::AMINO ACIDS REQUIREMENTS
FOR HOGS ::
Shifting emphasis from protein
requirement to amino acids requirement in research
Concerning pigs and chickens, much more emphasis
now is being placed on not the protein need but
rather daily amino acids intake. Such transition
should not come as too much of a surprise considering
the fact that protein needs to be transformed into
amino acids prior to absorption by the body.
There are two fundamental categorizations of amino
acids; one cannot be synthesized by the body, the
essential amino acids, and therefore has to rely
on feeds, while the other can be synthesized by
the body, hence the non-essential amino acids.
In general, non-essential amino acids in animal
feed cannot be transformed into restrictive amino
acids. Pig feed usually lacks in threonine, tryptophan,
lysine, and sulfuric amino acid. Among these, lysine
can be transformed into restrictive amino acids.
Essential amino acid can now be crystallized in
large quantity and is used as feed additive in Japan.
Since the use of crystalline amino acids has become
a reality and managed to reduce the cost of pork
production, inquiring the optimal quantity and theoretical
basis are therefore necessary.
::Ideal amino acids::
Protein is made up of about 20 amino acids and 10
of them are vital to pigs. These 10 amino acids
are referred to as ideal protein. ARC published
their molecular structures in 1981.
Ideal protein is set as the basis for comparison
when examining the protein score of stock feed.
Through calculating the protein score, the restrictive
amino acid could be known. For ordinary stock feed,
the amino acid usually means lysine. As such, much
attention is paid to the required amount of lysine
when researching livestock’s need for amino
acid.
::Representation of amino acid
requirement and variables::
Normally the content of the feed will display the
daily intake of amino acid, however various variables
stand to determine the actual need for amino acid.
For instance, the higher the feed energy, the further
the need for amino acids. In order to preserve body
temperature during wintry seasons, more energy is
required and the need for amino acid is relatively
lesser. In addition, other growth factors ?gender,
specie, feeding method, and much more will determine
the need for amino acid too. Growth rate is accelerated
if greater amount of amino acid is administrated
to livestock.
At present, the required amounts of amino acids
are expressed in term of its totality. However,
differences in the ingredient of stock feed will
affect the digestion of amino acid. As such, the
rate of digestion inevitably has an effect on the
total amino acids requirements.
When experimenting with various levels of amino
acids to determine the optimal amount, best is if
such is carried out using ordinary feed as the base.
Any change to the representation of amino acid requirement
is best avoided even in the presence of variables.
::LYSINE REQUIREMENTS FOR HOGS::
Lysine in livestock feed
This is based on research findings of the author
on lysine requirements of hogs throughout their
growth stages, and data collected by PhD. Yen Hong
Da and foreign scientists over the past ten years.
Lysine requirements vary as growth stage progresses.
By that it means the daily lysine need decreases
as growth stage progresses. Pigs?gender too has
effect on the daily lysine need. Sows require more
lysine throughout their life span.
Weight gain and Lysine
Regardless of growth stages, an average of 20g of
lysine is needed for every 1kg gain in live weight.
The table suggests that the relationship between
lysine amounts and weight gain is quite similar
for both genders. At any growth stage, for every
gain of 1kg, lysine usage remains constant. From
this we could assume that the proportion of body
weight and protein level is kept level throughout
the entire growth stage.
Threonine, Methionine, Tryptophan,
Isoleucine, and valine
Having determined the optimal quantity of lysine,
the author proceeded to hypothesize the requirement
for other types of essential amino acids. The balance
of amino acids relative to lysine is presented in
the table 1.
| Table one ?Balance of amino
acids relative to lysine |
| |
NRC* (1988) |
ARC (1981) |
Yen (1979) |
Kaji & Furuya (1987) |
Wang & Fuller (1989) |
| Lysine |
100 |
100 |
100 |
100 |
100 |
| Met+Cys |
55 |
50 |
50 |
<55 |
60 |
| Threonine |
64 |
60 |
57 |
55~66 |
66 |
| Tryptophan |
16 |
15 |
20 |
12~17 |
18 |
| Isoleucine |
61 |
55 |
55 |
<58 |
60 |
| Valine |
64 |
70 |
70 |
<72 |
75 |
| *20~50Kg |
|
|
|
|
|
Using lysine as the basis
for formulating stock feed
Compare to feeding instructions of the past, current
method of tying per kilogram weight gain to lysine
usage is less susceptible to variables. However
the actual mixing of feed ought to put into consideration
the amount of lysine needs to be added to the feed.
First formulation of feed has to be based on the
actual operation of respective pig farm and expected
weight gain. Next, determine the daily quantity
or nutritional requirement based on the energy content
of standard feed. Since it is possible to calculate
the daily lysine requirements from projected weight
gain, dividing the weight of the feed with per day
lysine requirement could determine the relative
amount of lysine in the feed. Relative amount of
all other amino acids could be derived with the
same approach.
LYSINE REQUIREMENTS FOR SOWS
Gestation
Changes in protein mass during gestation
According to J. Noblet’s report the protein
mass in the uterus (including fetus, placenta, etc)
and mammary gland at day 50 of gestation is 14 grams
and surges to 64 grams at day 110. As such, it is
right to assume that the amount of lysine needed
varies drastically as gestation progresses.
Lysine requirements for gestating
sows
The author has managed to determine the lysine requirements
for primiparous sows during mid gestation (50-65
days after inception) and late gestation (90-105
days after inception) with plasma free lysine as
the response criterion. Per day lysine requirements
during mid and late gestations are 6.3 and 10.8
grams respectively. With regard to amino acids requirements
for gestating sows, most feeds have only one set
of recommended amounts for the entire gestation.
Now according to the latest standard of lysine requirements
estimated by the author, different amounts of lysine
are required as gestation progresses. Lysine requirements
during mid and late gestation are presented in table
two.
Table Two - Lysine requirements for gilts during
pregnancy and for sows during lactation estimated
with plasma free lysine as the response criterion
in our study and recommended in Japanese Feeding
Standard for Swine (JFSS). NRC and ARC
| |
Daily requirement
(g) |
Percentage of
diet |
| |
Pregnancy |
Lactatio |
Pregnancy |
Lactation |
| |
Mid(1) |
Late(1) |
Whole |
Mid(2) |
Whole |
Mid(1) |
Late(1) |
Whole |
Mid(2) |
Whole |
| Present |
|
|
|
|
|
|
|
|
|
|
| Study |
6.3 |
10.8 |
|
47.9 |
|
0.30 |
0.51 |
|
0.85 |
|
| JFSS |
|
|
8.8 |
|
35.7 |
|
|
0.42 |
|
0.63 |
| NRC |
|
|
8.2 |
|
31.8 |
|
|
0.43 |
|
0.60 |
| ARC |
|
|
8.6 |
|
33.0 |
|
|
0.43 |
|
0.63 |
(1)Mid; from day 50 to day 65, late; from day 90
to day 105 of pregnancy.
(2)Mid; from day 12 to day 21 of lactation.
For the calculation of lysine requirements expressed
as percentage of diet in the present study, daily
feed intakes of sows during pregnancy and lactation
were based on the recommendations of JFSS, 2.1 and
5.65Kg, respectively.
From a sample of sows, the rates at which protein
mass increases during mid and late gestation, based
on J. Noblet’s formula, are 16.6 and 56.4 grams
per day respectively. In addition, according to
V. C. Speer’s calculation, the per day lysine
requirements during mid and late gestation are 1.8
and 5.9 grams respectively. With the findings above,
the differences in lysine requirements for various
stages of gestation strongly suggest that the lysine
requirements for fetus will differ as gestation
progresses.
Lactation
Factors affecting lactation
Factors affecting lactation are number of gestation,
stage of lactation, and size of litter. Primiparous
sows usually have weaker mammary secretory capability.
Post farrowing sows will yield the most milk at
3rd and 4th weeks. The bigger the size of litter,
the more milk a sow will produce.
Lysine requirements for lactating
sows
The lysine requirements of lactating sows are closely
correlated with the production of sow's milk. Hence,
if the sows are not producing enough milk, such
might very well be the result of inadequate lysine
intake.
Using plasma free lysine as the response criterion,
the author has estimated the lysine requirements
of lactating sows (12 - 20 days after farrowing)
to be 47.9 grams. Lysine requirements for the entire
lactating period could be derived with physiological
development of piglets as the experimenting criterion.
However, readings generated from 1st and 2nd weeks
after farrowing, during which mammary secretory
capability is at its weakest, will be lower than
that of peak secretion. Similar experiment carried
out by M. A. Sohail estimated that lysine requirement
of lactating sows to be 38.4 grams. Such discrepancy
might be the result of having fewer piglets in the
test sample, six to be exact. R. Wilkinson did the
same test with a litter size similar to that of
the author and concluded that lysine requirements
to be 49.9 grams, which is almost identical to the
author finding.
Future Research Emphasis
Digestion of amino acids
Digestion of amino acids could be assorted as either
surface or true digestion. Furuya pointed out that
current means of determining surface digestive amino
acids are questionable.
Nonetheless, formulation of applicable feed based
on truly digestible amino acids alone needs further
research.
Wang De Zhong and M. F. Fuller have released a report
on composition of ideal amino acids that is based
on digestible amino acids.
Accumulation of amino acids
Of all the amino acids absorbed by the sows, E.
S. Batterham pointed out in his report that 0.86
of digestible amino acids intake is accumulated.
Loss of amino acids due to physiological factors
is 0.94 gram per day. Factors affecting amino acids
accumulation will be emphasized in the laboratory.
Theoretical Method
Basically this method of estimating amino acid requirements
is expressed in the form of [requirements to sustain
+ requirements to produce]. Precise calculation
of amino acids requirements demands a firm grasp
of factors affecting production relative to composition
of amino acids.
(Source: Lin Bros Co. Ltd.)
Feed Nutrition Magazine (66 ?71) - Issue no. 4,
1991.
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