TÉCNICAS DE COLETA DE LÍQUIDO RUMINAL PARA ANÁLISE DA DIGESTIBILIDADE in vitro DE ALIMENTOS

Abstract

In vitro dry matter digestibility (IVDMD) is widely used in ruminant nutrition and depends directly on the quality of the ruminal inoculum employed, however, the literature is still inconclusive regarding the possible influence of the collection technique on this quality. This study aimed to compare the IVDMD of different forages using ruminal fluid obtained via ruminal fistula and esophageal probe. The experiment was conducted at the Experimental Farm of the Federal University of Mato Grosso do Sul, using four forages: BRS Capiaçu elephant grass silage, fresh BRS Capiaçu elephant grass, corn silage, and Marandu grass. Ruminal fluid was collected from three fistulated Nellore cattle by both collection methods, in two experimental runs conducted at one-week interval. After collection, the ruminal fluid was filtered, homogenized into a pooled sample for each collection technique, and transported to the Applied Nutrition Laboratory of the Faculty of Veterinary Medicine and Animal Science (FAMEZ/UFMS). The IVDMD was determined using the Tilley and Terry method, adapted to the Marconi® system, with the use of nonwoven fabric bags. The ruminal incubation period was 48 hours, followed by acid digestion with pepsin for 24 hours. Data were subjected to statistical analysis to compare collection methods, evaluating mean digestibility values as well as measures of variability (range, standard deviation, and coefficient of variation). The results indicated that, although differences in variability were observed between techniques depending on forage type, there was no significant effect (P > 0.05) of the collection technique on mean IVDMD values. It is concluded that ruminal fluid collection techniques using an esophageal probe or a ruminal fistula can be used in in vitro digestibility assays, considering their operational limitations and the characteristics of the evaluated feed.

Keywords: Esophageal probe; feed analysis; fistula; inoculum; ruminants.