title: Evaluation of a microwave method for dry matter determination in faecal samples from weaned pigs with or without clinical diarrhoea.
abstract: Microwave drying as a procedure for determination of faecal dry matter in weaned pigs was evaluated and clinical relevant cut-off values between faecal consistency scores were determined. Repeatability and reproducibility were evaluated. Overall coefficient of variation was 0.03. The 95% confidence limits for any future faecal subsample examined by any operator in any replica were ± 0.85% faecal dry matter. Robustness in relation to weight of wet faeces was evaluated. The weight categories were 0.5, 1.0, 1.5, 2.0 and 3.0 g. Samples of 0.5 g gave significantly different mean faecal dry matter content compared to weighing of 1.0-3.0 g. Agreement with freeze-drying was evaluated. Lin's concordance correlation coefficient was 0.94. On average the faecal dry matter values was 1.7% (SD=1.99%) higher in freeze dried compared to micro waved samples. Non-parametric ROC analyses were used to determine optimal faecal dry matter cut-off values for clinical faecal consistency scores. The 4 consistency scores were score 1=firm and shaped, score 2=soft and shaped, score 3=loose and score 4=watery. The cut-off values were score 1: faecal dry matter content >19.5%, score 2: faecal dry matter content ≤ 19.5% and >18.0%, score 3: faecal dry matter content ≤ 18.0% and >11.3%, score 4: faecal dry matter content ≤ 11.3%. In conclusion, the microwave procedure has an acceptable repeatability/reproducibility and good agreement with freeze drying can be expected. A minimum of 1.0 g of wet faeces must be used for analyses. Faecal dry matter cut-off values between 4 different clinical consistency scores were determined.
authors.affiliation: Department of Large Animal Sciences, University of Copenhagen, Groennegaardsvej 2, DK-1870 Frederiksberg C., Denmark. ken@life.ku.dk
authors.forename: Ken Steen
authors.initials: KS
authors.lastname: Pedersen
authors.forename: Helle
authors.initials: H
authors.lastname: Stege
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Nielsen
mesh_terms: D000818:Animals; D003967:Diarrhea / Q000175:diagnosis / Q000662:veterinary; D005243:Feces / Q000737:chemistry*; D008872:Microwaves; D012372:ROC Curve; D015203:Reproducibility of Results; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis