Introduction and experimental
 Results and discussion
 Literature cited

Group Title: Animal science research report - University of Florida Department of Animal Science ; AL73-8
Title: Influence of sex, grinding of corn, and potassium supplementation on feedlot performance and carcass characteristics of pigs fed corn and supplement free-choice
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00073049/00001
 Material Information
Title: Influence of sex, grinding of corn, and potassium supplementation on feedlot performance and carcass characteristics of pigs fed corn and supplement free-choice
Series Title: Animal science research report
Physical Description: 7 leaves : ; 28 cm.
Language: English
Creator: Wallace, H. D ( Harold Dean )
University of Florida -- Dept. of Animal Science
University of Florida -- Agricultural Experiment Station
Publisher: Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1973
Subject: Swine -- Feeding and feeds -- Florida   ( lcsh )
Swine -- Carcasses -- Quality -- Florida   ( lcsh )
Corn as feed   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (leaf 7).
Statement of Responsibility: H.D. Wallace ... et al..
General Note: Caption title.
General Note: "November, 1973."
Funding: Animal science research report (University of Florida. Dept. of Animal Science) ;
 Record Information
Bibliographic ID: UF00073049
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 80015644

Table of Contents
    Introduction and experimental
        Page 1
    Results and discussion
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
    Literature cited
        Page 7
Full Text

~ Department of Animal Science Florida Agricultural
, Animal Science Research Report AL73-8 Experiment Station
November, 1973 Gainesville, Florida /


H. D. Wallace, A. Z. Palmer, J. W. Carpenter
and G. E. Combs _/

A report published last year (1) indicated that gilts consumed about one

percent more protein than barrows when fed shelled corn and a complete supplement

free-choice (calculated as a complete feed mixture). Gilt gains were below those

of barrows more than normally observed suggesting that free-choice feeding may

nutritionally stress the gilt more than the barrio eire-

ments for protein. The main objective of this st dy was to further inves igate

the relative protein needs of barrows and gilts b4 the fi- ch~c~ e /ethod of

feeding. Secondly, it was of interest to determine the effect of grinding corn
c \S U- niv. of Floridal
as opposed to using shelled corn in free-choice fea H''s" desired

to evaluate potassium supplementation in an effort to confirm results reported

in a previous paper (2).


Twenty-eight barrows and twenty-eight gilts averaging approximately 60

pounds initially were used in the study. The barrows were divided into four

pens of seven pigs each, as were the gilts. Two pens of barrows and two pens

I/ The data published in this report were generated in swine unit experiment
No. 195-F, Barn No. 4.
2/ Wallace and Combs, Animal Nutritionists; Palmer and Carpenter, Meat Scien-
tists, Department of Animal Science.

This public document was promulgated at an annual cost of
$108.66, or elevencents per copy to inform county agricul-
tural directors, ranchers and growers of research results
in swine management and nutrition.

Department of Animal Science
Institute of Food and Agricultural Sciences


of gilts were fed shelled yellow corn and a complete supplement free-choice.

Similarly, two pens of barrows and two pens of gilts were fed ground yellow corn

and supplement free-choice. One pen of barrows and one pen of gilts on each type

corn were supplemented with potassium.

All pigs were self fed in an open shed type barn on partially slotted floors

over manure storage pits.

Composition of the protein supplement fed to all pigs is shown in Table 1.

Table 1. Composition of Protein Supplement
Soybean oilmeal (50%) 47.20
Meat scraps (45%) 25.00
Alfalfa meal (20%) 25.00
Iodized salt 2.00
Trace mineral supplement 1/ 0.40
Vitamin premix (UF) 2/ 0.40
Potassium 3/
1/ Calcium Carbonate Co., Quincy, Illinois.
Formula 35Z-95. Contains: 20% zinc, 10%
iron, 5.5% manganese, 1.1% copper, 0.15%
iodine, 0.10% cobalt and 2% calcium.
2/ Contains 6,000 mg. riboflavin; 20,000 mg.
niacin; 12,000 mg. pantothenic acid;
80,000 mg. choline chloride; 10,000 mcg.
Vitamin B12; 2,500,000 I.U. Vitamin A;
400,000 I.C.U. Vitamin D3 and 10,000 I.U.
of Vitamin E per pound premix.
3/ Dyna K, a product produced and generously
supplied by International Minerals and
Chemical Corporation, Skokie, Illinois,
was used as a source of potassium. Po-
tassium was added at a level of 1% to
the protein supplement of those pigs
supplemented with potassium.

All pigs were weighed and feed consumption determined at two week intervals.

Slaughtering and carcass measurements were according to previously described

procedures (3).

Data were analyzed statistically using the analysis of variance.

Results and Discussion

Results of the experiment are summarized by lots in Table 2 and according to main

variables in Table 3. Table 4 summarizes the sex influence on dietary protein intake.

Table 2. Influence of Sex, Grinding of Corn, and Potassium
Supplementation on Feedlot Performance and

Carcass Characteristics
Supplement Free-Choice

of Pigs Fed Corn and

Lot No. 5 5A 6 6A 7 7A 8 8A
Sex (M = Barrow)
(F = Gilt) M F M F M F M F
Form of corn Shelled Shelled Shelled Shelled Ground Ground Ground Ground
Potassium + + + +

Number of pigs 7 7 7 7 7 7 7 7
Av. initial wt., lb. 59.6 59.2 59.9 59.1 59.6 58.9 59.7 59.4
Av. final wt., lb. 217.7 216.0 218.0 221.1 220.3 218.1 223.4 219.0
Av. daily gain 1.56 1.35 1.48 1.39 1.50 1.48 1.59 1.48
Feed/unit gain, lb.
corn 2.87 2.88 2.84 2.67 2.88 2.52 2.71 2.63
supplement 0.54 0.78 0.56 0.68 0.55 0.66 0.60 0.66
Dressing % 71.3 73.8 70.9 71.0 72.1 73.0 72.9 71.8
Backfat, in. 1.34 1.11 1.27 1.10 1.24 1.24 1.44 1.27
Carcass length, in. 31.1 32.0 30.8 31.9 31.7 31.7 30.8 31.4
Loin eye area, sq. in. 4.00 4.70 4.19 4.92 3.88 4.24 4.38 4.32
% lean cuts 52.1 55.4 53.5 57.8 52.6 53.9 52.0 53.3
Marbling scores a/ 13.9 10.0 13.3 13.0 14.3 15.0 15.9 16.7

a/ Scores were coded from 0 to 33; small = 10-12, modest = 13-15, moderate = 16-18, etc.


Table 3. Summary of Combined Performance and
Carcass Characteristics,as Influenced

by Sex, Grinding

of Corn and Potassium

Number of pigs
Av. initial wt.; lb.
Av. final wt., lb.
Daily gain, lb.
Feed/gain, lb.
Dressing %
Backfat, in.
Carcass length, in.
Loin eye area, sq. in.
% lean cuts
Marbling scores

28 28
59.7 59.2
219.9 218.6
1.53** 1.43
3.39 3.38
2.83 2.68
0.56 0.70
71.8 72.4
1.32** 1.18
31.1 31.8**
4.11 4.55**
52.6 55.1**
14.4 13.7

Form of Corn
Shelled Ground
28 28
59.5 59.4
218.2 220.2
1.45 1.51*
3.46 3.31
2.82 2.69
0.64 0.62
71.8 72.5
1.21 1.30
31.5 31.4
4.45* 4.21
54.7** 53.0
12.6 15.5*

28 28
59.3 59.5
218.0 220.4
1.47 1.49
3.42 3.34
2.79 2.71
0.63 0.63
72.6 71.7
1.23 1.27
31.6 31.2
4.21 4.45*
53.5 54.2
13.3 14.7

* P < .05
** P < .01

Table 4. Protein Intake (%) By Barrows
and Gilts in Free-Choice
Corn-Supplement Feeding

Wt. range (lb.) Period Barrows Gilts

60 96 4 week 15.45 15.47
60 144 8 week 15.19 16.04
60 220 entire 13.66 14.99

I_ _____ _

5 -

Daily gain Barrows gained significantly faster than gilts (1.53 vs. 1.43

pounds per day). A comparable number of barrows and gilts fed complete feed

mixtures simultaneously under comparable conditions (2) gained 1.60 and 1.46

pounds per day respectively. Thus results from the present trial tend to confirm

the generally held opinion that pigs fed free-choice usually gain somewhat slower

than pigs fed complete mixed rations. Pigs fed ground corn gained faster (P < .05)

than pigs fed shelled corn. Potassium supplementation did not influence rate of


Feed/gain Feed conversion data were not statistically analyzed due to

experimental design. The mean values obtained indicate a clear difference in

protein supplement consumption per pound of gain (0.56 vs. 0.70 lb.) for barrows

and gilts. In table 4 these differences were calculated as a percentage of a

complete feed mixture and indicate that gilts by choice will consume more than

1% higher level of protein than barrows. Most of the difference observed occurred

after the first four weeks of the trial. Grinding the corn and potassium supple-

mentation both appeared to exert a modest improvement in feed conversion.

Dressing percent Dressing percent was not significantly affected by any

of the variables imposed.

Backfat Barrow carcasses measured significantly more backfat (P < .01)

than gilt carcasses. Numerical values indicated fatter carcasses from pigs fed

ground corn and those supplemented with potassium but these differences were non-


Carcass length Gilt carcasses averaged 31.8 in. compared to 31.1 for

barrows, a highly significant difference. The other variables did not influence

this measurement significantly.

Loin eye area Differences were significant (P < .01) for sex. Barrows

averaged 4.11 sq. in. compared to 4.55 sq. in. for gilts. Pigs fed shelled corn

showed loin eyes of 4.45 sq. in. compared to 4.21 sq. in. (P < .05) for pigs

6 -

given the ground corn. Gilts increased in loin eye size relatively more on shelled

corn than barrows resulting in a highly significant sex x form of corn interaction.

Gilts gained relatively slower on shelled corn. This may have influenced carcass

leanness and final loin eye size. Potassium supplementation also increased loin

eye area (P < .05).

Percent lean cuts Gilts yielded significantly higher (P < .01) percent of

lean cuts than barrows (55.1 vs. 52.6). Pigs fed shelled corn yielded 54.7 percent

lean cuts compared to 53.0 for pigs fed ground corn, a highly significant difference.

A significant interaction of sex x form of corn was again apparent. Gilts fed

shelled corn were relatively leaner compared to barrows than gilts fed ground corn.

Potassium supplementation did not increase lean cut out significantly.

Marbling scores Marbling scores were significantly higher (P < .05) for

pigs fed ground corn compared to shelled corn. Other variables did not affect

this measurement.


An experiment involving 56 pigs was conducted to determine the influence of

sex (barrows vs. gilts), corn preparation (shelled vs. ground) and potassium

supplementation on feedlot performance and carcass characteristics of pigs fed

corn and supplement free-choice.

Barrows gained faster than gilts, consumed less protein supplement (calculated

as 1.33% less protein on a complete mixed feed basis) and yielded shorter, fatter

carcasses with smaller loin eye areas that cut out lower percentages of lean cuts.

Grinding of the corn induced more rapid gains and fatter carcasses as indicated

by differences in backfat thicknesses, loin eye area, percent lean cuts and marbling


Potassium supplementation did not improve gains but did result in a signifi-

cant increase in loin eye size (P < .05), an observation not readily explained

on the basis of feedlot performance data.

7 -

Literature Cited

1. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1972.
Influence of sex, pen space and feeder holes per pig on protein con-
sumption, feedlot performance and carcasses of pigs fed shelled corn
and supplement free-choice. Fla. Animal Sci. Res. Rpt. No. AL 1972-4.

2. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1973.
Influence of sex, dietary protein level and potassium supplementation
on feedlot performance and carcass characteristics of pigs. Fla.
Animal Sci. Res. Rpt. No. AL 1973-7.

3. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1966.
Feed restriction of swine during the finishing period. Fla. Agr. Expt.
Sta. Bul. 706.

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