Nutrition Vol. 2 • No. 1 • 2003
Technical Update
Grow - Finish Nutrition Concepts: Impact of
Nutrition on Lean Growth
Introduction
The pig industry must continue to improve the efficiency
and quality of meat production in order to sustain a
competitive position on the global market. Efficient production
requires a genetic package that delivers:
• a high output of weaned pigs (24-28 pigs/sow/year),
• that can grow rapidly (1.80-1.95 lbs/d) and efficiently under
commercial conditions;
• they must have a high lean percentage and desirable meat quality
and the production system must manage sub-clinical disease since
health normally is the first limit to the expression of genetic
potential for growth.
The choice of genetics is important since it sets the 'ceiling' for
growth performance and meat quality. However, inadequate management
of the environment (health, temperature) and nutrition will lower the operational ceiling.
Development of the optimum nutrition program requires an understanding of commercially
achievable rates and efficiency of gain, percent carcass lean and carcass yield. Each are
influenced by nutrition.
The balance that must be achieved between nutrient input and performance output to optimize
profit varies with the payment system. There are no short cuts to finding the proper balance.
The best estimate for the Lysine:Energy ratio must be selected and then challenged through onfarm test. The purpose of PIC USA Nutrition guidelines is to provide a starting point for nutrient
levels that support expected performance under good commercial conditions. Data are also
provided to illustrate how the growth response varies with nutrient level.
This Update discusses the impact of Nutrition on lean growth. Nutrient specifications for the
grow- finish phase are presented in a companion Update (Vol. 2 No. 2). Nutritional Guidelines
for all phases of production are presented in a single guide (Vol. 1 No. 1).
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Item
Growth rate, lbs/day c
Feed: Gain c
Lean growth, lbs/day c
Feed:Lean Gain
FOM backfat, in.
Lean %
Table 1. Expected Performance Levels
for Progeny of PIC 300 Series Sires
Commercial Potential a
Suggested Targets b
1.95 (.89kg)
1.82 (.83)
2.70
2.75
0.95 (.43kg)
0.89 (.40)
5.40
5.75
0.75 (19mm)
0.80 (20.3)
54
53
a
From PIC USA Oklahoma multi-site system (5000 head/site) weight range, 60-260 lbs (27-118kg),
Mixed sex.
b
Based on data for 2 midwest producers (over 100,000 head).
c
Corn-soybean meal diets with 1% added fat.
Performance Targets
Growth rate (ADG) and feed conversion (FCR) have the greatest impact on profitability after
market price. FCR is primarily driven by percent carcass lean (or body fat to lean ratio) and
determines the diet Lysine:Energy ratio. Realistic performance levels are provided in Table 1 for
progeny of PIC terminal sire products (327,337,356) mated to Camborough® 22 sows. ADG
and FCR data represent achievements when sub-clinical disease was properly managed and when
reared under conditions of thermo-neutral temperature with adequate nutrition. Appendix Table
1 shows how environment and animal variables impact performance. The PIC Growth model
allows for more dynamic estimates.
Progeny of the three PIC 300 series sires have similar ADG and FCR. Nutrient specifications
are the same since the composition of daily gain is virtually identical. Meat quality and carcass
yield differ slightly among their progeny and forms the basis for market-based choices. PIC 427
sires are available for certain niche markets. Their progeny are inferior to PIC 300 series progeny
in ADG, FCR and meat quality. However, PIC 427 progeny excel in carcass yield and lean
content.
The biological capacity for growth is determined by genotype, sex and body weight. However,
the degree to which this can be expressed is dependent on external factors such as immune stress,
thermal stress and nutrition. The biggest constraints to the expression of genetic potential for
ADG are heat and disease. Each can be devastating to ADG and should be investigated prior to
any consideration of a suspected nutritional limit to growth. FCR is the most sensitive measure
to monitor when comparing Nutrient levels.
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Figure 1
Lean Tissue Growth Curves For Genetically
Improved and Unimproved Pigs
Lean Gain, lbs/day
1.2
1
0.8
Improved
0.6
Unimproved
0.4
0.2
0
60
100
140
180
220
245
280
Body Weight, lbs.
Principles of Growth
Lean Growth Patterns. The rate of lean tissue growth increases during early growth and
eventually reaches a plateau. The point at which this plateau is achieved depends on the
genotype and sex. In early maturing or unimproved pigs, maximum lean deposition may be
achieved at smaller bodyweights and (or) decline sooner than later maturing improved pigs (See
Figure 1).
Once maximum lean deposition is achieved, it inevitably declines while fat
deposition holds constant or increases. The rate of decline in lean deposition depends on the
genetic line (under thermo-neutral conditions). Maximum lean growth may also be greater for
improved pigs than for unimproved pigs (Krick and co-workers, 1992) and also differs with sex.
Boars have the highest potential for lean tissue growth with gilts being intermediate and castrates
having the lowest potential (see Boyd and Beerman, 1992). The ratio of body protein:fat is
greater for improved pigs (as compared to unimproved pig), which accounts for the improved
FCR and higher dietary Lysine:Energy need. Improved pigs require a more expensive die t but
the cost of gain is lower than unimproved pigs because it contains more water.
Immune Stress and Growth. Research with segregated early weaning shows that sub-clinical
disease can de-rail genetic advances in ADG. PIC pioneered methods to manage sub-clinical
disease by segregating young pigs from sows and then systematized site segregated rearing as a
first step toward managing serial disease challenge for nursery and finish phases. This procedure
allows producers to minimize exposure to chronic and acute disease so that they capture more of
the genetic potential for growth. Therefore, achieving 1.80-1.95 lbs/day ADG (800-900 g/d) is
commercially possible but it requires managing rather than treating disease (Table 1).
The adverse effect of immune system stress on ADG and FCR was illustrated by PIC USA
research (see Figure 2). High lean growth pigs were injected weekly with increasing levels of E.
Coli endotoxin called lipopolysaccharide, LPS (PIC USA Exp. 9817). The challenge adversely
affected both ADG and FCR. The mechanism by which a sub-clinical disease challenge disrupts
growth is unclear. The effect may be to depress appetite directly. It may also involve depression
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in the level of a key growth factor (IGF-1) for muscle growth. We have achieved closeout ADG
in sites of 5000 pigs of 1.95-2.05 lbs/day (900-925 g/d) when sub-clinical disease was controlled
through multi-site production. Failure to achieve the high rates of ADG generally means that
immune stress exists to some degree, provided that thermal stress is not present. Compensating
for depressed appetite through increased Nutrient input (Energy or Amino acid density) is not an
effective means of overcoming the effects of immune stress because appetite is simply a
reflection of the willingness of tissues to grow.
Nutrition and Lean Growth. Inadequate dietary Nutrient concentration will compromise ADG,
FCR and percent carcass Lean. The impact of Nutrient input on lean growth is illustrated in
detail below.
Diet and Lean Growth
Pigs require a proper supply of nutrients to meet the demands for maintenance and tissue growth.
The key nutrients for lean growth are energy, amino acids, phosphorus and B-vitamins. Energy
is first limiting to growth.
Dietary Energy. Feed energy is used for maintenance and then for protein and obligatory fat
deposition. Energy supplied above the need for protein deposition will be deposited as fat and
result in an increase in ADG and depression in FCR (see Figure 3, top frame, point B). In early
growth (to about 160 lbs or 75 kg in PIC pigs), the potential for protein deposition is high and fat
deposition is low (point A). Energy intake is low because tissue needs are low. The result is an
impressive FCR. The dogma is that pigs cannot consume enough energy to maximize protein
deposition during this phase. We believe that this interpretation is erroneous and that pigs
weighing more than 40 lbs consume the amount of energy that is needed to support the tissue
drive for protein deposition. They are unwilling to deposit fat at the high levels characteristic of
later growth. Therefore, feeder management must allow for unrestricted feed access in order to
support the increasing rates of protein deposition that are characteristic of the early growth
phase. ADG during early growth can be rapid, very efficient and at relatively low cost ($/lb
gain) when compared to later growth. Inadvertent feed restriction impairs growth without
benefit to FCR during this phase.
During later growth (beyond 195 lb or 90 kg), the PIC pig consumes more than enough energy to
maximize protein deposition. Surplus energy is deposited as fat (see point B). This increase in
fat tissue growth rate occurs because fat cells are becoming more responsive to the hormone
insulin. Limiting energy during this phase by feeder restriction or with low energy density diets
may not compromise protein deposition rate but back fat depth will be slightly reduced. There
will also be a reduction in ADG, which must be considered in the cost-benefit ana lysis. FCR
will be impaired with a reduction in dietary energy density.
The source of dietary energy (fat vs carbohydrate) also influences the efficiency of gain. Pigs
fed diets with added fat convert feed to body weight gain more efficiently (FCR). Fat addition
appears to benefit ADG in nursery pigs to 40 lbs (18 kg) because of a physical limit to feed
consumption. Fat addition to diets of pigs beyond 40 lbs results in a slight improvement in
growth rate and FCR but the kcal ME/lb gain is similar (Tech. Report 48, 1997). It is not clear
whether the percent improvement in ADG and FCR with fat addition differs for early (50-150
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lbs) as compared to later growth (150-250 lbs) for PIC 300 series progeny. These relationships
are being determined under commercial conditions to aid in Energy optimization considerations.
An increase in dietary energy density beyond that typical of the Corn-Soy diet (e.g., from 1500
kcal NRC ME to 1570 Kcal) during the grow- finish period may lead to a slight increase in fat
depth (1.5-2.0 mm). This difference may be even greater if (1) the Lysine:ME ratio is not
maintained at required levels, or (2) if high levels of dietary fat are added (> 5-6%). The dietary
energy density (1450 - 1570 Kcal ME/lb) that optimizes profit depends on a number of factors
since ADG, FCR, lean %, carcass yield and $/lb of gain are all affected. These concepts are
discussed in a recent review by Usry and co-workers (1998).
Figure 2
Immunte Stress Modifies Growth and Feed
Efficiency in Growing Pigs
3.25
3.08
3.13
3.00
2.75
2.50
2.25
1.99
2.00
1.90
1.75
1.50
1.25
1.00
Control
LPS
Control LPS
ADG, lbs/d
F/g ratio
*LPS, Lipoplysaccharide - see
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Figure 3
Relationship Between Energy Intake and
Deposition of Body Protein and Fat
Gain of Fat and Muscle, g/day
1000
800
Fat
600
Muscle
400
200
0
A
B
Diet Energy Intake, Mcal/day
Low Feed Intake. PIC pigs are expected to have a lower feed intake (FI) than competitor
products because they deposit less fat and more water. Put another way, fat pigs require more
feed. The analysis should focus on whether ADG meets or exceeds target. The lower FI is
simply a reflection of improved FCR. If ADG is below expectations, the analysis should then
focus on what is limiting growth, which, inturn; determines the amount of FI needed.
Amino Acid Supply. Amino acid intake also influences ADG, composition of growth and
therefore FCR. An amino acid deficient diet reduces muscle growth rate and increased body fat
deposition results. Energy that is normally used to synthesize muscle is diverted to body fat.
The relationship between amino acid intake and performance is shown in Figure 4. Increasing
dietary lysine percentage from deficient to adequate levels also increased protein deposition and
decreased body fat with the result being improved ADG and FCR (data not shown).
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Figure 4. Relationship Between Amino Acid Intake and Performance of Growing Pigs
3.4
0.9
3.2
Efficiency of Gain (F/G)
Efficiency of Gain (F/G)
0.8
3
2.8
2.6
0.7
0.6
2.4
Krick et al. 1993
2.2
0.5
6.4
10.0
15.0
20.0
25.0
6.4
10
15
20
25
30
Dietary Lysine Intake, g/day
The effect of an amino acid deficiency on the response of experimental pigs (see Figure 4) tends
to be a little more pronounced than is typically observed under good commercial conditions
because the latter are more variable in weight and age. In other words, the response curve to
dietary Lysine has a lower slope for a commercial test compared to more controlled experiments.
In trials conducted under commercial conditions, a 15% deficit in dietary lysine percentage from
60-260 lbs. reduced ADG by about 0.05 lbs/day, FCR by 0.07 units and increased backfat depth
by 1 mm (Tech. Memos 160 and 183, 1997). In contrast, feeding diets that contained a 10-12%
excess of amino acids depressed ADG by 0.06 lbs/d, FCR by 0.06 units but no effect was
observed for fat and loin depth (Tech. Memos 183 and 204, 1997-8).
The adverse effect of excess amino acids on FCR is more pronounced with temperature stress
(Tech. Memo 183, Exp. No. 9611) since heat increment needs to be reduced rather than
increased. This reduction in tissue growth with oversupply of amino acids is due to the fact that
excess amino acids must be degraded and removed from the body. This is an energy requiring
process. The effect of amino acid oversupply under conditions of thermal neutrality and thermal
stress is shown in Figure 5. Note that FCR improved with each increment of Lysine until the
optimum FCR was achieved (i.e., maximum body protein:fat ratio). FCR began to erode after
the optimum Lysine percentage was achieved but was more pronounced under temperature
stress.
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Figure 5
Response to increasing dietary Lysine under
two Enviornmental temperatures
PIC USA Exp. 9611
4.4
Feed Conversion, F/G
4.2
4
Heat
3.8
3.6
3.4
Thermoneutral
3.2
3
0.4
0.5
0.6
0.7
0.8
0.9
Dietary Lysine, %
Amino Acid Balance. Dietary protein is required to supply the essential amino acids and
sufficient amino acid nitrogen for the pig to manufacture the so-called 'non-essential' amino
acids. Essential amino acids must be provided pre- formed in the diet. Protein deposition will be
decreased and ADG, FCR and lean percent will each be compromised if one or more of them are
deficient.
Amino Acid
Table 2. Ideal Balance of the most Limiting
Amino Acids
% of Lysine a
Lysine
Threonine
100
62
1.05
0.65
Methionine
27
0.28
Met + Cystine
57
0.60
Tryptophan
18
0.19
Isoleucine
55
0.58
a
Dietary % b
Pattern from PIC Nutrition Update 1.1.99 for 5-50 lb (2.3-23 kg).
Assumed female during 50-90 lb (23-44 kg) growth phase.
b
The balance of amino acids is said to be ideal when each essential amino acid and non-essential
amino acid nitrogen exactly meet the need for growth, lactation etc. This would not occur under
practical situations, however, the concept of an ideal balance for the most critical amino acids is
important to diet formulation. The minimum balance for the most limiting amino acids for G-F
pigs is shown in Table 2. Each amino acid is required in a specific ratio to lysine in order for
protein synthesis to occur. The practical benefit of having ideal amino acid patterns is that if the
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lysine requirement is known for the phase of growth, then minimum levels for other critical
amino acids can be specified. Amino acids supplied by dietary protein in excess of the ratio
shown will be degraded and the residual nitrogen excreted in urine.
Formulating diets to Lysine levels (% or g Lysine:Mcal ME) that exceed the minimum
requirement for optimum FCR and lean percent is expensive. The cost of over- fortification of
Lysine is even greater when one formulates to achieve a minimum level for the most limiting 3-4
amino acids since all of them would be over supplied. On- farm verification that Lysine levels
are at profit optimum will result in a percentage that is < 100% of the need for every pig.
Formulating to the minimum level of other amino acids using the ideal pattern will then be less
apt to be excessive and costly IF the ideal pattern is reliable. The pattern varies with phase of
growth and physiological state (growth vs lactation) and is presented in Vol 1 No. 1.
A deficiency of one or more amino acids in relation to lysine will depress performance even
though the intake of lysine and other amino acids is adequate. This concept is illustrated in
Figure 6. Less of a properly balanced protein is required to achieve the maximum response.
Formulating to the most limiting 4-5 amino acids generally assures that the need for all 10 amino
acids will be exceeded. A protein that is deficient in one or more amino acids will compromise
ADG unless a greater amount is consumed.
Table 3. Amino Acid Balance When Formulating Using the Thumbrule a
1.15% Lysine b
0.80% Lysine c
Amino Acid
Ideal Pattern
Corn-Soy
Milo Soy
Ideal Pattern
Corn-Soy
Lysine
100%
105%
104%
100%
100%
Methionine
27
28
27
27
31
Methionine +
57
57
52 d
60
65
Cystine
Threonine
62
65
64
65
65
Tryptophan
18
22
20
19
20
a
Thumbrule is 3 lbs synthetic Lysine per ton for corn-soybean diets. All diets were formulated using
3 lbs Lysine per ton.
b
Ideal pattern relative to Lysine for early (to 110 lbs) and late (>175 lbs) growth respectively.
c
Percent of the dietary amino acid relative to Lysine.
d
Box denotes a deficit.
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Figure 6. Performance Depends on
Proper Amino Acid Balance
Balanced
Lean Tissue Growth Rate
Unbalanced
Protein Intake, g/day
Table 4. Change in the Lysine to ME Ratio
in PIC females with Stage of Growth
Body weight, lbs.
Lysine:NRC:ME,a,b
g /Mcal ME
50-90
3.18
90-150
2.79
150-210
2.55
210-260
2.18
a
Total Lysine specified assuming a corn-soy diet. Digestible lysine assumed to be 83% of total.
Values derived from Nutrition Update 1-1-99.
b
Amino Acid Digestibility. The ability of dietary ingredients to meet minimum levels of each
amino acid differs with stage of growth and with the digestibility of amino acids contained by the
ingredient. This concept is discussed in greater detail in a Biokyowa report (Tech. Rev., 1991).
PIC guidelines for Lysine and other amino acids are presented on a total basis assuming that a
corn-soy diet is used. True Digestible Lysine needs are also presented for those using more
complex formulas. We prefer the use of True as compared to Apparently digestible estimates.
The ideal balance that one uses is the same when using Total and True digestible amino acid
levels but the balance is slightly different when Apparently digestible estimate are used (See Vol.
1 No. 1).
The amount of synthetic Lysine that is needed varies with stage of growth and complexity of diet
formulas (vs Corn-Soy). The historical 'thumb-rule' of 3 lbs of synthetic Lysine is applicable to
Corn-Soy diets under most situations. It doesn’t hold true for the more complex diets. During
early growth (1.15% Lysine), 3 lbs. of synthesized Lysine is too much unless methionine is also
used (Table 3). Addition of 3 lbs. Lysine to a milo-soy diet results in a deficit of total sulfur
amino acids (Met + Cystine). The Historical rule applies well to mid and later growth if fed
Corn-soy diets (See Table, 0.80%). More complex formulas involving alternative ingredients
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(e.g., wheat midds, canola and 2-3 synthetics may require 4-5 lbs. synthetic Lysine per ton of
diet, to achieve the proper balance of digestable amino acids.
Average Daily Gain lbs.
Figure 7. Effect of B-Vitamin Levels
on ADG and FCR of High Lean Pigs
Stahly et al., 1995
5-10 kg pigs
1.75
1.50
1.25
1.00
70
170
270
370
470
170
270
370
470
Feed/Gain ratio
1.75
1.5
1.25
1
70
Dietary B-Vitamins, % of NRC
Feeding lower protein, amino acid supplemented diets, is a means of reducing excess amino
acids and nitrogen pollution. This can be of practical significance for young nursery pigs where
protein load needs to be reduced and net energy increased. It may also be one of several
strategies used in hot environments to decrease metabolic heat production to minimize its
negative effects on FCR and ADG. For these reasons, the addition of 1-3 synthetic amino acids
has become routine. This procedure is also a means of keeping soybean meal use in formula's to
the maximum level without exceeding dietary protein maximums.
Integrating Energy and Amino Acids. Energy and amino acid nutrition cannot be considered in
isolation to one another. The supply of amino acids must be in proper balance to one another
and then in balance to dietary energy concentration. In general, a higher lean gain potential
requires a higher Lysine:Energy ratio. A higher Lysine:Energy ratio is required in the early
stages of growth when the body protein (or lean):fat ratio is high. The Lysine:Energy ratio can be
reduced as the pig grows because of a declining protein to fat ratio in the daily gain. This is
shown in Table 4. If the Lysine:Energy ratio is deficient for the stage of growth, then the rate of
protein deposition will be reduced and body protein:fat ratio will be below genetic potential.
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Surplus energy will be available for added fat deposition, which will occur at all stages of
growth. FCR will be hurt.
When dietary energy concentration is increased beyond typical corn-soy levels through fat
addition, the Lysine % needs to be increased in order to maintain the specified Lysine:ME need.
Specifications in Table 4 can be used to set dietary Lysine levels when diet ME levels vary. For
example, a 50-90 lb pig (23 - 41 kg) requires 1.05% total lysine when a 1500 Kcal/lb diet (3300
Kcal/kg) is fed. However, if the addition of fat results in a diet with 1580 KcalME/lb (3475
Kcal/kg), then 1.10% lysine is needed in order to maintain the specified 3.18 Lysine:ME ratio.
Phosphorus. The requirement for available phosphorus and B-Vitamins also depends on the
capacity for protein deposition and the FCR achieved. Feeding deficient levels of dietary
phosphorus depressed ADG and FCR (ISU Research Report, 1995a). A progressive increase in
phosphorus need was required with increased lean growth capacity.
PIC recommendations for available phosphorus attempt to balance dietary needs for lean content
against cost and environmental concerns.
Additional considerations for recommended
phosphorus levels include: (1) correction for the genetic advances in FCR over the past 6 years
with an allowance for the (2) extraordinary force of muscle contraction that is produced with
commercial "stunning" at slaughter. This requires a stronger bone than normally needed for the
better-controlled conditions of University Meat Labs. We discourage elimination of either Ca-P
supplements during part or all of the final phase of growth. Our recommendations show a
marked reduction in Total or Available Phosphorus during the final 50 lbs (23 kg) of growth.
B-Vitamins. The importance of adequate B-vitamin supplementation was also emphasized in
Iowa State research (ISU Research Report, 1995b). Growth rate and FCR were improved with
each increment of B-vitamins addition to 5 times NRC-1988 for nursery pigs having high lean
growth capacity (see Figure 7). Three times the NRC concentration was needed for moderate
lean-growth rate pigs (data not shown). This result has been shown for pigs up to at least 60 lbs
body weight. Vitamin need may also be greater with increased stress (Coelho and Cousins,
1997) but practical recommendations are not possible given present research.
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Profit Optimization Lysine Levels
Establishing the optimum nutritional program requires 'standing' the economic cost of dietary
inputs against performance output and lean payment. Making decisions based on cost per ton of
diet alone is misleading. The correct procedure is to (1) determine the Lysine level that
optimizes profit and then, (2) to work toward reduced diet cost per ton within those
specifications. Use of alt ernative ingredients, where possible, and making certain that the proper
amount of diet is fed within each phase (feed budget) are important but often missed
considerations.
FIGURE 8. Performance Response and
Dietary Nutrient Concentration
(+)
Performance Level
Maximum
Profit
Maximum
Response
Dietary Lysine Percent
(-)
Genetically lean pigs consume less feed but require a higher concentration of nutrients in order
to maintain constant nutrient intake per unit of lean tissue. The good news is that this allows
each pound of gain to contain more water. Therefore, the diet cost ($/ton) is greater for high lean
growth pigs, but the nutritional cost per unit of gain is less under most circumstances. The same
is true for Nursery pigs. Nursery diets are significantly more expensive, but the improved FCR
generally leads to a lower cost of gain when compared to pigs during the Finish phase.
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Table 5. Profit Optimization under Commercial Conditions: Economic Comparison,
using performance responses to 4 Lysine Curves (gender combined)
Lysine
Diet Cost a
ADG
FCR
Feed Cost b
Housing c
Total
%
$/ton
lbs/d
lbs/d
$/200 lbs
$/pig
$/pig
0.85-0.60
134.99
1.66
2.70
$36.45
14.46(+4d)
50.91
0.95-0.70
138.58
1.68
2.66
36.87
14.34(+3d)
51.21
1.10-0.85
144.25
1.72
2.63
37.85
13.99(+0d)
51.84
1.25-1.00
150.25
1.70
2.66
39.88
14.16(+1d)
54.04
Total Feed and Housing Cost Adjusted for Carcass Discounts.
Carcass Value, $/cwt d
FOM BF
FOM Lean
FOM Mus
Adjusted c
Mm
%
mm
Plant A
Plant B
Cost, $/pig
22.2
52.1
56.0
-1.00
0
52.84
21.5
52.6
57.2
-1.00
0
53.14
20.6
53.1
57.1
0
0
51.84
20.8
53.0
56.4
0
0
54.04
a
Weighted diet cost across 4 phases of growth.
Assumes 200 lbs of gain.
c
Assumes 12¢/pig/day.
d
Actual Plants, December 1997 payment. Plant A premium for 1.10-0.85% lysine curve is $3.50 cwt
carcass. Plant B premium is $2.76 cwt. Carcass yield assumed constant at 75%
e
Adjusted cost is ‘total’ production cost ($/pig) corrected for Swift carcass value as follows: (Feed cost and
Housing cost) - carcass value.
b
The optimum nutritional program is often, but not always, one that economically supplies the
nutrients needed to express the pig's capacity for lean tissue growth. The difficulty is choosing
the proper level for a population of pigs that vary widely in lean composition. A typical response
curve is shown in Figure 8 for dietary Lysine:ME (conceptual model). Formulating to achieve
the maximum group response means overfeeding most of the pigs to provide the higher levels
needed by a few. This is generally not cost effective. Meeting the needs for 85-92% is generally
closer to maximum profit when diet cost is compared to performance (ADG, FCR, lean %). The
data in Table 5 illustrates an important point relative to optimizing profit. The most costeffective curve for a lean payment program was the 1.10% Lysine curve (4 phases beginning
with 1.10% and ending with 0.85% lysine). Better ADG and FCR partially covered increased
diet cost but carcass benefits were needed to result in greatest profit (shown as reduced "net feed
cost"). Feeding to the highest lysine level (1.25% Lysine curve) resulted in greater feed cost
without further benefit to ADG, FCR or carcass lean. On the other hand, the best program for a
live weight basis (0.95% Lysine curve) was about 13-15% below the curve that optimized lean.
Even though some decline in ADG and FCR resulted, total feed plus housing cost was lower
than the 1.10% Lysine curve. Therefore, the correct curve depends on farm specific costs in
relation to performance trade-offs and the packer lean payment program. Data from Table 5
could be used to develop a simple spreadsheet to estimate profit optimization under different
market conditions.
PIC Nutrient Specifications
PIC nutrient specifications are suggested levels based on our experience for optimum profit
performance. They are presented in brief form in PIC USA Nutrient Specifications (Vol. 1. No.
1) and are presented in greater detail in the companion to this Update in this Grow-Finish series.
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(Vol. 2 No. 2). On- farm verification will continue to be a must in validating the optimum
program for the packer payment matrix. This will require the ability to feed 2 different diet
programs to challenge the current one. A simple method would be to use the same diets but to
change the weights over which they are fed to a challenge group (by 30-40 lbs). Pigs must be in
the same barn and under identical management.
SUMMARY
Key Nutritional Concepts for Lean Optimization
1. Maximum lean gain is dependent upon proper Nutrition.
2. Key Nutrients for lean growth:
• Energy
• Phosphorus
• Amino acids • B Vitamins
3. Limiting Energy intake during early growth compromises rapid lean growth.
4. Limiting Energy intake during late growth may improve lean percent but growth rate
(ADG) and feed efficiency (FCR) will deteriorate.
5. Insufficient Amino Acid intake will compromise ADG, FCR and Lean.
6. Amino acid balance is critical. Deficiency of a single Essential Amino Acid limits lean
deposition to the level of that Amino Acid.
7. Dietary Lysine and Energy must also be in proper balance.
• The Lysine:ME ratio declines as the pig grows.
• % Lysine must increase with fat addition to maintain Lysine:ME ratio.
8. Phosphorus and B-Vitamin needs increase with Lean growth capacity.
9. Vitamin needs may be greater during stress.
10. Water is the Central Nutrient. Flow rate, availability and quality are critical.
Bottom- line: High lean PIC pigs require more expensive diets ($/ton), but the improved
FCR reduces cost of gain
($/lb gain). Lean payment further improves profit potential.
PIC Technical Update
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Appendix Table 1. Impact of Animal and Environmental
Variables on Growth and Carcass Lean
Variable
Daily
Feed: Gaina
Backfatb
Lean
Gain
Market Weight:
(lbs/d)
(F/G)
(mm)
%
Increase from 240 to
Below .06 Below .04
Below 0.5
Below 0.2
280 lbs
(cumulative change
per 10 lbs)
Avg. from 60-240
Above .02 Below .16
Below 2.0
Above 0.8
vs. 60-280 lbs
Gender
Below .11 Below .07
Below 3.0
Above 2.4
Gilt vs. Castrate
Sire Line
NC
NC
Above .75
Below 0.5
PIC 337 vs. PIC 327
Diet Lysine: ME
Below .05 Above .07
Below 1.0
Below 0.8
15% below max lean
15% above max lean Below .07 Above .07
NC
NC
Thermal Stressc
Below .35 Above .05
Above 1.4
Above 0.7
15°F above UCT 16 hr
a
Mortality adversely affects F/G by +.035 for each 1% change. Floor space adversely
affects gain by -.06 and F/G by +.05 per square ft2 decrease in the 8.8 to 5.3 ft 2 range
during GF phase.
b
Location difference: P2 vs 10th rib (P2 -2.9 mm), 10th vs. last rib (10th , -1.4 mm).
c
PIC USA Exp. 9611 (210-260 lb phase of growth).
References
Biokyowa Technical Review No. 2. 1991. Digestible amino acids and digestible ammo acid
requirements for swine,
Bertram, M.J., T.S. Stahly, and R.C. Ewan. 1995a. The impact of dietary phosphorus regimen on
muscle quality in pigs of high and moderate lean growth genotypes. ISU Swine Research Report,
ASL-R1262.
Stahly, T.S., N. Williams, S.G. Swenson, and R.C. Ewan. 1995b. Dietary B vitamin needs of
high and moderate lean growth pigs fed from 20 to 62 pounds body weight. ISU Swine Research
Report, ASL-R1263.
Krick, B.J., R.D. Boyd, and co-workers. Influence of genotype and sex on the response of
growing pigs to recombinant porcine sonatotropin J.Anim. sci.70:3024.
Krick, B.J., R.D. Boyd, and co-workers, 1993. Somatotropin affects the dietary lysine
requirement and net lysine utilization for growing pigs. J. Nutr. 123:1913.
PIC Technical Update
Better solutions for better pork.™
J. Usry, R. G. Campbell and D. Burnham. Optimizing energy formulation for finishing swine.
1997. Proc. Carolina Swine Nutrition Conf., Raleigh, NC.
Boyd, R.D. and D.H. Beerman 1992.
Swine, 7th ed. Iowa State Univ.
Manipulation of Body Compostition. In Diseases of
PIC USA Tech. Memo 160. 1997. Comparison of two dietary lysine standards for growing PIC
pigs: PIC USA vs U. Illinois.
PIC USA Tech. Memo 183. 1997. Dietary lysine curve that optimizes lean growth and profit for
PIC427 progeny.
PIC USA Exp. 9611 Lysine dose respons e curves for 210-260 lb PIC pigs reared in a hot vs
thermo- neutral environment.
PIC USA Nutrition Tech. Update. Vol. 1 No. 1. 1999.
PIC USA Tech. Report 48. 1997. Comparison of two energy strategies for growth.
PIC USA Exp. 9817. 1998, Immune System challenge of growing pigs.
Coelho, M.B. and B. Cousins 1997. Vitamin supplementation supports higher performance.
Feedstuffs, Jan 27. 1997,
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