E L Kapiszka | PubMed Health

PubMedDate not supplied

Protein efficiency ratio: AACC/ASTM collaborative study.

Eight laboratories (7 of the laboratories conducted animal experiments) participated in a collaborative study to standardize some of the methodology associated with animal bioassays for determining protein efficiency ratios and to suggest improvements which would reduce the variation among laboratories. One-, 2-, 3-, and 4-week protein efficiency ratios (PER) with 0-, 2-, or 4-day adaptation periods were obtained from each laboratory, respectively, for 6 protein sources: casein, lean beef, lactalbumin, textured vegetable protein, peanut flour, and wheat flour. Analyses were computed for PER and adjusted PER (APER). From the analysis of variance for PER and APER, significant (P less than 0.05) effects were observed due to laboratories, adaptation length, protein sources, and/or interactions among these variables. In general, APER values show much less variation among laboratories than PER values. The reproducibility and repeatability variances were significantly (P less than 0.05) greater for an assay length of 2 weeks than they were for 3- or 4-week assays. Two protein sources, casein and textured vegetable protein, were fed at both high (10%) and low (6%) levels of protein. Analysis of variance of PER values shows a significant (P less than 0.05) laboratory by protein level by assay length interaction.

Animals↗

PubMedDate not supplied

Net protein ratio data: AACC-ASTM collaborative study.

Seven- and 14-day net protein ratio (NPR) data were obtained from 7 laboratories for 6 protein sources: ANRC casein, lean beef, lactalbumin, textured vegetable protein, and peanut flour were fed as 10% protein (N X 6.25) in the test diet. Wheat flour, casein, and textured vegetable protein were fed as 6% protein (N X 6.25) in the test diet. Weighed dry ingredients for each diet were sent to each collaborator , who mixed the dry ingredients, then added specified amounts of corn oil and water and mixed each complete diet thoroughly. Rats were adapted for 0, 2, or 4 days, and then were fed the test diets for 28 days for protein efficiency ratio (PER) diets. The animal weight gain and feed consumption data obtained after 7 or 14 days of feeding were used to calculate NPR values. Analyses of data were done before [net protein ratio (NPR)] and after (R-NPR [relative-NPR]) adjustment of the data from each laboratory by its results for the reference protein casein. From the analysis of variance for NPR, significant (P less than 0.05) interactions were observed among laboratories, protein sources, and adaptation times of the animals (0, 2, or 4 days). Inter- and intralaboratory variability were decreased by use of 14-day values compared with 7-day values. Adjustment of the NPR data to R-NPR did not lower the intralaboratory variability but did lower the interlaboratory variability of the data. Increasing adaptation time did not consistently decrease interlaboratory or intralaboratory variability or decrease coefficients of variation (CV) of R-NPR values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗