Effectiveness of cloprostenol sodium vs. dinoprost tromethamine in a GnRH/CIDR + PGF2a synchronization protocol in Angus...

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Effectiveness of cloprostenol sodium vs. dinoprost tromethamine in a GnRH/CIDR + PGF2a synchronization protocol in Angus, Brahmans, and Brahman x Angus cows
Series Title:
2009 Florida Beef Report
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Book
Creator:
Esterman, Regina
Austin, Brad
Woodall, Steaven
McKinniss, Erin
Yelich, Joel
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Institute of Food and Agricultural Sciences, University of Florida
Place of Publication:
Gainesville, Fla.
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University of Florida
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Effectiveness of Cloprostenol Sodium vs. Dinoprost Tromethamine in a
GnRH/CIDR + PGF2a Synchronization Protocol in Angus, Brahmans, and
Brahman x Angus Cows

Regina Esterman1
Brad Austin
Steaven Woodall
Erin McKinniss
Joel Yelich


Suckled Bos taurus, Bos indicus, and Bos indicus x Bos taurus cows had similar estrous responses,
conception, timed-AI pregnancy, and synchronized pregnancy rates when synchronized with a Select
Synch/CIDR + timed artificial insemination protocol with two PGF2a types. The cloprostenol sodium
PGF2, treatment tended to yield greater estrous response, timed-AI pregnancy, and synchronized
pregnancy rates compared to dinoprost tromethamine.


Summary
Suckled Bos taurus, Bos indicus, and Bos
indicus x Bos taurus cows were used to evaluate
the Select Synch/CIDR (intravaginal
progesterone releasing device) + timed artificial
insemination (TAI) synchronization protocol
with two prostaglandin F2a (PGF2,) types
(cloprostenol sodium vs. dinoprost
tromethamine). Cows received GnRH and a
CIDR on d 0, followed by CIDR removal and
either cloprostenol sodium or dinoprost
tromethamine on d 7. Estrus was detected for 3
following PGF2a and cows were AI 8 to 12 h
after observed in estrus. Cows not c liibi/ig,,
estrus by 72 h after PGF2a were timed-AI
between 76 to 80 h and received GnRH. Six
breeds were evaluated, including: Angus, %4
Angus '% Brahman, %8 Angus %s Brahman
(Brangus), /2 Angus '2 Brahman, Angus %
Brahman, and Brahman. Cloprostenol treated
cows tended to have a greater estrous response
(P=0.17), timed-AI pregnancy rate (P=0.09),
and synchronized pregnancy rate (P=0.15).
Breed of the cow did not (P>0.05) influence
estrous response, conception rate, or timed-AI
pregnancy rate, but tended (P=0.15) to
influence synchronized pregnancy rate. Year of
replication effected conception rate and
synchronized pregnancy rate, but only tended to
influence estrous response (P=0.07) and timed-
Al pregnancy rate (P=0.14). In summary, the


PGF2a treatment of cloprostenol sodium tended
to yield greater responses compared to
dinoprost tromethamine when used in the Select
Synch + timed-AI protocol and the response to
synchronization treatment was similar among
Bos taurus, Bos indicus, and Bos indicus x Bos
taurus breeds.

Introduction
Cattle of Bos indicus breeding are commonly
used by producers in tropical and subtropical
regions of the world due to their superior
tolerance to high temperatures, humidity,
parasites, and utilization of low quality forages
compared to Bos taurus cattle. Slight
differences in the reproductive physiology of
Bos indicus compared to Bos taurus cattle
include a reduced capacity for luteinizing
hormone (LH) secretion, an earlier LH surge and
ovulation relative to the onset of estrus, and a
greater sensitivity to exogenous gonadotrophins.
Behavioral differences are also apparent in Bos
indicus cattle, including a shorter, less evident
estrus and increased occurrence of 'silent
estrus'.

Utilization of the estrous synchronization
protocol of GnRH followed 7 d later by PGF2a is
commonly used in Bos taurus cows. A common
problem with the GnRH + PGF2, system is


2009 Florida BeefReport










expression of estrus several days prior to PGF2a,
which can be prevented with the addition of a
progestogen between the GnRH and PGF2a
treatments. Addition of a progestogen like
melengestrol acetate or the intravaginal
progesterone releasing device (CIDR) to the
GnRH + PGF2, system can also have a
beneficial effect by increasing the number of
anestrous cows that exhibit estrous cycles.
Studies using the GnRH + PGF2a systems with
or without a progestogen have been conducted in
Bos indicus x Bos taurus cattle with limited
success.

The effectiveness of prostaglandins like
cloprostenol sodium and dinoprost
tromethamine to synchronize estrus has been
well documented in Bos taurus cattle, but only
one comparison in cattle of Bos indicus breeding
has been conducted.

Therefore, the objectives of these experiments
was to evaluate the effectiveness of two PGF2a
treatments, cloprostenol sodium and dinoprost
tromethamine, in a GnRH + PGF2a
synchronization program combined with a CIDR
for synchronizing heifers and postpartum
lactating cows, and to evaluate breed effects for
cows of Angus (Bos taurus), Brahman (Bos
indicus), and Brahman x Angus breeding for
responses to the GnRH + PGF2, synchronization
program.

Materials and Methods
This experiment was conducted over a three year
period from February to May of 2005 to 2007 at
the University of Florida, Department of Animal
Sciences Beef Research Unit. Multiparous,
postpartum, lactating cows of varying degrees of
Brahman (Bos indicus) and Angus (Bos taurus)
breeding (n=504) were used. Cows had a mean
(+ SD) age of 5.1 2.4 yr, days postpartum
(DPP) of 65.5 16.2 d, body weight (BW) of
1,208 + 139 lb, and body condition score (BCS)
of 5.2 + 0.6 (1 = emaciated, 9 = obese). Breed
types represented included Angus, Brahman, and
different percentages of Brahman x Angus
breeding. The Brahman x Angus cows were /4
Angus /4 Brahman, %s Angus %3 Brahman
(Brangus), /2 Angus /2 Brahman, and /4 Angus


3/ Brahman. On d 0, all cows received GnRH
(100 ig i.m.; Fertagyl, Intervet) and a new
CIDR (1.38 g progesterone; Eazi-BreedTM
CIDR, Pfizer Animal Health). On d 7, CIDR
was removed and cows were equally distributed
by breed and DPP to receive either of two PGF2a
treatments, which included cloprostenol sodium
(500 ig i.m.; Estrumate, Schering-Plough
Veterinary Corp.) or dinoprost tromethamine (25
mg i.m.; Lutalyse, Pfizer Animal Health). All
cows also received an EstrotectTM estrous
detection patch (EstrotectTM, Rockway, Inc.).

Estrus was visually detected three times daily at
0700, 1200, and 1700 h for 3 d following PGF2a.
Estrus was defined as a cow standing to be
mounted by another cow and/or a half to full red
EstrotectTM patch. Cows were artificially
inseminated (AI) 8 to 12 h after an observed
estrus. All cows that had not displayed estrus by
0800 h, 73 h after PGF2, were timed-AI and
administered GnRH between 76 and 80 h after
PGF2,.

Cows were inseminated using frozen-thawed
semen from multiple pre-assigned sires and were
inseminated by three AI technicians. Pregnancy
was diagnosed approximately 29 d after
insemination using a real-time B-mode
ultrasound (Aloka 500V, Corometrics Medical
Systems) with a 5.0 MHz transducer.

The GENMOD procedure of SAS (SAS Inst.
Inc.) was used for the statistical analysis. The
effects of PGF2, treatment, breed, year, and all
appropriate interactions were evaluated for
estrous response, conception, timed-AI
pregnancy, and synchronized pregnancy rates.
Days postpartum, BCS and cow age were
included as covariates for the evaluation of
estrous response, conception, timed-AI
pregnancy, and synchronized pregnancy rates.

Results
Estrous response tended (P=0.17) to be greater
for cloprostenol treated cows compared to
dinoprost treated cows (Table 1). Estrous
response tended (P=0.07) to differ between
years of replication (Table 2), but estrous
response was not influenced (P>0.05) by breed


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(Table 3). There were no PGF2, treatment x
breed, PGF2~ treatment x year, or breed x year
effects (P>0.05) on estrous response. Cow age
affected (P<0.05) estrous response. Three-year
old cows (44.4%) had a decreased (P<0.05)
estrous response compared to cows that were 4
to 5 yr (57.1%), 6 to 7 yr (59.2%), and 8 to 16 yr
(59.7%), which had similar (P>0.05) estrous
responses. Days postpartum also tended
(P=0.06) to affect estrous response. Short (< 55
d) DPP cows had a lower (P<0.05) estrous
response (45.4%) than medium (56 to 74 d) DPP
cows (58.3%), but were similar (P>0.05) to long
(> 75 d) postpartum cows (54.6%). Medium
DPP cows had a similar (P>0.05) estrous
response compared to long DPP cows. Body
condition score did not (P>0.05) influence
estrous response. The average interval from
PGF2~ to the onset of estrus was not effected
(P>0.05) by PGF2a treatment or breed of cow,
nor did it effect (P>0.05) conception rates. For
cows that exhibited estrus, the average interval
from PGF2a to the onset of estrus was 54.7 + 9.4
h.

Conception rate was similar (P>0.05) between
PGF2, treatments (Table 1) and breed of cow
(Table 3). However, each year of replication
had different (P<0.05) conception rates from the
other years (Table 2). There were no PGF2a
treatment x breed, PGF2~ treatment x year, breed
x year, or PGF2~ treatment x year x breed effects
(P>0.05) on conception rate. Days postpartum
influenced (P<0.05) conception rate. Long
(70.8%) and medium (61.8%) DPP cows had a
similar (P>0.05) conception rate, which was a
greater (P<0.05) compared to short (49.2%)
DPP cows. Short DPP cows had a similar
(P>0.05) conception rate compared to medium
DPP cows. Cow age and BCS did not (P>0.05)
influence conception rate.


by yr of replication (Table 2). Breed did not
(P>0.05) effect timed-AI pregnancy rate (Table
3). There were no PGF2, treatment x breed,
PGF2, treatment x year, breed x year, or PGF2a
treatment x year x breed effects (P>0.05) on
timed-AI pregnancy rate. Cow age and DPP did
not (P>0.05) influence timed-AI pregnancy rate.

Synchronized pregnancy rate tended (P=0.15) to
be effected by PGF2a treatment (Table 1).
Cloprostenol treated cows tended (P=0.15) to
have greater synchronized pregnancy rates
compared to dinoprost treated cows (Table 1).
Synchronized pregnancy rates were greater
(P<0.05) for yr 1 compared to yr 2 and 3, which
were similar (P>0.05) to each other (Table 2).
Breed tended (P=0.15) to effect overall
synchronized pregnancy rates (Table 3). There
were no PGF2, treatment x breed, PGF2a
treatment x year, breed x year, or PGF2a
treatment x year x breed effects (P>0.05) on
synchronized pregnancy rate. Synchronized
pregnancy rates were greater (P < 0.01) for yr 1
compared to yr 2 (Table 2). Age did not
(P>0.05) influence synchronized pregnancy.
Synchronized pregnancy rate was greater
(P<0.05) for medium (54.0%) and long (54.6%)
DPP cows compared to short (40.8%) DPP
cows. Long DPP cows had similar (P>0.05)
synchronized pregnancy rates to medium DPP
cows.

The overall estrous response, conception rate,
timed-AI pregnancy rate, and synchronized
pregnancy rate pooled across both PGF2a
treatments were 53.8, 62.0, 37.8, and 50.8%,
respectively. Breed of cow did not influence
(P>0.05) estrous response, conception rate, or
timed-AI pregnancy rates, but tended (P=0.15)
to influence synchronized pregnancy rates.


Timed-AI pregnancy rates tended (P=0.09) to be
greater for cloprostenol treated cows compared
to dinoprost treated cows (Table 1). Timed-AI
pregnancy rate tended (P=0.14) to be influenced

'Regina Esterman, Graduate Student; Brad Austin, Graduate Student; Steaven Woodall, Former
Graduate Student; Erin McKinniss, Graduate Student; Joel Yelich; Associate Professor, UF-IFA,
Department of Animal Sciences, Gainesville, FL


2009 Florida BeefReport





















Table 1 Estrous, conception, and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos
taurus cows synchronized with a 7 d CIDR treatment with two different prostaglandin Fza (PGF2,)
treatments administered at CIDR removal.a

3 d Estrous Conception Timed-AI Synchronized
Response Rate Pregnancy Pregnancy
Treatments N (%)b (% Rate (%)d Rate (%)e

Cloprostenol 250 56.8 (250) 62.0 (142) 43.5 (108) 54.0 (250)

Dinoprost 254 50.8(254) 62.0(129) 32.8 (125) 47.6 (254)

P-values = 0.17 > 0.05 = 0.09 = 0.15


a All cows received GnRH (100 Gg) at initiation of the 7 d CIDR treatment, with either Estrumate (500 gg)
or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8-12 h later and
all cows not exhibiting estrus by the third day after PGF2, received GnRH and were timed-AI 72-80 h after
PGF2, injection. Results presented as mean (total).
b Percentage of cows displaying estrus during the 3 d after PGF2a of the total treated.
' Percentage of cows pregnant to AI of the total that exhibited estrus and were AI.
d Percentage of cows pregnant to timed-AI of the total that were timed-AI.

e Percentage of cows pregnant during the 3 d synchronized breeding of the total treated.


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Table 3 Estrous, conception and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos
taurus cows synchronized with a 7 d CIDR treatment with two different prostaglandin Fz, (PGF2,)
treatments administered at CIDR removal by breed.a

3 d Estrous Conception Timed-AI Synchronized
Response Rate Pregnancy Pregnancy
Breed Group N (%)b (%)c Rate (%)d Rate (%)e

Angus (AN) 106 58.5 (106) 64.5(62) 34.1(44) 51.9(106)

3/ AN 4 BR 106 51.9(106) 54.6(55) 43.1 (51) 49.1 (106)

% AN 3BR 57 63.2 (57) 55.6 (36) 38.1 (21) 49.1 (57)

AN BR 135 51.9 (135) 72.9 (70) 44.6 (65) 59.3 (135)

3/4 BR 14 AN 50 44.0 (50) 54.6 (22) 28.6 (28) 40.0 (50)

Brahman (BR) 50 52.0 (50) 57.7 (26) 25.0 (24) 42.0 (50)

P-value > 0.05 > 0.05 > 0.05 = 0.15


a All cows received GnRH (100 Gg) at initiation of the 7 d CIDR treatment, with either Estrumate (500
gg) or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8-12 h later
and all cows not exhibiting estrus by the third day after PGF2, received GnRH and were timed-AI 72-80 h
after PGF2a injection. Results presented as mean (total).
b Percentage of cows displaying estrus during the 3 d after PGF2a of the total treated.
' Percentage of cows pregnant to AI of the total that exhibited estrus and were AI.
d Percentage of cows pregnant to timed-AI of the total that were timed-AI.

e Percentage of cows pregnant during the 3 d synchronized breeding of the total treated.


2009 Florida BeefReport




Full Text

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Effectiveness o f Cloprostenol Sodium v s. Dinoprost Tromethamine i n a Gn RH / CIDR + PGF Synchronization Protocol i n Angus Brahmans a nd Brahman Angus Cows Regina Esterman 1 Brad Austin Ste a ven Woodall Erin McKinniss Joel Yelich Summary Suckled Bos taurus, Bos indicus, and Bos indicus Bos taurus cows were used to evaluate the Select Synch/CIDR (intravaginal progesterone releasing device) + timed artificial insemination (TAI) synchronization protocol with two prostaglandin F (PGF ) types (cloprostenol sodium vs. dinoprost tromethamine). Cows received GnRH and a CIDR on d 0, followed by CIDR removal and either cloprostenol sodium or dinoprost tromethamine on d 7. Estrus was detected for 3 d following PGF and cows were AI 8 to 12 h after observed in estrus. Cows not exhibiting estrus by 72 h after PGF were timed-AI between 76 to 80 h and received GnRH. Six breeds were evaluated, including: Angus, (Brangus), Angus Brahman, Angus Brahman, and Brahman. Cloprostenol treated cows tended to have a greater estrous response (P=0.17), timed-AI pregnancy rate (P=0.09), and synchronized pregnancy rate (P=0.15). Breed of the cow did not (P>0.05) influence estrous response, conception rate, or timed-AI pregnancy rate, but tended (P=0.15) to influence synchronized pregnancy rate. Year of replication effected conception rate and synchronized pregnancy rate, but only tended to influence estrous response (P=0.07) and timedAI pregnancy rate (P=0.14). In summary, the PGF treatment of cloprostenol sodium tended to yield greater responses compared to dinoprost tromethamine when used in the Select Synch + timed-AI protocol and the response to synchronization treatment was similar among Bos taurus, Bos indicus, and Bos indicus Bos taurus breeds. In troduction Cattle of Bos indicus breeding are commonly used by producers in tropical and subtropical regions of the world due to their superior tolerance to high temperatures, humidity, parasites, and utilization of low quality forages compared to Bos taurus cattle. Slight differences in the reproductive physiology of Bos indicus compared to Bos taurus cattle include a reduced capacity for luteinizing hormone (LH) secretion, an earlier LH surge and ovulation relative to the onset of estrus, and a greater sensitivity to exogenous gonadotrophins. Behavioral differences are also apparent in Bos indicus cattle, including a shorter, less evident Utilization of the estrous synchronization protocol of GnRH followed 7 d later by PGF is commonly used in Bos taurus cows. A common problem with the GnRH + PGF system is Suckled Bos taurus, Bos indicus, and Bos indicus Bos taurus cows had similar estrous responses, conception, timed AI pregnancy, and synchronized pregnancy rates when synchronized with a Select Synch/CIDR + timed artificial insemination protocol with two PGF types. The cloprostenol sodium PGF treatment tended to yield greater estrous response, timed AI pregnancy, and synchronized pregnancy rates compared to dinoprost tromethamine.

PAGE 2

expression of estrus several days prior to PGF which can be prevented with the addition of a progestogen between the GnRH and PGF treatments. Addition of a progestogen like melengestrol acetate or the intravaginal progesterone releasing device (CIDR) to the GnRH + PGF system can also have a beneficial effect by increasing the number of anestrous cows that exhibit estrous cycles. Studies using the GnRH + PGF systems with or without a progestogen have been conducted in Bos indicus Bos taurus cattle with limited success. The effectiveness of prostaglandins like cloprostenol sodium and dinoprost tromethamine to synchronize estrus has been well documented in Bos taurus cattle, but only one comparison in cattle of Bos indicus breeding has been conducted. Therefore, the objectives of these experiments was to evaluate the effectiveness of two PGF treatments, cloprostenol sodium and dinoprost tromethamine, in a GnRH + PGF synchronization program combined with a CIDR for synchronizing heifers and postpartum lactating cows, and to evaluate breed effects for cows of Angus ( Bos taurus ), Brahman ( Bos indicus ), and Brahman Angus breeding for responses to the GnRH + PGF synchronization program. Materials and Methods This experiment was conducted over a three year period from February to May of 2005 to 2007 at the University of Florida, Department of Animal Sciences Beef Research Unit. Multiparous, postpartum, lactating cows of varying degrees of Brahman ( Bos indicus ) and Angus ( Bos taurus ) breeding (n=504) were used. Cows had a mean ( SD) age of 5.1 2.4 yr, days postpartum (DPP) of 65.5 16.2 d, body weight (BW) of 1,208 139 lb, and body condition score (BCS) of 5.2 0.6 (1 = emaciated, 9 = obese). Breed types represented included Angus, Brahman, and different percentages of Brahman Angus breeding. The Brahman Angus cows were (Brangus), Angus Brahman, and Angus Brahman. On d 0, all cows received GnRH (100 g i.m.; Fertagyl Intervet) and a new CIDR (1.38 g progesterone; EaziCIDR Pfizer Animal Health). On d 7, CIDR was removed and cows were equally distributed by breed and DPP to receive either of two PGF treatments, which included cloprostenol sodium (500 g i.m.; Estrumate Schering-Plough Veterinary Corp.) or dinoprost tromethamine (25 mg i.m.; Lutalyse Pfizer Animal Health). All Estrus was visually detected three times daily at 0700, 1200, and 1700 h for 3 d following PGF Estrus was defined as a cow standing to be mounted by another cow and/or a half to full red inseminated (AI) 8 to 12 h after an observed estrus. All cows that had not displayed estrus by 0800 h, 73 h after PGF were timed-AI and administered GnRH between 76 and 80 h after PGF Cows were inseminated using frozen-thawed semen from multiple pre-assigned sires and were inseminated by three AI technicians. Pregnancy was diagnosed approximately 29 d after insemination using a real-time B-mode ultrasound (Aloka 500V, Corometrics Medical Systems) with a 5.0 MHz transducer. The GENMOD procedure of SAS (SAS Inst. Inc.) was used for the statistical analysis. The effects of PGF treatment, breed, year, and all appropriate interactions were evaluated for estrous response, conception, timed-AI pregnancy, and synchronized pregnancy rates. Days postpartum, BCS and cow age were included as covariates for the evaluation of estrous response, conception, timed-AI pregnancy, and synchronized pregnancy rates. Results Estrous response tended (P =0.17) to be greater for cloprostenol treated cows compared to dinoprost treated cows (Table 1). Estrous response tended ( P =0.07) to differ between years of replication (Table 2), but estrous response was not influenced ( P >0.05) by breed

PAGE 3

(Table 3). There were no PGF treatment breed, PGF treatment year, or breed year effects ( P >0.05) on estrous response. Cow age affected ( P <0.05) estrous response. Three-year old cows (44.4%) had a decreased (P<0.05) estrous response compared to cows that were 4 to 5 yr (57.1%), 6 to 7 yr (59.2%), and 8 to 16 yr (59.7%), which had similar ( P >0.05) estrous responses. Days postpartum also tended ( P d) DPP cows had a lower ( P <0.05) estrous response (45.4%) than medium (56 to 74 d) DPP cows (58.3%), but were similar ( P >0.05) to long DPP cows had a similar ( P >0.05) estrous response compared to long DPP cows. Body condition score did not ( P >0.05) influence estrous response. The average interval from PGF to the onset of estrus was not effected ( P >0.05) by PGF treatment or breed of cow, nor did it effect ( P >0.05) conception rates. For cows that exhibited estrus, the average interval from PGF to the onset of estrus was 54.7 9.4 h. Conception rate was similar ( P >0.05) between PGF treatments (Table 1) and breed of cow (Table 3). However, each year of replication had different ( P <0.05) conception rates from the other years (Table 2). There were no PGF treatment breed, PGF treatment year, breed year, or PGF treatment year breed effects ( P >0.05) on conception rate. Days postpartum influenced ( P <0.05) conception rate. Long (70.8%) and medium (61.8%) DPP cows had a similar ( P >0.05) conception rate, which was a greater ( P <0.05) compared to short (49.2%) DPP cows. Short DPP cows had a similar ( P >0.05) conception rate compared to medium DPP cows. Cow age and BCS did not ( P >0.05) influence conception rate. Timed-AI pregnancy rates tended ( P =0.09) to be greater for cloprostenol treated cows compared to dinoprost treated cows (Table 1). Timed-AI pregnancy rate tended ( P =0.14) to be influenced by yr of replication (Table 2). Breed did not ( P>0.05) effect timed-AI pregnancy rate (Table 3). There were no PGF treatment breed, PGF treatment year, breed year, or PGF treatment year breed effects ( P >0.05) on timed-AI pregnancy rate. Cow age and DPP did not ( P >0.05) influence timed-AI pregnancy rate. Synchronized pregnancy rate tended ( P =0.15) to be effected by PGF treatment (Table 1). Cloprostenol treated cows tended ( P =0.15) to have greater synchronized pregnancy rates compared to dinoprost treated cows (Table 1). Synchronized pregnancy rates were greater ( P<0.05) for yr 1 compared to yr 2 and 3, which were similar ( P >0.05) to each other (Table 2). Breed tended ( P =0.15) to effect overall synchronized pregnancy rates (Table 3). There were no PGF treatment breed, PGF treatment year, breed year, or PGF treatment year breed effects ( P >0.05) on synchronized pregnancy rate. Synchronized pregnancy rates were greater ( P < 0.01) for yr 1 compared to yr 2 (Table 2). Age did not ( P>0.05) influence synchronized pregnancy. Synchronized pregnancy rate was greater ( P<0.05) for medium (54.0%) and long (54.6%) DPP cows compared to short (40.8%) DPP cows. Long DPP cows had similar ( P >0.05) synchronized pregnancy rates to medium DPP cows. The overall estrous response, conception rate, timed-AI pregnancy rate, and synchronized pregnancy rate pooled across both PGF treatments were 53.8, 62.0, 37.8, and 50.8%, respectively. Breed of cow did not influence ( P>0.05) estrous response, conception rate, or timed-AI pregnancy rates, but tended ( P =0.15) to influence synchronized pregnancy rates. 1 Regina Esterman, Graduate Student; Brad Austin, Graduate Student; Steaven Woodall, Former Graduate Student; Erin McKinniss, Graduate Student; Joel Yelich ; Ass ociate Professor UF IFA, Department of Animal Sciences, Gainesville, FL

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Table 1 Estrous, conception, and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos taurus cows synchronized with a 7 d CIDR treatment with two different prostaglandin F 2 (PGF 2 ) treatments administered at CIDR removal. a Treatments N 3 d Estrous Response (%) b Conception Rate (%) c Timed AI Pregnancy Rate (%) d Synchronized Pregnancy Rate (%) e Cloprostenol 250 56.8 (250) 62.0 (142) 43.5 (108) 54.0 (250) Dinoprost 254 50.8 (254) 62.0 (129) 32.8 (125) 47.6 (254) P values = 0.17 > 0.05 = 0.09 = 0.15 a All cows received GnRH or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8 12 h later and all cows not exhibiting estrus by the third day after PGF 2 received G nRH and were timed AI 72 80 h after PGF 2 injection. Results presented as mean (total). b Percentage of cows displaying estrus during the 3 d after PGF 2 of the total treated. c Percentage of cows pregnant to AI of the total that exhibited estrus and we re AI. d Percentage of cows pregnant to timed AI of the total that were timed AI. e Percentage of cows pregnant during the 3 d synchronized breeding of the total treated.

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Table 2 Estrous, conception and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos taurus cows synchronized with a 7 d CIDR treatment with two different prostaglandin F 2 (PGF 2 ) treatments administered at CIDR removal by treatment (TRT), year, and a treatment by year interaction (TRT*YEAR). a Treatments N 3 d Estrous Response (%) b Conception Rate (%) c Timed AI Pregnancy Rate (%) d Synchronized Pregnancy Rate (%) e YEAR 1 157 52.9 (157) 77.1 (83) 46.0 (74) 62.4 (157) Cloprostenol 78 57.7 (78) 82.2 (45) 54.6 (33) 70.5 (78) Dinoprost 79 48.1 (79) 71.1 (38) 39.0 (41) 54.4 (79) YEAR 2 178 48.3 (178) 47.7 (86) 37.0 (92) 42.1 (178) Cloprostenol 88 51.1 (88) 46.7 (45) 44.2 (43) 45.5 (88) Dinoprost 90 45.6 (90) 48.8 (41) 30.6 (49) 38.9 (90) YEAR 3 169 60.4 (169) 61.8 (102) 29.9 (67) 49.1 (169) Cloprostenol 84 61.9 (84) 57.7 (52) 31.3 (32) 47.6 (84) Dinoprost 85 58.8 (85) 66.0 (50) 28.6 (35) 50.6 (85) TRT P = 0.17 P > 0.05 P = 0.09 P = 0.15 YEAR P = 0.07 P < 0.05 P = 0.14 P < 0.05 TRT*YEAR > 0.05 > 0.05 > 0.05 > 0.05 a All cows received GnRH or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8 12 h later and all cows not exhibiting estrus by the third day after PGF 2 received G nRH and were timed AI 72 80 h after PGF 2 injection. Results presented as mean (total). b Percentage of cows displaying estrus during the 3 d after PGF 2 of the total treated. c Percentage of cows pregnant to AI of the total that exhibited estrus and we re AI. d Percentage of cows pregnant to timed AI of the total that were timed AI. e Percentage of cows pregnant during the 3 d synchronized breeding of the total treated.

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Table 3 Estrous, conception and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos taurus cows synchronized with a 7 d CIDR treatment with two different prostaglandin F 2 (PGF 2 ) treatments administered at CIDR removal by breed. a Breed Group N 3 d Estrous Response (%) b Conception Rate (%) c Timed AI Pregnancy Rate (%) d Synchronized Pregnancy Rate (%) e Angus (AN) 106 58.5 (106) 64.5 (62) 34.1 (44) 51.9 (106) AN BR 106 51.9 (106) 54.6 (55) 43.1 (51) 49.1 (106) 57 63.2 (57) 55.6 (36) 38.1 (21) 49.1 (57) AN BR 135 51.9 (135) 72.9 (70) 44.6 (65) 59.3 (135) BR AN 50 44.0 (50) 54.6 (22) 28.6 (28) 40.0 (50) Brahman (BR) 50 52.0 (50) 57.7 (26) 25.0 (24) 42.0 (50) P value > 0.05 > 0.05 > 0.05 = 0.15 a All cows received GnRH (100 g) at initiation of the 7 d CIDR treatment, with either Estrumate (500 12 h later and all cows not exhibiting estrus by the third day after PGF 2 received GnRH and were timed AI 72 80 h after PGF 2 injection. Results presented as mean (total). b Percentage of cows displaying estrus during the 3 d after PGF 2 of the total treated. c Percentage of cows pregnant to AI of the total that exhibited estrus and were AI. d Percentage of cows pregnant to timed AI of the total that were timed AI. e Percentage of cows pregnant during the 3 d synchronized breeding of the total treated.