Feed for animals and process for producing same

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a feed for animals containing 0.
0005 to 5.
0 wt.
% of an .
omega.
6-unsaturated fatty acid, and a process for producing the feed.
The .
omega.
6-unsaturated fatty acids usable in the present invention are preferably highly unsaturated fatty acids having at least two carbon-to-carbon double bonds such as 2,4-decadienoic acid, linolenic acid, .
gamma.
-linolenic acid, 8,10,12-octadecatrienoic acid and arachidonic acid.
Among them, .
gamma.
-linolenic acid is particularly preferred.
Seeds of evening primrose, etc.
and molds containing .
gamma.
-linolenic acid, etc.
are used as the sources of the .
omega.
6-unsaturated fatty acids.
Among them, the molds containing .
gamma.
-linolenic acid, etc.
are preferred, since they are available on the market stably at a low cost.
The molds are those of Mortierella, Mucor, Cunninghamella, etc.
In the present invention, the mold is cultured in a nutrient culture medium by an ordinary method, then harvested and heat-treated.
The heat treatment is conducted preferably in two steps.
Namely, a pretreatment is conducted at 50 to 100.
degree.
C.
, preferably 60.
degree.
to 90.
degree.
C.
, for 10 to 60 min.
, preferably 20 to 40 min.
and then the main treatment is conducted at 100 to 150.
degree.
C.
, preferably 120.
degree.
to 130.
degree.
C.
to dry the product.
When the heat treatment is conducted in one step, thermal decomposition products of the residual components of the medium such as sugar and minerals are contained in the feed unfavorably.
Thus, it is desirable to wash the pretreated product with water to remove unnecessary substances prior to the main treatment.
The product thus obtained after the heat treatment may be used as the .
omega.
6-unsaturated fatty acid either as it is or after extraction with, for example, n-hexane, acetone or ethanol.
The results of the analysis of the heat-treated mold (Mortierella isabellina) is shown in the following Table 1.

TABLE 1
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Component Amount (%)
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Components of Mortierella isabellina
water 5