dietary protein) were replaced by an organic protein matrix consisting
of PC, HB and RS in the ratio 1.07:1.00:0.66 (Table 1) in diet B, C, and
D, respectively. The maximum inclusion level of the plant protein concentrate
(PPC) matrix (i.e., 44% of total dietary protein) was determined
by the protein content and amino acid composition of the PPC matrix.
Wheat was used as filler to balance the diets.
The diets were produced by the Danish Technological Institute
using a twin-screw Werner & Pfleider 37 extruder and fabricated as
3.0 mm pellets. They were stored at 2 °C throughout the study.
The crude protein and lipid content of the four experimental diets
was quite similar, ranging between 44.2–46.0% for protein and 29.0–
30.8% for lipid (Table 1). The total phosphorus (TP) content of the
four diets was also very similar (1.43–1.47%), while the phytate-P
content increased with increasing plant protein supplementation
that is, increasing from 8.5% of TP in diet A to 21.5% of TP in diet D.
High TP levels in the PPC diets were due to unexpectedly high levels
of TP in the analyzed PPC batches deviating from common literature
values.
There was generally little variation between the four diets in the
content of essential amino acids except for methionine and threonine
whose content decreased with increasing PPC inclusion (Table 1).