Animal Husbandry and Nutrition Florida Agricultural
Mimeograph Series No. 60-12 Experiment Station
February, 1960 Gainesville, Florida
THE INFLUENCE OF SLAUGHTER WEIGHT ON ECONOMY OF
PRODUCTION AND CARCASS VALUE OF SWINE
H. D. Wallace, G. E. McCabe, A. Z. Palmer, M. Koger,
J. W. Carpenter and G. E. Combs I
Leaders in the swine industry are devoting much effort toward the
production of more efficient hogs with meatier carcasses. To attain these
objectives emphasis is given to better breeding, feeding and overall man-
agement. The importance of these aspects of swine production is readily
conceded. However, it is also true that other factors, such as those re-
lated to marketing and processing, are important. At present the most
desirable slaughter weight for finished hogs is generally accepted as
ranging from 180-220 pounds. There is little experimental evidence to
indicate that this weight range actually represents the optimum from the
standpoint of both production costs and excellence of the carcasses produced.
The object of this study was to determine the influence of slaughter
weight on the economy of production and carcass value of swine.
This study consisted of two trials. Trial I involved forty-eight
weanling pigs divided into four slaughter weight groups of 150, 180, 210
and 240 pounds. Four pigs were placed in each lot and each slaughter
group was!replicated three times for a total of twelve pigs. The pigs
were all maintained in shaded concrete pens which were cleaned and washed
as necessary. In Trial II, eighty weanling pigs were divided into the same
four slaughter-weight groups as in Trial I. One-half of the pigs in each
group (10,animals) were placed into four I acre oat-wheat pasture lots,
while the remaining one-half of each group (10 animals) were allotted into
four shaded concrete pens.
All pigs were self fed the rations described in a previous report
(Fla. An. Husb. and Nutr. Mimeo Series No. 60-11, 1960). Feeding, manage-
ment and carcass measurements were also the same as described in the above
Trial I was initiated in October of 1958 and completed i rj-I959.
Trial II was initiated in December, 1958 and completed in J -959 ...
. ...- ..... .
/ Wallace, McCabe, Palmer, Koger, Carpenter and Combs; ciatenjmal
Husbandman, Graduate Assistant, Associate Animal Husba'd n, AnimmaCO-'
Husbandman, Assistant Animal Husbandman and Assistant AI Husban fa
respectively, Department of Animal Husbandry and NutritiOe&W ss)-
tance of W. E. Collins and L. S. Taylor, Swine Herdsmen, is ~ eftly
Results and Discussion
A preliminary examination of the results Indicated that the replicated
lots of Trial I performed very similarly, as did the pigs fed on concrete or
pasture in Trial 11. Thus, all data from the two trials have been combined
according to the various slaughter weights and are presented as such in
Table I. THE INFLUENCE OF SLAUGHTER WEIGHT ON ECONOMY OF
PRODUCTION AND CARCASS CHARACTERISTICS OF SWINE
Slaughter Weight, lb. 150 180 210 240
Number of pigs 31 30 32 31
Av. initial wt., lb. 44.8 44.5 44.4 44.2
Av. daily gain, lb. 1.44 1.48 1.53 1.52
Feed per lb. gain, lb. 3.17 3.24 3.33 3.41
Selling price per cwt. liveweight, $ 15.00 15.50 16.00 16.00
Returns per pig over feed and initial
cost of pig -L$ 1.40 4.15 5.24 6.04
Dressing percent 70.6 70.8 71.7 72.6
Carcass length, in. 26.7 28.2 29.1 30.6
Av. backfat thickness, in. 1.13 1.27 1.48 1.52
Loin eye area, sq. in. 3.43 3.85 4.07 4.45
Percent lean cuts (carcass wt. basis) 53.7 53.4 51.0 49.3
Percent lean cuts (liveweight basis ) 38.0 37.8 36.6 35.8
Percent fat trim 17.6 17.8 19.7 20.3
Av. weight of hams per pig, lb. 21.5 25.8 28.9 32.9
Av. weight of loins per pig, Ib. 17.2 20.6 23.1 25.6
Av. weight of butts per pig, lb., 7.0 8.1 8.9 10.4
Av. weight of picnics per pig, lb. 10.5 12.9 14.5 16.2
Av. weight of sides per pig, lb. 12.5 15.9 18.9 22.9
Adjusted cut value 2/ 80.3 79.5 76.4 73.8
Initial cost of pigs -- $10.00 per head: Feed cost -- $69.00 per ton.
2/ A study by Breidensteinof tne Illinois Station.revealed that the re-
lative sale value of the four lean cuts suggested the following value
ratios: picnic shoulder -- 1.000; Boston butt -- 1.363; loin -- 1.699
and ham -- 1.642. By using these factors the adjusted cut values
shown in the table were determined.
In this study pigs that were fed to the heavier weights (210 and 240
Ib.) gained significantly faster (P / .01) than pigs fed to the lighter
weights (150 and 180 lb.). However, these differences were not as great as
might have been expected. The pigs made excellent gains from weaning to
150 pounds but did not increase rate of gain greatly from thereon. Weather
conditions were less than ideal during the finishing period of these trials
and may partially explain the rather unimpressive performance of the pigs.
As would be expected, the feed required per pound gain increased as
the slaughter weight increased. All groups were very efficient in the
conversion of feed to gain. Pigs fed to the heaviest weight of 240 pounds
required 3.41 pounds of feed per pound of gain while those fed to the
lightest weight of 150 pounds required 3.17 pounds.
Total returns per pig over initial cost and feed increased as the
slaughter weights increased, but at a diminishing rate. Pigs fed to 180
pounds returned $2.75 per head more than pigs fed to 150 pounds. Pigs
fed to 210 pounds returned $1.09 per head more than pigs fed to 180 pounds
and pigs fed to 240 pounds returned $0.80 more per-head than pigs fed to
210 pounds. The prices received for tne hogs as shown in Table I were the
actual prices prevailing at the time the hogs were sold. A study of the
data in Table I reveals that these prices do not coincide very well with
the value of the hogs based on lean cut yields of the carcasses. The pigs
slaughtered at 150 pounds produced carcasses with the highest percent of
lean cuts but sold for the lowest price per hundredweight as, live hogs.
Dressing percentages increased as slaughter weights increased. This
result is probably explained by the increase in fat as the animals became
heavier. Carcass-lengths increased proportionately as the slaughter weights
increased. Backfat thicknesses also increased with slaughter weight but
surprisingly the change between the 210 and 240 pound weights was very
small. Loin eye area increased with the increase in slaughter weight. The
data suggest that approximately 77 percent of the loin eye area of the 240
pound animal was present at the time he weighed 150 pounds.
Percentage lean cuts, which is probably the best single measure of
carcass meatiness, decreased as the slaughter weights increased. There
was very little difference between tie 150 and 180 pound pigs in this
regard. However, a sharp reduction in percent lean cuts was apparent
at the two heaviest weights. Percent lean cuts remained in approximately
the same relationship between the slaughter weight groups whether expressed
on a carcass or liveweight basis.
Percent fat trim increased with an increase in slaughter weight.
The weight of each of the five major primal cuts (these included the
ham, loin, Boston butt and picnic shoulder, which constitute the so called
lean cuts, plus the side) increased as would be expected as the slaughter
An adjusted cut value, involving the four lean cuts, clearly indicated
that the lighter the hog (within the weight range studied) the more valuable
was the pork produced per unit of carcass weight. Furthermore, job and car-
lot prices are generally higher for the lighter wholesale cuts which are
produced by the lighter weight hogs.
Two feeding trials, involving 128 weanling pigs, were conducted to
determine the influence of slaughter weight on economy of production and
carcass value. Pigs were slaughtered at 150, 180, 210 and 240 pounds.
Returns over feed cost and the initial cost of pigs indicated an
increase in total returns but at a diminishing rate with each increase
in slaughter weight.
Dressing percent, carcass length, backfat thickness, loin eye area
and percent fat trim increased with increased slaughter weight.
Percent lean cuts and adjusted cut value decreased as the slaughter
weights increased, indicating that the light weight pigs (150 and 180
pounds) produced more valuable carcasses per unit of weight than did the
heavier pigs (210 and 240 pounds).