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Arkansas Animal Science Department Report 2001
ing order: 1) 1.5-inch thick chop; 2) 1 inch thick chop; and 3)
1.5-inch thick chop.
The two 1.5-inch thick chops were used for drip loss
determinations following modifications to the suspension
procedure of Honikel et al. (1986). A 1.5-inch diameter core
was removed from each 1.5-inch thick chop, weighed, and
suspended on a fishhook (barb removed) mounted to the lid
of a plastic container (18 in. deep x 15 in. wide x 24 in. long)
and stored at 34°F. After 48 hr, each core was blotted with a
paper towel and reweighed. The loss in weight due to drip
and evaporation was divided by the original weight, multiplied
by 100 and reported as drip loss percentage.
Furthermore, a 2 g sample of longissimus muscle was excised
after core removal for muscle pH determination following the
protocol outlined by Bendall (1973).
A1 inch thick bone-in chop was removed from the loin,
over-wrapped with PVC film, and, after a 45 minute bloom
period, chops were evaluated by a three-person panel for marbling
(1 = 1% intramuscular fat and 10 = 10% intramuscular
fat; NPPC, 1999), firmness (1 = very soft/watery and 5 = very
firm/dry; NPPC, 1991), and color based on both the 6-point
American (1 = pale, pinkish gray to 6 = dark purplish-red)
and Japanese (Nakai et al., 1975) color scale. The Japanese
color standards system is composed of six plastic disks with
meat-like texture and appearance developed from objective
colorimetry, and scores range from 1(pale gray) to 6 (dark
purple). Also, CIE (1976) L*, a*, b* values were determined
from a mean of three or four random readings made with the
Hunter MiniScan XE (model 45/0-L, Hunter Associates
Laboratory, Reston, VA) using illuminant C and a 10° standard
observer.
Data were analyzed using the general linear model
(GLM) procedure of SAS (SAS Inst., Cary, NC), with pen as
the experimental unit for all performance data and loin as the
experimental unit for all carcass data. Least squares means
were generated and separated statistically by PDIFF option
of GLM.
Implications
Results from this study confirm that supplementing the
diets of growing-finishing swine with excess manganese does
not affect live animal performance. Even though drip loss,
marbling, or subjective color scores were not influenced by
elevated dietary manganese, supplemental manganese at a
level of 350 ppm may have beneficial effects on L* values.
Literature Cited
Bendall, J. R. 1973. In: G. H. Bourne (ed.). Structure and
Function of Muscle, Vol. 2. p. 244. Academic Press,
New York.
CIE. 1976. Commission Internationale de I’Eclairage, Paris.
Grummer, R. H., et al. 1950. J. Anim. Sci. 9:170.
Honikel, K. O., et al. 1986. Meat Sci. 16:267.
Leibholz, J. M., et al. 1962. J. Anim. Sci. 21:772.
Nakai, H., et al. 1975. Bull. Natl. Inst. Anim. Industry (Chiba)
29:69.
NPPC. 1999. Official Color and Marbling Standards.
National Pork Producers Council, Des Moines, IA.
NPPC. 1991. Procedures to evaluate Market Hogs (3rd
Edition). National Pork Producers Council, Des
Moines, IA.
NRC. 1998. Nutrient Requirements of Swine (10th Edition).
National Academic Press, Washington, DC.
Plumlee, M. P., et al. 1956. J. Anim. Sci. 15:352.
Svajgr, A. J., et al. 1969. J. Anim. Sci. 29:439.
Results and Discussion
Neither Mn source or supplementation level had an
effect (P > 0.10) on ADG, ADFI, or F/G (Table 1). Our results
concur with those of Plumlee et al. (1956) and Leibholz et al.
(1962), who reported that ADG and F/G were not affected in
pigs fed diets supplemented with Mn. However, Grummer et
al. (1950) observed improvements in ADG and F/G in pigs
fed supplemental Mn at levels of only 40, 80, and 160 ppm.
The effects of Mn on carcass characteristics are presented
in Table 2. Backfat depth at the first rib, last rib, and
last lumbar vertebra, as well as average backfat depth, loin
eye area, drip loss percentage, ultimate pH, Japanese color,
American color, marbling, or a* values were not (P > 0.10)
affected by Mn supplementation. However, pork from pigs
fed diets containing 350 ppm Mn from AvailaMn-80 was
darker (lower L* values; P < 0.05) than pork from pigs fed
diets containing 700 ppm Mn from AvailaMn-80.
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