Sex provided the most significant and consistent response for both growth and carcass
performance. Gilts grew slower (P<.01), consumed less feed (P<.05), were more efficient
(P<.10) and had lower feed cost/pound of gain (P<.10). Gilt carcasses were leaner (P<.05), but
carcass yield, hot carcass weight and total carcass value were similar to that of barrows.
Pig performance, when fed either soybean meal or field pea, was similar for daily gain and feed to gain, but pigs consuming field pea ate less daily feed (P<.10), had lower feed cost/pound of gain (P<.05) and, subsequently, lower feed cost/head (P<.01). The overall lower cost of production for field pea was a function of more efficient growth and a lower cost for locally-grown pea grain.
Carcasss performance was not affected by protein supplement. No differences due to protein
source were detected for carcass yield, percent lean, hot carcass weight, fat depth, loin depth or
total carcass value.
Increasing lysine concentration above normal levels did not improve pig growth or overall
carcass performance, although carcass yield was lower (P<.10). The reduction in yield resulted
in a total carcass value reduction of $3.32 per carcass. A protein source by lysine interaction
suggested that it was unnecessary to feed additional lysine in these diets and that diets formulated
with Trapper field pea should be both efficient and economical.
Pigs finished during the winter months were less efficient (P<.01), requiring more energy for
maintenance than summer fed pigs. While winter fed pigs were less efficient, carcass yield was
higher (P<.01) during the winter. Interactions between sex and season fed suggest that gilts were
more sensitive during the summer and can be expected to eat less (P<.001) and gain slower
(P<.001), but that efficiency between barrows and gilts, within a given season is likely to be
similar. An interaction between sex, protein source and season was detected for feed efficiency,
loin depth, and fat free lean index. The interaction suggested that both sexes were more efficient
during the summer feeding period, that gilts can be expected to be leaner than barrows regardless
of season, and that barrows and gilts, in this study, perform as well when fed field pea as they do
when fed soybean meal.
Trapper field pea was shown to be a suitable replacement supplement for soybean meal when
replaced on a percentage of protein basis within each growth phase from 75 to 265 pounds. With
the exception of the phase-1 diet for 50 to 80 pound pigs, field pea, as tested in this investigation,
contained sufficient lysine to maximize efficiency of feed utilization and carcass leanness.
Seasonal increases in lysine levels for hot weather recommended in other regions of the country
do not seem to be necessary in western North Dakota. This is probably because the window of
hot temperatures is not long, evenings are cool, and pigs compensate during cooler hours of the
day. Based on the results of the pigs tested, gilts would be expected to be leaner, eat less and
gain slower, but be equally efficient as their barrow counter-parts.
Lysine is generally accepted as being the first limiting amino acid in barley-soybean meal based
growing-finishing diets for pigs. Seasonal variations in temperature on dietary lysine
requirements have been reported, documenting variations in eating patterns as pigs encounter
temperatures above and below thermal neutrality (Schenck et al., 1992). Ina cold environment,
pigs normally eat more to compensate for increasing maintenance needs, whereas in a hot
environment pigs reduce feed intake in an attempt to reduce the need to dissipate heat from
digestion and metabolic processes (Holmes and Close, 1977, Close and Stanier, 1984).
Sex also affects lysine requirement. Generally, gilts require a higher level of protein to maximize
performance and carcass leanness than barrows. Growth performance studies conducted by the
NCR-42 Committee (Cromwell, et al., 1993) defined gilts as being more efficient, leaner, having
larger loin-eye muscle area and greater percentage of carcass muscle. They were also more
sensitive to low protein diets than barrows. In this large study, designed to evaluate the effect of
lysine level on lean growth rate, barrows reached a plateau in perfor-mance relative to lysine
supply at approximately 13% CP (.58% lysine). Gilts, however, continued to improve lean
growth (but at a decreasing rate) up to approximately 17% CP (.87% lysine).
Given the affect that sex, season and dietary protein/energy source can have on growth
perfor-mance, this growing-finishing experiment was de-signed to evaluate summer and winter
lean growth performance among split-sex fed barrows and gilts when Trapper field pea replaced
all of the soybean meal.
Four-phase, barley-based growing-finishing diets supplemented with either soybean meal or
Trapper field pea were fed. Diets were formulated to contain two levels of lysine. Formulations
of the diets for each feeding phase and calculated nutrient analysis are shown in Table 1.
Synthetic lysine was added to provide equal lysine concentrations across diets within each phase.
DL-methionine was added as necessary to provide a minimum of .49, .46, .46 and .43%
methionine+cystine in phases 1, 2, 3 and 4, respectively. All other amino acids were provided
for by dietary ingredients and their suggested balance, with respect to lysine, either just met or
exceeded NRC recommendations (NRC, 1988).
The winter group of pigs had heavier starting weights, therefore, the phase-1 diet was not used.
A sample of pigs from each sex were weighed on a weekly basis as the time for a phase change
approached. When the average of the sample pigs most closely matched the phase's ending
weight, the diets were changed to the next phase. Both barrows and gilts were fed to a weight
constant end point range between 260 and 270 pounds. Pigs were weighed and identified for
shipment to John Morrell Packing, Sioux Falls, SD, the week prior to expected slaughter. Then,
approximately 24 hours before slaughter each pig was back tattooed to the left of the mid-line
with an ID number and shipped to John Morrell Packing via the Southwest Shippers Association.
Carcass data was collected by John Morrell, entered into a database and returned for analysis.
Data was analyzed for main effects [sex (barrows vs. gilts), supplement source (soybean meal vs.
Trapper field pea), lysine level (low vs. high), season fed (winter vs. summer)] and all possible
interactions using GLM procedures of SAS (SAS, 1988).
Pig performance, when fed either soybean meal or field pea, was similar for daily gain and feed
to gain, but pigs consuming field pea ate less daily feed (P=.068), had lower feed cost/pound of
gain (P=.008), and subsequently, lower feed cost/head (P=.01). The overall lower cost of
production for field pea was a function of comparable growth efficiency and a lower cost for
locally-grown pea grain.
Carcass evaluation, following field pea or soybean meal supplementation, suggests that carcass
performance is similar with either supplement, since no differences for carcass yield, percent
lean, hot carcass weight, fat depth, loin depth or total carcass value were detected.
Increasing lysine concentration above normal levels did not improve pig growth or carcass
performance. Feeding higher lysine increased the cost of production and lowered carcass yield
(P=.081) resulting in a lower total carcass value of $135.99, as compared to a carcass return of
$139.31 when normal lysine levels were fed. A protein source by lysine interaction suggested
that it was unnecessary to feed additional lysine and that diets formulated with Trapper field pea
can be both efficient and economical.
Pigs finished during the winter months were less efficient, requiring more energy for
maintenance than summer fed pigs. Comparing summer and winter performance, daily gains for
the seasons were similar, however, daily feed intake during the summer was lower (P=.0001)
and feed efficiency was improved (P=.0001). Summer and winter carcass performance was
similar for most aspects. The one exception was carcass yield. Although winter fed pigs were
less efficient, their carcass yields were higher (74.6% vs. 72.9%) (P=.0001). Total carcass value
was higher for summer pigs. The documented increase was not entirely due to improved carcass
performance, but more likely was due to better hog prices, which increased dramatically between
the two seasons.
A sex by season interaction was observed for ADG and daily feed intake as shown in Table 3.
Gain and feed consumption were similar during the winter for barrows and gilts, but summer fed
gilts were more sensitive to summer warmth than barrows. Gilts consumed less daily feed
(P=.0003) and grew slower (P=.0001) than the barrows. Summer feed efficiency was improved
as compared to winter efficiency, but within a given season feed efficiency was similar. A sex by
protein source by season interaction was detected for feed efficiency, loin depth, and fat free lean
index. Comparing feed efficiency for barrows and gilts, gilts fed field pea during the winter were
the most efficient, whereas gilts fed soybean meal were the most efficient during the summer.
The interaction detected for loin depth did not differ for barrows fed either protein supplement in
either season. Gilts, however, were inconsistent between seasons. During the winter period, gilts
fed soybean meal had greater loin depth, but during the summer, gilts fed field pea had greater
loin depths. With respect to fat free lean index, gilts had consistently higher values during both
seasons when either of the protein sources was fed. The greatest fat free lean index was detected
among gilts fed field pea as a source of protein.
Based on the pigs' metabolic response to temperature fluctuations that increase or decrease eating
desire, a season by lysine interaction was anticipated, but none was detected. It is the feeling of
the authors, that the window of hot temperatures in the drier regions of the northern plains is not
long enough to anticipate a reduction in intake, thus, do not warrant higher than normal lysine
levels. Although summer temperatures of 100 F do occur, the duration is usually short, and any
given group of pigs would have opportunity for compensatory growth and efficiency.
Table 1. Composition and Calculated Analysis of Diets fed.
|PHASE 1 (50-80 LBS.)||PHASE 2 (80-140 LBS.)||PHASE 3 (140-190 LBS.)||PHASE 4 (190-265 LBS.)|
|Hi Lysine||Low Lysine||Hi Lysine||Low Lysine||Hi Lysine||Low Lysine||Hi Lysine||Low Lysine|
|Field Pea (Trapper)||0.0||40.0||0.0||40.0||0.0||40.0||0.0||40.0||0.0||40.0||0.0||40.0||0.0||35.0||0.0||35.0|
|Methionine + Cystine.||.49||.50||.50||.50||.46||.50||.46||.50||.46||.50||.46||.50||.46||.43||.46||.43|
|Energy, kcal ME/lb.||1.38||1.38||1.38||1.38||1.40||1.40||1.40||1.40||1.40||1.40||1.40||1.40||1.40||1.40||1.40||1.40|
|Lysine, gms./Mcal of ME||4.0||4.0||3.3||3.3||3.3||3.3||2.8||2.8||3.1||3.1||2.7||2.7||2.9||2.9||2.5||2.5|
Table 2. Combined Seasons Cumulative Performance.
|LOW LYSINE||HIGH LYSINE||
|Initial Wt., lb.||76||75||76||74||76||73||77||76||--|
|Final Wt., lb.||273||260||265||262||267||265||268||266||--|
|Daily Gain, lb.a||2.19||2.0||2.08||1.96||2.11||2.02||2.09||2.01||.04|
|Daily Feed, lb.a,d,f,g||8.22||7.35||7.41||6.88||7.67||7.11||7.72||7.20||.223|
|Fat Depth, in.b||.88||.78||.91||.68||.89||.73||.97||.61||.048|
|Loin Depth, in.b,j||1.99||2.15||1.93||2.07||2.00||2.09||1.95||2.16||.041|
|Hot Carcass Wt., lb.||199||188||194||185||186||190||190||186||3.47|
|Percent Yield, %e,f,j||74||75||74||74||73||74||74||72||.59|
|Percent Lean, %b,i||51||53||50||54||50||54||49||54||.73|
|Fat Free Lean Index, %b,i,j||48||49||47||50||47||49||46||50||.53|
|Feed Cost/Lb. of Gain,$a,c,e,g||.301||.293||.279||.275||.300||.290||.295||.287||.005|
|Feed Cost/Head, $b,c,h||59.29||55.20||52.83||51.46||57.21||55.70||56.16||54.34||1.50|
|Carcass Value, $||141.5||138.5||140.2||136.9||132.6||139.3||135.1||136.8||--|
|Return Over Feed, $||82.22||83.39||87.39||85.49||75.45||83.66||78.96||82.49||---|
a Sexes differ (P<.10).
b Sexes differ (P<.05).
c Protein supplement differs (P<.01).
d Protein supplement differs (P<.10).
e Lysine level differs (P<.10).
f Season differs (P<.0001).
g. Protein supplement x lysine level interaction (P<.05).
h Protein supplement x lysine level interaction (P<.10).
i Sex x lysine interaction (P<.10).
j Sex x protein supplement (P<.05).
Table 3. Performance interactions for sex x season and sex x protein source x season for selected criteriac.
Gilts a Sex x season interaction (P<.01).
SEX x SEASON Gilts
Barrows ADG, lb.a : Winter
2.16 SE = .028 Daily Feed, lb.a : Winter
7.63 SE = .157 Feed To Gain, lb.: Winter
3.52 SE = .046 SEX X PROTEIN SOURCE X SEASON Barrows SBM
PEA Feed To Gain, lbc : Winter
3.47 SE = .065 Loin Depth, in.b: Winter
1.94 SE = .041 Fat Free Lean Index, %d: Winter
46.8 SE = .53
c Sex x protein source x season interaction (P<.05).
d Sex x protein source x season interaction (P<.10).
a Sex x season interaction (P<.01).b Sex x protein source x season interaction (P<.01).
Cromwell, G.L., T.R. Cline, J.D. Crenshaw, R.C. Ewan, C.R. Hamilton, A.J. Lewis, D.C.
Mahan, E.R. Miller, J.E. Pettigrew, L. F. Tribble, and T.L. Veum. 1993. The dietary
protein and (or) lysine requirements of barrows and gilts: NCR-42 Committee on Swine
Nutrition Report. J. An. Sci., 71:1510.
Holmes, C.W., and W.H. Close. 1977. The influence of climatic variables on energy
metabolism and associated aspects of productivity in the pig. In: W. Haresign, H. Swan, and D.
Lewis (Ed), Nutrition and the Climatic Environment. pp 51-73. Butterworths, London.
NRC. 1988. Nutrient Requirements of Swine (9th Ed.). National Academy Press, Washington,
Schenck, B.C., T.S. Stahly, and G. L. Cromwell. 1992. Interactive effects of thermal
environment and dietary lysine and fat levels on rate, efficiency and composition of growth of
weanling pigs. J. Anim. Sci. 70:3791.
SAS. 1988. SAS User's Guide: Statistics. SAS Inst. Inc., Cary, NC.
Location where the research was (primarily) done
Dickinson Research Extension Center Ranch, Manning, ND and Dickinson Research Extension Center, Dickinson, ND
Additional credits the author(s) need to give
Authors greatly appreciate funding support provided by the ND Agricultural Products Utilization Commission and the ND Dry Pea and Lentil Association.
2.Doug Landblom, Animal Scientist, Dickinson Research Extension Center, Dickinson, ND
3.Chip Poland, Area Livestock Specialist, Dickinson Research Extension Center, Dickinson, ND email@example.com