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Retail cut yields of Rambouillet wether lambs fed the beta-adrenergic agonist
L644,969
S. D. Shackelford, J. W. Edwards, E. K. Smarr and J. W. Savell
J Anim Sci 1992. 70:161-168.
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Retail Cut Yields of Rambouillet Wether Lambs
Fed the P-Adrenergic Agonist I-,969 1
S. D. Shackelford, J. W. Edwards, E. K. Smarr,
and J. W. Save11
Department of Animal Science, Meat Science Section,
Texas Agricultural Experiment Station,
Texas A&M University, College Station 77843-2471
ABSTRACTS Twenty Rambouillet wether lambs BAA did not affect overall carcass yields of bone-
were given ad libitum access to a diet with (BAA, in retail cuts. However, BAA increased overall
n = 10) or without (control, n = 10) 1 ppm of the p- carcass yields of boneless retail cuts regardless of
adrenergic agonist L644.969. Lambs were fed to a fat trim level. The BAA increased bone-in leg
constant slaughter weight end point of 54.5 kg. yield. Yield of boneless sirloin, bone-in loin and
Carcasses were fabricated to yield bone-in and boneless loin were not affected by BAA. For these
boneless cuts that were trimmed progressively to cuts, the percentage change from the control was
1.27, 3 4 , .32, and .OO cm of S.C. fat remaining. highly dependent on fat trim level. There was no
Addition of BAA did not affect growth traits. difference in shortcut, shank-off,semiboneless leg
Actual and adjusted fat thickness, body wall
thickness, and percentage of kidney-pelvicfat did yield between control and BAA. Addition of BAA
not differ between control and BAA lambs. How- did not affect yield of bone-in rack regardless of
ever, BAA increased longissimus muscle area, fat trim level. However, BAA greatly increased
longissimus muscle depth, and leg score while yield of boneless ribeye. The BAA did not affect
decreasing USDA yield grade. The BAA increased yield of bone-in or boneless shoulder. Carcasses of
carcass conformation scores and decreased flank lambs fed BAA exceeded their control counter-
lean color scores. No other carcass quality parts in boneless retail cut yields but were similar
measurements were affected by BAA. Addition of in bone-in cut yields.
Key Words: Lambs, Carcass Yield, Fat Thickness, Growth Regulators
J. Anim. Sci. 1992. 70:101-168
Introduction to be .35 cm (Harris et al., 1990). Thus, lamb retail
cuts require extensive trimming to meet consumer
Tat- et al. (19891 conducted a national survey demand.
of lamb carcass cutability traits and reported that Some P-adrenergic agonists (BAA) have been
the average fat thickness was .73 cm and the shown to decrease fat deposition and increase
average USDA yield grade was 3.9. A national muscle accretion in lamb (Baker et al., 1984;
market basket survey for lamb reported the Beermann et al., 1986; Hamby et al., 1980; Kim et
average external fat trim level of retail lamb cuts al., 1987; Kretchmar et al., 1990; Koohmaraie and
Shackelford, 1991; Koohmaraie et a . 1991). Con-
l,
siderable research has investigated the effect of
'Technical Article 27071 from the Texas Agric. Exp. Sta. BAA on carcass yield and quality grade measure-
This study w s supported partially by the Texas Food and
a ments. Additionally, several researchers have
Fiber Commission and Merck, Sharpe and Dohme Research shown that BAA improves carcass chemical com-
Laboratories. Mention of trade name, proprietary product, or
specific equipment does not constitute a guarantee or war- position [Baker et al., 1984; Duquette et al., 1987).
ranty of the product by Texas A&M University and does not Moreover, BAA have been reported to increase
imply approval to the exclusion of other products that may wholesale cut weights (Beermann et al., 1986; Kim
also be suitable.
Received February 28, 1991.
et al., 1987). However, those studies involved
Accepted July 26, 1991. feeding lambs on a constant-time basis and, thus,
161
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162 SHACKELPORD ET AL.
Table 1. Composition of diet lean color, LM lean f i i e s s , primary flank
streaking, secondary flank streaking, flank lean
Inmedient % color, skeletal maturity, lean maturity, and USDA
quality grade were evaluated. The scoring system
Whole corn 53.487
Cotton seed hulls 18.000 used for LM lean color, LM lean firmness, and
Soybean meal, 44% CP 21.708 flank lean color was an 8-point scale (8 =
Limestone 1.027 bleached, f m ,or bleached, respectively, and 1 =
Ammonium chloride .500 dark, coarse, or dark, respectively). Actual per-
Vitamins A, D, and E .050
.500
centage of kidney-pelvic fat was determined dur-
salt
R ~ m e ~ 00n
i .008 ing subsequent carcass fabrication, and USDA
Liquid molasses 4.000 yield grade was calculated.
Aureomycin 50 ,050 Chilled carcass weight was determined before
fabrication. The fore- and hindsaddles were sepa-
rated and weighed and all kidneypelvic fat was
carcass weight was greater for the lambs given removed from the hindsaddle. Each saddle was
BAA. Wholesale cut weights were not expressed split longitudinally and the right side of the
as a percentage of carcass weight in those carcass was subsequently fabricated into bone-in
studies. No previous research has reported the retail cuts, and the left side of the carcass was
effect of BAA on lamb carcass or primal cut yields fabricated into boneless retail cuts.
of retail cuts at various fat trim levels. Therefore, The primal leg was separated from the primal
the present experiment investigated the effect of loin by making a straight cut perpendicular to the
feeding a BAA on carcass and primal cut yields of midline between the last two lumbar vertebrae.
bone-in and boneless retail cuts at various fat The flank was removed from the leg along the
trim levels and tail lengths when lambs were fed natural seam between the flank and the sirloin
to a constant weight end point. tip. The hindtrotter was removed from the leg by
breaking through the posterior epiphyseal plate,
and the achilles tendon w s removed flush with
a
Materials and Methods the muscle surface. The tail was removed from the
leg by cutting between the last sacral vertebra
Twenty paternal half-sibling Rambouillet and the first caudal vertebra. The loin tail was
wether lambs weighing approximately 31 kg were removed from the loin by a straight cut from a
given ad libitum access to a diet (Table 1) with point 2.54 cm from the lateral end of the L M on
(BAA, = 10) or without (control,n = 10) 1 ppm of
n the eye end to a point 2.54 cm from the lateral end
the P-adrenergic agonist L644,969 (6-amino-alpha- of the LM on the sirloin end. The breast and
{ [(l-methyl-3-phenylpropyl) amino1 methyl}-3-pyri- shank were removed from the forequarter by a
dine methanol dichloride; Merck, Sharpe and straight cut parallel to the length of the fore-
Dohme Research Laboratories, Division of Merck quarter that passed through the cartilaginous
and Co., Rahway, NJ).Within both control and joint of the fiist rib and the sternum. The shoulder
BAA,lambs were assigned to one of two pens five was separated from the rib between the 4th and
lambs per ped. Lambs were housed in an open-air 5th ribs by a straight cut perpendicular to the
barn and weighed every 7 d. Upon reaching the backbone. Ribends were removed from the rack
predetermined slaughter end point of 54.5 kg live by a straight cut from a point 2.54 cm from the
weight, lambs were shorn and fasted (with access lateral end of the LM on the eye end to a point
to water) for 24 h before slaughter. Lambs were 2.54 cm from the lateral end of the L M on the
transported to the Rosenthal Meat Science and blade end. The entire neck was removed from the
Technology Center and humanely slaughtered. shoulder by a straight cut perpendicular to the
Growth traits of ending weight, ADG, days on neckbone.
feed required to reach 54.5 kg, feed conversion, Bone-In Fabrication. The right leg, loin, rack,
wool weight, and wool adjusted ending weight and shoulder were trimmed progressively to 1.27,
(ending weight - wool weight) were analyzed. 3 4 , .32, and .OO cm of S.C. fat remaining. Then the
After chilling for 24 h, carcasses were ribbed 2.54 cm long tails were removed from the loin and
between the 12th and 13th ribs to determine rack along the lateral edge of the LM. In addition,
USDA quality and yield grade data (USDA, 1982). the thymus glands and blood clots were removed
Actual 12th rib fat thickness, adjusted fat thick- from the shoulder.
ness, body wall thickness (at a point 7.6 cm from Boneless Fabrication. The shank was removed
the lateral end of longissimus muscle LMII, LM from the left leg by cutting through the joint
area, and LM depth were recorded. Leg score, between the femur and the tibia and continuing
carcass conformation score, marbling score, LM straight across the heel. The sirloin section was
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fl-AGONIST AND INNOVATIVE L A M B FABRICATION 163
Table 2. Effect of feeding a p-adrenergic agonist on growth
characteristics of Rambouillet wether lambs
P- Percentage Probability
Trait Control Agonist chat.uze SEM level
Starting wt. kg 30.6 30.6 .O 1.o 1.0
Ending wt, k g 54.9 56.1 2.3 .7 .2240
Average daily gain, kg .25 .28 13.7 .02 .2 168
Days on f e e a 100.7 92.0 -8.6 4.5 .1849
Feed conversion (feed/gainl 6.8 7.0 2.9 .5 BO06
Wool wt, kg 2.3 2.2 -1.2 .1 .a326
Wool adjusted ending wt, kgb 52.6 53.9 2.5 .7 .a319
Hot cdrcass wt, kg 30.6 31.5 2.9 .5 .1842
Chilled carcam wt, kg 29.5 30.4 2.8 1.2 .5170
Dressing percentage 55.9 563 .1 .5 .6379
aDays on feed = number of days required to reach 54.5 kg live weight.
w o o l adjusted ending weight = ending weight - wool weight.
separated from the shortcut, shank-off, (SCSO) Statistical analyses were performed with the GLM
semiboneless leg by a straight cut passing be- procedure of SAS (1985).For a l traits the percent-
l
tween the 4th and 5th sacral vertebrae and age change of BAA from the control was calcu-
approximately 1.3 cm anterior to the knob of the lated as follows: percentage change = [(BAA -
aitch bone. The sirloin section was deboned and control)/control I x LOO.
the aitch bone was removed from the SCSO leg to
yield a semiboneless SCSO leg. The sirloin section
and SCSO leg were trimmed progressively to 1.27, Results and Discussion
3 4 , .32, and .OO cm of S.C. fat remaining. The left
loin was deboned to yield a peeled tenderloin and Growth Data. Ending weight, ADG, days on feed
a striploin. The striploin was trimmed progres- required to reach 54.5 kg live weight, and feed
sively to 1.27, 3 4 , .32, and .OO cm of s . ~ .fat conversion did not differ between treatments
remaining. Then the 2.54-cm long tail was re- CTable 2). Additionally,wool weight, wool adjusted
moved f o the loin along the laterd edge of the
rm ending weight, hot carcass weight, chilled carcass
LM. Yields for the boneless loin were based on the weight, and dressing percentage did not differ
s u m of the striploin weight and the tenderloin between control and BAA. Data have been incon
weight. The left rack was deboned to yield a sistent with regard to the effect of the BAA
boneless rib eye. Then the 2.54-cm long tail was L644,969 on growth traits. Duquette et al. (19871
removed from the rib eye roll along the lateral reported that .25 ppm of L644,969 increased
edge of the LM. The thymus glands and blood weight gain but did not affect feed conversion. In
clots were removed from the shoulder before the same study, 1 and 4 ppm of L644,969 tended to
deboning. Upon deboning, seam fat in excess of increase weight gain (P > .05) while improving
.64 cm in thickness was removed from the shoul- feed conversion (P < .051. Koohmaraie and Shack-
der and then the shoulder was trimmed progres- elford (1991) reported that feeding lambs a diet
sively to 1.27, 3 4 , .32, and .OO cm of s . ~ fat. containing 4 ppm of L644,969 did not increase
remaining. growth rate. Some notable differences between
StatisticaZ Analyses. By design, mean starting these studies that might have contributed to the
weight was the same for control and BAA. AU different responses to L644,969 included breed
other growth data were analyzed by analysis of type and length of the feeding trial. Duquette et
variance (Steel and Torrie, 1980)with BAA serving a . (19871 used Hampshire x Suffolk lambs,
l
as the fixed effect. Chilled c a r c & ~weight was
s whereas Koohmsraie and Shackelford (1991) fed
analyzed as a function of BAA. The model for al l 1/2 Finnsheep x 1/4 Dorset x 1/4 Rambouillet
other grade and carcass cutability traits included wether lambs. Feeding trial length was 6 wk in
chilled carcass weight as a covariate. The model both of the previous experiments, whereas a
for a l primal cut yield t a t was a one-way
l ris weight-constant ending point was used in the
analysis of variance with BAA serving as the present study and time on feed ranged from 10 to
main effect. For carcass fabrication, retail cut 16 wk.
yields were expressed as a percentage of chilled Carcass Characteristics. Actual and adjusted fat
carcass weight, and retail cut yields were ex- thickness, body wall thickness, and percentage of
pressed as a percentage of the appropriate primal kidney-pelvic fat did not differ between control
cut weight for boxed lamb primal fabrication. and BAA CTable 3). However, BAA increased LM
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164 SHACKELFORD ET AL.
Table 3. Effect of feeding a P-adrenergic agonist on carcass
f
characteristics o Rambouillet wether lambs
B Percentage Probability
Trait Control Agonist change SEM level
Actual 12th rib fat thickness, mm 4.4 3.7 -15.9 .5 .3887
Adjusted fat thickness, mm 5.3 4.2 -20.8 .4 .lo87
Body w l thickness, mm
al 21.7 20.6 -5.1 .9 .2014
~ongissimusmuscle area, cm2 15.0 16.6 10.7 .5 .0454
Longissimus muscle depth, mm 30.0 34.7 15.3 1.2 .0150
Percentage kidney and pelvic fat 4.7 4.4 -0.5 .2 .1733
Leg scorea 11.9 13.4 12.6 .3 .0048
USDA yield grade 3.6 3.2 -11.1 .1 .0287
Conformationa 11.8 13.4 13.6 .3 .0007
Marbling scoreb 235.0 228.0 -3.0 18.8 .6520
Longissimus muscle lean colorc 4.9 4.4 -10.2 .3 .4772
~ongissimus muscle lean iirmnessd 5.6 5.4 -3.0 .2 ,9824
primary flank streakingb 225.0 235.0 4.4 18.5 .E558
Secondary flank streakingb 180.0 185.0 2.8 13.2 .7032
Flank lean colorc 5.6 4.7 -16.1 .3 .0434
Skeletal maturitye 193.5 197.5 2.1 3.7 .3074
Lean maturitye 185.0 193.5 4.6 6.4 .1345
USDA quality gradea 11.7 12.6 7.8 .2 .0036
a l l = Choiceo 12 = Choice+, 13 = Prime-, 14 = Pie.
rm'
b l = ~ tracesd, 200 = slighto, 300 = small'.
~
%cored on an 8-point scale (1 = dark red, 8 = pale pink).
-
dScored on an &point scale (1 = extremely soft, 8 = extremely firm).
elOO A', 200 = Bo.
area, L M depth, and leg score while decreasing from untrimmed to .OO cm fat trim. These data
USDA yield grade. In addition, BAA increased suggested that BAA carcasses would not exceed
carcass conformation scores and USDA quality their control counterparts in value unless innova-
grade and had darker colored lean in the flank. tive fabrication techniques (boneless fabrication
No other carcass quality traits were affected by with retail cuts trimmed to I .32 cm S.C. fat
BAA. Most researchers have reported L644,969 to remaining) were used. In the United States, 72% of
decrease carcass fatness and increase muscling beef retail cuts are marketed in boneless form
(Duquette et al., 1987; Kretchmar et al., 1990; (Savell et al., 19911, whereas only 8.8% of lamb
Koohmaraie and Shackelford, 1991 ; Koohmaraie retail cuts are boneless (Harris et a . 1990). If
l,
et al., 1991).The lack of a BAA-inducedreduction lamb retail cuts were trimmed and deboned to the
in carcass fatness in the present study may be same extent as beef cuts, the greater value of
explained partially because none of the carcasses BAA carcasses would become apparent.
exceeded 6.35 mm actual 12th rib fat thickness Addition of BAA increased yields for bone-in leg
(data not presented in tabular form). Moreover, regardless of fat trim level (Table 51. Yield of
Hamby et al. (19861 hypothesized that feeding boneless sirloin was not affected by BAA (P > .051.
BAA during the finishing phase would not affect However, it is important to note that when no
kidney-pelvic fat weight because this fat depot trimming was employed, control carcasses tended
develops early in life. This may be particularly to yield a greater percentage of boneless sirloin
true of certain breed types. Baker et al. (1984) due to greater S.C. fat deposition. In contrast,
reported a reduction in kidney-pelvic fat of when trimmed of all S.C. fat, boneless sirloin yield
crossbred white-faced lambs when clenbuterol tended to be greater for BAA carcasses. This
WMI fed at 100 ppm but no effect was seen at lower trend was expected based on the findings of
levels. Griffin (1988) with beef. Griffin (1988) demon-
Carcass Fabrication Yields. The addition of BAA. strated conclusively that heifer carcasses were
did not affect overall carcass yields of bone-in more valuable than steer carcasses when mar-
retail cuts from the leg, loin, rack, and shoulder keted under commodity (2.54-cmfat trim) systems.
(Table 4). However, BAA increased overall carcass But, when trimming w s employed, the greater
a
yields when boneless fabrication styles were lean yield of the steer carcasses became appar-
employed. This was true regardless of fat trim ent. There was no difference in SCSO leg yield
level or length of tail on cuts from the loin and between control and BAA because SCSO leg is a
rack. However, the percentage change from the cut with little fat trim.
control was greater when fat trim level decreased Loin yields were not affected by BAA regard-
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BAGONIS" AND INNOVATIVE LAMB FABRICATION 165
f
Table 4. Effect o feeding Rambouillet wether lambs a B-adrenergic agonist
f
on carcass yields o bone-in and boneless retail cuts from the leg,
loin, rack, and shoulder at various fat trim levels and tail lengths
B Percentage Probability
Trait Control Agonist change SEM level
Yield of bone-in cuts with 2.54-cm tail, %a
Untrimmed 62.0 04.4 2.4 .6 .0882
1.27-cm fat trim level 62.8 64.4 2.6 .6 .lo84
.@-an fat trim level 61.0 63.6 2.7 .7 .0065
.32cm fat trim level 60.2 62.1 3.2 .7 .0700
.oO-cm fat trim level 56.4 58.0 2.0 .8 .1200
Yield of bone-in cuts with no tail, %e
Untrimmed 61.0 62.4 2.4 .% .1147
1.n-cm fat trim level 60.8 82.2 2.3 .6 A361
.@-cm fat trim level 50.0 61.5 2.7 .7 .1200
.32-cm fat trim level 58.2 60.1 3.2 .7 .OB60
.OO-cm fat trim level 54.4 56.0 2.9 .8 .1410
Yield of boneless cuts with 2.S-cm tail, %*
Untrimmed 46.3 47.5 2.7 .4 .01m
1.27-cm fat trim level 46.1 47.4 2.9 .4 .0183
.64-cm fat trim level 45.3 46.0 3.4 .5 .0176
.3&cm fat trim level 43.7 45.7 4.4 .6 .0114
.oo.cm fat trim level 40.2 42.1 4.7 .7 . O m
Yield of boneless cuts with no tail, %a
Untrimmed 44.4 45.5 2.7 .4 .0288
1.27-cm fat trim level 44.2 45.4 2.0 .5 .0287
.@-an fat trim level 43.4 44.0 3.4 .5 .0257
.32-cm fat trim level 41.8 43.7 4.5 .6 .0160
.OO-cm fat trim level 8
32 40.1 4.8 .7 .0287
%xpressed as a percentage of chilled carcass weight.
f
Table 5. Effect o feeding Rambouillet wether lambs a p-adrenergic agonist
on carcass yields of bone-in and boneless retail cuts
from the leg at various fat trim levels
B Percentage Probability
Trait Control Agonist change SEM level
Yield of bone-in leg, %a
Untrimmed 28.1 29.0 3.2 .3 .0168
1.27-cm fat trim level 28.0 28.8 3.0 .3 .0104
.64-cm fat trim level 27.6 28.5 3.3 .4 .0188
.32-cm fat trim level 26.0 27.0 3.6 .4 .0101
.Wcm fat trim level 25.2 25.0 2.0 .4 .0466
Yield of boneless sirloin. %*
Untrimmed 5.0 5.8 -1.0 .2 .8144
1.27-Cm fat trim level 5.8 5.8 -1.1 .2 .Oll9
.64-cm fat trim level 5.7 5.7 -. 1 .2 .0132
rm
.32-cm fat t i level 5.3 5.4 2.6 .2 ,4760
.oo-Cm fat trim level 4.5 4.6 2.6 .2 .5E3
Yield of shortcut, shank-off,semiboneless leg, %"
Untrimmed 16.4 16.5 1.o .2 SO16
1.27-cm fat trim level 16.3 16.5 1.4 .2 2882
.04-cm fat trim level 16.1 16.3 1.4 .2 2810
.32-cm fat trim level 15.6 15.9 1 .o .3 2200
.oOanfat trim level 14.5 14.8 2.1 .3 2421
aExpressed as a percentage of chilled carcaas weight.
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166 SHACKELFORD ET AL.
Table 6. Effect of feeding Rambouillet wether lambs a P-adrenergic agonist
on carcass yields of bone-in and boneless retail cuts from the loin
at various fat trim levels and tail lengths
B Percentage Probability
Trait Control Agonist change SEM level
Yield of bone-in loin with 2.54-cm tail, %a
Untrimmed 7.9 7.7 -2.0 .2 8749
1.27-cm fat trim level 7.8 7.7 -1.9 .2 .e707
.64-cm fat trim level 7.6 7.5 -.3 a .9170
.32-cm fat trim level 7.1 7.3 2.3 .2 .606 1
.OO-cm fat trim level 6.5 6.6 2.2 .2 .5223
Yield of bone-in loin with no tail, %a
Untrimmed 7.0 6.8 -2.8 .2 5208
1.27-cm fat trim level 7.0 6.8 -3.1 .2 .5187
.64-cm fat trim level 6.7 6.7 -.7 .2 .9669
.32-cm fat trim level 6.3 6.4 1.1 .2 .6619
.OO-cm fat trim level 5.6 5.8 2.7 .2 .5662
Yield of boneless loin with 2.54-cm tail, l a
Untrimmed 6.2 6.1 -1.6 .2 .OM2
1.27-cm fat trim level 6.1 6.0 -1.7 .2 .9270
.64-cm fat trim level 5.9 5.9 .7 a .5774
.32-cm fat trim level 5.4 5.6 4.1 .2 .3147
.OO-cm fat trim level 4.8 5.0 5.0 .2 .2156
Yield of boneless loin with no tail, %a
Untrimmed 5.3 5.2 -2.8 .1 .7454
1.27-cm fat trim level 5.3 5.2 -3.0 .2 .7369
.64-cm fat trim level 5.1 5.0 -.2 .2 3772
.32-cm fat trim level 4.6 4.8 3.7 .2 .3454
.OO-cm fat trim level 4.0 4.1 4.8 .
2 .2244
~~
aExpressed as a percentage of chilled carcass weight.
less of fabrication style (Table 61. The change tended to yield a higher percentage of loin. Again,
(control vs BAA) indicated that the control tended these results were expected based on the results
to yield a higher percentage of loin when not reported by Griffin (1988).
trimmed or when trimmed to 1.27 cm. However, When bone-in fabrication systems were em-
when trimmed to .32 cm or less, BAA carcasses ployed, BAA did not affect yield of rack cuts
Table 7. Effect of feeding Rambouillet wether lambs a p-adrenergic agonist
on carcass yields of bone-in and boneless retail cuts from the rack
at various fat trim levels and tail lengths
B Percentage Probability
Trait Control Agonist
~ _ _ _
change SEM
~______ ~~
level
Yield of bone-in rack with 2.54-cm tail, %a
Untrimmed 6.2 6.3 1.7 .2 .5559
1.27-cm fat trim level 8.2 6.3 1.7 .2 .5559
.64-cm fat trim level 8.1 6.2 1.4 .I .5072
.32-cm fat trim level 5.8 5.9 2.1 .1 .2696
.OO-cm fat trim level 5.4 5.5 2.2 .1 3028
Yield of bone-in rack with no tail, %a
Untrimmed 5.0 5.1 2.4 a .6462
127-cm fat trim level 5.0 5.1 2.4 a .e462
.64-cm fat trim level 5.0 5.0 1.5 .1 .e136
.32-cm fat trim level 4.7 4.8 2.3 .1 .3645
.OO-cm fat trim level 4.2 4.4 2.5 .1 .4277
Yield of boneless rib eye, %a
2.54-cm tail 3.5 3.8 9.0 .1 .0064
No tail 2.4 2.7 13.0 .1 .0045
aExpressed as a percentage of chilled carcass weight.
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&AGONIST AND INNOVATIVE LAMB FABRICATION 167
Table 8. Effect of feeding Rambouillet wether lambs a P-adrenergic agonist
on carcass yields of bone-in and boneless retail cuts from the shoulder
at various fat ti levels
rm
~~~~
& Percentage Probability
Trait Control Agonist change SEM level
Yield of bone-in shoulder, %a
Untrimmed 20.8 21.5 3.2 .4 .7030
1.27-cm fat trim level 20.8 21.5 3.2 .4 .7162
.84-cm fat trim level 20.7 21.3 3.1 .4 .7233
.32-cm fat trim level 20.4 21.0 3.2 .4 .7144
.oO-cm fat trim level 19.3 20.0 3.2 .4 .6977
Yield of boneless shoulder, %a
Untrimmed 14.4 15.4 6.8 .4 .0842
1.27-cm fat t i level
rm 14.4 15.3 6.8 .4 .0923
.84-cm fat trim level 14.2 15.2 6.8 .4 .0895
.32-cm fat t i level
rm 13.9 14.9 6.9 .4 .0825
.OO-cm fat ti level
rm 12.9 13.8 7.2 .4 .0860
aExpressed as a percentage of chilled carcass weight.
regardless of fat trim level or tail length lTable 7). fed a P-adrenergic agonist did not exceed their
However, BAA increased yield of boneless rib eye control counterparts in most retail cut yields, but
(tail-offl by 13%. the value of subprimals from lambs fed a P-
Addition of BAA did not affect yield of bone-in adrenergic agonist was more apparent when
or boneless shoulder (Table 8). Boneless shoulder retail cuts were trimmed of external fat.
yields tended to favor BAA regardless of fat trim
level. The trend toward higher boneless shoulder
yield for BAA was not due to decreased trimmable Literature Cited
seam fat in the shoulder (data not presented in
tabular forml. Moreover, this trend was not due to Baker, P. 11,R. H. Dalrymple, D. L. Ingle, and C. A. Ricks. 1984.
Use of a &adrenergic agonist to alter muscle and fat
a higher muscle to bone ratio for BAA. Appar- deposition in lambs. J. Anim. Sci. 59:1256.
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