanks in a recirculation system, with two tanks per genetic group, where they remained until they reached 495 days of age. They were then weighed and analyzed according to the following morphometric parameters: Standard Length (SL), Head Length (HL), Body Height (BH), and Body Width (BW). The identity of each fish was confirmed with two SNPs and two mitochondrial markers. Two analyses were performed: one for the validating the imputation and another for imputing a genetic composition of animals considered to be advanced hybrids (post F1). In both analyses, we used linear mixed models with a mixture of normal distributions to impute the genetic makeup of the fish based on phenotype. We applied the mixed models method, whereby the environmental effects were estimated by the Empirical Best Linear Unbiased Estimator (EBLUE) and genetic effects are considered random, obtaining the Empirical Best Linear Unbiased Predictor (EBLUP) from the general (GCA) and the specific (SCA) combining ability effects. The results showed that validation of the genetic makeup imputation based on body weight can be used because of the strong correlation between the observed and imputed genotype. The fish classified as advanced hybrids had a genetic composition with a high probability of belonging to known genotypes and there was consistency in genotype imputation according to the different characteristics used.

O conhecimento de como os animais depositam componentes químicos como água, proteína, gordura e cinzas na carcaça é importante para a formulação de uma dieta equilibrada, permitindo o máximo desempenho com baixo impacto ambiental. Logo, o trabalho foi conduzido, com o objetivo de avaliar a influência de diferentes linhagens de tilápia sobre a deposição de componentes químicos na carcaça. Os componentes corporais analisados foram água, proteína, gordura e cinzas. Para a determinação das curvas de deposição química corporal em função da idade foram ajustados os modelos exponencial, Brody, logístico, Gompertz e vonBertalanffy. Houve ajuste apenas do modelo exponencial para a água, tendo as linhagens UFLA e Comerciais as que depositaram numa velocidade mais rápida (P<0,05) em relação às demais linhagens. Quanto à proteína, a linhagem Vermelha foi a que teve menor peso à maturidade, estimado (49,37g) e foi mais precoce quanto à deposição máxima em relação as outras linhagens (Chitralada, UFLA e Comercial), no qual obtiveram peso a maturidade estimada em 231,5g e deposição máxima aos 337 dias de idade. Não houve diferença (P>0,05) dos parâmetros do modelo logístico entre as linhagens Vermelha,UFLA e Comercial para extrato etéreo, sendo a deposição máxima (0,23 g) aos 310 dias de idade. Em relação à deposição de cinzas, a linhagem Comercial teve maior deposição máxima (0,10 g) e, aos 337 dias de idade, sendo mais tardia em relação as outras linhagens que obtiveram deposição máxima de 0,033 g, aos 254 dias de idade. Portanto, conclui-se que as linhagens genéticas avaliadas diferem quanto às curvas de deposição química de água, proteína, extrato etéreo e cinzas.

The knowledge of how animals deposited chemical components as water, protein, fat and ash in the carcass is importance for the formulation of a balanced diet, allowing maximum performance with a low environmental impact. So, the study was carried out to evaluate the influence of different tilapia strains (Chitralada, Commercial, Red and Universidade Federal de Lavras [UFLA]) on the deposition of bodily chemical components in the carcass. The bodily components analyzed were water, protein, fat and ash. For the determination of the bodily chemical deposition curves by age, the exponential, Brody, logistic, Gompertz and von Bertalanffy models were adjusted. The Commercial and UFLA strains deposited water at a faster speed (P<0.05) compared with the remaining strains. As for protein, the Red strain had a lower estimated maturity weight (49.37 g), and was more precocious (202 days) with regard to maximum deposition in comparison to the other strains (Chitralada, UFLA and Commercial) in which there was an estimated maturity weight of 231.5 g and maximum depositionfor 337 days. There were no differences (P>0.05) for the logistic model parameter between Red, UFLA and Commercial strains for fat, which presented a maximum fat deposition (0.23 g) at 310 days of age. Regarding ash deposition, the Commercial strain presented a higher maximum deposition (0.10 g) at 337 days, occurring later than the other strains that presented maximum deposition (0.033g) at 254 days of age. Thus, it was concluded that the genetic strains evaluated differ in chemical deposition curves of water, protein, fat and ash.

Objetivou-se avaliar o desempenho, glicerol sérico e umidade da cama de pintos de corte recebendo rações com diferentes níveis e fontes de glicerina. Foram utilizados 1300 pintos de corte machos Cobb 500, num arranjo fatorial 4x3+1, com delineamento inteiramente casualizados, sendo quatro níveis de inclusão (17,5; 35,0; 52,5 e 70,0g/kg) de três glicerinas (bruta de soja (GS), bruta mista (GM) e semipurificada (GPUR) nas dietas isonutritivas e um tratamento sem glicerina, sendo que para as fontes e níveis de glicerina foram teste de Student-Newman-Keuls e análise de regressão, respectivamente; e para o tratamento, teste de Dunnett. Utilizou-se quatro repetições e 25 aves por parcela. O consumo de ração foi influenciado (P<0,05) pelas fontes de glicerina, sendo a GM a fonte que promoveu menor consumo nas aves, porém, não houve diferença dos tratamentos em relação ao controle. Não houve diferença significativa para o ganho de peso. Houve interação dos níveis e fontes de glicerina para a conversão alimentar. Para a GS, a melhor conversão alimentar com a inclusão de 50,35g; para a GM, houve uma piora linear com o aumento da inclusão de glicerina. Houve interação para a concentração de glicerol sérico nas aves, obtendo aumento linear nas aves que ingeriram a GS e GPUR, e redução linear para a GM. O ganho de umidade da cama foi influenciado pelas fontes de glicerina, sendo que a mista apresentou menor umidade. As glicerinas estudadas podem ser incluídas nas rações para pintos de corte até 70,0g/kg, sem prejudicar o desempenho dos animais.

This work aimed to evaluate the performance, serum glycerol and litter moisture of 1300 male Cobb 500 chicks fed diets containing different levels and sources of glycerin. A 4x3+1 factorial arrangement of treatments in a completely randomized design was used, with four inclusion levels of three glycerine (crude soybean (GS), gross mixed (GM) and semipurified (GPUR)) on isonutrient diets and one control treatment without glycerin. The methods of Student-Newman-Keuls test and regression analysis were applied for sources and levels of glycerin, respectively; and Dunnett test for treatment. It was used four replicates and 25 chickens per pen. Feed intake was affected (P <0.05) by the sources of glycerin, and GM was the source that promoted lower consumption in birds, however, there was no difference in the treatments when compared to control. Also there was no significant difference in weight gain. An interaction of levels and sources of glycerine to the feed conversion was seen.GS had the best feed conversion with the inclusion of 50,35g; GM had a linear worsening with increasing addition of glycerin. There was an interaction for the concentration of serum glycerol in birds, obtaining linear increase in birds consuming the GS and GPUR, and linear decrease for GM. The gain of litter moisture was influenced by the sources of glycerin, with a lower humidity for GM. The glycerine studied may be included in diets for broiler chicks until 70,0g/kg, without harming animal performance.

Para o desenvolvimento de uma tecnologia de cultivo é necessária a determinação da densidade de estocagem ideal. Objetivou-se determinar a melhor densidade de estocagem para juvenis de Brycon orthotaenia, cultivados em tanques-rede, durante a fase de recria. A pesquisa foi conduzida na Fazenda Experimental da Epamig, em Felixlândia, Estado de Minas Gerais, na represa de Três Marias. Foram utilizados 9.000 alevinos, distribuídos em 12 berçários com 2 m³ em tanques-rede, seguindo o delineamento inteiramente casualizado, com três repetições e quatro diferentes densidades de estocagem (150, 300, 450, 600 peixes m-3). Amostras aleatórias de cada tanque-rede foram coletadas para as avaliações, no início do experimento e aos 60 dias de cultivo. Foram estimados os parâmetros produtivos, índice de crescimento específico e uniformidade. Obteve-se uma relação linear positiva (p < 0,05) para biomassa final (r² = 0,88), ganho de peso da biomassa (r² = 0,87), produtividade (r² = 0,86), conversão alimentar aparente (r² = 0,96) e para viabilidade econômica (r² = 0,96). Para sobrevivência (r² = 0,98), a relação linear foi negativa (p < 0,05). Não houve diferença significativa entre os tratamentos (p > 0,05) para os parâmetros de crescimento, uniformidade e peso final. Conclui-se que a densidade de 300 peixes m-3 é a mais indicada, pois, proporciona maior receita líquida, sobrevivência e boa conversão alimentar.

Developing a rearing technology requires the determination of the optimum stocking density. This study aimed to determine the best stocking density for Brycon orthotaenia juveniles grown in net cages, during the rearing phase. The research was conducted at the Experimental Farm of EPAMIG, in Felixlândia, Minas Gerais State, in the Três Marias Reservoir. 9,000 fingerlings were distributed into 12 net cages, 2 m³ each, according to a completely randomized design with three replications and four different stocking densities (150, 300, 450, 600 fish m-3). Random samples were taken from each net cage, at the onset of the experiment and at 60 rearing days, to assess production parameters, specific growth rate and uniformity. We verified a positive linear relationship (p < 0.05) for final biomass (r² = 0.88), weight gain (r² = 0.87), productivity (r² = 0.86), apparent feed conversion (r² = 0.96) and economic viability (r² = 0.96). For survival (r² = 0.98), the relationship was negative (p < 0.05). There were no significant differences between treatments (p > 0.05) for growth parameters, uniformity and final weight. It can be concluded that the density of 300 fish m-3 is the most suitable, because it provides higher net revenue, survival, and a good feed conversion.

The main factor considered in breeding programs for fish is growth, which can be assessed in terms of a gain in either weight or body measurements. This study was undertaken to evaluate the morphometric traits of GIFT strain tilapia (Oreochromis sp.) selected for weight gain. The data set used contained information on 6,650 animals. The genetic values of 8,590 animals in a relationship matrix of five generations were predicted. The following morphometric measurements were evaluated: standard length; body depth and body width. Body area and volume were also calculated. Bi-character analyses involving morphometric traits were used to estimate (co)variance components. Heritability, larval and fingerling common environmental effects were estimated for each trait, together with the genetic and phenotypic correlations between traits. Bayesian procedures were utilised by Gibbs chains, and the convergence of the chains was tested using the Heidelberger and Welch method. Genetic trends were estimated by segmented regression of the fish breeding values of the generations considered in this study. Estimates of heritability (0.28 a 0.31) had moderate to high magnitudes for all traits. Genetic correlations between traits were all above 0.8, and the genetic gains were satisfactory from the third generation onwards. From the estimates of the genetic parameters and genetic gain the morphometric traits evaluated have good potential for selection.

O estudo foi realizado com o objetivo de verificar quais medidas e razões morfométricas estão mais diretamente relacionadas com os rendimentos corporais da tilápia do Nilo, Oreochromis niloticus, em duas classes de peso. Foram analisados os dados de 257 exemplares de tilápia divididos em duas categorias de peso: p1 = 400 a 599 g e p2 = 600 a 900 g. As medidas morfométricas comprimento padrão (CP), comprimento da cabeça (CC), altura do corpo (AC) e largura do corpo (LC), e as razões entre estas medidas (CC / CP, AC / CP, LC / CP, LC / CC, LC / AC, CC / AC) foram avaliadas. Os rendimentos corporais calculados foram: carcaça (RCAR), filé (RFILE) e cabeça (RCAB). Os dados foram inicialmente submetidos ao procedimento 'stepwise' para eliminar os problemas de multicolinearidade entre as variáveis morfométricas, em seguida, as correlações entre as variáveis dependentes (rendimentos corporais) e as variáveis independentes (medidas e razões morfométrica) foram calculados. Posteriormente estas correlações foram desdobradas em efeitos diretos e indiretos por meio de análise de trilha e as contribuições diretas e indiretas de cada variável foram quantificadas percentualmente. A razão morfométrica LC / CC, para ambas as classes de peso, foi a variável mais altamente correlacionada e com o maior efeito direto sobre RFILE e RCAB, mostrando ser a variável morfométrica estudada mais importante para determinação das características de carcaça da tilápia.

The study was carried out with the objective of verifying which measures and morphometric ratios are more directly related to the body yield of Nile tilapia, Oreochromis niloticus, in two weight classes. Data were analyzed from 257 specimens of tilapia divided into two weight classes: p1 = 400 to 599 g and p2 = 600 to 900 g. The morphometric measurements standard length (SL), head length (HL), body height (BH) and body width (BW), and the ratios of these measures (HL / SL, BH / SL, BW / SL, HL / BH, BW / BH, BW / HL) were evaluated. The following body yields were calculated: carcass (RCAR), fillet (RFILE) and head (RCAB). The data were initially submitted to the "stepwise" procedure to eliminate problems of multicollinearity among the morphometric variables, then the correlations between the dependent variables (body yield) and the independent variables (measured and morphometric relationships) were calculated. Later, these correlations were divided into direct and indirect effects through path analysis, and the direct and indirect contributions of each variable measured in percentage terms. The morphometric ratio BW/HL, for both weight classes, was the variable most highly correlated and with the highest direct effect on RFILE and RCAB, showing to be the most important morphometric variable studied for tilapia carcass trait determination.

O objetivo deste trabalho foi determinar a densidade de estocagem de matrinxã (Brycon orthotaenia) em tanques-rede, considerando o desempenho produtivo. Foram utilizados 5.280 juvenis de Brycon orthotaenia com peso inicial de 115,2g±5,7, os quais foram distribuídos em 16 tanques-rede de 4³m nas densidades de 45, 70, 95 e 120 peixes m-3 em quatro repetições. Os peixes foram alimentados com ração comercial de 40% de proteína bruta durante o período experimental. Os dados foram submetidos à análise de variância e à regressão linear para estimativa do melhor ajuste a 5% de probabilidade. Os parâmetros produtivos como sobrevivência, peso inicial, peso final, conversão alimentar e taxa de crescimento específico não foram influenciados pela densidade de estocagem, assim como os parâmetros de qualidade da água. Entretanto, para a variável biomassa final, ganho de biomassa e consumo de ração total, o efeito foi significativo e estas apresentaram relação linear positiva com a densidade de estocagem. Avaliando os resultados, pode-se concluir que a densidade de estocagem de matrinxã (Brycon orthotaenia) até 120 peixes m-3 é a que proporciona maior produtividade e não representa efeitos negativos sobre o desempenho dos peixes.

The objective of this study was to determine the stocking density of matrinxã (Brycon orthotaenia) in cages, considering the productive performance. Juvenile Brycon orthotaenia (n = 5280) were distributed in 16 cages of 4m³ at densities of 45, 70, 95 and 120 fish m-3. The fish were fed with commercial feed with 40% crude protein during all experimental period. Data were subjected to analysis of variance and linear regression to estimate the best fit using 5% probability. The production parameters such as survival, initial weight, final weight, feed conversion and specific growth rate were not influenced by stocking density, as well as the parameters of water quality. However, final biomass, biomass gain and feed intake showed a positive linear relationship with stocking density. Evaluating these results, it was concluded that the stocking density of matrinxã (Brycon orthotaenia) up to 120 fish m-3 represent the best productive performance.

The objective of this study was to evaluate the morphometric growth and weight gain of strains of tilapia (Thai, Red, UFLA and Commercial) by nonlinear models. Initially, 500 male fingerlings of each strain, at 85 (Red and UFLA) and 86 (Thai and Commercial) days of age, were stocked separately in raceways with 56 m³. Twenty fish of each strain were randomly sampled, weighed and measured monthly. Five nonlinear models (Brody, von Bertalanffy, Gompertz, logistic and exponential) were tested, choosing one that best fit to the data. The variables studied were: weight, standard length (SL), head length (HL), height 1 (H1), height 2 (H2), height 3 (H3), first distance (D1), second distance (D2), first width (W1), second width (W2) and third width (W3). The exponential model had the best fit to weight and morphometric data, with the exception of W2, in which the best fitted model was von Bertalanffy. The convergence of the exponential model to data indicates that the cultivation period studied was not enough for the strains to reach maturity weight. The UFLA strain presented the lowest value for parameter "a" (initial weight estimate), 8.71 g, and the highest for parameter k (specific growth rate), 0.0127, when compared with other evaluated strains. However, the highest k of UFLA was not enough to overcome the final weight observed for the Commercial strain (603.1 g), which was higher than all other strains. Regarding the morphometric measurements, the UFLA strain also had the highest k for the variables SL, HL, HH, H1, H2, H3 and D2, and similar k to Commercial and Thai strains for the variables D1 and W3 respectively. The strains differ as to weight gain and morphometric growth.

With the purpose of evaluating the changes and the degree of heterosis on performance and carcass traits of fish from the diallel crossing between Pacu and Tambaqui, four genetic groups were generated through hormonal induction: pacu, tambaqui, tambacu and paqui. For 196 days, 400 juveniles of each genetic group were stocked in a pond divided into four parts of equal size, one for each group. At the end of this period, when the fish weighed on average 1024 g (±115.52 g), 20 specimens of each genetic group were sampled, weighed, measured: head length; standard length; body height; and width; and also processed resulting in following body yield: viscera; carcass; head; fillet; rib; residue and skin yields. There was positive heterosis for body weight, viscera and skin yield and head measures and negative heterosis for carcass and filet yield and body width, indicating that the hybrids have better performance on weight gain, but are inferior in relation to the carcass conformation.

The objective of this study was to verify which morphometric measures and ratios are more directly associated with the weight and body yields of rounded fish. A total of 225 specimens of rounded fish (59 pacus, 61 tambaquis, 52 tambacus and 53 paquis) with average weight of 972.43 g (±115.52 g) were sampled, stunned, slaughtered, weighed, measured, and processed for morphometric and processing yield analysis. The morphometric measures taken were: standard length (CP); head length (CC); head height (AC); body height (A1); and body width (L1). For completeness, the following morphometric ratios were calculated: CC/CP, AC/CP, A1/CP, L1/CP, CC/A1, AC/A1, L1/A1, CC/AC and L1/CC. The yields of carcass, filet, rib and filet with rib were estimated after processing. Initially, a "stepwise" procedure was performed in order to eliminate multicollinearity problems among the morphometric variables, and the phenotypic correlations were then calculated for the dependent variables (weight and body yields) and independent variables (morphometric measurements and ratios). These correlations were later deployed in direct and indirect effects through path analysis, and the direct and indirect contributions of each variable were measured in percentage terms. The CC and A1 measures were important for determining the weight of rounded fish. The CC/A1 ratio was the variable most directly associated with carcass yield. For filet, filet with rib and rib yields, the L1/CC ratio was found to be more appropriate and can be used directly.

The objective of this study was to evaluate the performance of three Nile tilapia Oreochromis niloticus strains cultivated in cages and subjected to different feeding programmes. Initially, 31,200 Nile tilapia juveniles with an average weight of 61.15 g were distributed in 48 cages. Two genetically improved strains were used together with one from the Fish Culture Section of Universidade Federal de Lavras (UFLA). The fish were subjected to four feeding programmes, consisting of different levels of crude protein (CP) in diets provided at different stages of cultivation. There was no interaction effect of the strain and feeding programme for most variables. The UFLA strain presented the highest weight gain, but with greatest lack of uniformity at the end of cultivation. The feeding programme with diets containing 36%, 32% and 28% CP, consecutively, promoted the highest weight gain and highest final biomass. The UFLA strain has great growth potential, justifying the development of a breeding programme for this strain. Crude protein levels below 36% for tilapias between 60 and 170 g and below 32% for tilapias between 170 and 700 g worsen fish performance.

Em experimentos de desempenho e metabolismo, avaliaram-se os efeitos do fornecimento de rações com níveis reduzidos de proteína bruta, cálcio e fósforo disponível sobre o desempenho, as características de carcaça, o conteúdo de cinzas na tíbia, o balanço e a retenção de nitrogênio e fósforo de frangos de corte nos períodos de 8 a 21 e 8 a 35 dias de idade. Em cada uma destas fases no ensaio de desempenho, foram utilizadas 30 e 25 aves por unidade experimental e, no ensaio de metabolismo, cinco e três aves, respectivamente, em delineamento inteiramente casualizado, com seis repetições. Os tratamentos constituíram-se de rações com 21% proteína bruta sem fitase (controle), formuladas com níveis nutricionais recomendados nas tabelas brasileiras, e rações com 21, 20, 19 e 18% de proteína bruta com fitase (8 a 21 dias) e, no período de 8 a 35 dias, ração com 20% proteína bruta sem fitase (controle), e rações com 20, 19, 18 e 17% de proteína bruta, com fitase. Nas rações com fitase (80 g de fitase - Ronozyme NP(M) por tonelada de ração), o nível de fósforo disponível reduziu em 0,15 e o de cálcio em 0,30 ponto percentual em relação ao da ração controle. Não houve efeito da redução da composição em nutrientes das rações sobre o consumo, o ganho de peso e a conversão alimentar em ambas as fases nem diferença nas características de carcaça aos 35 dias. Todavia, verificou-se maior teor de gordura abdominal quando as aves consumiram ração com o menor nível proteico. A excreção de nitrogênio e fósforo foi menor quando as aves receberam ração com níveis reduzidos desses nutrientes. A porcentagem de cinzas na tíbia, nas fases avaliadas, não diferiu entre os tratamentos. É possível reduzir em até três pontos percentuais o nível proteico das rações, em 0,15 o de fósforo disponível e em 0,30 ponto percentual o de cálcio quando as rações são suplementadas com fitase e aminoácidos.

In performance and metabolism trials, diets with reduced levels of crude protein, calcium and available phosphorus on the performance, carcass characteristics, tibia ashes, balance and retention of nitrogen and phosphorus of broiler chickens in phase from 8 to 21 and 8 to 35 days were evaluated. In each phase, 30 and 25 birds per experimental unit were used in the performance assay and five and three in the metabolism assay, respectively, in a completely randomized experimental design, with six replications. Treatments consisted of diet with 21% crude protein without phytase (control), formulated with nutritional levels recommended on the Brazilian tables, and diets with 21, 20, 19 and 18% crude protein with phytase (8 to 21 days) and from 8 to 35 days, the control diet had 20% crude protein without phytase (control), and others diets with 20, 19, 18, 17% crude protein, with phytase. In the diets with phytase (80 g of Ronozyme NP(M) phytase per ton of diet), the level of available phosphorus was reduced in 0.15 and the calcium in 0.30 percentage points in relation to the control diet. No effect was observed with the reduction of nutrients on feed intake, weight gain, or feed conversion in either phase or for the study of carcass characteristics to the 35 days. However, higher abdominal fat percentage was observed when the broilers were fed diet with lower protein level. The excretion of nitrogen and phosphorus decreased when birds received diets with reduced levels of these nutrients. Ash percentage in the tibia was not influenced by treatments. It is possible to reduce protein level, available phosphorus, and calcium of the diets in up to 3, 0.15 and 0.30 percentage points when the diets are supplemented with phytase and amino acids, respectively.

Dois experimentos independentes, um na fase pré-inicial (1 a 7 dias) e outro na fase inicial (8 a 21 dias de idade), foram realizados com frangos de corte para avaliar níveis de cálcio e fósforo disponível (Pdisp) em rações suplementadas com 500 unidades de atividade de fitase/kg de ração. Cada experimento constou de um ensaio de desempenho e outro de metabolismo e foi conduzido em esquema fatorial (3 × 4) + 1, sendo três níveis de Pdisp (0,42; 0,37; 0,32% na fase pré-inicial e 0,39; 0,34; 0,29% na fase inicial), quatro níveis de cálcio (0,94; 0,84; 0,74; 0,64% na fase pré-inicial e 0,88; 0,78; 0,68; 0,58% na fase inicial) mais uma ração controle. O controle correspondeu à única ração sem fitase e continha 0,47% de Pdisp e 0,94% de cálcio (fase pré-inicial) ou 0,44% de Pdisp e 0,88% de cálcio (fase inicial). Nos ensaios de desempenho, aos 7 e aos 21 dias de idade, foram avaliados o consumo de ração, o ganho de peso, a conversão alimentar e o teor de cinzas na tíbia. Nos ensaios de metabolismo, determinaram-se a energia metabolizável aparente corrigida pelo balanço de nitrogênio (EMAn) das rações e os coeficientes de digestibilidade da matéria seca (CMMS). Na fase pré-inicial, os níveis de cálcio influenciaram o consumo de ração, a EMAn e o CMMS e, na fase inicial, afetaram o conteúdo de cinzas ósseas, a EMAn e o CMMS. Os níveis de Pdisp influenciaram o teor de cinzas na tíbia, a EMAn e o CMMS na fase pré-inicial e as cinzas ósseas e o CMMS na fase inicial. Adicionando 500 unidades de atividade de fitase/kg de ração, é possível reduzir, respectivamente, os níveis de cálcio e Pdisp para 0,64% e 0,37% na fase pré-inicial e 0,58% e 0,29% na fase inicial, pois essa redução não tem efeito negativo sobre o desempenho e a mineralização óssea dos frangos de corte nessas fases.

Two independent experiments, one in pre-starter phase (1 to 7 days) and the other in the starter phase (8 to 21 days of age), were carried out with broilers to evaluate levels of calcium and available phosphorus (aP) in diets supplemented with 500 units of phytase activity/kg of diet. Each experiment consisted of a performance and a metabolic assay, and was conducted in a factorial schedule (3 × 4) + 1, with three aP levels (0.42, 0.37, 0.32% in the pre-starter phase and 0.39, 0.34, 0.29% in the starter phase), four calcium levels (0.94, 0.84, 0.74, 0.64% in the pre-starter phase and 0.88; 0.78, 0.68, 0.58% in the starter phase) plus a control diet. The control corresponded to the only diet without phytase and contained 0.47% of aP and 0.94% of calcium (pre-starter phase) or 0.44% of aP and 0.88% of calcium (starter phase). In the performance assays, at 7 and 21 days of age the feed intake, weight gain, feed conversion and the ash content in the tibia were evaluated. In the metabolic assays the apparent metabolizable energy corrected for nitrogen balance (AMEn) of the feed, and dry matter digestibility coefficients (DMDC) were determined. Calcium levels influenced the feed intake, AMEn and DMDC in the pre-starter phase, and in the starter phase they influenced bone ash, AMEn and DMDC. The aP levels influenced the content of tibia ash, AMEn and DMDC in the pre-starter phase, and bone ash and DMDC in the starter phase. By adding 500 units of phytase activity/kg of diet, it is possible to reduce, respectively, the calcium and aP levels to 0.64% and 0.37% in the pre-starter phase, and to 0.58% and 0.29% in the starter phase, since this reduction does not cause a negative effect on performance or bone mineralization of broilers in the evaluated periods.

Este trabalho foi realizado para se obter uma equação de predição para estimar os valores de energia metabolizável aparente corrigida (EMAn) dos alimentos proteicos usualmente utilizados em rações para frangos de corte utilizando-se o princípio da meta-análise. Realizou-se uma revisão bibliográfica de estudos no Brasil para catalogar informações sobre valores de EMAn e composição química dos alimentos: proteína bruta (PB), extrato etéreo (EE), matéria mineral (MM), fibra bruta (FB), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA). Foram considerados os efeitos de: sexo, em três níveis (macho, fêmea e mistos); idade, em quatro níveis (1ª e 2ª semana de vida, 3ª e 4ª semana, 5ª e 6ª semana e acima ou indefinido) e metodologia empregada no metabolismo em dois níveis: coleta total (CT) e alimentação forçada + (CT). Os dados foram analisados em um esquema fatorial 3 × 4 × 2, podendo totalizar até 24 grupos, adotando-se o procedimento Stepwise para a seleção de variáveis e o Proc Reg do (SAS) para ajustar o modelo de regressão linear múltipla. A equação obtida que melhor se ajustou foi EMAn = 2707,71 + 58,63EE - 16,06FDN (R² = 0,81), sendo o EE a variável mais importante, em se tratando de possíveis variações nos teores energéticos dos alimentos proteicos.

This study was accomplished aiming to obtain prediction equations to estimate the values of corrected apparent metabolizable energy (AMEn) of the protein feedstuffs usually used in broiler rations, through the meta-analysis principle. Literature review of the studies realized in Brazil was performed to catalog information about values of AMEn and chemical composition of the feedstuffs reported (CP = crude protein; EE = ether extract; CF = crude fiber; NDF = neutral detergent fiber; ADF = acid detergent fiber). Effects of sex at three levels (male; female and mixed); age at four levels (1st and 2nd weeks of life; 3rd and 4th weeks; 5th and 6th weeks; above or indefinite) and the methodology employed in the metabolism assay at two levels (total collection of excreta - CT and forced fed plus + CT) were considered. The data were analyzed in a 3 × 4 × 2 factorial arrangement, capable of amounting up to 24 groups. The Stepwise procedure was adopted for selection of variables, and the Proc Reg of the (SAS), to fit the multiple linear regression model. The equation obtained which best fitted was AMEn = 2707.71 + 58.63EE - 16.06NDF (R² = 0.81), with the EE as the most important variable, concerning the possible variations in the energy contents of protein feedstuffs.

Objetivando-se avaliar a forma física da ração, o uso de enzimas e níveis nutricionais em dietas à base de milho e farelo de soja, foram conduzidos dois experimentos utilizando um total de 1.344 frangos de corte machos de 22 a 42 dias de idade, distribuídos em um delineamento inteiramente casualizado em esquema fatorial 2 x 2 x 2, sendo duas formas físicas de ração (farelada ou triturada); com ou sem complexo enzimático (amilase, celulase e protease) e dois níveis nutricionais, 95 ou 100% das recomendações de Rostagno et al. (2005). No experimento 1, 1200 aves foram distribuídas nos oito tratamentos com cinco repetições de 30 aves cada para avaliação de consumo de ração (CR), ganho de peso (GP), conversão alimentar (CA) e características de carcaça. Simultaneamente, foi realizado o experimento 2 (ensaio de metabolismo), em que 144 aves foram distribuídas em gaiolas metálicas, recebendo os oito tratamentos experimentais com seis repetições de três aves cada. Aos 38 dias de idade iniciou-se a coleta total de excretas, realizada uma vez ao dia, por três dias consecutivos para determinação da energia metabolizável aparente corrigida (EMAn) e dos coeficientes de metabolizabilidade da matéria seca (CMMS) e proteína bruta (CMPB) das rações experimentais. De uma maneira geral, pelos resultados obtidos, pode-se concluir que a suplementação enzimática não resulta em melhora no desempenho das aves e na digestibilidade dos nutrientes das rações, independentemente da forma física, devendo estas serem formuladas com 100% das recomendações nutricionais.

In order to evaluate the physical form of diet and the use of enzymes and nutritional levels in diets based on corn and soybean meal, two experiments were carried out using a total of 1344 male broilers from 22 to 42 days of age, distributed in a randomized design in a 2 x 2 x 2 factorial scheme with two physical forms of diet (meal or crushed), with and without enzymatic complex (amylase, cellulase and protease) and two nutritional levels (95 or 100% of the recommendations). In experiment 1, 1200 birds were distributed to the eight treatments with five replicates of 30 chickens each, to evaluate the feed intake (FI), weight gain (WG) and feed conversion (FC) and carcass traits of birds. Simultaneously, in the experiment 2 (assay metabolism), 144 birds were distributed in metal cages and received the eight experimental treatments in six replicates of three birds each. At 38 days of age the total excreta collection were started, and the collect for three consecutive days to determine the apparent metabolizable energy corrected (AMEn) and the metabolizability coefficients of dry matter (MCDM) and crude protein (MCCP) of experimental diets. In general, the results can conclude that enzyme supplementation results in no improvement in bird performance and nutrient digestibility of diets, regardless of physical form, which should be made with 100% nutritional recommendations.