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 metaanalysis 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.Keywords: aflatoxins, deoxynivalenol, nutrition, swine, trichothecenes ImplicationsThe mycotoxin effect on animal performance is recognized. However, this effect may be modified by several factors, which are noticeable in the large variability observed in previous results. This study is innovative, because it seeks to understand and quantify the interactions among mycotoxins and other factors such as nutrition, sex or growth phase of the pigs. The meta-analysis used the complementarities among previous studies in order to highlight gaps in mycotoxicology, which is hardly studied in traditional experimental designs. Furthermore, it aimed to assist in understanding the mycotoxin effects that this approach can support in the determination of dynamic growth standards for challenged animals.

RESUMO -Este texto descreve os princípios básicos de sistematização com enfoque em meta-análise. É apresentado o estado da arte da meta-análise, recuperando informações de sua evolução e metodologias básicas para sua realização. São descritos seus antecedentes históricos, os limites das abordagens clássicas de revisão de literatura, as bases conceituais, os objetivos e justificativas. É indicada uma metodologia geral para realização da meta-análise.São apresentados os critérios para a definição dos objetivos. São descritos os procedimentos de sistematização das informações e gestão de base bibliográfica de dados destinada aos estudos meta-analíticos (seleção, codificação, filtragem de dados). São apresentadas as análises mais comuns (gráfica, ponderações), a escolha do modelo estatístico (um fator explicativo qualitativo, um efeito qualitativo ou quantitativo), os fatores de interferência, os procedimentos pós-analíticos (variações residuais, heterogeneidade entre resultados). Em síntese, este texto mostra que a metaanálise é superior às formas tradicionais de revisão de literatura por estimar com maior precisão os efeitos dos tratamentos, ajustando-os para a heterogeneidade experimental. No entanto, a meta-análise exige os efeitos na sistematização e análise dos resultados da pesquisa.Palavras-chave: análise sistêmica, produção animal, revisão de literatura, sistematização Meta analysis in scientific research: a methodological approachABSTRACT -This text describes a basic approach of systematization with focus on meta-analysis. It is presented the art state of the meta-analysis, recovering information of its evolution and basic methodologies for its accomplishment. In this text are described the historical antecedents of meta-analysis, the limits of the classic approaches of literature review, the conceptual bases and the objectives. It is indicated a general methodology for meta-analysis procedures. The criteria for the definition of the objectives are presented. The procedures of the systematization and management of bibliographical data base selected to meta-analytic studies are described (selection, code, data filtration). The most common analysis (graph, adjustments) are presented, the choice of the statistical model (a qualitative explanatory factor, a qualitative or quantitative effect), the interference factors and the post-analytic procedures (residual variations, heterogeneity among results). In conclusion, this text shows that meta-analysis is better than traditional methods of literature review for esteeming with more precision the treatments effects adjusting it's for the experimental heterogeneity. However, the meta-analysis requires discipline in the systematization and analysis of the research results.

The impact of moving from conventional to precision feeding systems in growing-finishing pig operations on animal performance, nutrient utilization, and body and carcass composition was studied. Fifteen animals per treatment for a total of 60 pigs of 41.2 (SE = 0.5) kg of BW were used in a performance trial (84 d) with 4 treatments: a 3-phase (3P) feeding program obtained by blending fixed proportions of feeds A (high nutrient density) and B (low nutrient density); a 3-phase commercial (COM) feeding program; and 2 daily-phase feeding programs in which the blended proportions of feeds A and B were adjusted daily to meet the estimated nutritional requirements of the group (multiphase-group feeding, MPG) or of each pig individually (multiphase-individual feeding, MPI). Daily feed intake was recorded each day and pigs were weighed weekly during the trial. Body composition was assessed at the beginning of the trial and every 28 d by dual-energy X-ray densitometry. Nitrogen and phosphorus excretion was estimated as the difference between retention and intake. Organ, carcass, and primal cut measurements were taken after slaughter. The COM feeding program reduced (P < 0.05) ADFI and improved G:F rate in relation to other treatments. The MPG and MPI programs showed values for ADFI, ADG, G:F, final BW, and nitrogen and phosphorus retention that were similar to those obtained for the 3P feeding program. However, compared with the 3P treatment, the MPI feeding program reduced the standardized ileal digestible lysine intake by 27%, the estimated nitrogen excretion by 22%, and the estimated phosphorus excretion by 27% (P < 0.05). Organs, carcass, and primal cut weights did not differ among treatments. Feeding growing-finishing pigs with daily tailored diets using precision feeding techniques is an effective approach to reduce nutrient excretion without compromising pig performance or carcass composition.

This study was developed to assess the impact on performance, nutrient balance, serum parameters and feeding costs resulting from the switching of conventional to precision-feeding programs for growing-finishing pigs. A total of 70 pigs (30.4 ± 2.2 kg BW) were used in a performance trial (84 days). The five treatments used in this experiment were a three-phase group-feeding program (control) obtained with fixed blending proportions of feeds A (high nutrient density) and B (low nutrient density); against four individual daily-phase feeding programs in which the blending proportions of feeds A and B were updated daily to meet 110%, 100%, 90% or 80% of the lysine requirements estimated using a mathematical model. Feed intake was recorded automatically by a computerized device in the feeders, and the pigs were weighed weekly during the project. Body composition traits were estimated by scanning with an ultrasound device and densitometer every 28 days. Nitrogen and phosphorus excretions were calculated by the difference between retention (obtained from densitometer measurements) and intake. Feeding costs were assessed using 2013 ingredient cost data. Feed intake, feed efficiency, back fat thickness, body fat mass and serum contents of total protein and phosphorus were similar among treatments. Feeding pigs in a daily-basis program providing 110%, 100% or 90% of the estimated individual lysine requirements also did not influence BW, body protein mass, weight gain and nitrogen retention in comparison with the animals in the group-feeding program. However, feeding pigs individually with diets tailored to match 100% of nutrient requirements made it possible to reduce ( P < 0.05) digestible lysine intake by 26%, estimated nitrogen excretion by 30% and feeding costs by US$7.60/pig (−10%) relative to group feeding. Precision feeding is an effective approach to make pig production more sustainable without compromising growth performance.Keywords: nutrition, nutrient requirements, precision feeding, protein, swine ImplicationsPresent study investigated the impact of using a mathematical model estimating real-time daily lysine requirements in a sustainable precision-feeding program for growing pigs. Results clearly indicate that this is an effective approach for reducing nutrient intake, nutrient excretion and feeding costs. Feeding pigs individually with daily tailored diets that provide 100% of estimated requirements can reduce lysine intake by 26% and nitrogen excretion by 30% without compromising the pig performance. The proposed precisionfeeding system represents a paradigm shift in pig production, as it takes into account between-animal differences in nutrient requirements within a population and their dynamic evolution over time.