Luciano Hauschild

Meta-análise em pesquisas científicas: enfoque em metodologias

ABSTRACT - This text describes a basic approach of systematization with focus on meta-analysis. It ispresented the art state of the meta-analysis, recovering information of its evolution and basic methodologies for itsaccomplishment. In this text are described the historical antecedents of meta-analysis, the limits of the classicapproaches of literature review, the conceptual bases and the objectives. It is indicated a general methodology formeta-analysis procedures. The criteria for the definition of the objectives are presented. The procedures of thesystematization 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 thestatistical model (a qualitative explanatory factor, a qualitative or quantitative effect), the interference factors andthe post-analytic procedures (residual variations, heterogeneity among results). In conclusion, this text shows thatmeta-analysis is better than traditional methods of literature review for esteeming with more precision the treatmentseffects adjusting it’s for the experimental heterogeneity. However, the meta-analysis requires discipline in thesystematization and analysis of the research results.

Applying precision feeding techniques in growing-finishing pig operations

The high cost of feed ingredients, the use of non-renewable sources of phosphate and the dramatic increase in the environmental load resulting from the excessive land application of manure are major challenges for the livestock industry. Precision feeding is proposed as an essential approach to improve the utilization of dietary nitrogen, phosphorus and other nutrients and thus reduce feeding costs and nutrient excretion. Precision feeding requires accurate knowledge of the nutritional value of feedstuffs and animal nutrient requirements, the formulation of diets in accordance with environmental constraints, and the gradual adjustment of the dietary nutrient supply to match the requirements of the animals. After the nutritional potential of feed ingredients has been precisely determined and has been improved by the addition of enzymes (e.g. phytases) or feed treatments, the addition of environmental objectives to the traditional feed formulation algorithms can promote the sustainability of the swine industry by reducing nutrient excretion in swine operations with small increases in feeding costs. Increasing the number of feeding phases can also contribute to significant reductions in nutrient excretion and feeding costs. However, the use of precision feeding techniques in which pigs are fed individually with daily tailored diets can further improve the efficiency with which pigs utilize dietary nutrients. Precision feeding involves the use of feeding techniques that allow the provision of the right amount of feed with the right composition at the right time to each pig in the herd. Using this approach, it has been estimated that feeding costs can be reduced by more than 4.6%, and nitrogen and phosphorus excretion can both be reduced by more than 38%. Moreover, the integration of precision feeding techniques into large-group production systems can provide real-time off-farm monitoring of feed and animals for optimal slaughter and production strategies, thus improving the environmental sustainability of pork production, animal well-being and meat-product quality.

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.

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.

Precision feeding can significantly reduce feeding cost and nutrient excretion in growing animals

Precision feeding is an agricultural concept that relies on the existence of between-animal variation and involves the use of feeding techniques that allow the right amount of feed with the right composition to be provided at the right time to each pig of the herd. Precision feeding is proposed as an essential approach to improve nutrient utilization and thus reduce feeding cost and nutrient excretion. The potential impact of using precision feeding techniques on feeding cost and nitrogen (N) and phosphorus (P) excretion was evaluated in this study. The growing pig module of InraPorc® was slightly modified and used to estimate lysine requirements and simulate growth of individual pigs and the overall population. Detailed information of body composition of individual pigs, feed intake and growth performance was used to calibrate the model. Simulated pigs were fed either according to a typical three-phase feeding program or individually with a daily tailored feed as could be provided using precision feeding techniques. Feeding cost was determined according to common commercial pig feeds sold in Quebec, Canada. As expected, simulated N and P retention was not affected (P>0.05) by the feeding method. However, feeding pigs with daily tailored diets reduced (P<0.001) N and P intake by 25% and 29%, respectively and nutrient excretions were reduced both by more than 38%. Feed cost was 10.5% lower for pigs fed daily tailored diets. In fact, population protein and P requirements were established to optimize average daily gain of the population. Estimated nutrient requirements did not include safety margins as normally used in commercial feeds and therefore, the simulated N and P reductions are probably underestimated. Phosphorus excretion should be interpreted with caution because actual models simulating P retention seldom take into account the effect of P intake in P retention and bone mineralisation. Precision feeding can be an efficient approach to significantly reduce feeding cost and the excretion of N and P in animal production systems.

Digestibilidade e balanços metabólicos da silagem de grãos úmidos de milho para suínos

Two experiments were carried out to evaluate metabolic balances and the digestibility of the high moisture corn in pigs. Twelve littermates barrows were used, weighting 47kg of initial BW, kept into metabolic cages. Experiment one compared the metabolic balances of animals fed with diets contend dry corn and high moisture. Experiment two evaluated the digestibility of high moisture corn. In experiment one, the design was completely randomized. Each experiment had two treatments, four repetitions of one animal. The substitution of the dry corn for high moisture corn did not influence the balances of either nitrogen or energy. The digestibility coefficients of the high moisture corn were: 85% to crude protein, 90% to crude energy and 90% to dry matter. The substitution of dry corn for high moisture corn in the swine diets does not affect the balances of both nitrogen and energy. The digestibility of the dry matter, crude energy and metabolizavel energy of the high moisture corn were higher than the dry corn ones.

Alimentação de leitoas pré-púberes com dietas contendo zearalenona

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%BW), liver (699 x 699g and 2.31 x 2.26%BW), kidneys (47 x 49g and 0.15 x 0.16%BW), and spleen (166 x 171g and 0.55 x 0.55% BW). However, zearalenone increased (P<0.05) the length (17 x 27cm) and weight (23 x 157g and 0.07 x 0.51%BW) of the reproductive tract. The final vulvae volume was 820% larger (P<0.05) in gilts fed diets containing zearalenone than those fed control diet (941 x 8658mm 3 /kgBW 0.6 ). Results suggested that zearalenone and its metabolites have an estrogenic

Digestibilidade de dietas e balanços metabólicos de suínos alimentados com dietas contendo aflatoxinas

An experiment was conducted in order to investigate the digestibility of diets and metabolic balances of piglets fed diets containing 800ug kg-1 of aflatoxins. This study used eight with littermate barrows whith an average initial weight of 13kg, housed in metabolic cages in a semi-acclimatized environment. A completely randomized experimental design was used, with two treatments (control diet and control + 800ug kg-1 of aflatoxins) and four replications, with the animal as the experimental unit. The digestibility coefficients of dry matter, protein and gross energy were not affected (P>0.05) by the addition of 800ug kg-1 of aflatoxins in the diet. The gross energy metabolization was 6% (P 0.05) by the addition of aflatoxins in the diet. Energy losses in urine increased (P<0.05) 52% in the pigs fed diets containing aflatoxins. The presence of an aflatoxin level of 800ug kg-1 in the diet did not affect the digestibility, but it altered the protein and energy metabolism of weaned piglets.

Alimentação de leitões na creche com dietas sem aditivos antimicrobianos, com alho (Allium sativum, L.) ou colistina

An experiment was carried out to evaluate piglet performance, ranging from 35 to 62 days of age, fed with diets with no growth parameters, with the addition of garlic and colistina in diets. Ninety-six piglets were distributed in four treatments in a complete randomized block design. The treatments were: control diet, without anti-microbials (DC); diet two: DC + 0.05% of powder garlic; diet three: DC + 0.15% of powder garlic; diet four: DC + 0.25% of colistina sulfate. Feed intake was 16.2% higher (P 0.05) than animals fed with the diet with colistine. In conclusion, diets without anti-microbial or with powder garlic can not replace diets with colistine sulfate when fed to piglets during the post weaning phase.