Environmental Nutrition to
Reduce Nutrient Excretion and
Air Emissions
Nutrient excretion
Nutrients excreted =
Nutrient ingested - Nutrients digested
Therefore, excretions represent an inefficiency
10-2
Nutrient excretion dependent on:
• Quantity of endogenous losses (function of maintenance)
• Amount of dietary nutrient consumed relative to nutrient
needs (excesses)
• Efficiency of nutrient utilization and retention
• Interrelationships of nutrients
10-3
Precision nutrition
Meeting nutrient needs while minimizing
nutrient excesses
10-4
Challenges to precision feeding
• Determining nutrient needs
– Stage of growth
– Genetic-specific
– Management-dependent
• Estimation of nutrient digestibility/bioavailability
• Variation in feed ingredient composition
10-5
The key: understanding
inefficiencies in nutrient utilization
Feed provided
Waste
Feed waste
Feed consumed
Inefficiencies
Intestinal secretions
(enzymes, cells)
Undigested
feed
and secretions
Nutrients absorbed
Maintenance
Nutrients available for
growth
Mismatch
Nutrients used for
growth
Inefficiencies
• Many steps are involved in
the utilization of nutrients.
– Each step has
inefficiencies associated
with it.
• The key to reducing waste is
to understand where
utilization can be influenced.
Growth
10-6
Feed Waste:
an expensive waste of nutrients
• Feed waste:
Feed provided
Waste
Feed waste
-Rooting: Dairy
cows pick
through their
feed; refusing as
much as 10% of
what is offered
– Adherence: pigs take 1.5 g
feed away from feeder 60
times per day (~ 4% of
“intake”)

Portion may be returned
– Spillage: pigs push feed out of
feeder (in practice, range 1.5%
to 20%)
10-7
Feeder management
• Traditional guidelines:
– Proper feeder care and adjustment can reduce feed
waste drastically

Bottom of feeder should be 50% covered with
FRESH feed
 Pig

needs to exert effort to eat
Feeders should be inspected at least weekly
 Clean
and adjust where necessary
10-8
Present feed in most palatable form
• Feed should be pelleted
– Reduces feed waste ~5%
• Dry feed is not very palatable
– Pigs move back and forth from feeder to
waterer while eating

Augments feed waste
10-9
Present feed in most palatable form
(continued)
• Wet-dry or liquid feeders
– Back and forth motion is prevented

Reduces feed waste

Increases feed intake

Increases gain
10-10
Enzymes required for digestive process contribute
to waste through catabolism
Feed provided
Feed consumed
Waste
Feed waste
Inefficiencies
Intestinal secretions
(enzymes, cells)
• Upon consumption, the animal
excretes proteins and enzymes,
e.g., during chewing
– Equals to ~30% of protein
intake
10-11
Enzymes required for digestive process contribute
to waste through catabolism (continued)
– During synthesis, inefficiencies occur

Protein is catabolized
N
is excreted (mainly in urine)
As much as 10% of dietary N may be excreted
10-12
Enzymes required for digestive process
contribute to waste and not all are reabsorbed
• Approximately 25% of the
Feed provided
Waste
Feed waste
Inefficiencies
Intestinal secretions
(enzymes, cells)
Undigested
feed and
secretions
enzymes secreted are not
reabsorbed in the small
intestines
– Are fermented in large
intestines

Contribute to odor
– Remains are excreted

Contribute to waste
Feed quality affects enzyme
production and thus catabolism
• Factors augmenting enzyme secretions:
– Anti-nutritional factors such as trypsin inhibitor

Found in (underprocessed) soybean meal
– Protein content of the diet
– Overprocessed ingredients?
10-14
Enzymes open opportunities
• Fiber-degrading enzymes
– Wheat/barley/rye as major ingredients:

Xylanase/beta-glucanase improve
digestibility 2% to 9%
– Corn-soy diets:

Alpha-galactosidase, proteases, etc.
may prove effective
10-15
Phytase has a major effect
on P availability
• Plants contain a large portion of P in the form of
phytate
– Pigs cannot digest phytate

Most plant phosphorus is thus unavailable
• Phytase can break down phytate, releasing the P
– The availability of P increases from 30% to 50% in
typical diet

30% reduction in P excretion
10-16
Phytase to reduce P excretion
• Some research has demonstrated added performance with
phytase
• Potential to increase critical amino acid digestibility
• May increase zinc and other trace mineral absorption
• Diet costs are typically not increased
10-17
Nutrient Digestibility
Available nutrients = absorbed - “expenses”
Feed provided
Waste
Feed waste
Feed consumed
Intestinal secretions
(enzymes, cells)
Nutrients absorbed
Inefficiencies
Undigested
feed and
secretions
• Ileal digestible nutrients
– Estimate of availability
• Available nutrients are
destined for:
– Maintenance
– Growth
10-18
Nutrient Digestibility
Feed provided
Waste
Feed waste
Inefficiencies
Intestinal secretions
(enzymes, cells)
Undigested
feed and
secretions
• For a typical diet, 8% of protein
and 70% of phosphorus is not
digested
– Indigestible proteins are
fermented in large intestines

Contributes to odor
– Remains are excreted

Contributes to waste
10-19
Reduce the indigestible fraction
by selecting highly digestible ingredients
Protein
Digestibility, Content,
%
%
85
8.5
87
49.0
84
45.6
89
13.3
75
15.7
85
10.6
83
9.2
84
49.1
77
57.7
88
62.9
Phosphorus
Feed Ingredient
Digestibility, Content,
%
%
Corn
14
0.28
Soybean meal 48
23
0.69
Soybean meal 44
31
0.65
Wheat
50
0.37
Wheat bran
29
1.20
Barley
30
0.36
Sorghum
20
0.29
Meat & bone meal
95
4.98
Poultry byproducts
95
2.41
Fish meal
95
2.20
Dicalcium phosph
100
18.50
Adapted from NRC 1998, and the Rhone-Poulenc Nutrition Guide 1993.
10-20
Table XX. Commonly Used Forms of Minerals in Swine Diets.
__________________________________________________________________________________________________
Mineral
Form
Bioavailability
Nutrient Contenta
__________________________________________________________________________________________________
calcium
bone meal
excellent
24
carbonate
excellent
38
mono-or dicalcium phosphate
excellent
18-21
dolomitic limestone
good
22
copper
sulfate
oxide b
lysine
excellent
poor
excellent
25
79
10
iron
ferric oxide
ferrous carbonate
ferrous sulfate b
iron methionine
unacceptable
poor
excellent
excellent
---32
32
14.5
magnesium
sulfate
oxide
carbonate
excellent
good
excellent
10
54
30
manganese
sulfate
methionineb
excellent
excellent
25
16
phosphorus
bone meal
dicalcium phosphate
monocalcium phosphate
soft rock phosphate
deflourinate rock phosphate
excellent
excellent
excellent
poor
excellent
12
18.5
21
17
20
selenium
sodium selenite
sodium selenate
excellent
excellent
45.6
41.8
lysineb
excellent
10
methionineb
excellent
18
oxide
medium
72
sulfate
excellent
36
carbonate
excellent
78
_____________________________________________________________________________________________
a
The concentrations may differ due to different water of hydration molecules attached to the element.
b
The mineral protienates or chelates may differ in their compositions due to different chemical bonding structures.
See the manufacturer's composition of the different products that are available.
10-21
zinc
New crops offer solutions as well
Low - phytate
P, %
Normal Corn
Corn
Total
0.25
0.28
Phytate
0.20
0.10
Bio - available
0.05
0.18
•De-germed, de-hulled corn
10-22
Processing can improve
nutrient digestibility
• Grinding:
– Grind feed to uniform particle size of ~ 600 microns.
• Pelleting:
– Improves protein digestibility 3.7%.
• Expanding/extruding:
– Improves pellet quality.
– Effects on digestibility very diet-dependent.
 Effects can be negative!
• Flaking/rolling/cracking:
– Improves digestibility by >10%
10-23
Mineral bioavailability
• 30% improvement in bioavailability of organic mineral
sources (chelates) compared to inorganic sources (Leeson et
al., 2003)
10-24
Table 4. Effect of mineral level and source on fecal mineral excretiona
Treatment
Mineral
Control
Reduced inorganic
Reduced chelate
------------------------------ mg/kg feces ----------------------------Copper
163.6
92.2
79.6
Zinc
835.1
458.7
394.2
Iron
2430
2115
2001.3
581
343
311
Manganese
a
Spears, et al., 1998
10-25
Maintenance, although essential,
results in waste
Feed provided
Feed consumed
Intestinal secretions
(enzymes, cells)
Nutrients absorbed
Waste
Feed waste
Inefficiencies
Undigested
feed and
secretions
Maintenance
• Maintenance is obligatory
– Basic function of life
• Nutrients used for
“maintenance” are ultimately
catabolized (broken down)
– Maintenance requirement
depends on size of animal
10-26
Maintenance, although essential,
results in waste (continued)
– Five-lb pig:

Lysine: 2.6% of requirement

Threonine: 6.1% of requirement
– 250-lb pig:

Lysine: 8.8% of requirement

Threonine: 19.4% of requirement
10-27
Maintenance-linked waste
cannot be reduced
• By improving daily lean gain, maintenance
waste becomes relatively less important
– Optimize production

Optimize management

Optimize animal health

Optimize nutrition, etc.
10-28
Absorbed nutrients can be used for maintenance,
followed by growth, presuming the profile matches
• Nutrients are required in specific
ratio for growth
Feed provided
Feed consumed
Intestinal secretions
(enzymes, cells)
Nutrients absorbed
Waste
Feed waste
Inefficiencies
Undigested
feed and
secretions
Maintenance
Nutrients available
for growth
Mismatch
– The most limiting nutrients
sets the upper limit for growth
– Excesses for other nutrients
are catabolized and/or
excreted
• For a typical diet,
– 30%-35% is “mismatched”
Ideal protein
concept
Contributions
of amino acids
from corn and
SBM, relative to the requirement of a 40 kg pig
Corn (74.1% of diet) + Soybean meal (24.3% of
diet)
350
300
250
200
150
100
50
0
Corn
Arg His
Ile
SBM 48%
Leu Lys M+C P+T Thr Trp Val
10-30
Contributions of amino acids from corn and
SBM, relative to the requirement of a 40 kg pig
Corn (84.1% of diet) + Soybean meal (12.9% of
diet) + Synthetic Lys, Met, Thr, Trp.
350
300
250
200
150
100
50
0
Corn
Arg His
Ile
SBM 48%
Syn AA
Leu Lys M+C P+T Thr Trp Val
10-31
Protein requirements
Theory for lowering protein
• All excess protein above requirements have no value
• Excess protein is absorbed at the small intestine
– Protein is deaminated in the liver
– Urea is subsequently excreted in urine at the kidney
10-32
Protein requirements
(Continued)
• Urea is rapidly converted to ammonia following
deposition Therefore,
– feeding less protein leads to less urea excretion
– reduced urea excretion should decrease ammonia
• A 1% point reduction in dietary protein results in a
10% decrease in N excretion and ammonia emission
10-33
Ideal Pattern of Essential Amino Acids for Pigs for Three
Weight Catergories.
Body Weight (lb.):
20-45
45-110
110-250
Amino Acid
% of Lysine
Lysine
100
100
100
Arginine
42
30
18
Histidine
32
32
32
Isoleucine
60
60
60
Leucine
100
100
100
Methionine + cystine 60
62
64
Phenlyalanine +
tyrosine
95
95
95
Threonine
65
67
70
Tryptophan
17
18
19
Valine
68
68
68
10-34
The more ingredients used,
the better the match!
• Major portion of nutrients in feed is wasted because diet is
not ideal
• Contributors to this problem:
– Small number of ingredients

Limits flexibility in matching animal-specific profile
Theoretical Reduced N Excretion
Diet Concentration
N Balance
14% CP
12% CP
+ lysine
10% CP + lysine
+threonine
+ typtophan
N intake, g/d
67
58
50
N absorbed, g/d
60
51
43
N excreted feces, g/d
7
7
7
N retained, g/d
26
26
26
N excreted urine, g/d
34
25
17
N excreted, total, g/d
41
32
24
Reduction N excreted, %
---
22
41
Change diet costs, $/ton
0
-1.40
+3.50
10-36
Diets should be optimally matched
to the animal’s requirement
• Nutritional requirements change with:
– Maintenance requirement (affected by sex, age,
and weight).
– Gain and composition of gain.
– Product yield and composition.
– Health status, environmental conditions, and
activity.
10-37
Diets should be optimally matched
to the animal’s requirement
(continued)
– Temperature outside of thermo-neutral zone.

Energy used for thermo-regulation.

Increase energy-to-protein ratio.
10-38
Phase feeding reduces waste
• Nutritional requirements
– Protein to energy ratio of
feed decreases with age

Diet should be
adjusted to match
this decrease
 Phase
feeding
3 phase
2 phase
1 phase
0.90
Lysine requirement (%)
change continuously
Continuous
0.80
0.70
0.60
0.50
0.40
50
100
150
bodyweight (lbs)
200
250
Diets should be optimally matched
to the animal’s requirement
(continued)
• Examples of nutritional strategies
– Grouping for production, stage of growth, or
weight range
– Split-sex feeding

Barrows require more energy for
maintenance than gilts
 Increase
energy to protein ratio of
the feed for barrows
10-40
Inefficiencies occur when the diet provides
more nutrients than the animal needs:
More phases/groups = less waste
10-41
Phase-feeding diets are also cheaper, but the extra
hassle may outweigh the benefits
• More phases/groups = less waste and cheaper diets
– But also = more hassle
– Compromise between number of phases/groups and
benefits achievable
• In-line mixers/liquid feeding systems allow for
continuously changing the diet composition without
increasing hassle
10-42
Precision nutrition is further hindered by
feed manufacturing problems
• Feed manufacturing problems
– Variation in ingredient quality

Somewhat compensated for by over
formulating (= more waste)
– Weighing errors
– Mixing problems
10-43
Inefficiencies are linked to
tissue accretion
Feed provided
Waste
Feed consumed
Feed waste
Inefficiencies
Undigested
feed and
secretions
Maintenance
Intestinal secretions
(enzymes, cells)
Nutrients absorbed
Nutrients available
for growth
• Inefficiencies occur in the
production of tissues
– A portion of the nutrients is
broken down
– Remnants are excreted

Mismatch
Nutrients used for
growth
Inefficiencies
Growth
N Mainly in urine
• Responsible for excretion of
10% of dietary N
10-44
Improving the efficiency of
tissue accretion requires
pharmacological interventions
• Difficult to improve through nutritional means
• Compounds such as the beta-agonists (Ractopamine),
improve the efficiency of nutrient utilization
– Offer great potential for reducing nutrient waste
10-45
Potential reduction
Examples
10-46
P Intake, Retention and Excretion
Agristats, 1999 (control)
Industry+Phy
17.1g P
12.2 g
17.0g P
12.2g
13.8 g
17.1g P
19.3 %
13.8 g P
26 g
36.2g P
30.8g P
6.38 lb bird
1.93 feed to gain
49 days of age
RA0109 exp results
10-47
P Intake, Retention and Excretion
Agristats, 1999 (control)
UMD Rcmd
17.1g P
12.2 g
16.9g P
12.2g
13.8 g
17.1g P
22.5 %
14.8 g P
26 g
36.2g P
31.7g P
6.38 lb bird
1.93 feed to gain
49 days of age
RA0109 exp results
10-48
P Intake, Retention and Excretion
Agristats, 1999 (control)
UMD Rcmd+Phy
17.1g P
12.2 g
16.9g P
12.2g
13.8 g
17.1g P
30.5 %
11.9 g P
26 g
36.2g P
28.8g P
6.38 lb bird
1.93 feed to gain
49 days of age
RA0109 exp results
10-49
P Intake, Retention and Excretion
Agristats, 1999 (control)
UMD Rcmd+Phy+25OHD3
17.1g P
12.2 g
16.8g P
12.2g
13.8 g
17.1g P
41.5 %
10.0 g P
26 g
36.2g P
26.8g P
6.38 lb bird
1.93 feed to gain
49 days of age
RA0109 exp results
10-50
Table 2. Annual feed nutrient inputs and reductions with diet manipulation for a 4,000
space swine feeder-finisher unit
Diet manipulation
Nitrogen
Nutrient input
Ratio
(kg/yr)
(%)
Corn-soy diet
73,586
100
Corn-soy diet + lysine
63,886
86.8
Corn-soy diet + lysine, threonine, methionine, tryptophan
54,653
74.2
Corn-soy diet
14,367
100
Corn-soy diet with reduced safety margin
13,228
92
Corn-soy diet + phytase
11,522
80
Phosphorus
Corn-soy diet with reduced safety margin + phytase
10,384
72.2
______________________________________________________________________________________
_
10-51
90
80
70
60
-22%
50
40
30
-33%
20
-48%
C
LCP
ULCP
10
0
Daily ammonia emissions, mg kg-1
animal liveweight
Powers et al., 2004 (unpublished)
P<0.0001
10-52
Where does all of the waste
end up?
• Feces contain the remnants of the digestive
process
Feed waste
Manure pit
Undigested feed
–
Endogenous losses

Undigested
feed and
secretions
Maintenance
Inefficiencies
* enzyme prod.
* tissue
accretion
Mismatch
–
Feces
}
–
But also excess zinc and copper

Urine
–
Odor
Excreted through bile and excreted
as feces
Uptake of calcium and phosphorus is
regulated

Excess is excreted as feces
Where does all of the waste
end up? (continued)
• Urine contains the remnants of metabolism
– Urea from protein breakdown

Some diverted to feces
– Excess potassium, sodium, and chlorine
10-54
Odor compounds:
fermentation products of remnants
of the digestive process
• Undigested feed + endogenous losses
– Subject to fermentation in the large intestines

Fiber and carbohydrates:
 Volatile
fatty acids (e.g., butyric acid)
10-55
Odor compounds:
fermentation products of remnants of
digestive process (continued)

Proteins:
 Volatile
fatty acids
 Phenolics
(para-cresol, skatole)
 Mercaptans
(hydrogen sulfide, methyl
mercaptan)
 Amines

(putrescine, cadaverine)
Sulfur:
 Mercaptans
10-56
Diets can be formulated to
yield less odor
• Odor emission is difficult to study
– Data on effects of feed digestibility on odor are
circumstantial

But theoretically effect should be strong
• Low-protein diets proven to reduce odor
• Low-sulfur diet proven to reduce odor
10-57
Sulfur converts to mercaptans
• Methionine, cysteine, and taurine are sulfur-containing
“amino acids”
– Upon catabolism, they can contribute to sulfur
odor.
• Many minerals are fed as sulfur salts
– High bio-availability with relatively low cost

Impact on odor has been ignored
10-58
Urea in urine:
major source of ammonia
• Urea, the form in which nitrogen is excreted, is not stable
– Urease (of bacterial origin) converts urea to ammonia

Ammonia is volatilized from urine/manure based on
 Surface
area
 Temperature
 Air
flow across manure surface
 pH
 Ammonia
concentration