期刊名称：Western Australia. Fisheries Department. Fisheries Research Reports
印刷版ISSN：1035-4549
出版年度：2008
卷号：178
页码：54-54
出版社：Government of Western Australia / Department of Fisheries
摘要：This study examined the effect of the extrusion process on the digestibilities of whole diets
and also the component test ingredients when fed to rainbow trout. Six diets were prepared
using either a screw-press or an extruder based on the same batches of raw materials and
formulations in each case. Correlations between diets were highly significant for all four
parameters examined of dry matter, nitrogen, energy and the sum of amino acids. The
correlations showed that extrusion significantly improved the energy digestibility of the diets
but effects on the other parameters were negligible. Correlations between ingredients for
energy and dry matter digestibilities were highly significant, but correlations between the
digestibility of nitrogen and the sum of amino acids were poor. The ingredient correlations
also showed that extrusion improved the digestible energy value of the test ingredients (e.g.
ADE of 70% when screw-pressed, but ADE of 80% when extruded), but any improvement
in the dry matter digestibility was nominal and no advantages were gained for protein
digestibility. The results of this study show that diet digestibility responses obtained from
screw-press manufactured diets provide a proportional, but not necessarily direct indication
of the responses achieved from extruded diets. The ingredient digestibilities showed that
while dry matter and energy digestibilities are also proportional that nitrogen and the sum of
amino acid digestibilities are not proportional between the two diet manufacturing methods.
Observations of pellet stability in vivo showed distinct differences between the reference,
L. angustifolius cv. Myallie kernel meal and soybean meal test diets. Changes in pellet
integrity were noted after 2, 4 and 8 h. Pellet integrity after 8 h was best in the reference diet
and worst in the soybean meal diet. The soybean meal diet lost its structural integrity quicker
than that of the reference and L. angustifolius cv. Myallie kernel meal diets. The specific
nutritional implications of these observations need to be more fully explored.
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