NUTRITION PIH-126
PURDUE UNIVERSITY. COOPERATIVE EXTENSION SERVICE.
WEST LAFAYETTE, INDIANA
Forages for Swine
Authors
Kenneth B. Kephart, Pennsylvania State University
Gilbert R. Hollis, University of Illinois
D. Murray Danielson, University of Nebraska
Reviewers
Robert F Barnes, Madison, Wisconsin
Bill and Sharron Loy, New Market, Tennessee
Gerald C. Shurson, The Ohio State University
W. Randy Walker, University of Florida
Use of Forage
Pork producers have long recognized the value of forages in
the swine enterprise. Prior to 1950, pasture was considered a
vital component in swine feeding programs. But after synthetic
vitamins became universally available during the early '50s, the
need for forage crops in swine production was diminished. But
even today, pastures and forages may contribute a practical and
economical part of feeding hogs.
Can hogs utilize forage? Research demonstrates that pigs
make better use of forage crops than previously assumed. Studies
have also shown that the digestibility of fiber improves as the
pig matures. They absorb more nutrients from forages after an
adaptation period of at least two months with nearly all of the
fiber digestion taking place in the large intestine. The impor-
tance of using forage when it is at an early stage of maturity is
more critical with swine than with ruminants.
Why use forage? The primary reason a pork producer would
consider using forage in his feeding program is to save on grain
or protein costs. Before making forage a major part of the diet,
first consider the potential savings that may be realized. Since
most forages contain more protein than do the grains, both grains
and protein supplements may be reduced when using forages. But
it is also important to remember that the digestibility of pro-
tein in forages is lower than that of soybean meal or other pro-
tein supplements. If the diet contains more than 25% forages, the
protein content in the complete feed should be slightly higher
than that of a typical grain-soybean meal diet.
Forage can simplify feeding and management of the breeding
herd. For example, sows on good quality pasture can be fed less
often and with a smaller amount of concentrate. With the proper
amounts of forage in a complete feed, sows can be self-fed during
gestation without adversely affecting weight gain or reproductive
performance (although some feed wastage may occur). Sows appear
more content when the diet contains a significant amount of
forage, compared to limit-fed sows that receive only 4-5 lb. of
concentrate each day.
Forage may also be used to provide a source of fiber. Nutri-
tionists and producers have both recognized that fiber prevents
constipation during late gestation and early lactation. Diets for
newly arrived feeder pigs and starter diets containing increased
fiber levels have been shown to reduce diarrhea problems. While
it's not a direct benefit of the forage, pigs and sows on pasture
may have fewer health problems because of improved sanitation and
air quality.
Potential drawbacks to forage. Fresh forages are low in dry
matter, which means the pig must consume more material to get the
same amount of nutrients found in grain or in complete feed. For
this reason, pastures and/or high levels of forage in the diet
are less practical for pigs weighing less than 40 lb. and for
sows in lactation.
Another drawback to using forages, especially pastures, is
that they might not be available during the entire year. This
means that the feeding program may have to be modified from one
season to the next.
Hogs should be rotated off pastures periodically to prevent
heavy bacterial and parasite contamination.
Feed value from pastures is often over-estimated by produc-
ers since forages may be heavily damaged by hogs. Both the pas-
ture and the forage crop must be well-managed to provide optimum
feed savings. Producers may find this difficult especially during
the spring and fall months when damage from hogs rooting the soil
reaches a peak.
Finally, hogs housed in a pasture setting have a higher
energy requirement since hogs outside get more exercise than
those housed in pens or enclosed facilities. Sows will require
more feed during gestation, and market hogs may gain slower and
less efficiently.
Table 1. Average nutrient composition of some forage crops1.
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Dry matter basis
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Dry Crude Metab. Ether Crude
matterprotein energy extractfiber
Forage Crop2 (%) (%) Kcal/lb. (%) (%)
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Alfalfa, fresh, er blm 23 19.0 986 3.1 25.0
Alfalfa, fresh, fl blm 25 14.0 905 2.8 31.0
Alfalfa meal, dehyd 92 18.9 1005 3.0 26.2
Alfalfa hay, sun-cured, er blm 90 18.0 986 3.0 23.0
Alfalfa hay, sun-cured, lt blm 90 14.0 854 1.8 32.0
Alfalfa haylage, wltd, er blm 35 17.0 986 3.2 28.0
Alfalfa haylage, wltd, fl blm 45 14.0 905 2.7 33.2
Barley hay, sun-cured 87 8.7 923 2.1 27.5
Bluegrass, Kentucky, fresh,
er vegetative 31 17.4 1182 3.6 25.3
Bluegrass, Kentucky, hay,
sun-cured 89 13.0 923 3.5 31.0
Brome, smooth, hay,
sun-cured, midblm 90 14.6 923 2.6 31.8
Clover, alsike, hay,
sun-cured 88 14.9 955 3.0 30.1
Clover, crimson, hay,
sun-cured 87 18.4 936 2.4 30.1
Clover, ladino, hay,
sun-cured 90 22.0 986 2.7 21.2
Clover, red, fresh, er blm 20 19.4 1136 5.0 23.2
Clover, red, hay,
sun-cured 89 16.0 905 2.8 28.8
Corn, dent yellow, silage,
well-eared 33 8.1 1150 3.1 23.7
Lespedeza, common-
lespedeza, Korean, hay,
sun-cured, er blm 93 15.5 905 - 28.0
Orchardgrass, fresh, midblm 31 11.0 932 3.5 33.5
Rape, fresh, er blm 11 23.5 1232 3.8 15.8
Rye, fresh 24 15.9 1136 3.7 28.5
Ryegrass, perennial, hay,
sun-cured 86 8.6 986 2.2 30.3
Sorghum, sudangrass,
fresh, mid-blm 23 8.8 1036 1.8 30.0
Sweetclover, yellow, hay,
sun-cured 87 15.7 886 2.0 33.4
Timothy hay,
sun-cured, er blm 90 15.0 968 2.9 28.0
Timothy, hay, sun-cured, fl blm 89 8.1 922 3.1 32.0
Trefoil, birdsfoot, hay,
sun-cured 92 16.3 968 2.5 30.7
Wheat, fresh, er vegetative 22 28.6 1200 4.4 17.4
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Table 1. (Continue...)
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Dry matter basis
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Hemi- Phos-
celluloseCelluloseLigninCalciumphorus
Forage Crop2 (%) (%) (%) (%)
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Alfalfa, fresh, er blm 8 23 7 2.33 .31
Alfalfa, fresh, fl blm 13 27 10 1.53 .27
Alfalfa meal, dehyd - 24 11 1.52 .25
Alfalfa hay, sun-cured, er blm 9 24 8 1.41 .22
Alfalfa hay, sun-cured, lt blm 12 26 12 1.43 .25
Alfalfa haylage, wltd, er blm 9 23 10 - -
Alfalfa haylage, wltd, fl blm 12 25 12 - -
Barley hay, sun-cured - - - .23 .26
Bluegrass, Kentucky, fresh,
er vegetative - 26 3 .50 .44
Bluegrass, Kentucky, hay,
sun-cured - - - .33 .25
Brome, smooth, hay,
sun-cured, midblm 22 31 4 .29 .28
Clover, alsike, hay,
sun-cured 13 - - 1.29 .26
Clover, crimson, hay,
sun-cured - - - 1.40 .22
Clover, ladino, hay,
sun-cured - - 7 1.35 .31
Clover, red, fresh, er blm - - - 2.26 .38
Clover, red, hay,
sun-cured 9 26 10 1.53 .25
Corn, dent yellow, silage,
well-eared - - - .23 .22
Lespedeza, common-
lespedeza, Korean, hay,
sun-cured, er blm - - - 1.23 .25
Orchardgrass, fresh, midblm 27 33 6 .23 .23
Rape, fresh, er blm - - - - -
Rye, fresh - - - .39 .33
Ryegrass, perennial, hay,
sun-cured - - 2 .65 .32
Sorghum, sudangrass,
fresh, mid-blm 25 34 5 .43 .36
Sweetclover, yellow, hay,
sun-cured - - - 1.27 .25
Timothy hay,
sun-cured, er blm 29 31 4 .53 .25
Timothy, hay, sun-cured, fl blm 30 34 6 .43 .20
Trefoil, birdsfoot, hay,
sun-cured - 24 9 1.70 .27
Wheat, fresh, er vegetative 18 24 4 .42 .40
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1Adapted from Nutrient Requirements of Beef, National Academy
Press. Metabolizable energy values shown are for beef, since com-
parable values are unavailable for swine. Similarly, amino acid
levels are unknown for most forages.
2er=early; blm=bloom; fl=full; dehyd=dehydrated; lt=late;
wltd=wilted; midblm=midbloom.
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Forage analysis. Table 1 lists the average nutrient composi-
tion for various forages. The table can be used as a guide to
formulation, but forage analysis should form the base for diet
formulation whenever practical. Crude protein, calcium and phos-
phorus can be assayed at most analytical laboratories at a rela-
tively low cost. In addition, most laboratories offer Neutral
Detergent Fiber (NDF) analysis. NDF provides an estimate of the
percentage of cell walls contained in the forage. The cell walls
contain all of the fiber, which is the least digestible component
of the forage. The fibrous components of the cell wall primarily
include cellulose, hemicellulose and lignin. None of the lignin
is digestible and only 30 to 40% of the hemicellulose and cellu-
lose is digestible. The percent of cellulose in the forage is
estimated by subtracting Acid Detergent Fiber (ADF), another
fiber analysis, from NDF. Percent lignin is estimated with an
Acid Detergent Lignin (ADL) analysis. Percent hemicellulose is
calculated by subtracting ADL from ADF. If levels of hemicellu-
lose and lignin are significantly higher than the average values
shown in Table 1, metabolizable energy and crude protein concen-
trations in the forage will likely be lower.
Table 2. Suggested diets1 to supplement pasture for gestating
sows.
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Type of pasture
__________________________________________________________
Legume Grass Legume-grass mix Rape
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Ingredients, lb.
Corn 1756 1744 1371 1335 1521 1495 1858 1857
Soybean meal, 48% 173 - 525 - 372 - 11 -
Soybean meal, 44% - 186 - 562 - 398 - 12
Ground limestone - - 16 16 24 24 18 18
Dicalcium phosphate - - 64 63 59 59 89 89
Monosodium phosphate 47 46 - - - - - -
Salt 12 12 12 12 12 12 12 12
Vitamin premix2 6 6 6 6 6 6 6 6
Trace mineral premix3 6 6 6 6 6 6 6 6
____ ____ ____ ____ ____ ____ ____ ____
Totals 2000 2000 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy,kcal/lb.1499 1492 1470 1449 1469 1442 1453 1452
Crude protein, % 11.7 11.5 18.6 18.0 15.5 15.1 8.2 8.2
Lysine (estimated), % .49 .49 .99 .99 .77 .77 .25 .25
Calcium, % .05 .05 1.16 1.16 1.23 1.23 1.44 1.44
Phosphorus, % .81 .81 .95 .95 .88 .88 1.09 1.09
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1Assumptions: Sows will consume 3.5 lb. pasture dry matter and
will be fed 2.5 lb. of the diet per day. Pasture and feed
together will provide a minimum of .75 lb. protein, 17 g lysine,
18 g calcium and 14 g phosphorus per day, respectively.
2Should provide the following amounts per ton of complete feed:
8,000,000 IU vitamin A; 800,000 IU vitamin D; 64,000 IU vitamin
E; 3.2 g vitamin K; 8 g riboflavin; 48 g niacin; 29 g pantothenic
acid; 24 mg vitamin B12; 1.6 g choline; 1.76 g folic acid; 320 mg
biotin. (Concentrations higher than normal to compensate for
reduced dry feed intake).
3Should provide the following amounts per ton of complete feed:
15 g copper; 144 g iron; 144 g zinc; 40 g manganese; 320 mg
iodine; 435 mg selenium. (Concentrations higher than normal to
compensate for reduced dry feed intake).
Table 3. Suggested diets1 to supplement pasture for growing hogs
(40-125) lb.
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Type of Pasture
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Legume Grass Legume-Grass Mix Rape
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Ingredients, lb.
Corn 1486 1454 1423 1387 1450 1416 1496 1465
Soybean meal, 48% 464 - 514 - 493 - 438 -
Soybean meal, 44% - 497 - 551 - 528 - 469
Ground limestone 4 4 15 15 10 10 15 15
Dicalcium phosphate 26 25 28 27 27 26 31 31
Salt 10 10 10 10 10 10 10 10
Vitamin premix2 5 5 5 5 5 5 5 5
Trace mineral premix3 5 5 5 5 5 5 5 5
____ ____ ____ ____ ____ ____ ____ ____
Totals 2000 2000 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy,kcal/lb 1512 1494 1502 1482 1507 1488 1500 1468
Crude protein, % 17.6 17.1 18.5 18.0 18.1 17.6 17.0 16.5
Lysine (estimated), % .91 .91 .98 .98 .95 .95 .87 .87
Calcium, % .48 .48 .70 .70 .59 .59 .74 .74
Phosphorus, % .60 .60 .62 .62 .61 .61 .64 .64
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1 Assumptions: Hogs will consume 0.75 lb. pasture dry matter plus
3.75 lb. of the diet per day. Pasture and feed together will
provide a minimum of 0.76 lb. protein, 18 g lysine, 13 g calcium
and 11 g phosphorus per day, respectively.
2Should provide the following amounts per ton of complete feed:
3,600,000 IU vitamin A; 600,000 IU vitamin D; 36,000 IU vitamin
E; 2 g vitamin K; 5 g riboflavin; 29 g niacin; 14 g pantothenic
acid; 17 mg vitamin B12; 480 mg choline; 650 mg folic acid. (Con-
centrations higher than normal to compensate for reduced dry feed
intake).
3Should provide the following amounts per ton of complete feed: 9
g copper; 90 g iron; 90 g zinc; 16 g manganese; 185 mg iodine;
327 mg selenium. (Concentrations higher than normal to compensate
for reduced dry feed intake).
Table 4. Suggested diets1 to supplement pasture for finishing
hogs (125-240) lb.
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Type of pasture
__________________________________________________________
Legume Grass Legume-grass mix Rape
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Ingredients, lb.
Corn 1600 1576 1538 1511 1566 1540 1617 1596
Soybean meal, 48% 346 - 396 - 375 - 313 -
Soybean meal, 44% - 371 - 424 - 401 - 335
Ground limestone 5 5 16 16 10 10 16 16
Dicalcium phosphate 29 28 30 29 29 29 34 33
Salt 10 10 10 10 10 10 10 10
Vitamin premix2 5 5 5 5 5 5 5 5
Trace mineral premix3 5 5 5 5 5 5 5 5
____ ____ ____ ____ ____ ____ ____ ____
Totals 2000 2000 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy,kcal/lb 1510 1497 1501 1485 1506 1491 1498 1475
Crude protein, % 15.2 14.9 16.1 15.7 15.7 15.4 14.5 14.1
Lysine (estimated), % .74 .74 .81 .81 .78 .78 .69 .69
Calcium, % .51 .51 .73 .73 .62 .62 .77 .77
Phosphorus, % .60 .60 .62 .62 .61 .61 .64 .64
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1Assumptions: Hogs will consume 1.0 lb. pasture dry matter plus 5
lb. of the diet per day. Pasture and feed together will provide a
minimum of .90 lb. protein, 20 g lysine, 18 g calcium and 15 g
phosphorus per day, respectively.
2Should provide the following amounts per ton of complete feed:
1,800,000 IU vitamin A; 600,000 IU vitamin D; 24,000 IU vitamin
E; 2 g vitamin K; 2 g riboflavin; 19 g niacin; 10 g pantothenic
acid; 12 mg vitamin B12; 480 mg choline; 648 mg folic acid. (Con-
centrations higher than normal to compensate for reduced dry feed
intake).
3Should provide the following amounts per ton of complete feed: 7
g copper; 65 g iron; 65 g zinc; 16 g manganese; 185 mg iodine;
327 mg selenium. (Concentrations higher than normal to compensate
for reduced dry feed intake).
Table 5. Suggested diets1 to supplement silage and haylage for
gestating sows.
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Type of silage
_________________________________________
Legume haylage Corn silage
(45% dry matter) (33% dry matter)
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Ingredients
Corn 1660 1641 1332 1294
Soybean meal, 48% 271 - 560 -
Soybean meal, 44% - 290 - 599
Ground limestone - - 24 24
Dicalcium phosphate - - 60 59
Monosodium phosphate 45 45 - -
Salt 12 12 12 12
Vitamin premix2 6 6 6 6
Trace mineral premix3 6 6 6 6
____ ____ ____ ____
Totals 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb. 1499 1488 1467 1445
Crude protein, % 13.6 13.4 19.2 18.7
Lysine (estimated), % .63 .63 1.04 1.04
Calcium, % .06 .08 1.26 1.26
Phosphorus, % .81 .81 .92 .92
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1Assumptions: Sows will consume 3.5 lb. haylage or silage dry
matter and will be fed 2.5 lb. of the diet per day. The ensiled
forage and feed together will provide a minimum of .75 lb. pro-
tein, 17 g lysine, 18 g calcium and 14 g phosphorus per day,
respectively.
2Should provide the following amounts per ton of complete feed:
8,000,000 IU vitamin A; 800,000 IU vitamin D; 64,000 IU vitamin
E; 3.2 g vitamin K; 8 g riboflavin; 48 g niacin; 29 g pantothenic
acid; 24 mg vitamin B12; 1.6 g choline; 1.76 g folic acid; 320 mg
biotin. (Concentrations higher than normal to compensate for
reduced dry feed intake).
3Should provide the following amounts per ton of complete feed:
15 g copper; 144 g iron; 144 g zinc; 40 g manganese; 320 mg
iodine; 435 mg selenium. (Concentrations higher than normal to
compensate for reduced dry feed intake).
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Methods of Feeding Forage
Pasture. Pastures containing a high percentage of legumes
are normally the most practical for pork producers. On a dry
matter basis, legumes are similar in energy content and higher in
crude protein than are the grasses. Some grass species in the
mixture may help prevent soil erosion.
Optimum stocking rates depend on soil types, plant species
and weather conditions. Normally, 4 to 6 gestating sows per acre
(8 to 12 if irrigated) or 10 to 12 growing hogs (15 to 25 if
irrigated) will make good use of the pasture crop without exces-
sive damage. Damage to the pasture from hogs rooting the soil is
most prevalent in the spring and fall months.
Sows should be fed approximately 2 to 3 lb. of complete feed
while on pasture. Grower-finisher pigs should have free access to
complete feed at the same time they are grazing a pasture crop.
Suggested feed formulas for sows and growing pigs are shown in
Tables 2, 3 and 4.
Pastures should be plowed, disked and reseeded at least
every other year. This serves to level the pasture, re-establish
plant growth and reduce bacterial and parasite contamination.
When grazing hogs on legume pastures in northern latitudes,
allow enough time in the fall to permit at least 6 in. of growth
before the arrival of a killing frost. This helps reduce winter-
kill by enabling the plant to build root reserves.
Silage and haylage. Feeding programs for gestating sows or
replacement gilts weighing more than 250 lb. in gestation can
include silage and haylage. These forages should be finely
chopped to prevent sorting by sows. To avoid reproductive prob-
lems, be sure that any ensiled forage is fresh and free of mold.
Offer corn silage as a free-choice item. Intake is variable,
but under most conditions sows will consume 10 to 12 lb. per head
per day. Sows should also be fed approximately 2.5 lb. of a com-
plete feed in addition to the silage. For best results the corn
silage should be made when the ears are formed, and at the same
time the plant is still green and not frosted. Silage made from
corn nearing maturity is less palatable.
When feeding legume haylage, offer all the haylage sows will
clean up (usually 6 to 8 lb. per head per day), plus 2.5 lb. of
complete feed.
Suggested feed formulations for use with haylage and silage
are listed in Table 5.
Complete Feed. Dried forages can be included in a complete
feed. For many producers this is the most practical feeding
method. Hammermills equipped with screens containing 3/16 to
1/4-inch openings will provide the correct particle size. Pellet-
ing the diets that contain high amounts of forage will reduce
separation, and improve palatability and fiber digestion. Recom-
mended diets containing dried forages for sows and growing-
finishing pigs are listed in Tables 6, 7, 8, and 9.
Value of Forage Crops
Legumes
Alfalfa. Most of the research on the use of forage in swine
diets has been with alfalfa. It appears to be the most practical
forage crop for the pig because it can be used for both pasture
and silage. Because of their maturity, sows make the better use
of alfalfa (and other forages) than do growing-finishing hogs.
Potential benefits to feeding alfalfa during gestation include
improved survival of the baby pigs during the nursing period and
a reduced culling rate in the sow herd. Some research has shown
that as much as 97% can be included in gestation diets without
impairing reproductive performance. For commercial operations,
however, no more than 65% alfalfa should be used in gestation
diets. Gestation diets containing approximately 60% alfalfa can
be self-fed.
Growing pigs show satisfactory performance on diets contain-
ing alfalfa, provided the level does not exceed 20% of the diet.
Even at this level, you can expect a 5 to 15% depression in feed
efficiency compared to a grain-soybean meal diet. Receiving diets
containing 10% alfalfa may improve gain and feed intake in newly
arrived feeder pigs.
Alsike clover. This clover provides a leafy crop with fine
stems, and it grows well in soils that are too acidic or too wet
for red clover. It is less desirable where hot, dry summer condi-
tions are common. It is often used in pasture mixtures.
Birdsfoot trefoil. Birdsfoot trefoil is palatable and simi-
lar in nutrient content to alfalfa. Unlike alfalfa, it grows well
on poorly drained soils. While it is not as productive as
alfalfa on good soils, birdsfoot trefoil yields have exceeded
yields of alfalfa on the wetter soils. Most varieties perform
better in cooler climates. It will normally outlive red clover by
several years.
Crimson clover. Crimson clover provides a good spring forage
and sometimes winter forage in warm climates.
Ladino clover. Under optimum conditions, ladino clover will
not produce as much forage per acre as alfalfa. But the protein
content of ladino clover is superior to that of alfalfa. Ladino
clover works best as an all-summer pasture crop in the
northeastern and north central states.
Lespedeza. Also called Japanese clover, this species is less
palatable to pigs than all clovers except sweetclover. It cannot
be grazed until mid-summer, but it does grow reasonably well
without lime and fertilizer and will adapt to soils that cannot
be used for red clover.
Red clover. Red clover is a short-lived, relatively easy-
to-establish perennial legume that will grow on soils too acidic
or too wet for alfalfa. Red clover does not yield as much forage
early in the spring as alfalfa and it is not as drought resistant
as alfalfa. It is useful for pasture or silage. It will provide
good forage through most of the grazing season if it is not over-
grazed nor allowed to become too mature. Several studies have
shown that pigs on red clover forage gain as rapidly as those on
alfalfa.
Soybean forage. Soybeans as a green forage are less valuable
than alfalfa, red and ladino clovers and rape. The soybeans
should be grown in rows to reduce damage from trampling. Unlike
most forages, soybeans cannot regenerate new growth from the
crowns. Soybeans are less sensitive to nutrient levels in the
soil than are alfalfa and clovers. In hot climates, soybeans may
out-yield other legumes during the same period of time.
Pigs grazing mature soybeans should also have access to
grain fortified with vitamins and minerals. However, inhibitors
in the raw soybeans will prevent the pig from utilizing the
dietary protein efficiently. In addition, the oil contained in
the beans tends to make the carcass soft.
Sweetclover. Since pigs find sweetclover unpalatable, it may
be more suitable for soil improvement. Sweetclover may be planted
on soils not adapted for alfalfa or other clovers. If biennial
sweetclover is sown in the spring, the first season's growth is
more succulent and palatable than that harvested during the
second summer.
White clover. White clover is a practical perennial legume
to use with permanent pasture, especially those containing
bluegrass. White clover makes a high-quality pasture and it does
well in years of frequent rain. Note that ladino clover is a
large-type white clover. Dutch or common white clover is a
small-type.
Brassicas
Rape. Rape is a high-yielding, fast-growing annual forage
that belongs to the brassica family. Related species include kale
and swede. Rape provides an excellent pasture for swine. When
overgrazing is avoided, it provides abundant, palatable forage
for a long-growing season. Rape can lead to photosensitization
(sun-burning), when grazed wet. Pigs with white skin are most
sensitive.
Grasses
Bluegrass. Bluegrass may serve as a permanent pasture for
swine. The pasture can be grazed early, but it contains less pro-
tein than do legumes and is usually dormant during the warmest
part of the summer.
Smooth bromegrass. Bromegrass is a palatable crop that with-
stands heavy grazing. Its early spring growth enables it to be
pastured for longer periods than many legumes. Studies show that
pigs on bromegrass pastures require more grain and supplement
than pigs grazing alfalfa. Bromegrass can be successfully mixed
with legumes.
Orchardgrass. Orchardgrass, a perennial, is a hardy species
that can tolerate trampling. It quickly loses its palatability if
not grazed down to prevent the grass from becoming tall and
mature.
Sudangrass. Sudangrass, an annual, is palatable to pigs, and
when seeded thickly, it provides ample forage during the hottest
part of the summer when other species are dormant. The early
growth of sudangrass contains a cyanogen, which may be converted
to prussic acid (extremely toxic to pigs) under certain condi-
tions such as wilting, trampling, chewing, frost and drought.
Because of the near-neutral pH in the rumen, ruminants are more
sensitive to cyanogens than are nonruminants. Poisoning can be
avoided if the grass is grazed only after it reaches a height of
at least 18 to 24 in. Because sudangrass is low in protein, it is
better adapted for sows and older market hogs.
Timothy. Timothy withstands heavy use, but it should only be
included as a minor part of a pasture mixture since it is less
desirable than most other pasture crops.
Winter rye. Winter rye seeded during late summer will pro-
vide a useful forage crop for winter or early spring grazing.
Optimal planting time should provide just enough growth so that
seed stems are starting to shoot when the plant enters winter
dormancy. When pigs are allowed to graze rye during the winter
and spring months, stock the pasture with no more than 8 growing
pigs, or 3 to 5 sows per acre.
Winter wheat and barley. These two cereal grains are at
least as palatable and nutritious as rye, but they do not provide
as much fall production as rye and they cannot be grazed as
heavily. Note that fresh wheat forage contains significantly more
crude protein than is contained in barley forage.
Economics of Forage Use
Pasture. Costs for establishing and maintaining pasture
crops should be estimated before making this forage system a part
of your feeding program. For example, the annual cost for main-
taining alfalfa pasture in the northeast is about $260/acre
(including land costs of $62/acre) according to the 1989-1990
Penn State Agronomy Guide. If the pasture were available for 180
days, the cost per day would be $1.44. For a stocking rate of 5
sows per acre, the daily feeding cost associated with the pasture
would be $0.29 per sow per day. Using the pasture should reduce
feed requirments by about 3.5 lb. per sow per day. If the cost
for 3.5 lb. of complete feed is more than $0.29, then the pasture
system would be economical.
If the same pasture were used for growing-finishing hogs at
the rate of 10 pigs per acre, the daily feeding cost associated
with the pasture would be $0.14 per pig per day. Using the pas-
ture should reduce feed requirements by 0.75 to 1.0 lb. per pig
per day. To make the pasture profitable in this situation, the
cost of purchasing 0.75 to 1.0 lb. of feed should be more than
$0.14.
In summary, making pasture a viable feeding system for sows
or growing pigs will require low land costs, land that is unsuit-
able for crop production, or expensive feed.
Silage and haylage. Using corn silage or haylage will
reduce sow feed requirements by about 3.5 lb. per head per day
(see Table 5). But higher than normal lysine and mineral concen-
trations are required in the feed used to supplement corn silage.
That means the reduction in feed requirement is partly offset by
a higher feed cost (usually about $20) per ton.
For example, if corn silage is worth $18/ton, a feeding rate
of 10 lb. per sow per day would cost $0.09 per sow per day, (10
lb. X [$18/2000 lb.]). If gestation feed normally costs $140 per
ton, then the feed used to supplement corn silage would cost
about $160 per ton because of the increased nutrient concentra-
tions. Since sows would require about 2.5 lb. per day of this
supplementary feed, the cost would be $0.19 per day. Adding this
to the silage costs of $0.09 per day brings the total feed costs
to $0.29 per day per sow on a corn silage program. This compares
favorably to $0.35 per day associated with feeding 5 lb. of con-
ventional gestation feed (assuming $140/ton).
Feed used to supplement legume haylage is similar in cost to
conventional gestation feed since the only change in formulation
is a reduction in the level of calcium (an inexpensive nutrient).
If alfalfa hay costs $100 per ton, alfalfa haylage (45% dry
matter) would be worth about $50 per ton ([45%/90%] X $100/ton =
$50/ton). At a feeding rate of 7.75 lb. per day, the haylage
would cost $0.19 per sow per day. Sows would require 2.5 lb. of
feed to supplement the silage. Assuming the supplementary feed
costs $140 per ton, the daily expense for this feed would be
$0.18. Adding this to the haylage costs of $0.19 per day would
bring the total feed cost to $0.37 per day for a sow on an
alfalfa haylage program. This is slightly higher than the $0.35
per day associated with feeding 5 lb. of conventional gestation
feed (assuming $140/ton).
Table 6. Suggested diets containing alfalfa hay for gestating
sows.
_______________________________________________________________________________
Diet
________________________________________________________
1 2 3 4 5 6 7 8
_______________________________________________________________________________
Ingredients, lb.
Corn 1201 1187 1001 990 799 792 599 593
Soybean meal, 48% 205 - 163 - 122 - 80 -
Soybean meal, 44% - 220 - 175 - 130 - 86
Alfalfa 500 500 750 750 1000 1000 1250 1250
Limestone 32 31 23 22 14 14 5 5
Monosodium phosphate 44 44 45 45 47 46 48 48
Salt 8 8 8 8 8 8 8 8
Vitamin premix1 5 5 5 5 5 5 5 5
Trace mineral premix2 5 5 5 5 5 5 5 5
____ ____ ____ ____ ____ ____ ____ ____
Totals 2000 2000 2000 2000 2000 2000 2000 2000
Calculated Composition
Metab. energy, kcal/lb.1338 1330 1273 1267 1208 1204 1144 1141
Protein, % 14.6 14.4 15.0 14.8 15.4 15.2 15.7 15.7
Lysine (estimated), % .65 .65 .65 .65 .65 .65 .65 .65
Calcium, % 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
Phosphorus, % .77 .77 .77 .77 .77 .77 .77 .77
_______________________________________________________________________________
1Should provide the following amounts per ton of complete feed:
5,000,000 IU vitamin A; 500,000 IU vitamin D; 40,000 IU vitamin
E; 2 g vitamin K; 5 g riboflavin; 30 g niacin; 18 g pantothenic
acid; 15 mg vitamin B12; 1 g choline; 200 mg folic acid; 1.1 mg
biotin.
2Should provide the following amounts per ton of complete feed: 9
g copper; 90 g iron; 90 g zinc; 25 g manganese; 200 mg iodine;
272 mg selenium.
Table 7. Suggested high-forage diets for gestating sows.
________________________________________________________________
Diet
___________________________________
1 2 3 4 5
________________________________________________________________
Ingredients, lb.
Corn 1194 1180 1217 1204 1179
Soybean meal, 48% 217 - 194 - 239
Soybean meal, 44% - 232 - 208 -
Birdsfoot trefoil 500 500 - - -
Red clover - - 500 500 -
Kentucky bluegrass - - - - 500
Orchardgrass - - - - -
Ryegrass - - - - -
Ground limestone 28 28 30 30 14
Dicalcium phosphate - - - - 50
Monosodium phosphate 43 42 41 40 -
Salt 8 8 8 8 8
Vitamin premix1 5 5 5 5 5
Trace mineral premix2 5 5 5 5 5
___ ___ ___ ___ ___
Totals 2000 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb. 1338 1329 1380 1372 1331
Crude protein, % 14.4 14.2 14.7 14.5 14.1
Lysine (estimated), % .65 .65 .65 .65 .65
Calcium, % 1.00 1.00 1.00 1.00 1.00
Phosphorus, % .77 .77 .77 .77 .77
________________________________________________________________
Table 7. (Continue... )
______________________________________________________________
Diet
____________________________________
6 7 8 9 10
______________________________________________________________
Ingredients, lb.
Corn 1162 1163 1146 1153 1135
Soybean meal, 48% - 253 - 270 -
Soybean meal, 44% 256 - 271 - 289
Birdsfoot trefoil - - - - -
Red clover - - - - -
Kentucky bluegrass 500 - - - -
Orchardgrass - 500 500 - -
Ryegrass - - - 500 500
Ground limestone 14 15 15 11 11
Dicalcium phosphate 50 51 50 48 47
Monosodium phosphate - - - - -
Salt 8 8 8 8 8
Vitamin premix1 5 5 5 5 5
Trace mineral premix2 5 5 5 5 5
___ ___ ___ ___ ___
Totals 2000 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb. 1322 1332 1322 1351 1340
Crude protein, % 13.8 13.8 13.6 13.6 13.3
Lysine (estimated), % .65 .65 .65 .65 .65
Calcium, % 1.00 1.00 1.00 1.00 1.00
Phosphorus, % .77 .77 .77 .77 .77
______________________________________________________________
1Should provide the following amounts per ton of complete feed:
5,000,000 IU vitamin A; 500,000 IU vitamin D; 40,000 IU vitamin
E; 2 g vitamin K; 5 g riboflavin; 30 g niacin; 18 g pantothenic
acid; 15 mg vitamin B12; 1 g choline; 200 mg folic acid; 1.1 mg
biotin.
2Should provide the following amounts per ton of complete feed: 9
g copper; 90 g iron; 90 g zinc; 25 g manganese; 200 mg iodine;
272 mg selenium.
_________________________________________________________________
Table 8. Suggested high-forage diets for growing hogs (40-125) lb.
_________________________________________________________________
Diet
__________________________________________
1 2 3 4 5 6
_________________________________________________________________
Ingredients, lb.
Corn 1358 1334 1354 1330 1364 1341
Soybean meal, 48% 346 - 352 - 341 -
Soybean meal, 44% - 371 - 377 - 365
Alfalfa 250 250 - - - -
Birdsfoot trefoil - - 250 250 - -
Red clover - - - - 250 250
Kentucky bluegrass - - - - - -
Orchardgrass - - - - - -
Ryegrass - - - - - -
Ground limestone 6 6 5 5 7 7
Dicalcium phosphate 24 23 23 22 22 21
Salt 8 8 8 8 8 8
Vitamin premix1 4 4 4 4 4 4
Trace mineral premix2 4 4 4 4 4 4
___ ___ ___ ___ ___ ___
Totals 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb.1445 1432 1445 1431 1465 1452
Crude protein, % 16.4 16.1 16.3 16.0 16.5 16.2
Lysine (estimated), % .80 .80 .80 .80 .80 .80
Calcium, % .65 .65 .65 .65 .65 .65
Phosphorus, % .55 .55 .55 .55 .55 .55
_________________________________________________________________
Table 8. (Continue..)
________________________________________________________________
Diet
__________________________________________
7 8 9 10 11 12
________________________________________________________________
Ingredients, lb.
Corn 1333 1307 1326 1299 1320 1294
Soybean meal, 48% 364 - 371 - 380 -
Soybean meal, 44% - 390 - 398 - 407
Alfalfa - - - - - -
Birdsfoot trefoil - - - - - -
Red clover - - - - - -
Kentucky bluegrass 250 250 - - - -
Orchardgrass - - 250 250 - -
Ryegrass - - - - 250 250
Ground limestone 14 14 14 14 12 12
Dicalcium phosphate 23 23 23 23 22 21
Salt 8 8 8 8 8 8
Vitamin premix1 4 4 4 4 4 4
Trace mineral premix2 4 4 4 4 4 4
___ ___ ___ ___ ___ ___
Totals 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb1432 1418 1432 1418 1442 1427
Crude protein, % 16.1 15.8 16.0 15.6 15.9 15.5
Lysine (estimated), % .80 .80 .80 .80 .80 .80
Calcium, % .65 .65 .65 .65 .65 .65
Phosphorus, % .55 .55 .55 .55 .55 .55
________________________________________________________________
1 Should provide the following amounts per ton of complete feed:
3,000,000 IU vitamin A; 500,000 IU vitamin D; 3000 IU vitamin E;
2 g vitamin K; 4 g riboflavin; 24 g niacin; 12 g pantothenic
acid; 14 mg vitamin B12; 400 mg choline; 540 mg folic acid.
2Should provide the following amounts per ton of complete feed: 7
g copper; 75 g iron; 75 g zinc; 15 g manganese; 150 mg iodine;
272 mg selenium.
Table 9. Suggested high-forage diets for finishing hogs (125-240)
lb.
_________________________________________________________________
Diet
__________________________________________
1 2 3 4 5 6
_________________________________________________________________
Ingredients, lb.
Corn 1326 1312 1321 1306 1339 1325
Soybean meal, 48% 218 - 227 - 209 -
Soybean meal, 44% - 233 - 244 - 224
Alfalfa 400 400 - - - -
Birdsfoot trefoil - - 400 400 - -
Red clover - - - - 400 400
Kentucky bluegrass - - - - - -
Orchardgrass - - - - - -
Ryegrass - - - - - -
Ground limestone 17 16 14 13 16 15
Dicalcium phosphate - - - - - -
Monosodium phosphate 23 23 22 21 20 20
Salt 8 8 8 8 8 8
Vitamin premix1 4 4 4 4 4 4
Trace mineral premix2 4 4 4 4 4 4
___ ___ ___ ___ ___ ___
Totals 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb.1396 1388 1396 1387 1429 1421
Crude protein, % 14.5 14.3 14.4 14.2 14.6 14.4
Lysine (estimated), % .65 .65 .65 .65 .65 .65
Calcium, % .65 .65 .65 .65 .65 .65
Phosphorus, % .55 .55 .55 .55 .55 .55
_________________________________________________________________
Table 9. (Continue..)
________________________________________________________________
Diet
__________________________________________
7 8 9 10 11 12
________________________________________________________________
Ingredients, lb.
Corn 1300 1284 1288 1270 1281 1262
Soybean meal, 48% 246 - 257 - 270 -
Soybean meal, 44% - 263 - 275 - 290
Alfalfa - - - - - -
Birdsfoot trefoil - - - - - -
Red clover - - - - - -
Kentucky bluegrass 400 400 - - - -
Orchardgrass - - 400 400 - -
Ryegrass - - - - 400 400
Ground limestone 12 12 13 13 9 9
Dicalcium phosphate 26 25 26 26 24 23
Monosodium phosphate - - - - - -
Salt 8 8 8 8 8 8
Vitamin premix1 4 4 4 4 4 4
Trace mineral premix2 4 4 4 4 4 4
___ ___ ___ ___ ___ ___
Totals 2000 2000 2000 2000 2000 2000
Calculated composition
Metab. energy, kcal/lb1385 1375 1386 1376 1401 1390
Crude protein, % 14.1 13.8 13.9 13.7 13.7 13.5
Lysine (estimated), % .65 .65 .65 .65 .65 .65
Calcium, % .65 .65 .65 .65 .65 .65
Phosphorus, % .55 .55 .55 .55 .55 .55
________________________________________________________________
1Should provide the following amounts per ton of complete feed:
1,500,000 IU vitamin A; 500,000 IU vitamin D; 2000 IU vitamin E;
2 g vitamin K; 2 g riboflavin; 16 g niacin; 8 g pantothenic acid;
10 mg vitamin B12; 400 mg choline; 540 mg folic acid.
2Should provide the following amounts per ton of complete feed: 5
g copper; 55 g iron; 55 g zinc; 15 g manganese; 150 mg iodine;
272 mg selenium.
Complete feed. When any forage is incorporated into a com-
plete feed, the energy density of the feed is decreased because
of the low concentrations of metabolizable energy in forages.
Tables 6 and 7 provide suggested gestation diets containing
alfalfa and other forage. To determine whether these diets are
more economical than conventional diets, the producer must do two
things. First, calculate the costs per lb. of the conventional
diet and the high forage diets using current market prices. Next,
calculate the feed cost per day of feeding a sow on each of the
diets-keeping in mind that sows will require about 0.5 lb. of
additional feed per day for every 500 lb. of forage included in a
1-ton formulation.
For example, a conventional diet may cost $140/ton. At a 5
lb. feeding rate, the feed cost per sow per day would be $0.35 (5
lb. X [$140/2000 lb.]). A high forage diet (containing 500 lb. of
alfalfa) may cost only $130 per ton. But since the sow will need
5.5 lb. each day to meet her energy requirements, the daily feed
cost would be $0.36 (5.5 lb. X [$130/2000 lb.]).
Table 8 provides suggested high-forage diets for grower
pigs. Since the amounts of forage in these formulations are at a
moderate level of 250 lb. per ton, little or no change in weight
gain or feed conversion is expected. This means that as long as
the feed cost per ton of the high-forage diets is similar or
lower than a conventional diet, feed cost per lb. of gain should
also be similar to that of a conventional diet.
However, in Table 9, 400 lb. of forage per ton of feed are
suggested in each of the diets for finisher pigs. Research shows
that although finisher pigs can utilize higher levels of forage
than that of grower pigs, growth rate in finishing pigs consuming
the diets in Table 9 would be reduced by 5 to 10%, and feed/gain
ratios would be increased by 10 to 15%. Therefore, the feed cost
of the high-forage diet should be at least 10% less than a con-
ventional finisher diet to be economical. For example, if a con-
ventional finisher diet costs $130 per ton, a high forage diet
should cost no more than $117 per ton (130 - [10% X $130] =
$117).
Summary
Forages in the form of pasture, or as part of a complete
feed, can be successfully used in pork production. However,
because of their high-fiber content and low-energy density, they
should be used only to a limited extent for young pigs and lac-
tating sows. Even in growing-finishing, and gestation diets,
forage is best utilized at an early stage of maturity. Forages
may be used to reduce both grain and protein costs, but producers
should consider all factors discussed before making forage a
major part of the diet.
NEW 6/90(5M)
______________________________________________
Cooperative Extension Work in Agriculture and Home Economics,
State of Indiana, Purdue University and U.S. Department of Agri-
culture Cooperating. H.A. Wadsworth, Director, West Lafayette,
IN. Issued in furtherance of the Acts of May 8 and June 30, 1914.
It is the policy of the Cooperative Extension Service of Purdue
University that all persons shall have equal opportunity and
access to our programs and facilities.
.