Feed composition for breeding pigs with N-3 fatty acid-accumulated pork

A feed composition for breeding pigs contains about 70 to 90% by weight of an n-3 fatty acid source, about 10 to 20% by weight of a carbohydrate source, about 0.1 to 1.0% by weight of an agent for promoting a decrease in the level of cholesterol, and about 0.1 to 1.0% of an antioxidant.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a feed composition for breeding pigs in 
order to produce pork rich in n-3 fatty acid and more particularly, to a 
feed containing about 70 to 90% by weight of an n-3 fatty acid source, 
about 10 to 20% by weight of carbohydrate source, about 0.1 to 1.0% by 
weight of an agent for promoting a decrease in the cholesterol level, and 
about 0.1 to 1.0% by weight of an antioxidant, which is rich in n-3 fatty 
acid which is beneficial to humans and further can prevent various 
physiological disorders caused by pork having a high n-6 fatty acid 
content. 
2. Description of the Prior Art 
In pork presently on the market, the content of n-3 fatty acid is around 1% 
and the content of n-6 fatty acid is approximately 15 to 30%. 
Unfortunately, n-6 fatty acid may act as to cause various adverse 
physiological effects. For this reason, the field of Chinese medicine has 
warned against the bad effects of pork and the general public has often 
been warned to avoid the intentional intake of pork. 
As shown in Table 1 below, 18:2.sub.n-6 as n-6 fatty acid is metabolized to 
arachidonic acid which is then further metabolized in the cell membranes 
of body tissues. It has been recognized that various metabolites produced 
due to the excessive intake of n-6 fatty acids, i.e., eicosanoids such as 
2-series prostaglandins and 4-series leukotrienes, may cause various 
physiological disorders such as atherosclerosis, hypertension, myocardial 
infarction, ischemia, thrombosis, heart disease, osteomyelitis and skin 
disease. 
However, 18:3.sub.n-3 as n-3 fatty acid is converted into eicosapentaenoic 
acid (EPA) in the cell membrane of body tissue and then EPA produces 
3-series prostaglandins and 5-series leukotrienes through metabolism. 
The 3-series prostaglandins and 5-series leukotrienes thus produced block 
the production of 2-series prostaglandins and 4-series leukotrienes 
produced by the metabolism of arachidonic acid, and thus prevent various 
physiological disorders caused by excessive 2-series prostaglandins and 
4-series leukotrienes. Further, n-3 fatty acid itself blocks the metabolic 
pathway of n-6 fatty acid, as shown in Table 2 below, and therefore, 
inhibits the production of eicosanoids from n-6 fatty acid. 
TABLE 1 
__________________________________________________________________________ 
Metabolic pathway of arachidonic acid 
##STR1## 
##STR2## 
##STR3## 
##STR4## 
__________________________________________________________________________ 
TABLE 2 
______________________________________ 
Inhibition of n-6 fatty acid 
metabolic pathway by n-3 fatty acid 
##STR5## 
______________________________________ 
In Biochimica et Biophysica Acta (1989) 1001:25-30, the present inventors 
have reported that when EPA as n-3 fatty acid is administered to a 
Sprague-Dawley rat, the amount of arachidonic acid, as n-6 fatty acid, 
present in cell membranes, is reduced drastically. 
In another reference, Biochimica et Biophysica Acta (1989) 1006:9-11, the 
present inventors reported, as the result of investigation on the 
biosynthesis of various fatty acids in experimental animals to which EPA 
is administered and then (.sup.3 H) glycerol is injected, that the 
synthesis of arachidonic acid as n-6 fatty acid is drastically reduced 
whereas the content of EPA and DHA (docosahexaenoic acid) as n-3) fatty 
acid increases significantly. 
Furthermore, the present inventors disclose in Lipids (1990) 25:811-814, 
that after EPA administration, the biosynthesis of liver fat in 
Sprague-Dawley rats decreased by about 40 percent. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a feed 
composition for breeding animals having pork rich in n-3 fatty acid. 
Another object of the present invention is to provide a feed composition 
for pigs used as a source of pork, which contains about 70 to 90% by 
weight of an n-3 fatty acid source, about 10 to 20% by weight of a 
carbohydrate source, about 0.1 to 1.0% by weight of an agent for promoting 
a decrease in the level of cholesterol, and about 0.1 to 1.0% by weight of 
an antioxidant, for breeding pigs used as a source of pork rich in n-3 
fatty acid by supplying pigs with the present feed composition from 7 to 
15 days prior to slaughtering. 
Other objects and further scope of applicability of the present invention 
will become apparent from the detailed description given hereinafter. It 
should be understood, however, that the detailed description and specific 
examples, while indicating preferred embodiments of the invention, are 
given by way of illustration only, since various changes and modifications 
within the spirit and scope of the invention will become apparent to those 
skilled in the art from this detailed description. 
Briefly described, the present invention relates to a feed composition for 
breeding pigs, which contains about 70 to 90% by weight of a n-3 fatty 
acid source, about 10 to 20% by weight of a carbohydrate source, about 0.1 
to 1.0% by weight of an agent for promoting a decrease in the level of 
cholesterol, and about 0.1 to 1.0% of an antioxidant.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now in detail to the present invention, there is provided a feed 
composition for breeding pigs having pork rich in n-3 fatty acid, which 
contains about 70 to 90% by weight of a n-3 fatty acid source, about 10 to 
20% by weight of a carbohydrate source, about 0.1 to 1.0% of an agent for 
promoting a decrease in the level of cholesterol, and about 0.1 to 1.0% by 
weight of an antioxidant. 
The present inventors have studied the results of previous experiments on 
the metabolism of n-6 fatty acid and n-3 fatty acid in large animals, 
i.e., pigs, to invent a feed composition which can most effectively reduce 
the content of n-6 fatty acid in pork without any adverse effects. 
The present inventors have succeeded in reducing drastically the content of 
n-6 fatty acid and, instead, increased the content of n-3 fatty acid 
several ten-fold by administering the feed composition of the present 
invention to pigs. In addition, the feed composition of the present 
invention decreases drastically the content of saturated fatty acids and 
cholesterol, and it can therefore even prevent various consequences due to 
saturated fatty acids, such as for example, increases in human cholesterol 
levels and the like. 
Specifically, the present inventors have developed a feed composition for 
pigs, which contains linseed containing about 50% .alpha.-linolenic acid 
as n-3 fatty acid in the extracted oil therefrom, perilla seed containing 
about 60% linolenic acid, wheat, barley, oats, fish meal, salt, an 
antioxidant, dicalcium phosphate and limestone. 
It has been disclosed that when the feed composition of the present 
invention is administered to pigs for only 10 days after 10 days of 
adjusting the feeding-period, in the fillet portion of pigs the content of 
n-3 fatty acid increases several ten-fold, whereas the content of n-6 
fatty acid is significantly reduced, in comparison with pork from pigs in 
a control group which are fed conventional feed on the market. 
Heretofore, many experiments similar to the present invention have been 
carried out in a number of countries. However, in all experiments, the 
individually developed n-3 fatty acid-containing feed compositions have 
been supplied to the pigs from the piglet stage to the slaughter stage. As 
a result, there are the disadvantages that the growth rate decreases and, 
especially, the oxidation of feed cannot be prevented from the root 
thereof and therefore the breeding cost increases. 
However, even in the case wherein the feed composition of the present 
invention is fed to a pig for only 10 days, the pork contains several 
ten-fold more n-3 fatty acid than that of the control group. Therefore, 
the feed composition of the present invention has the advantages of 
reducing pig breeding costs, high feeding efficiency and allowance for a 
very normal growth rate. 
In contrast to pigs fed with the commercially available common feed, the 
subcutaneous fat tissue of pigs fed with the feed composition of the 
present invention is very thin, and the content of n-3 fatty acid is much 
higher, whereas the content of n-6 fatty acid is significantly reduced. 
Thus, by intake of meat produced from pigs fed with the feed composition of 
the present invention, it can be expected that various physiological 
disorders caused by arachidonic acid, which is an n-6 fatty acid, are 
prevented and further treated, and the occurrence of the adverse effects 
due to the excessive intake of pork are reduced. Thus, according to the 
present invention, the acceptability of eating pork can be improved and, 
therefore, nutritious pork as a good n-3 fatty acid source can be widely 
eaten. 
The absorption into the pig's body is the most important factor which 
should be considered in preparing the feed composition. Compared to the 
general feed composition presently on the market, the feed composition of 
the present invention contains a specific fatty acid. 
Accordingly, such a different composition may cause a change in the pig's 
taste and a further reduction of internal absorption. For this reason, the 
conventional n-3 fatty-acid-containing feed compositions are fed to pigs 
from the beginning of breeding to slaughtering time and, therefore, create 
the burden of enermous breeding costs. 
In addition, conventional feed compositions show a tendency to cause tardy 
growth because of the unfitness for native pig taste and low body 
absorbancy, and therefore, have not been welcomed by hog farmers. 
The present inventors have investigated the means for overcoming the 
above-mentioned disadvantages of the prior feed compositions. As a result, 
the present inventors determined that in order to increase the body 
absorbancy of a feed composition, it is preferred to adjust the 
proportions of fatty acid and protein so as to be identical to each other 
or to increase the proportion of protein to fatty acid, and further that 
other kinds of n-3 fatty acid sources are preferably incorporated into the 
feed composition because the large administration of the only one feeding 
component may cause nutritional imbalance. 
In view of this, the present inventors created an optimal feed composition 
and confirmed its effect through many experiments, and thus now have 
completed the present invention. 
In the present invention, linseed and perilla seed are used in a mixing 
ratio of 100:1-10 as a source of n-3 fatty acid. In the prior impractical 
n-3 fatty acid-enriched feed compositions, perilla cake, rape seed, fish 
meal and the like are used as n-3 fatty acid sources. However, these 
components cause some problems due to a comparatively low n-3 fatty acid 
content and low body absorbancy and further, such compositions are 
uneconomical because of the required long-term feeding procedure from the 
young pig to the slaughter stage. 
Linseed used in the present invention is inexpensive and has a high body 
absorbancy because it contains about 25% protein which is higher than that 
in other n-3 fatty acid sources. However, when only linseed is used as the 
n-3 fatty acid source, nutritional imbalance may result. Therefore, in the 
present invention, linseed is blended with a small amount of perilla seed 
which has a relatively lower protein content and a higher n-3 fatty acid 
content compared to linseed, and suits a pig's taste very well. According 
to this, as demonstrated by experiments, the feed composition of the 
present invention maintains the balance between protein and fatty acid, 
and provides for various nutrients moderately, and thus can increase the 
weight gaining effect. 
In blending linseed with perilla seed, if the proportion of perilla seed in 
the blend is below 1%, the blending of perilla seed has no significant 
effect, whereas if the proportion of perilla seed is greater than 10%, the 
proportion of fatty acid is higher than that of protein and thus is 
unsuitable. In addition, the content of the n-3 fatty acid source thus 
composed above is preferably about 70 to 90% of the total feed 
composition. If the content of the n-3 fatty acid source is below 70%, the 
substitution effect of fatty acid in the pork is lowered, and if the 
content is greater than 90%, the feed composition of the preset invention 
exhibits a low weight gaining effect because of the low body absorbancy of 
the feed and the nutritional imbalance, and thus is uneconomical. The more 
preferred n-3 fatty acid source contains, in addition to linseed and 
perilla seed, about 2 to 5% of fish meal having a high EPA and DHA content 
and, therefore, can efficiently produce the accumulation of EPA and DHA in 
the body. Thus, an n-3 fatty acid source composed of linseed, perilla seed 
and fish meal in a ratio of 100:1 - 10:2 - 5 causes the best substitution 
effect on fatty acids. 
It is most preferable that the above-mentioned n-3 fatty acid source 
accounts for 75 to 85% by weight of the total feed composition. As a 
source of carbohydrates, conventional cereals, for example, wheat, barely, 
etc., are used in the mixture. In order to promote the decrease of 
cholesterol level, oats are blended in an amount of about 0.1-1.0% in the 
total composition. 
Another feature of the composition of the present invention is the use of 
santoquin as an antioxidant for feed. This antioxidant is inexpensive and 
also plays a biological role in the pig, as well as in the feed 
composition, to prevent the oxidative decomposition of n-3 fatty acid and 
the spoilage of feed during long-term storage. 
Further features of the present invention are associated with the 
administration time of the present feed composition. As a result of many 
breeding experiments, it has been discovered that when the feed 
composition of the present invention is supplied for approximately 7 to 15 
days before slaughtering the pig, the desired high quality pork rich in 
n-3 fatty acid can be obtained. However, supplying the present feed 
composition prior to 15 days from slaughtering is uneconomical, and a 
supply period shorter than 7 days does not greatly increase the n-3 fatty 
acid content in the pork. 
As described above, the feed composition of the present invention does not 
cause a decrease in the rate of weight gain of pigs due to the change of 
feed, since it is supplied for a short period. The feeding of the feed 
composition of the present invention rapidly decreases the content of n-6 
fatty acid in the pork within a short period and, instead, increases the 
content of n-3 fatty acid, which is an essential fatty acid for the human 
body and also acts as an inhibitor against n-6 fatty acid and its 
metabolites, and further decreases greatly the content of saturated fatty 
acids and cholesterol, which may cause various sequelae. Therefore, by 
utilizing the feed composition of the present invention, a high quality 
pork can be obtained. 
The detailed embodiment of the present invention is illustrated in the 
following examples. However, it should be understood that the scope of the 
present invention is not limited to the matters described in these 
examples in any way. 
EXAMPLE 1 
Preparation of n-3 fatty acid-enriched feed composition for pig 
______________________________________ 
Components Ratio (wt. %) 
______________________________________ 
n-3 fatty acid 
.smallcircle. Linseed 
76.0 
source .smallcircle. Perilla seed 
2.0 
.smallcircle. Fish meal 
4.0 
Carbohydrate .smallcircle. Wheat 
13.0 
source .smallcircle. Barley 
2.0 
Agent for decreasing 
.smallcircle. Oats 
0.3 
cholesterol 
Antioxidant .smallcircle. Santoquin 
0.1 
Others .smallcircle. Salt 
0.3 
.smallcircle. Limestone 
1.0 
.smallcircle. Dicalcium phosphate 
1.0 
.smallcircle. Vitamin mixture 
0.2 
.smallcircle. Mineral mixture 
0.1 
Total 100.0% 
______________________________________ 
All components as mentioned above are blended uniformly in the given ratios 
to prepare the pig feed composition of the present invention. 
Experiment 1: Comparative test for growth rate (weight gaining rate) 
utilizing the pig feed composition of the present invention 
34 pigs (species: LY (Landsace-Yorkshire) hybrid) are divided into three 
groups. The first and second groups are fed with two kinds of commercially 
available feedstuff for pigs, and the third group is fed with the feed 
composition as prepared in Example 1. In all three groups, pigs are given 
freely the feed compositions for 10 days after a 10 day adjustment period 
and then the weight gains are determined. The results are given in Table 
3. 
TABLE 3 
__________________________________________________________________________ 
Pig growth rate (10 days feeding) with commercial 
feed compositions (control groups) and the feed 
composition of the present invention (test group) 
First Group Second Group 
Third Group 
(Commercial feed A) 
(Commercial feed B) 
(Feed of Example 1) 
Weight (kg) 
Weight 
Weight (kg) 
Weight 
Weight (kg) 
Weight 
Before 
After 
gain 
Before 
After 
gain 
Before 
After 
gain 
feeding 
feeding 
(kg) 
feeding 
feeding 
(kg) 
feeding 
feeding 
(kg) 
__________________________________________________________________________ 
53 64 11 63 75 12 46 58 12 
50 63 13 45 59 14 57 71 14 
51 62 11 57 70 13 52 64 12 
60 72 12 71 86 15 52 66 14 
61 74 13 59 67 8 62 68 6 
59 71 12 57 66 9 55 68 13 
50 62 12 59 69 10 60 72 12 
51 66 15 55 66 11 50 61 11 
45 52 7 49 60 11 51 64 13 
55 66 11 47 60 13 56 70 14 
61 73 23 69 82 13 
64 78 14 55 66 11 
55.0 
66.9 
11.9 
57.1 
68.8 
11.7 
54.1 
66.2 12.1 
__________________________________________________________________________ 
In this test, feeds A and B used for comparison are the most frequently 
used two products among various commercially available feed compositions. 
From the results given in Table 3, it can be seen that the average weight 
gain is 11.9 kg in the first group, 11.7 kg in the second group and 12.1 
kg in the third group. That is, there is no difference in weight gain 
among three groups. 
Experiment 2: Comparative test for lipid content in each organ of pig fed 
with the commercial feeds and the feed composition of the present 
invention 
Pigs fed in the above Experiment 1 are slaughtered and then divided into 
halves. Thereafter, meat between the 11th and 13th ribs, abdominal 
subcutaneous fat, seam fat in the shoulder, liver, heart and kidney are 
isolated and the total lipid content in each portion is determined. As a 
result, the total lipid content in each organ, except for subcutaneous fat 
and seam fat which are, on the whole, composed only of lipid, is shown in 
Table 4. 
TABLE 4 
__________________________________________________________________________ 
Total lipid content (mg/g of tissue) in each organ of pigs of the first 
and 
second groups (commercial feeds A and B, respectively) and the third 
group 
(feed composition of Example 1) 
Meat Liver Heart Kidney 
First Second 
Third 
First 
Second 
Third 
First 
Second 
Third 
First 
Second 
Third 
Group Group 
Group 
Group 
Group 
Group 
Group 
Group 
Group 
Group 
Group 
Group 
__________________________________________________________________________ 
Total 
32.91 
34.59 
24.96 
53.43 
52.71 
40.55 
38.84 
46.04 
26.53 
34.82 
39.66 
27.09 
lipid 
Average Average Average Average 
content 
33.75 53.07 42.44 37.24 
(mg/g of 
tissue) 
__________________________________________________________________________ 
Note: 
All the numerical values mean the average value in each group. 
As shown in Table 4, the total lipid contents in meat, liver, heart and 
kidney of pigs belonging to the third group are decreased by 26.0%, 23.6%, 
37.5% and 27.3%, respectively, as compared with those in the first and 
second groups fed with the commercial feed compositions. Accordingly, it 
is seen that the feed composition of the present invention has an effect 
on the prevention of excessive fat accumulation in all organs including 
meat and also is effective for increase of the relative proportion of meat 
to fat tissue. 
Experiment 3: Comparative test for fatty acid composition in each organ of 
pigs fed with commercial feed compositions and the feed composition of the 
present invention 
The fatty acid composition in total fat extracted from each organ isolated 
in Experiment 2 is analyzed. As a result of this analysis, the contents of 
n-6 fatty acid and n-3 fatty acid are given in Table 5. 
TABLE 5 
__________________________________________________________________________ 
Fatty composition (n-6/n-3 fatty acid ratio) in 
each organ of pigs fed with commercial feed 
compositions (the first and second groups) and the 
feed composition of the present invention (the 
(third group) 
First Second 
Third 
First 
Second 
Third 
First 
Second 
Third 
Group Group 
Group 
Group 
Group 
Group 
Group 
Group 
Group 
__________________________________________________________________________ 
Meat Subcutaneous fat 
Seam fat 
Fatty 
13.6 2.1 14.7 2.6 14.2 2.5 
acid 
ratio 
(n-6/n-3) 
Liver Heart Kidney 
Fatty 
22.7 1.0 21.0 1.9 21.4 1.8 
acid 
ratio 
(n-6/n-3) 
__________________________________________________________________________ 
Wherein all the numerical values mean the average value in each group. 
As shown from the n-6/n-3 fatty acid ratios given in Table 5, in the first 
and second groups as control groups fed with the commercial feed 
compositions, the proportion of n-6 fatty acid is significantly greater 
than that of n-3 fatty acid. However, in the n-6/n-3 fatty acid ratio in 
each organ of the third group, pigs fed with the feed composition of the 
present invention, the proportion of n-3 fatty acid is rapidly increased. 
Pork produced from pigs fed with the feed composition of the present 
invention has a small content of n-6 fatty acid but is rich is n-3 fatty 
acid. Therefore, by intake of such pork, various physiological disorders 
due to n-6 fatty acid can be prevented, n-3 fatty acid is accumulated in 
the body to inhibit the metabolism of n-6 fatty acid and therefore, and 
any sequela caused by excessive n-6 fatty acid intake can be treated. 
Since the n-6 fatty acid/n-3 fatty acid ratio decreases, the physiological 
balance of the human body can be maintained. 
Therefore, it is understood that pork contains excessive saturated fatty 
acids and n-6 fatty acid. Accordingly, when many people ingest pork, they 
generally remove the fatty layer of pork. Pork produced from pigs fed with 
the feed composition of the present invention does not require one to 
remove the fatty layer and further, the intake of such pork can provide a 
balance of fat for human metabolism. 
The invention being thus described, it will be obvious that the same may be 
varied in many ways. Such variations are not to be regarded as a departure 
from the spirit and scope of the invention, and all such modifications as 
would be obvious to one skilled in the art are intended to be included in 
the scope of the following claims.