RESUMO A utilização de valores preditos de energia metabolizável aparente (EMA), obtidos a partir de equações de regressão, pode ser útil para instituições de pesquisa e indústrias de nutrição. Contudo, há a necessidade de validação em amostras independentes para assegurar que a equação de predição da EMA seja confiável. Neste estudo, foram coletados dados para estimar equações de predição da EMA do milho, sorgo e farelo de trigo para suínos em função de composição química, além de avaliar a validade do procedimento stepwise de seleção de regressoras pelo método de reamostragem bootstrap não paramétrico. Dados de ensaios de metabolismo com suínos e de composição química dos alimentos foram coletados na literatura científica nacional e internacional e expressos na matéria seca. Após a análise de resíduos, foram ajustados cinco modelos de regressão linear múltipla e geradas aleatoriamente 1000 amostras bootstrap de mesmo tamanho a partir do banco de dados formado via meta-análise. Em todas as amostras bootstrap foram ajustados os cinco modelos estimados, utilizando-se do stepwise. Os maiores percentuais de significância por regressora (PSR) ocorreram para a energia digestível (100%) no modelo EMA1, e para a energia bruta (95,7%) no modelo EMA2, indicando alta correlação das regressoras com a EMA. As regressoras selecionadas nos EMA4 e EMA5 apresentaram PSR maior que 50% e são válidas para estimar a EMA de alimentos energéticos para suínos. Entretanto, os percentuais de ocorrência conjunta de regressoras dos modelos apresentaram baixa confiabilidade, com valores entre 2,6% (EMA2) e 23,4% (EMA4), invalidando o procedimento stepwise.

ABSTRACT The use of predicted values of apparent metabolisable energy (AME), obtained from regression equations, can be useful for both research institutions and nutrition industries. However, there is a need to validate independent samples to ensure that the predicted equation for AME is reliable. In this study, data was collected in order to estimate the prediction equations of corn, sorghum and wheat bran for pig feed, based on the chemical composition, in addition to evaluating the validity of the stepwise selection procedure regressive method of non-parametric bootstrap resampling. Data from metabolism trials in pigs and the chemical composition of feedstuffs was collected from both Brazilian and international literature, expressed as dry matter. After the residue analysis, five models of multiple linear regression were adjusted to randomly generate 1000 bootstrap samples of equal size from the database via meta-analysis. The five estimated models were adjusted for all bootstrapped samples using the stepwise method. The highest percentage significance for regressor (PSR) value was observed for digestible energy (100%) in the AME1 model, and gross energy (95.7%) in the AME2 model, indicating high correlation of the regressive model with AME. The regressors selected for AME4 and AME5 resulted in a PSR of greater than 50%, and were validated for estimating the AME of pig feed. However, the percentage of joint occurrence of regressor models showed low reliability, with values between 2.6% (AME2) and 23.4% (AME4), suggesting that the stepwise procedure was invalid.

RESUMO O presente estudo teve por objetivo determinar a energia metabolizável aparente (EMA) de seis cultivares de milho, dois cultivares de sorgo e dois farelos de trigo e avaliar a validação cruzada de modelos de predição da EMA do milho, sorgo e farelo de trigo para suínos em crescimento, estimados com base na composição química. Quarenta e quatro suínos, com peso médio inicial de 24,3 kg, foram utilizados em delineamento experimental de blocos ao acaso, com 11 tratamentos (dez alimentos e a ração referência), quatro repetições e um suíno por unidade experimental. A ração referência foi substituída, na base da matéria natural, em 30% para os milhos e sorgos, e em 20% para os farelos de trigo. Os valores de EMA dos milhos, sorgos e farelos de trigo para suínos variaram de 3161 a 3275, 3317 a 3457 e 2767 a 2842 kcal kg-1 de matéria natural, respectivamente. A metabolizabilidade média da energia bruta não diferiu entre milhos e sorgos, que formaram um grupo homogêneo de alimentos. Em seguida, ajustaram-se modelos de regressão linear de 1º grau dos valores observados em função dos preditos de EMA, para teste da hipótese β0 = 0 e β1 = 1 em amostra experimental e em 200 amostras bootstrap. Quatorze modelos de predição apresentaram baixos percentuais de validação cruzada (0 a 29,5%). O modelo EMA1A = 2,547 + 0,969EDA foi validado em amostra experimental e em 68% das amostras bootstrap, sendo acurado para estimar a EMA de milhos e sorgos nacionais para suínos em crescimento.

ABSTRACT The present study aimed to determine the apparent metabolizable energy (AME) of six corn cultivars, two sorghum cultivars and two wheat brans and to evaluate the cross-validation of predictive models of AME for corn, sorghum and wheat bran for growing pigs, as estimated from the data of chemical composition. Forty-four pigs, with an average initial weight of 24.3 kg, were distributed in a randomized block design, with 11 treatments (ten food treatments and the reference diet), four replicates and one pig per experimental unit. The reference diet was replaced by 30% for the ground corn and sorghum conditions and 20% for the wheat bran condition. The values of AME for corn, sorghum and wheat meal for pigs ranged from 3161 to 3275, 3317 to 3457 and 2767 to 2842 kcal kg-1 as a feed basis, respectively. The average metabolizability of the gross energy did not differ between the corn and sorghum cultivars, which formed a homogeneous group of food. Next, linear regression models were fitted to the 1st degree of the observed values as a function of the predicted AME, to test the hypothesis β0 = 0 and β1 = 1 in an experimental sample and 200 bootstrap samples. Fourteen predictive models had low percentages of cross-validation, ranging from 0-29.5%. The AME1A = 2.547 + 0.969ADE model was validated in experimental sample and 68% of bootstrap samples, proving its accuracy in estimating the AME of corn and sorghum from national data for growing pigs.

A semente do maracujá é um subproduto da extração da polpa do maracujá, podendo ser utilizado na alimentação dos suínos. Foram conduzidos dois experimentos (digestibilidade e desempenho), objetivando avaliar a utilização do farelo da semente de maracujá na alimentação de suínos em crescimento e terminação. Inicialmente foi realizado um ensaio de digestibilidade com suínos em crescimento e terminação, em que o farelo da semente de maracujá (FSM) substituiu a ração referência (0% FSM) em níveis de 4, 8, 12 e 16%. Foram utilizados 30 suínos, machos castrados, com peso vivo médio inicial de 36,85±4,19. O FSM apresentou ED e EM de 3.244 e 3.223 Mcal/kg, respectivamente. No ensaio de desempenho, foram utilizados 150 suínos, sendo 75 na fase de crescimento e 75 na fase de terminação, com peso vivo inicial de 30,63±1,49 e final de 60,38±4,75 kg e 60,40±1,50 e 90,02±4,84 kg, respectivamente. Foram utilizadas cinco dietas, sendo quatro níveis de inclusão do FSM (4, 8, 12 e 16%) e uma ração testemunha (0% do FSM). Os níveis do FSM não influenciaram (P>0,05) as variáveis de desempenho. Na fase de crescimento, os níveis séricos de colesterol aumentaram linearmente (P<0,05) com os níveis de inclusão do FSM. As variáveis quantitativas de carcaça e qualitativas da carne não foram influenciadas (P>0,05) pelos níveis crescentes do FSM nas dietas. Conclui-se que o FSM pode ser utilizado em até 16% em dietas de suínos em crescimento e terminação.

The passion fruit seed is a byproduct of the extraction of the passion fruit pulp and can be used for feeding to pigs. Two experiments were conducted (digestibility and performance) to evaluate the use of the passion fruit seed meal in feed for growing and finishing pigs. A digestibility trial was conducted with growing and finishing pigs, in which the passion fruit seed meal (PSM) replaced the reference diet (0% PSM) in levels of 4, 8, 12 and 16%. Thirty barrows were used with average weight of 36.85±4.19. The PSF showed DE and ME of 3.244 and 3.223 Mcal/kg, respectively. In the performance trial, were used 150 pigs, which 75 in the growing phase and 75 pigs in the finishing, with initial body weight of 30.63±1.49 and final of 60.38±4.75 kg and 60.40±1.50 and 90.02±4.84 kg, respectively. Five diets were used, with four inclusion levels of PSM (4, 8, 12 e 16%) and one control diet (0% of PSM). The PSM levels did not influence (P>0.05) the performance variables. In the growing pigs, serum levels of cholesterol increased linearly with (P<0.05) inclusion levels of PSM. Quantitative of carcass traits and meat quality were not affected (P>0.05) by increasing levels of PSM in the diets. We conclude that the PSM can be used up to 16% in growing and finishing pigs diets.

The objective of this study was to estimate the nutrient requirements of digestible threonine for meat-type quails (Coturnix coturnix sp) in the growth phase. A total of 1350 not sexed meat-type quails were distributed in a completely randomized design with six threonine levels (10.80, 11.50, 12.20, 12.90, 13.60 and 14.30 g/kg as fed), five replications and 45 quails per experimental unit, from 1 to 14 days of age. The threonine levels in the diet had a quadratic effect on body weight, feed intake and weight gain. Estimates for highest body weight (79.41 g), feed intake (128.96 g/bird) and weight gain (70.73 g) were observed with diets containing 12.60 g/kg of digestible threonine. According to the LRP model, the threonine intake was estimated at 13.40 g/kg of digestible threonine. Protein deposition rate and energy retained in the carcass showed quadratic effect, with estimated digestible threonine levels of 11.80 and 12.00 g/kg in the diet for maximum protein deposition rate (2.00 g/bird) and retained energy in the carcass (15.88 kcal/g), respectively. There was a linear effect on feed cost per kg of live weight gain as threonine levels were increased. Nutritional requirement of digestible threonine for meat-type quails for maximum growth is 12.60 g/kg, corresponding to a digestible threonine:digestible lysine ratio of 67.02.

The objective of this experiment was to estimate the digestible tryptophan (DTrp) requirements for growing meat quails. In the first experiment (1-14 days of age), 1,950 quails were distributed in a completely randomized design, with six levels of DTrp (0.27; 0.30; 0.33; 0.36; 0.39 and 0.42% of diet), five replications and 65 quails per experimental unit. There was a linear increase of feed intake, tryptophan intake, weight gain and body weight with the DTrp levels increase. In the second experiment (15-35 days of age), 1,350 quails were distributed in a completely randomized design, with six levels of DTrp (0.22; 0.25; 0.28; 0.31; 0.34 and 0.37% of diet), five replications and 45 quails per experimental unit. There was a linear increase for tryptophan intake, carcass yield, ash levels and protein deposition rate with the DTrp levels increase. In the third experiment (28-35 days of age), conducted to determine the nitrogen balance, 150 males were housed in galvanized wire cages featuring drinker, feeder and individual metal tray lined with plastic to collect the excreta. The design was completely randomized, with six levels of DTrp (0.22; 0.25; 0.28; 0.31; 0.34 and 0.37% of diet), five replicates and five quails per experimental unit. Linear decrease was observed on the nitrogen balance and metabolization coefficient with the DTrp levels increase. The nutritional requirement of digestible tryptophan for maximum growing of meat quail, in the period from 1 to 14 days of age, is higher or equal to 0.42%; in the period from 15 to 35 days, it is 0.22%.