A 145-day finishing trial was conducted to evaluate implant strategies on performance and carcass characteristics of yearling steers. Implanting steers with Synovex® C initially and then reimplanting with Synovex® Plus 75 days prior to slaughter improved feed efficiency compared to a single implant of Synovex® Plus or a reimplant program using Synovex® S. Carcass quality, as measured by the percentage USDA Choice carcasses and marbling scores, was unaffected by implant strategy. However, implanting steers with Synovex® PlusTM as a single implant or in a reimplant program increased profitability because feed efficiency and  carcass weight were increased without decreasing carcass merit

Cooper, Rob

Milton, Todd

Prouty, Frank

English

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 1999 
Implant Strategies on Performance and Carcass Characteristics 
of Finishing Steers 
Rob Cooper 
University of Nebraska-Lincoln 
Todd Milton 
University of Nebraska-Lincoln 
Frank Prouty 
Overland Park, Kansas 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Cooper, Rob; Milton, Todd; and Prouty, Frank, "Implant Strategies on Performance and Carcass 
Characteristics of Finishing Steers" (1999). Nebraska Beef Cattle Reports. 399. 
https://digitalcommons.unl.edu/animalscinbcr/399 
This Article is brought to you for free and open access by the Animal Science Department at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle 
Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
1999 Nebraska Beef Report — Page 54
Table 5. Effect of initial implant (IMP) and overall growth promoting regimen (GP) on ovary development and functiona,
Treatment (Trt) group
Feed additive: None MGA None MGA Chi-square (P-values) by treatment number
        GP
Implant (day 0): C C C H H H I MP (1 & 4 vs
Implant ( day 70): H/F H/F F H/F H/F F (1 2 3 vs 2 & 5 vs 1 & 4 vs 3 & 6 vs 2&3 vs
Trt No.: 1 2 3 4 5 6 4 5 6) 3 & 6) 2 3 5&6 1 2 4 & 5 5&6
Missing, % 0.0 0.0 0.0 2.9 0.0 0.0 .31 .35 .15 .48 —
Very immature,(<15mm),% 0.0 0.0 0.0 0.0 0.0 0.0 — — — — —
Immature, (15-20mm), % 5.7 0.0 0.0 5.7 5.9 0.0 .36 .08 .05 .08 .14
Mature, (>20mm, no follicle), % 28.6 35.3 17.6 34.3 38.2 20.6 .66 .41 .35 .02 .49
Mature (multiple follicle), % 5.7 2.9 0.0 2.9 2.9 5.9 .67 .83 .54 .79 .26
Mature (Corpus Luteum), % 0.0 0.0 0.0 0.0 0.0 0.0 — — — — —
aC= Synovex-C, H = Synovex-H, F = Finaplix-H, and MGA = Melengestrol acetate, fed from day 28 to 170.
implanting with Finaplix alone reduced 
the number of immature ovaries and 
number of mature ovaries with no fol-
licle, but increased the number of mature 
not fed MGA had the greatest number 
of immature ovaries. However, these 
conversion (lower feed to gain ratio).
Data suggest optimum growth 
promotant systems for heifer calves, 
managed under the above-mentioned 
conditions, includes an initial implant 
with either Synovex-C or Synovex-H, 
followed by reimplant with Synovex-H 
and Finaplix-H.
1Mari Lubberstedt, research technician, 
Terry Mader, professor, Animal Science and Jill 
Heemstra, former research technician, North-
east Research and Extension Center, Concord; and 
Kelly Lechtenberg, Consultant Midwest Veterinary 
Research, Oakland, Nebraska.
Implant Strategies on Performance and Carcass 
Characteristics of Finishing Steers
Rob Cooper
Todd Milton
Frank Prouty1
Synovex® C followed by 
Synovex® PlusTM resulted in a 
substantial improvement in feed 
implant of Synovex® PlusTM or a 
reimplant program with Synovex® 
S.
Summary
-
ducted to evaluate implant strategies 
on performance and carcass charac-
teristics of yearling steers. Implanting 
steers with Synovex® C initially and then 
reimplanting with Synovex® Plus  75 
days prior to slaughter improved feed 
of Synovex® Plus  or a reimplant 
program using Synovex® S. Carcass 
quality, as measured by the percentage 
USDA Choice carcasses and marbling 
scores, was unaffected by implant strat-
egy. However, implanting steers with 
Synovex® Plus  as a single implant 
or in a reimplant program increased 
carcass weight were increased without 
decreasing carcass merit.
Introduction
The use of growth-promoting im-
plants has been widely adapted by 
the cattle feeding industry. Managing 
implant strategies requires matching 
payout, animal performance and carcass 
merit. Several growth-promoting im-
plants varying in dosage and hormonal 
composition are available. Numerous 
in performance with a combination of 
trenbolone acetate and estradiol com-
pared to estradiol alone. However, the 
percentage of cattle grading Choice can 
be reduced with this combination. Re-
cently, experiments have demonstrated 
improved performance, and little change 
in carcass merit, when steers were im-
planted with a low-dose estrogen fol-
lowed by a combination of trenbolone 
acetate and estradiol, compared to a 
single combination implant administered 
at the beginning of the feeding period. 
In most of these experiments, Ralgro®
has been the initial source of low-dose 
estrogen. Because Synovex® C is simi-
lar in estrogenic activity to Ralgro®, it 
may be an effective source of low-dose 
estrogen as an initial implant in a reim-
Page 55 — 1999 Nebraska Beef Report
plant program.
Objectives of this trial were to: 1) 
compare Synovex® C (Syn-C) and 
Ralgro® (Ralgro) as initial sources 
of low-dose estrogen and 2) compare 
a single administration of Synovex®
PlusTM (Syn-Plus) versus a reimplant 
program of Syn-C followed by Syn-Plus 
versus a reimplant program using only 
Synovex® S (Syn-S).
Procedure
One hundred and eighty crossbred 
yearling steers (average initial weight = 
722 lb) were used in a randomized com-
plete block design to evaluate implant 
strategies on performance and carcass 
weight replicates. Within each replicate, 
one of four pens (nine steers per pen) such 
that average pen weights were similar. 
Pens were randomly assigned to one of 
treatment): 1) Syn-S on day one and 
day 70, 2) Ralgro on day one followed 
by Syn-Plus on day 70, 3) Syn-C on day 
one followed by Syn-Plus on day 70 and 
4) Syn-Plus on day one only.
-
cent dry-rolled corn, 22.5 percent wet 
corn gluten feed, 7.5 percent alfalfa hay, 
3 percent tallow and 4 percent dry supple-
ment (DM basis) and was formulated to 
contain 13.5 percent crude protein, 6.8 
percent degradable intake protein, .7 
percent calcium, .4 percent phosphorus, 
.7 percent potassium, 29 g/ton Rumen-
sin and 10 g/ton Tylan. Steers were 
brought up to full-feed in 17 days using 
four step-up diets containing 45, 35, 25 
and 15 percent alfalfa hay (DM basis). 
Steers were fed once daily and allowed 
ad libitum access to feed and water. Feed 
refusals were collected and weighed as 
needed throughout the trial.
Steers were weighed initially on two 
consecutive days after being limit-fed 
at 2 percent of body weight for six days 
Interim body weights were determined 
on day 70 when appropriate reimplant 
treatments were applied. Treatment 2 
(Ralgro followed by Syn-Plus) was not 
reimplanted on day 70 under direction 
of the FDA, and thus, these steers were 
implanted only on day one with Ralgro. 
Steers were fed for 75 days follow-
ing the second implant. Final 145-day 
body weights were measured on two 
consecutive days prior to feeding and 
pencil shrunk 4 percent. Additionally, 
-
ing hot carcass weight adjusted to a 
common dressing percentage (63). All 
steers were slaughtered in a commercial 
processing facility. Hot carcass weights 
and incidence of liver abscesses were 
recorded at slaughter. Following a 24-
hour chill, fat thickness, longissimus 
muscle area, yield grade, USDA quality 
grade, marbling score and maturity score 
were measured.
Results
The effects of implant strategy on 
feedlot performance during the 145-day 
1. Under direction from the FDA, steers 
receiving Ralgro on day one were not 
reimplanted with Syn-Plus on day 70.
Steers implanted with Syn-Plus on 
day one consumed more (P < .05) feed 
than those implanted with Ralgro and 
those initially implanted with Syn-C 
followed by Syn-Plus (Table 1). Dry 
matter intakes of steers implanted with 
Syn-S on day one and 70 were greater (P
< .05) than those implanted with Ralgro. 
However, when expressed as a percent-
age of average body weight, dry matter 
intakes were similar among implant 
strategies. Daily gains, expressed on 
both a live and carcass-adjusted basis, 
of steers implanted with Syn-Plus on 
day one or 70 were 4.3 to 6.6 percent 
higher (P < .01) than those implanted 
with Syn-S on day one and 70, and 18 to 
19 percent higher than those implanted 
with Ralgro only. Daily gains of steers 
implanted with Syn-C followed by Syn-
Plus on day 70 and those implanted with 
Synovex Plus on day one were similar. 
Implanting steers with Syn-S on day one 
and 70 improved (P < .01) daily gains 
11 (live basis) and 12 percent (carcass 
basis) compared to those implanted with 
Ralgro only. Implanting steers with Syn-
C followed by Syn-Plus improved (P < 
basis and tended (P = .06) to improve 
basis compared to those implanted with 
Syn-Plus on day one. Implanting steers 
with Syn-S on day one and 70 improved 
(P
live basis and 5.2 percent on a carcass 
basis compared to those implanted with 
Ralgro only.
The effects of implant strategy 
Implant Strategya
  1 2 3 4
Initial implant Syn-S Ralgro Syn-C Syn-Plus
Reimplant Syn-S None Syn-Plus None SEM
Number of pens 5 5 5 5
Number of steers 45 45 45 45
Initial weight, lb 723 721 720 723 .8
Final weightb, lb 1315e 1248d 1339f 1343f 5.1
DM intake
lb/hd/day 25.9ij 24.5h 25.5i 26.4j .22
% of BW 2.54 2.53 2.43 2.55 .04
Daily gain, lb 4.09e 3.63d 4.27f 4.27f .03
Feed DM/gain 6.34i 6.75h 5.97k 6.18j .04
Carcass adjusted performancec
Final weight, lb 1317e 1255d 1353f 1359f 6.1
Daily gain, lb 4.10e 3.68d 4.37f 4.38f .04
Feed DM/gain 6.32e 6.67d 5.84f 6.03f .06
aImplant strategy: Syn-S = Synovex® S; Ralgro = Ralgro®; Syn-C = Synovex® C; Syn-Plus = Synovex®
PlusTM; None = no implant.
bPencil shrunk 4%.
c
d,e,fMeans in a row not bearing a common superscript differ (P < .01).
h,i,j,kMeans in a row not bearing a common superscript differ (P < .05).
(Continued on next page)
1999 Nebraska Beef Report — Page 56
on interim feedlot performance are 
70 days on feed, dry matter intakes 
as a percentage of body weight were 
similar among implant strategies. Steers 
implanted with Syn-Plus gained faster 
(P P < .01) 
than those given implants containing 
estrogen only. Daily gains of steers 
implanted with Syn-S were higher (P < 
.05) than those implanted with Ralgro, 
but were similar to those implanted with 
Syn-C. Additionally, daily gain of steers 
implanted with Syn-C tended (P = .12) 
to be higher than those implanted with 
for steers implanted with any of the three 
estrogenic compounds.
implanted with Syn-S on day one and 
70 and Syn-Plus on day one consumed 
more (P < .05) feed than those implanted 
with Ralgro only, whereas dry matter 
intake of steers implanted initially with 
Syn-C followed by Syn-Plus on day 70 
was intermediate. Similar to the overall 
intakes as a percentage of body weight 
were similar among implant strategies. 
Steers implanted with Syn-C followed 
by Syn-Plus on day 70 gained faster (P
P < .01) 
than those receiving the other implant 
strategies. Implanting steers with Syn-C 
followed by Syn-Plus on day 70 resulted 
in a .71 or .42 lb/day increase in daily 
gain and 22 or 12 percent improvement 
on day one or with Syn-S on day one 
and 70, respectively. Steers reimplanted 
with Syn-S on day 70 gained faster (P < 
P < .01) than 
those implanted with Ralgro or Syn-Plus 
feed, steers implanted with Syn-Plus on 
day one maintained their advantage in 
daily gain (P
(P = .01) above those implanted on day 
one with Ralgro only.
Short intervals between body weight 
measurements can be misleading. 
However, these interim data clearly 
demonstrate steers were becoming less 
weight. Delaying the administration of 
Syn-Plus until day 70 reduced the mag-
nitude of this change compared to both a 
Implant strategya
  1 2 3 4
Initial implant Syn-S Ralgro Syn-C Syn-Plus
Reimplant Syn-S None Syn-Plus None SEM
Hot Carcass wt, lb 830e 791d 852f 856f 3.9
Dressing percentage 63.09 63.34 63.62 63.73 .20
12th rib fat thickness, in .62 .62 .63 .61 .02
KPH fatb 2.30 2.31 2.30 2.32 .05
Longissimus muscle area
square inches 12.29gh 11.95g 12.77h 12.61h .17
sq. in./cwt HCW 1.49 1.51 1.49 1.48 .02
Yield grade 3.00 3.04 2.91 3.00 .08
Maturity
Skeletal A68 A65 A69 A67 .02
Lean A57 A58 A56 A58 .02
Overall A62 A62 A62 A62 .01
Marbling scorec 5.47 5.45 5.32 5.48 .15
Percent Choicei 79.6 75.6 68.9 73.3 —
Liver abscessesj, % 6.7 2.2 0 4.4 —
aImplant strategy: Syn-S = Synovex® S; Ralgro = Ralgro®; Syn-C = Synovex® C; Syn-Plus = Synovex®
PlusTM; None = no implant.
bKPH = kidney, heart, and pelvic.
cMarbling score of 5.0 = Small 0; 5.5 = Small 50; etc.
d,e,fMeans in a row not bearing a common superscript differ (P < .01).
g,hMeans in a row not bearing a common superscript differ (P < .05).
iChi square statistic (P = .71).
jChi square statistic (P = .32).
Implant strategya
  1 2 3 4
Initial implant Syn-S Ralgro Syn-C Syn-Plus
Reimplant Syn-S None Syn-Plus None SEM
Period 1 (Day 1-70)
Weight, lb 1064c 1048b 1056bc 1113d 4.0
DM intake
  lb/hd/day 25.0gh 24.1f 24.6fg 25.5h .24
  % of BW 2.82 2.75 2.75 2.76 .03
Daily gain, lb 4.88g 4.67f 4.81fg 5.57h .06
Feed DM/gain 5.12b 5.16b 5.11b 4.57c .05
Period 2 (Day 71-145)
Weight, lb 1315c 1248b 1339d 1343d 5.1
DM intake
  lb/hd/d 26.8gh 24.9f 26.4g 27.3h .27
  % of BW 2.27 2.22 2.17 2.22 .05
Daily gain, lb 3.35h 2.67f 3.77i 3.06g .07
Feed DM/gain 8.00c 9.35b 7.00e 8.93d .17
aImplant strategy: Syn-S = Synovex® S; Ralgro = Ralgro®; Syn-C = Synovex® C; Syn-Plus = Synovex®
PlusTM; None = no implant.
b,c,d,eMeans in a row not bearing a common superscript differ (P < .01).
f,g,h,iMeans in a row not bearing a common superscript differ (P < .05).
single implant of Syn-Plus initially and 
a reimplant program using Syn-S.
Syn-Plus, administered on day one 
or 70, increased hot carcass weight 
(P < .01) compared to Ralgro only or a 
reimplant program using Syn-S (Table 
3). Additionally, hot carcass weights 
of steers implanted with Syn-S were 
greater (P < .01) than those implanted 
with Ralgro only. Implanting steers with 
Syn-Plus on day one or 70 increased (Chi 
square statistic; P < .01) the distribution 
of carcasses weighing between 800 and 
900 pounds. However, there was no sub-
stantial impact of Syn-Plus, administered 
on day 0 or 70 on overweight carcasses 
(>950 lb).
Longissimus muscle area (square 
Page 57 — 1999 Nebraska Beef Report
inches) was increased by implanting with 
Syn-Plus on day one or 70 compared to 
those implanted with estrogenic com-
pounds. However, expressed in square 
inches/100 lb of hot carcass weight, lon-
gissimus muscle area was unaffected by 
of implant on twelfth rib fat thickness, 
kidney, heart and pelvic fat, yield grade, 
lean and skeletal maturity, marbling 
score, percentage of abscessed livers 
or the percentage of carcasses grading 
USDA Choice.
Implanting steers with Syn-C initially 
and then reimplanting with Syn-Plus 75 
days prior to slaughter resulted in a sub-
compared to a single implant of Syn-Plus 
or a reimplant program using Syn-S. 
Carcass quality, as measured by the 
percentage of USDA Choice carcasses 
and marbling scores, was unaffected 
by implant strategy. Increased carcass 
weight without substantial changes in 
carcass quality should increase economic 
return when Syn-Plus is utilized as a 
single implant or in a reimplant program 
with Syn-C initially compared to reim-
plant programs using Syn-S.
1Rob Cooper, research technician, Animal 
Science, Lincoln; Todd Milton, assistant professor, 
Animal Science, Lincoln; Frank Prouty, Fort Dodge 
Animal Health, Overland Park, Kansas.
Feedlot Marketing/Sorting Systems to Reduce 
Carcass Discounts
Introduction
Our objective was to evaluate feedlot 
marketing/sorting systems. The primary 
goal of these systems is not to optimize 
marketing, which attempts to obtain 
maximum value for each individual 
animal, but to avoid carcass discounts. 
The primary discounts addressed were 
overweight and overfat carcasses. While 
underweight and underfat carcasses were 
addressed, less emphasis was placed on 
these discounts.
Two levels of technology were com-
pared in this project: 1) a fat estimate 
made by rib palpation and 2) use of 
ultrasound for determination of fat depth 
at reimplant time. Objectives were to: 1) 
determine if potential discount carcasses 
and 2) determine if use of ultrasound 
was necessary for accurate fat depth 
determination.
Procedure
Five Nebraska feedlots (ranging in 
one-time capacity of 3,500 to 25,500 
head), participated in the project. Co-
operating feedlots were responsible for 
cattle procurement. Upon arrival, cattle 
were randomly split into three treat-
ment groups: control (no sorting); low 
tech sort; and high tech sort. At initial 
processing, all cattle were processed 
according to the feedlot’s normal pro-
tags and individually weighed. All cattle 
were sent to their respective pens and 
fed according to the feedlot’s normal 
procedures.
At reimplant time (or the last time 
the cattle were worked before slaugh-
ter, which might have been processing 
time for some short-fed yearlings), all 
cattle were again worked according to 
the feedlot’s normal reimplant proce-
individually weighed and a fat depth 
estimated by hand palpation over the 
twelfth and thirteenth ribs. Based on 
the average weight and distribution of 
weights in the control pen, maximum and 
minimum sort weights were determined. 
These sort weights were calculated as 1.5 
standard deviations from the average, 
approximately 8 percent of the cattle 
on both ends of the range of weights. 
Maximum and minimum sort fat depths 
were determined in the same manner. 
Cattle in the low tech treatment pen were 
individually weighed and a fat depth 
estimated by visual appraisal and rib 
Rob Cooper
Terry Klopfenstein
Todd Milton
Dillon Feuz1
Potential Yield Grade 4 carcasses 
Fat depth determined approximately 
90 days prior to slaughter did not 
correlate to carcass fat depth.
Summary
A project involving 4,348 cattle and 
was conducted to evaluate marketing/
sorting systems to reduce overweight 
and overfat carcasses . At reimplant 
time, cattle were weighed and fat depth 
estimated either by ultrasound or by 
manual rib palpation. Cattle heavier 
and/or fatter than a predetermined 
reduce carcass discounts. Reimplant fat 
depth was poorly correlated to carcass 
fat depth. At reimplant time (~90 days 
prior to slaughter), we were unable to 
consistently identify cattle which would 
become Yield Grade 4 carcasses. (Continued on next page)


Implant Strategies on Performance and Carcass Characteristics of Finishing Steers

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 1999 Implant Strategies on Performance and Carcass Characteristics of Finishing Steers Rob Cooper University of Nebraska-Lincoln Todd Milton University of Nebraska-Lincoln Frank Prouty Overland Park, Kansas Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Cooper, Rob; Milton, Todd; and Prouty, Frank, "Implant Strategies on Performance and Carcass Characteristics of Finishing Steers" (1999). Nebraska Beef Cattle Reports. 399. https://digitalcommons.unl.edu/animalscinbcr/399 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 1999 Nebraska Beef Report — Page 54Table 5. Effect of initial implant (IMP) and overall growth promoting regimen (GP) on ovary development and functiona,Treatment (Trt) groupFeed additive: None MGA None MGA Chi-square (P-values) by treatment number        GPImplant (day 0): C C C H H H I MP (1 & 4 vsImplant ( day 70): H/F H/F F H/F H/F F (1 2 3 vs 2 & 5 vs 1 & 4 vs 3 & 6 vs 2&3 vsTrt No.: 1 2 3 4 5 6 4 5 6) 3 & 6) 2 3 5&6 1 2 4 & 5 5&6Missing, % 0.0 0.0 0.0 2.9 0.0 0.0 .31 .35 .15 .48 —Very immature,(<15mm),% 0.0 0.0 0.0 0.0 0.0 0.0 — — — — —Immature, (15-20mm), % 5.7 0.0 0.0 5.7 5.9 0.0 .36 .08 .05 .08 .14Mature, (>20mm, no follicle), % 28.6 35.3 17.6 34.3 38.2 20.6 .66 .41 .35 .02 .49Mature (multiple follicle), % 5.7 2.9 0.0 2.9 2.9 5.9 .67 .83 .54 .79 .26Mature (Corpus Luteum), % 0.0 0.0 0.0 0.0 0.0 0.0 — — — — —aC= Synovex-C, H = Synovex-H, F = Finaplix-H, and MGA = Melengestrol acetate, fed from day 28 to 170.implanting with Finaplix alone reduced the number of immature ovaries and number of mature ovaries with no fol-licle, but increased the number of mature not fed MGA had the greatest number of immature ovaries. However, these conversion (lower feed to gain ratio).Data suggest optimum growth promotant systems for heifer calves, managed under the above-mentioned conditions, includes an initial implant with either Synovex-C or Synovex-H, followed by reimplant with Synovex-H and Finaplix-H.1Mari Lubberstedt, research technician, Terry Mader, professor, Animal Science and Jill Heemstra, former research technician, North-east Research and Extension Center, Concord; and Kelly Lechtenberg, Consultant Midwest Veterinary Research, Oakland, Nebraska.Implant Strategies on Performance and Carcass Characteristics of Finishing SteersRob CooperTodd MiltonFrank Prouty1Synovex® C followed by Synovex® PlusTM resulted in a substantial improvement in feed implant of Synovex® PlusTM or a reimplant program with Synovex® S.Summary-ducted to evaluate implant strategies on performance and carcass charac-teristics of yearling steers. Implanting steers with Synovex® C initially and then reimplanting with Synovex® Plus  75 days prior to slaughter improved feed of Synovex® Plus  or a reimplant program using Synovex® S. Carcass quality, as measured by the percentage USDA Choice carcasses and marbling scores, was unaffected by implant strat-egy. However, implanting steers with Synovex® Plus  as a single implant or in a reimplant program increased carcass weight were increased without decreasing carcass merit.IntroductionThe use of growth-promoting im-plants has been widely adapted by the cattle feeding industry. Managing implant strategies requires matching payout, animal performance and carcass merit. Several growth-promoting im-plants varying in dosage and hormonal composition are available. Numerous in performance with a combination of trenbolone acetate and estradiol com-pared to estradiol alone. However, the percentage of cattle grading Choice can be reduced with this combination. Re-cently, experiments have demonstrated improved performance, and little change in carcass merit, when steers were im-planted with a low-dose estrogen fol-lowed by a combination of trenbolone acetate and estradiol, compared to a single combination implant administered at the beginning of the feeding period. In most of these experiments, Ralgro®has been the initial source of low-dose estrogen. Because Synovex® C is simi-lar in estrogenic activity to Ralgro®, it may be an effective source of low-dose estrogen as an initial implant in a reim-Page 55 — 1999 Nebraska Beef Reportplant program.Objectives of this trial were to: 1) compare Synovex® C (Syn-C) and Ralgro® (Ralgro) as initial sources of low-dose estrogen and 2) compare a single administration of Synovex®PlusTM (Syn-Plus) versus a reimplant program of Syn-C followed by Syn-Plus versus a reimplant program using only Synovex® S (Syn-S).ProcedureOne hundred and eighty crossbred yearling steers (average initial weight = 722 lb) were used in a randomized com-plete block design to evaluate implant strategies on performance and carcass weight replicates. Within each replicate, one of four pens (nine steers per pen) such that average pen weights were similar. Pens were randomly assigned to one of treatment): 1) Syn-S on day one and day 70, 2) Ralgro on day one followed by Syn-Plus on day 70, 3) Syn-C on day one followed by Syn-Plus on day 70 and 4) Syn-Plus on day one only.-cent dry-rolled corn, 22.5 percent wet corn gluten feed, 7.5 percent alfalfa hay, 3 percent tallow and 4 percent dry supple-ment (DM basis) and was formulated to contain 13.5 percent crude protein, 6.8 percent degradable intake protein, .7 percent calcium, .4 percent phosphorus, .7 percent potassium, 29 g/ton Rumen-sin and 10 g/ton Tylan. Steers were brought up to full-feed in 17 days using four step-up diets containing 45, 35, 25 and 15 percent alfalfa hay (DM basis). Steers were fed once daily and allowed ad libitum access to feed and water. Feed refusals were collected and weighed as needed throughout the trial.Steers were weighed initially on two consecutive days after being limit-fed at 2 percent of body weight for six days Interim body weights were determined on day 70 when appropriate reimplant treatments were applied. Treatment 2 (Ralgro followed by Syn-Plus) was not reimplanted on day 70 under direction of the FDA, and thus, these steers were implanted only on day one with Ralgro. Steers were fed for 75 days follow-ing the second implant. Final 145-day body weights were measured on two consecutive days prior to feeding and pencil shrunk 4 percent. Additionally, -ing hot carcass weight adjusted to a common dressing percentage (63). All steers were slaughtered in a commercial processing facility. Hot carcass weights and incidence of liver abscesses were recorded at slaughter. Following a 24-hour chill, fat thickness, longissimus muscle area, yield grade, USDA quality grade, marbling score and maturity score were measured.ResultsThe effects of implant strategy on feedlot performance during the 145-day 1. Under direction from the FDA, steers receiving Ralgro on day one were not reimplanted with Syn-Plus on day 70.Steers implanted with Syn-Plus on day one consumed more (P < .05) feed than those implanted with Ralgro and those initially implanted with Syn-C followed by Syn-Plus (Table 1). Dry matter intakes of steers implanted with Syn-S on day one and 70 were greater (P< .05) than those implanted with Ralgro. However, when expressed as a percent-age of average body weight, dry matter intakes were similar among implant strategies. Daily gains, expressed on both a live and carcass-adjusted basis, of steers implanted with Syn-Plus on day one or 70 were 4.3 to 6.6 percent higher (P < .01) than those implanted with Syn-S on day one and 70, and 18 to 19 percent higher than those implanted with Ralgro only. Daily gains of steers implanted with Syn-C followed by Syn-Plus on day 70 and those implanted with Synovex Plus on day one were similar. Implanting steers with Syn-S on day one and 70 improved (P < .01) daily gains 11 (live basis) and 12 percent (carcass basis) compared to those implanted with Ralgro only. Implanting steers with Syn-C followed by Syn-Plus improved (P < basis and tended (P = .06) to improve basis compared to those implanted with Syn-Plus on day one. Implanting steers with Syn-S on day one and 70 improved (Plive basis and 5.2 percent on a carcass basis compared to those implanted with Ralgro only.The effects of implant strategy Implant Strategya  1 2 3 4Initial implant Syn-S Ralgro Syn-C Syn-PlusReimplant Syn-S None Syn-Plus None SEMNumber of pens 5 5 5 5Number of steers 45 45 45 45Initial weight, lb 723 721 720 723 .8Final weightb, lb 1315e 1248d 1339f 1343f 5.1DM intakelb/hd/day 25.9ij 24.5h 25.5i 26.4j .22% of BW 2.54 2.53 2.43 2.55 .04Daily gain, lb 4.09e 3.63d 4.27f 4.27f .03Feed DM/gain 6.34i 6.75h 5.97k 6.18j .04Carcass adjusted performancecFinal weight, lb 1317e 1255d 1353f 1359f 6.1Daily gain, lb 4.10e 3.68d 4.37f 4.38f .04Feed DM/gain 6.32e 6.67d 5.84f 6.03f .06aImplant strategy: Syn-S = Synovex® S; Ralgro = Ralgro®; Syn-C = Synovex® C; Syn-Plus = Synovex®PlusTM; None = no implant.bPencil shrunk 4%.cd,e,fMeans in a row not bearing a common superscript differ (P < .01).h,i,j,kMeans in a row not bearing a common superscript differ (P < .05).(Continued on next page)1999 Nebraska Beef Report — Page 56on interim feedlot performance are 70 days on feed, dry matter intakes as a percentage of body weight were similar among implant strategies. Steers implanted with Syn-Plus gained faster (P P < .01) than those given implants containing estrogen only. Daily gains of steers implanted with Syn-S were higher (P < .05) than those implanted with Ralgro, but were similar to those implanted with Syn-C. Additionally, daily gain of steers implanted with Syn-C tended (P = .12) to be higher than those implanted with for steers implanted with any of the three estrogenic compounds.implanted with Syn-S on day one and 70 and Syn-Plus on day one consumed more (P < .05) feed than those implanted with Ralgro only, whereas dry matter intake of steers implanted initially with Syn-C followed by Syn-Plus on day 70 was intermediate. Similar to the overall intakes as a percentage of body weight were similar among implant strategies. Steers implanted with Syn-C followed by Syn-Plus on day 70 gained faster (PP < .01) than those receiving the other implant strategies. Implanting steers with Syn-C followed by Syn-Plus on day 70 resulted in a .71 or .42 lb/day increase in daily gain and 22 or 12 percent improvement on day one or with Syn-S on day one and 70, respectively. Steers reimplanted with Syn-S on day 70 gained faster (P < P < .01) than those implanted with Ralgro or Syn-Plus feed, steers implanted with Syn-Plus on day one maintained their advantage in daily gain (P(P = .01) above those implanted on day one with Ralgro only.Short intervals between body weight measurements can be misleading. However, these interim data clearly demonstrate steers were becoming less weight. Delaying the administration of Syn-Plus until day 70 reduced the mag-nitude of this change compared to both a Implant strategya  1 2 3 4Initial implant Syn-S Ralgro Syn-C Syn-PlusReimplant Syn-S None Syn-Plus None SEMHot Carcass wt, lb 830e 791d 852f 856f 3.9Dressing percentage 63.09 63.34 63.62 63.73 .2012th rib fat thickness, in .62 .62 .63 .61 .02KPH fatb 2.30 2.31 2.30 2.32 .05Longissimus muscle areasquare inches 12.29gh 11.95g 12.77h 12.61h .17sq. in./cwt HCW 1.49 1.51 1.49 1.48 .02Yield grade 3.00 3.04 2.91 3.00 .08MaturitySkeletal A68 A65 A69 A67 .02Lean A57 A58 A56 A58 .02Overall A62 A62 A62 A62 .01Marbling scorec 5.47 5.45 5.32 5.48 .15Percent Choicei 79.6 75.6 68.9 73.3 —Liver abscessesj, % 6.7 2.2 0 4.4 —aImplant strategy: Syn-S = Synovex® S; Ralgro = Ralgro®; Syn-C = Synovex® C; Syn-Plus = Synovex®PlusTM; None = no implant.bKPH = kidney, heart, and pelvic.cMarbling score of 5.0 = Small 0; 5.5 = Small 50; etc.d,e,fMeans in a row not bearing a common superscript differ (P < .01).g,hMeans in a row not bearing a common superscript differ (P < .05).iChi square statistic (P = .71).jChi square statistic (P = .32).Implant strategya  1 2 3 4Initial implant Syn-S Ralgro Syn-C Syn-PlusReimplant Syn-S None Syn-Plus None SEMPeriod 1 (Day 1-70)Weight, lb 1064c 1048b 1056bc 1113d 4.0DM intake  lb/hd/day 25.0gh 24.1f 24.6fg 25.5h .24  % of BW 2.82 2.75 2.75 2.76 .03Daily gain, lb 4.88g 4.67f 4.81fg 5.57h .06Feed DM/gain 5.12b 5.16b 5.11b 4.57c .05Period 2 (Day 71-145)Weight, lb 1315c 1248b 1339d 1343d 5.1DM intake  lb/hd/d 26.8gh 24.9f 26.4g 27.3h .27  % of BW 2.27 2.22 2.17 2.22 .05Daily gain, lb 3.35h 2.67f 3.77i 3.06g .07Feed DM/gain 8.00c 9.35b 7.00e 8.93d .17aImplant strategy: Syn-S = Synovex® S; Ralgro = Ralgro®; Syn-C = Synovex® C; Syn-Plus = Synovex®PlusTM; None = no implant.b,c,d,eMeans in a row not bearing a common superscript differ (P < .01).f,g,h,iMeans in a row not bearing a common superscript differ (P < .05).single implant of Syn-Plus initially and a reimplant program using Syn-S.Syn-Plus, administered on day one or 70, increased hot carcass weight (P < .01) compared to Ralgro only or a reimplant program using Syn-S (Table 3). Additionally, hot carcass weights of steers implanted with Syn-S were greater (P < .01) than those implanted with Ralgro only. Implanting steers with Syn-Plus on day one or 70 increased (Chi square statistic; P < .01) the distribution of carcasses weighing between 800 and 900 pounds. However, there was no sub-stantial impact of Syn-Plus, administered on day 0 or 70 on overweight carcasses (>950 lb).Longissimus muscle area (square Page 57 — 1999 Nebraska Beef Reportinches) was increased by implanting with Syn-Plus on day one or 70 compared to those implanted with estrogenic com-pounds. However, expressed in square inches/100 lb of hot carcass weight, lon-gissimus muscle area was unaffected by of implant on twelfth rib fat thickness, kidney, heart and pelvic fat, yield grade, lean and skeletal maturity, marbling score, percentage of abscessed livers or the percentage of carcasses grading USDA Choice.Implanting steers with Syn-C initially and then reimplanting with Syn-Plus 75 days prior to slaughter resulted in a sub-compared to a single implant of Syn-Plus or a reimplant program using Syn-S. Carcass quality, as measured by the percentage of USDA Choice carcasses and marbling scores, was unaffected by implant strategy. Increased carcass weight without substantial changes in carcass quality should increase economic return when Syn-Plus is utilized as a single implant or in a reimplant program with Syn-C initially compared to reim-plant programs using Syn-S.1Rob Cooper, research technician, Animal Science, Lincoln; Todd Milton, assistant professor, Animal Science, Lincoln; Frank Prouty, Fort Dodge Animal Health, Overland Park, Kansas.Feedlot Marketing/Sorting Systems to Reduce Carcass DiscountsIntroductionOur objective was to evaluate feedlot marketing/sorting systems. The primary goal of these systems is not to optimize marketing, which attempts to obtain maximum value for each individual animal, but to avoid carcass discounts. The primary discounts addressed were overweight and overfat carcasses. While underweight and underfat carcasses were addressed, less emphasis was placed on these discounts.Two levels of technology were com-pared in this project: 1) a fat estimate made by rib palpation and 2) use of ultrasound for determination of fat depth at reimplant time. Objectives were to: 1) determine if potential discount carcasses and 2) determine if use of ultrasound was necessary for accurate fat depth determination.ProcedureFive Nebraska feedlots (ranging in one-time capacity of 3,500 to 25,500 head), participated in the project. Co-operating feedlots were responsible for cattle procurement. Upon arrival, cattle were randomly split into three treat-ment groups: control (no sorting); low tech sort; and high tech sort. At initial processing, all cattle were processed according to the feedlot’s normal pro-tags and individually weighed. All cattle were sent to their respective pens and fed according to the feedlot’s normal procedures.At reimplant time (or the last time the cattle were worked before slaugh-ter, which might have been processing time for some short-fed yearlings), all cattle were again worked according to the feedlot’s normal reimplant proce-individually weighed and a fat depth estimated by hand palpation over the twelfth and thirteenth ribs. Based on the average weight and distribution of weights in the control pen, maximum and minimum sort weights were determined. These sort weights were calculated as 1.5 standard deviations from the average, approximately 8 percent of the cattle on both ends of the range of weights. Maximum and minimum sort fat depths were determined in the same manner. Cattle in the low tech treatment pen were individually weighed and a fat depth estimated by visual appraisal and rib Rob CooperTerry KlopfensteinTodd MiltonDillon Feuz1Potential Yield Grade 4 carcasses Fat depth determined approximately 90 days prior to slaughter did not correlate to carcass fat depth.SummaryA project involving 4,348 cattle and was conducted to evaluate marketing/sorting systems to reduce overweight and overfat carcasses . At reimplant time, cattle were weighed and fat depth estimated either by ultrasound or by manual rib palpation. Cattle heavier and/or fatter than a predetermined reduce carcass discounts. Reimplant fat depth was poorly correlated to carcass fat depth. At reimplant time (~90 days prior to slaughter), we were unable to consistently identify cattle which would become Yield Grade 4 carcasses. (Continued on next page)

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Implant Strategies on Performance and Carcass Characteristics of Finishing Steers

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