Evaluation of a mechanistic model that estimates feed intake, growth and body composition, nutrient requirements, and optimum economic response of broilers.

Efficient meat production is crucial in addressing global market demands and sustainability goals. Modeling production systems has gained worldwide attention, offering valuable insights for predicting outcomes and optimizing economic returns. In the poultry industry, researchers have developed mathematical models to predict animal performance and maximize profits. These models incorporate theories to explain real-world processes and enable future event predictions. One such model is the Broiler Growth Model (BGM), which serves as a predictive tool for estimating feed intake, growth, and body composition of broilers. The BGM takes into account the genetic potential of the broilers, the feed they are provided, and several constraining factors that may prevent the animal from achieving their genetic potential. To evaluate the BGM, a series of simulations were performed: (i) model behavior was evaluated by simulating the response of males and females from 22 to 35 d to feeds differing in dietary protein content and nutrient density; (ii) model prediction was evaluated using the results of a protein response trial conducted at UNESP in which six dietary protein levels were fed to male and female broilers over a 56 d period; and (iii) model optimization was used to maximize economic returns in the above trial. The model behaved as expected when feeds differing in protein content were fed, with feed intake per kg of BW increasing as protein level was decreased, resulting in lower gains and higher body lipid contents. Increasing nutrient density resulted in higher feed intake in the second level, followed by a reduction in feed intake in the highest nutrient feed. The simulated response to nutrient density resulted in increasing body lipid deposition as the nutrient density increased. In comparing the simulated and actual results of the protein response trial, the overall error of prediction was up to 15% for feed intake, BW, and body protein. The optimization routine allows the simulation of different economic scenarios, helping in decision-making. The Broiler Growth Model emerges as a valuable tool for the poultry industry, offering predictive capabilities and economic optimization potential. While minor discrepancies between simulated and actual results exist, the BGM holds significant promise for enhancing efficiency and profitability in broiler production, contributing to the broader goals of sustainable broiler meat production.

A first model of the fate of dietary calcium and phosphorus in broiler chickens.

To reduce P excretion and increase the sustainability of poultry farms, one needs to understand the mechanisms surrounding P metabolism and its close link with Ca metabolism to precisely predict the fate of dietary P and Ca and related requirements for birds. This study describes and evaluates a model developed to estimate the fate of Ca and P consumed by broilers. The Ca and P model relies on three modules: (1) digestion of Ca and P; (2) dynamics of Ca and P in soft tissue and feathers; and (3) dynamics of body ash. Exogenous phytase affects the availability of Ca and P; thus, to predict the absorption of those minerals, the model also accounts for the effect of phytase on Ca and P digestibility. We used a database to estimate the consequences of dietary Ca, P, and phytase over feed intake response. This study followed a four-step process: (1) Ca and P model development and its coupling with a growth broiler model; (2) model behavior assessment; (3) sensitivity analysis to identify the most influential parameters; and (4) external evaluation based on three databases. The proportion of P in body protein and the Ca to P ratio in bone are the most sensitive parameters of P deposition in soft tissue and bone, representing 91 and 99% of the total variation. The external evaluation results indicated that body water and protein had an overall mean square prediction error (rMSPE) of 7.22 and 12.3%, respectively. The prediction of body ash, Ca, and P had an rMSPE of 7.74, 11.0, and 6.56%, respectively, mostly errors of disturbances (72.5, 51.6, and 90.7%, respectively). The rMSPE for P balance was 13.3, 18.4, and 22.8%, respectively, for P retention, excretion, and retention coefficient, with respective errors due to disturbances of 69.1, 99.9, and 51.3%. We demonstrated a mechanistic model approach to predict the dietary effects of Ca and P on broiler chicken responses with low error, including detailed simulations to show the confidence level expected from the model outputs. Overall, this model predicts broilers' response to dietary Ca and P. The model could aid calculations to minimize P excretion and reduce the impact of broiler production on the environment. A model inversion is ongoing that will enable the calculation of Ca and P dietary quantities for a specific objective. This will simplify the use of the model and the feed formulation process.

Toward better estimates of the real-time individual amino acid requirements of growing-finishing pigs showing deviations from their typical feeding patterns.

Pigs exposed to stressors might change their daily typical feeding intake pattern. The objective of this study was to develop a method for the early identification of deviations from an individual pig's typical feeding patterns. In addition, a general approach was proposed to model feed intake and real-time individual nutrient requirements for pigs with atypical feeding patterns. First, a dynamic linear model (DLM) was proposed to model the typical daily feed intake (DFI) and daily gain (DG) patterns of pigs. Individual DFI and DG dynamics are described by a univariate DLM in conjunction with Kalman filtering. A standardized tabular cumulative sum (CUMSUM) control chart was applied to the forecast errors generated by DLM to activate an alarm when a pig showed deviations from its typical feeding patterns. The relative feed intake (RFI) during a challenge period was calculated. For that, the forecasted individual pig DFI is expressed as its highest DFI relative to the intake during pre-challenge period. Finally, the DLM and RFI approaches were integrated into the actual precision-feeding model (original model) to estimate real-time individual nutrient requirements for pigs with atypical feeding patterns. This general approach was evaluated with data from two studies (130 pigs, at 35.25 ± 3.9 kg of initial BW) that investigated during 84 days the effect of precision-feeding systems for growing-finishing pigs. The proposed general approach to estimating real-time individual nutrient requirements (updated model) was evaluated by comparing its estimates with those generated by the original model. For 11 individuals out of 130, the DLM did not fit the observed data well in a specific period, resulting in an increase in the sum of standardized forecast errors and in the number of time steps that the model needed to adapt to the new patterns. This poor fit can be identified by the increase in the CUMSUM with a consequent alarm generated. The results of this study show that the updated model made it possible to reduce intra-individual variation for the estimated lysine requirements in comparison with the original model, especially for individuals with atypical feeding patterns. In conclusion, the DLM in conjunction with CUMSUM could be used as a tool for the online monitoring of DFI for growing-finishing pigs. Moreover, the proposed general approach allows the estimation of real-time amino acid requirements and accounts for the reduced feed intake and growth potential of pigs with atypical feeding patterns.

Precision livestock farming: real-time estimation of daily protein deposition in growing-finishing pigs.

Precision feeding using real-time models to estimate daily tailored diets can potentially increase nutrient utilization efficiency. However, to improve the estimation of amino acid requirements for growing-finishing pigs, it is necessary to accurately estimate the real-time body protein (BP) mass. The aim of this study was to predict individual BP over time in order to obtain individual daily protein content of the gain (i.e., protein deposition/daily gain, PD/DG) to be integrated into a real-time model used for precision feeding. Two databases were used in this study: one for the development of the equations for the model and the other for model evaluation. For the equations, data from 79 barrows (25 to 144 kg BW) were used to estimate the parameters for a Gompertz function and a mixed linear-quadratic regression. Individual BP predictions obtained by dual X-ray absorptiometry were regressed as a function of BW. Individual pig BP estimates were obtained by linear-quadratic regression using the MIXED procedure of SAS, considering pig measurements repeated in time. Individual Gompertz curves were obtained using the NLMIXED procedure of SAS. Both procedures generate an average or a general model, which was assessed for accuracy with the database used to generate the equations. Coefficients of concordance and determination were both 0.99, and the RMSE was 0.21 kg for the linear-quadratic regression. The Gompertz curve coefficients of concordance and determination were both 0.99, and the RMSE was 0.36 kg. In sequence, the linear-quadratic regression and Gompertz curve were evaluated in an independent data set (488 observations; 21 to 126 kg BW). The linear-quadratic regression to predict BP mass was accurate (mean absolute percentage error (MAPE) = 2.5%; bias = 0.03); the Gompertz model performed worse (MAPE = 3.9%; bias = 0.04) than the linear-quadratic regression. When using the derivative of these equations to predict PD/DG, the linear-quadratic regression was more accurate (MAPE = 4.8%, bias = 0.17%) compared to the Gompertz (MAPE = 10.6%, bias = -0.99%) mainly due to the linear decrease in PD/DG in the observed data. Further analysis using individual pig data showed that the goodness of fit of PD/DG curve depends on the individual shape of the growth curve, with either the Gompertz or the linear-quadratic regression being more accurate for specific individuals. Therefore, both approaches are provided to allow end users to select the model that best fits their needs. The proposed update of the empirical component of the original model, using either linear-quadratic regression or the Gompertz function, is able to predict BP in real-time with good accuracy.

Simulated amino acid requirements of growing pigs differ between current factorial methods.

Significant differences in the estimation of amino acid requirements exist between the available factorial methods. This study aimed to compare current factorial models used to estimate the individual and population standardised ileal digestible (SID) lysine (Lys) requirements of growing pigs during a 26-day feeding phase. Individual daily feed intake and BW data from 40 high-performance pigs (25-kg initial BW) were smoothed by linear regression. Body weight gain was constant (regression slope not different from 0) for all the pigs. The CV of the SID Lys requirements ranged from 22% at the beginning of the trial to 8% at the end. The population Brazilian tables (BT-2017) and National Research Council (NRC-2012) SID Lys requirements for the average pig were 16% higher than the average requirement estimated by the individual precision-feeding model (IPF), but similar to the estimated for the population assuming that population requirements are those of the 80th-percentile pig of the population (IPF-80). Meaning that, the IPF-80, BT-2017, and NRC-2012 models would yield similar recommendations when pigs are group-fed in conventional multi-phase systems. Additionally, the IPF-80 estimates are independent of the phase length, whereas the BT-2017 and NRC-2012 models use average population values in the middle of the feeding phase for the calculations and therefore, conventional requirement estimations decrease as the length of the feeding phase increases. In conclusion, the BT-2017 and NRC-2012 methods were calibrated for maximum population responses, which explains why these methods yield higher values than those estimated for the average pig by the IPF model. This study shows the limitations of conventional factorial methods to estimate amino acid requirements for precision-feeding systems.

Environmental impacts of precision feeding programs applied in pig production.

This study was undertaken to evaluate the effect that switching from conventional to precision feeding systems during the growing-finishing phase would have on the potential environmental impact of Brazilian pig production. Standard life-cycle assessment procedures were used, with a cradle-to-farm gate boundary. The inputs and outputs of each interface of the life cycle (production of feed ingredients, processing in the feed industry, transportation and animal rearing) were organized in a model. Grain production was independently characterized in the Central-West and South regions of Brazil, whereas the pigs were raised in the South region. Three feeding programs were applied for growing-finishing pigs: conventional phase feeding by group (CON); precision daily feeding by group (PFG) (whole herd fed the same daily adjusted diet); and precision daily feeding by individual (PFI) (diets adjusted daily to match individual nutrient requirements). Raising pigs (1 t pig BW at farm gate) in South Brazil under the CON feeding program using grain cultivated in the same region led to emissions of 1840 kg of CO2-eq, 13.1 kg of PO4-eq and 32.2 kg of SO2-eq. Simulations using grain from the Central-West region showed a greater climate change impact. Compared with the previous scenario, a 17% increase in climate change impact was found when simulating with soybeans produced in Central-West Brazil, whereas a 28% increase was observed when simulating with corn and soybeans from Central-West Brazil. Compared with the CON feeding program, the PFG and PFI programs reduced the potential environmental impact. Applying the PFG program mitigated the potential climate change impact and eutrophication by up to 4%, and acidification impact by up to 3% compared with the CON program. Making a further adjustment by feeding pigs according to their individual nutrient requirements mitigated the potential climate change impact by up to 6% and the potential eutrophication and acidification impact by up to 5% compared with the CON program. The greatest environmental gains associated with the adoption of precision feeding were observed when the diet combined soybeans from Central-West Brazil with corn produced in Southern Brazil. The results clearly show that precision feeding is an effective approach for improving the environmental sustainability of Brazilian pig production.

Feeding behavior of growing-finishing pigs reared under precision feeding strategies.

The feeding behavior of growing-finishing pigs reared under precision feeding strategies was studied in 35 barrows and 35 females (average initial BW of 30.4 ± 2.2 kg) over 84 d. Five different feeding programs were evaluated, namely a conventional 3-phase program in which pigs were fed with a constant blend of diet A (high nutrient density) and diet B (low nutrient density) and 4 daily phase-feeding programs in which pigs were fed daily with a blend meeting 110, 100, 90, or 80% of the individual Lys requirements. Electronic feeder systems automatically recorded the visits to the feeder, the time of the meals, and the amount of feed consumed per meal. The trial lasted 84 d and the database contained 59,701 feeder visits. The recorded database was used to calculate the number of meals per day, feeding time per meal (min), intervals between meals (min), feed intake per meal (g), and feed consumption rate (feed intake divided by feeding time per meal, expressed in g/min) of each animal. The feeding pattern was predominantly diurnal (73% of the feeder visits). Number of meals, duration of meals, time between meals, feed consumed per meal, and feed consumption rate were not affected by the feeding programs. The females ingested 19% less feed per meal and had a 6% lower feed consumption rate in comparison with the barrows ( < 0.05). Pig feeding behavior was not correlated with diet composition. However, feed efficiency was negatively correlated with amount of feed consumed per meal ( = -0.38, < 0.05) and feed consumption rate ( = -0.44, < 0.05). Feed consumption rate was also negatively correlated with protein efficiency ( = -0.44, < 0.05). Multivariate analysis indicated that feed consumption rate and number of meals per day are the variables related most closely to pig production performance results. Current results indicate that using precision feeding as an approach to reduce Lys intake does not interfere with the feeding behavior of growing-finishing pigs.

A meta-analysis of the feed intake and growth performance of broiler chickens challenged by bacteria.

The aim of this meta-analysis was to determine the effect of a bacterial immune challenge (Clostridium spp., Escherichia coli, and Salmonella spp.) on the ADFI, ADG, and nutrient partitioning (maintenance requirements and feed efficiency) of broiler chickens. The database used for the meta-analysis included 65 articles that were published between 1997 and 2012 concerning a total of 86,300 broilers and containing information on the feed intake, protein intake, methionine intake, and weight gain of broilers that were challenged with Clostridium spp., E. coli, or Salmonella spp. and were fed or not fed feed additives. The results of the ADFI and the ADG of the challenged broilers were transformed into values relative to those obtained in control broilers (ADG and ADFI). The meta-analysis involved 3 sequential analyses: graphical, correlation, and variance-covariance analysis. The results obtained for the birds that were challenged with Clostridium spp., E. coli, or Salmonella spp. indicated that the ADFI was reduced by 16, 7, and 9%, respectively, and the ADG was reduced by 40, 10, and 29%, respectively. When the results for the challenged birds that were treated or nontreated were compared, ADFI reductions of 26.0 and 26.5% and ADG reductions of 2.9 and 21.6% were observed, respectively. Regression analyses of the ADG as a function of the protein or methionine intake of the challenged birds suggested that nutrients were diverted to the immune system. The relationship between the ADG and the ADFI was quadratic in the challenged and nontreated or treated broilers, as well as for each disease. The intercept of the regression-based curves for the data from all of the challenges were different from zero and negative (-2.20, -0.70, and -3.37, respectively), indicating that all of the challenges increased the maintenance requirements. In general, this meta-analysis allowed for the quantification of the effects of bacteriological challenges on the maintenance and feed efficiency of broiler chickens, and the knowledge that was generated in this study is applicable to broiler nutrition and for modeling their nutritional requirements.

Meta-analytical study of productive and nutritional interactions of mycotoxins in growing pigs.

A meta-analysis was carried out in order to study the association of mycotoxins with performance and organ weights in growing pigs. A total of 85 articles published between 1968 and 2010 were used, totaling 1012 treatments and 13 196 animals. The meta-analysis followed three sequential analyses: graphical, correlation and variance-covariance. The presence of mycotoxins in diets was seen to reduce the feed intake by 18% and the weight gain in 21% compared with the control group. Deoxynivalenol and aflatoxins were the mycotoxins with the greatest impact on the feed intake and growth of pigs, reducing by 26% and 16% in the feed intake and by 26% and 22% in the weight gain. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination in equations for estimating the effect of mycotoxins on weight gain. The mycotoxin effect on growth proved to be greater in younger animals. In addition, the residual analysis showed that the greater part of the variation in weight gain was explained by the variation in feed intake (87%). The protein and methionine levels in diets could influence the feed intake and the weight gain in challenged animals. The weight gain in challenged pigs showed a positive correlation with the methionine level in diets (0.68). The mycotoxin effect on growth was greater in males compared with the effect on females. The reduction in weight gain was of 15% in the female group and 19% in the male group. Mycotoxin presence in pig diets has interfered in the relative weight of the liver, the kidneys and the heart. Mycotoxins have an influence on performance and organ weight in pigs. However, the magnitude of the effects varies with the type and concentration of mycotoxin, sex and the animal age, as well as nutritional factors.

Development of sustainable precision farming systems for swine: estimating real-time individual amino acid requirements in growing-finishing pigs.

The objective of this study was to develop and evaluate a mathematical model used to estimate the daily amino acid requirements of individual growing-finishing pigs. The model includes empirical and mechanistic model components. The empirical component estimates daily feed intake (DFI), BW, and daily gain (DG) based on individual pig information collected in real time. Based on DFI, BW, and DG estimates, the mechanistic component uses classic factorial equations to estimate the optimal concentration of amino acids that must be offered to each pig to meet its requirements. The model was evaluated with data from a study that investigated the effect of feeding pigs with a 3-phase or daily multiphase system. The DFI and BW values measured in this study were compared with those estimated by the empirical component of the model. The coherence of the values estimated by the mechanistic component was evaluated by analyzing if it followed a normal pattern of requirements. Lastly, the proposed model was evaluated by comparing its estimates with those generated by the existing growth model (InraPorc). The precision of the proposed model and InraPorc in estimating DFI and BW was evaluated through the mean absolute error. The empirical component results indicated that the DFI and BW trajectories of individual pigs fed ad libitum could be predicted 1 d (DFI) or 7 d (BW) ahead with the average mean absolute error of 12.45 and 1.85%, respectively. The average mean absolute error obtained with the InraPorc for the average individual of the population was 14.72% for DFI and 5.38% for BW. Major differences were observed when estimates from InraPorc were compared with individual observations. The proposed model, however, was effective in tracking the change in DFI and BW for each individual pig. The mechanistic model component estimated the optimal standardized ileal digestible Lys to NE ratio with reasonable between animal (average CV = 7%) and overtime (average CV = 14%) variation. Thus, the amino acid requirements estimated by model are animal- and time-dependent and follow, in real time, the individual DFI and BW growth patterns. The proposed model can follow the average feed intake and feed weight trajectory of each individual pig in real time with good accuracy. Based on these trajectories and using classical factorial equations, the model makes it possible to estimate dynamically the AA requirements of each animal, taking into account the intake and growth changes of the animal.

Meta-analytical study of productive and nutritional interactions of mycotoxins in broilers.

A meta-analysis was carried out to study the association of mycotoxins with performance, productive indices, and organ weights in broilers. Ninety-eight papers published between 1980 and 2009 were used, totaling 1,401 diets and 37,371 animals. Meta-analysis followed 3 sequential analyses: graphical, correlation, and variance-covariance. The mycotoxin presence in diets reduced (P < 0.05) feed intake by 12% and weight gain by 14% compared with control group. Ochratoxins and aflatoxins were the mycotoxins with the greatest effect on feed intake and bird growth, reducing (P < 0.05) feed ingestion by 17 and 11%, respectively, and weight gain by 20 and 11%, respectively. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination for equations to estimate mycotoxin effect on weight gain. The mycotoxin effect on growth proved to be greater in young poultry. The residual analysis revealed that 65% of the variation in weight gain was explained by feed intake. The variation in weight gain of challenged broilers in relation to nonchallenged broilers was also influenced by ingestion of nutrients such as protein and methionine. Mortality was 8.8 and 2.8 times greater (P < 0.05) in groups that received diets with deoxynivalenol and aflatoxins, respectively. Mycotoxins also increased (P < 0.05) the relative weight of liver by 15%, of kidneys by 11%, of lungs by 9%, and of gizzard by 3%. Mycotoxins influenced broiler performance, productive indices, and organ weights. However, the magnitude of the effects varied with type and concentration of mycotoxin, animal age, and nutritional factors.

Alimentação de porcas lactantes com dietas contendo silagem de grãos úmidos de milho e ácido fumárico / Lactating sows fed diets with high moisture corn silage and fumaric acid

Estudou-se o efeito de dietas elaboradas com silagem de grãos úmidos de milho e ácido fumárico sobre os desempenhos de porcas lactantes e suas leitegadas. Foram utilizadas 20 porcas de genética comercial em um delineamento de blocos ao acaso com quatro tratamentos - dieta basal (DB), elaborada a cada 24h; DB + 0,3 por cento de ácido fumárico - (AF); DB + 0,6 por cento AF; e DB + 0,9 por cento de AF, e cinco repetições. As dietas contendo ácido fumárico foram elaboradas a cada 48 horas. O consumo médio diário da dieta das porcas lactantes foi de 7,42kg de matéria natural e não houve diferença (P>0,05) entre os tratamentos. A adição de 0,9 por cento de ácido fumárico às dietas reduziu (P<0,01) em 6 por cento o pH do leite em relação à dieta-basal. A média de ganho diário e a média de peso dos leitões não diferiram (P>0,05) entre os tratamentos. A adição de ácido fumárico às dietas não alterou os desempenhos de porcas lactantes e de suas leitegadas. A adição de ácido fumárico às dietas de lactação elaboradas com silagem de grãos úmidos de milho reduziu o pH do leite e aumentou a frequência de fezes normais dos leitões lactentes.

The effect of lactation diets containing high moisture corn silage and fumaric acid was evaluated on the performance of lactating sows and their piglets. Twenty sows of commercial genetic lines were used in a randomized complete block experimental design with four treatments (basal diet - BD, elaborated each 24h; BD + 0.3 percent fumaric acid - FA; BD + 0.6 percent FA; and BD + 0.9 percent FA) and five replicates. Diets with fumaric acid were elaborated each 48 hours. The average daily feed intake of lactating sows was 7.42kg of natural matter and it was not affected (P>0.05) by treatments. The 0.9 percent fumaric acid addition in diets reduced in 6 percent (P<0.01) the pH of milk compared to basal diet. The average daily weight gain and average weaning live weight of piglets were not influenced (P>0.05) by treatments. The addition of fumaric acid in diets did not alter the performance of lactating sows and piglets. The addition of fumaric acid in lactation diets elaborated with high moisture corn silage increased the normal feces frequency in sucking piglets.

Systematic comparison of the empirical and factorial methods used to estimate the nutrient requirements of growing pigs.

Empirical and factorial methods are currently used to estimate nutrient requirements for domestic animals. The purpose of this study was to estimate the nutrient requirements of a given pig population using the empirical and factorial methods; to establish the relationship between the requirements estimated with these two methods; and to study the limitations of the methods when used to determine the level of a nutrient needed to optimize individual and population responses of growing pigs. A systematic analysis was carried out on optimal lysine-to-net-energy (Lys : NE) ratios estimated by the empirical and factorial methods using a modified InraPorc® growth model. Sixty-eight pigs were individually simulated based on detailed experimental data. In the empirical method, population responses were estimated by feeding pigs with 11 diets of different Lys : NE ratios. Average daily gain and feed conversion ratio were the chosen performance criteria. These variables were combined with economic information to estimate the economic responses. In the factorial method, the Lys : NE ratio for each animal was estimated by model inversion. Optimal Lys : NE ratios estimated for growing pigs (25 to 105 kg) differed between the empirical and the factorial method. When the average pig is taken to represent a population, the factorial method does not permit estimation of the Lys : NE ratio that maximizes the response of heterogeneous populations in a given time or weight interval. Although optimal population responses are obtained by the empirical method, the estimated requirements are fixed and cannot be used for other growth periods or populations. This study demonstrates that the two methods commonly used to estimate nutrient requirements provide different nutrient recommendations and have important limitations that should be considered when the goal is to optimize the response of individuals or pig populations.

Alimentação de leitoas pré-púberes com dietas contendo zearalenona / Feeding of pre-pubertal gilts with diets containing zearalenone

O desempenho, o peso de alguns órgãos e a morfologia vulvar de leitoas pré-púberes, alimentadas por 28 dias com dietas contendo zearalenona, foram avaliados. O delineamento experimental utilizado foi inteiramente ao acaso, com dois tratamentos, dieta controle (DC) e dieta controle + 2mg kg-1 de zearalenona (DZ), e seis repetições cada. Não houve diferença (P>0,05) entre os tratamentos para consumo médio diário de ração (1,24 x 1,19kg), ganho médio diário de peso (0,68 x 0,71kg), conversão alimentar (1,86 x 1,71) e peso vivo (PV); (30,9 x 30,4kg). A zearalenona não alterou (P>0,05) os pesos absoluto e relativo do coração (137 x 141g e 0,45 x 0,45 por cento PV), fígado (699 x 699g e 2,31 x 2,26 por centoPV), rins (47 x 49g e 0,15 x 0,16 por centoPV) e baço (166 x 171g e 0,55 x 0,55 por centoPV). Houve aumento (P<0,05) no comprimento (17 x 27cm) e no peso (23 x 157g e 0,07 x 0,51 por centoPV) do trato reprodutivo das leitoas do grupo DZ. O volume vulvar ao final do período foi 820 por cento maior (P<0,05) nos animais alimentados com zearalenona (941 x 8658mm³/kgPV0,6). Os resultados indicam que em suínos a zearalenona e seus metabólitos possuem atividade estrogênica, mas não interferem no desempenho dos animais.

The performance, the weights of some organs, and the vulvae morphology in pre-pubertal gilts fed diets containing zearalenone were evaluated during 28 days. The experimental design was completely randomized with two treatments (control diet, ZD - control diet + 2mg kg-1 of zearalenone) and six replications of each were done. No differences (P>0.05) between treatments for daily feed intake (1.24 x 1.19kg), average daily gain (0.68 x 0.71kg), feed conversion ratio (1.86 x 1.71), and live weight (30.9 x 30.4kg) were observed. Zearalenone did not change (P>0.05) the absolute and relative weights of heart (137 x 141g and 0.45 x 0.45 percentBW), liver (699 x 699g and 2.31 x 2.26 percentBW), kidneys (47 x 49g and 0.15 x 0.16 percentBW), and spleen (166 x 171g and 0.55 x 0.55 percent BW). However, zearalenone increased (P<0.05) the length (17 x 27cm) and weight (23 x 157g and 0.07 x 0.51 percentBW) of the reproductive tract. The final vulvae volume was 820 percent larger (P<0.05) in gilts fed diets containing zearalenone than those fed control diet (941 x 8658mm³/kgBW0.6). Results suggested that zearalenone and its metabolites have an estrogenic activity in pigs without changing the animal performance.

Utilização do triticale e de enzimas em dietas para suínos: digestibilidade e metabolismo / Utilization of triticale and of enzymes in pig diets: digestibility and metabolism

Avaliou-se o efeito da inclusão de níveis de triticale sobre o valor nutritivo de dietas para suínos com ou sem enzimas. Foram utilizados 24 suínos machos, castrados, com peso inicial de 59kg, alojados em gaiolas metabólicas. O delineamento foi de blocos ao acaso em arranjo fatorial 3 x 2 (níveis de triticale, 0, 30 e 60 por cento, com ou sem enzimas), com quatro repetições cada. A inclusão de triticale na dieta em até 60 por cento e a adição de enzimas não influenciou (P>0,05) a digestibilidade da matéria seca, fósforo, energia bruta, metabolização da energia, energia digestível e metabolizável e o balanço do N. Os valores médios de energia digestível e metabolizável foram de 3.537 e 3.435kcal. Houve interação triticale x enzimas na proteína digestível aparente (PDa) (P<0,01). Na dieta com 60 por cento de triticale sem adição de enzimas a PDa foi 6 por cento inferior à controle. Na dieta com 30 e 60 por cento de triticale com enzimas, a PDa foi similar à controle e 5 por cento superior à dieta com 60 por cento de triticale sem enzimas. A inclusão de 60 por cento de triticale em dietas para suínos reduz a PDa. A adição de enzimas melhora a PDa em dietas com 30 e 60 por cento de triticale.

The effect of triticale levels with or without enzyme supplementation on nutritive value of pig's diet was evaluated using twenty four barrows weighting 59kg, housed in metabolic crates. A complete randomized experimental block design in a 3 x 2 factorial arrangement (triticale levels -0, 30 e 60 percent with or without enzymes) with four replicates each was utilized. No effects of triticale levels and enzymes supplementation (P>0.05) were observed on dry matter digestibility, phosphorus, crude energy, metabolization of energy, digestible and metabolizable energy and nitrogen balance. The average values of digestible and metabolizable energy were 3,537 e 3,435kcal. An interaction triticale x enzymes effect on apparent digestible protein (DPa) (P<0.01) was observed. Apparent digestible protein for 60 percent triticale diets without enzymes supplementation was 6 percent lower than control diet while DPa of 30 and 60 percent triticale diets with enzymes supplementation were similar to DPa of the control diet and 5 percent higher than 60 percent triticale diets without enzyme supplementation. The inclusion of 60 percent triticale in pig diets reduces the DPa. Enzymes supplementation improves the DPa for diets containing 30 and 60 percent of triticale.

Substituição de milho por sorgo baixo tanino em dietas para suínos: digestibilidade e metabolismo / Replacement of corn by low tannin sorghum in pig diets: digestibility and metabolism

Um experimento foi realizado para avaliar os efeitos digestivos e metabólicos da substituição de milho por sorgo em dietas para suínos. Foram utilizados 12 suínos machos castrados, meio-irmãos paternos, com peso vivo médio inicial de 40,8kg, mantidos em gaiolas metabólicas. O delineamento experimental foi inteiramente casualizado com três tratamentos (T1 = dieta controle; T2 = substituição de 50 por cento do milho por sorgo e T3 = substituição de 100 por cento) e quatro repetições. As digestibilidades da proteína e da energia brutas foram 5 e 4 por cento superiores (P<0,05), respectivamente, nos suínos alimentados com a dieta que tinha 50 por cento de substituição, comparadas àquela com substituição total do milho por sorgo. A substituição total do milho por sorgo reduziu (P<0,05) as digestibilidades, em relação à dieta-controle, em 3 por cento para MS, 8 por cento para PB e 5 por cento para EB. O N fecal foi 25 por cento maior (P<0,05), o N absorvido 10 por cento menor (P<0,05) e a excreção fecal de energia 15 por cento maior (P<0,05) para a dieta com substituição total, em relação à dieta-controle. A excreção fecal de N e energia e a absorção de N são influenciadas negativamente pela substituição total de milho por sorgo nas dietas. A substituição em até 50 por cento do milho por sorgo em dietas para suínos não influi na digestibilidade das dietas e no metabolismo dos animais.

An experiment was carried out to evaluate metabolic and digestive effects replacement of corn by sorghum in pig diets. Twelve half brothers barrows weighing 40.8kg and housed in metabolic cages in a completely randomized design with three treatments (T1 = control diet; T2 = replacement of 50 percent corn by sorghum and T3 = replacement of 100 percent) with four replicates. Crude protein and gross energy the digestibilities were 5 percent and 4 percent higher (P<0.05), respectively, for pigs fed 50 percent of corn replacement diet, in comparison with the diet where corn was totally replaced by sorghum. Total replacement of corn by sorghum diets decreased (P<0.05) the digestibilities, in comparison to control diet, in 3 percent for DM, 8 percent for CP and 5 percent for GE. Fecal N was 25 percent higher (P<0.05), absorbed N was 10 percent lower (P<0.05), and the fecal excretion energy was 15 percent higher (P<0.05) for total substitution diet in comparison to control diet. Fecal excretion and absorption of nitrogen are negatively influenced by total replacement of corn by sorghum in the diets. Replacements of up to 50 percent of corn by sorghum in pig diets do not affect the digestibility diet and metabolism of animals.