Estudos colaborativos para avaliação da composição química de alimentos

• Autor(a) principal: Souza, Marjorrie Augusto de
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1776
• topic: Análise de alimentos; Estudo colaborativo; Métodos analíticos; Variação interlaboratorial; Food analysis; Collaborative studies; Analytical methods; Interlaboratory variation; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL::AVALIACAO DE ALIMENTOS PARA ANIMAIS

The objective was to conduct collaborative studies for evaluation of dry matter (DM), neutral detergent fiber (NDF), crude protein (CP), ether extract (EE), mineral matter (MM), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) contents in feeds. All seven laboratories participating in the study were from institutions of the National Institute of Science and Technology in Animal Science: Federal University of Viçosa, Viçosa, Minas Gerais; Federal University of Minas Gerais, Belo Horizonte, Minas Gerais; Federal University of Lavras, Lavras, Minas Gerais; State University of Santa Cruz, Ilhéus, Bahia; São Paulo State University, Jaboticabal, São Paulo; Federal University of Mato Grosso, Cuiabá, Mato Grosso; and Federal University of Mato Grosso, Sinop, Mato Grosso. In all studies it were evaluated characteristics of accuracy, and inter and intra-laboratory variation. The levels of DM were evaluated by oven-drying method, involving six laboratories and using samples of sugarcane, corn silage, elephant grass, soybean meal, citrus pulp, and corn grain mixture with urea at a ratio 9:1. The Karl Fischer method was used to evaluate the accuracy of results. NDF contents were evaluated in equipments Ankom220® or Ankom200®, using F57 filter bags (Ankom®) and involving three laboratories and considering the same samples used in the evaluation of DM. Purified cellulose, starch and a mixture comprised 60% sand and 40% starch were used to measure the accuracy of estimates. The CP levels were evaluated by the Kjeldahl method involving seven laboratories and using samples of sugarcane, corn silage, soybean meal and corn grain. To quantify the accuracy of the estimates, samples of urea, ammonium phosphate monobasic, ethylene diamine tetra-acetic acid and ammonium sulfate were sent to the laboratories. The levels of EE were evaluated by the Goldfish method involving five laboratories and using samples of corn silage, soybean meal, corn grain and whole soybean. Samples of starch containing 5 and 15% olive oil were adopted as standards to quantify the accuracy of estimates. The levels of MM were evaluated by seven laboratories using samples of signal grass hay, sugarcane, corn silage, soybean meal, corn grain and citrus pulp. To measure the accuracy, celite was used as standard. The contents of iNDF and iADF were evaluated by six laboratories using samples of signal grass hay, sugarcane, corn silage, soybean meal, corn grain and citrus pulp. For all components the laboratories were invited to respond questionnaires to elucidate the main procedures and quantitative and qualitative analytical parameters adopted in each analysis. Characteristics of accuracy and precision (repeatability and reproducibility) and the procedures used in each laboratory were presented and discussed. For all components evaluated it was found that the estimates are dependent on the interaction effect of material analyzed and laboratory. The results indicate low reproducibility of the estimates of chemical composition of feeds and show lack of standardization of procedures among laboratories.