Comparison of two progestogen based estrous synchronization protocols and cloprostenol sodium vs. dinoprost tromethamine...

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Comparison of two progestogen based estrous synchronization protocols and cloprostenol sodium vs. dinoprost tromethamine in suckled post partum cows and yearling heifers of Bos indicus x Bos taurus breeding
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2009 Florida Beef Report
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Book
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McKinniss, Erin
Esterman, Regina
Woodall, Steaven
Austin, Brad
Yelich, Joel
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Institute of Food and Agricultural Sciences, University of Florida
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Gainesville, Fla.
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Comparison of Two Progestogen Based Estrous Synchronization Protocols
and Cloprostenol Sodium vs. Dinoprost Tromethamine in Suckled Post
Partum Cows and Yearling Heifers of Bos Indicus x Bos Taurus Breeding

Erin McKinniss1
Regina Esterman
Steaven Woodall
Brad Austin
Joel Yelich

Synch/CIDR+timed-AI had increased conception and synchronized pregnancy rates compared to the
7-10 treatment in suckled cows of Bos indicus x Bos taurus breeding. Body condition score and
days postpartum influenced the effectiveness of the synchronization treatments. There were no
synchronization or prostaglandin treatment effects on any of the reproductive responses measured in
the yearling heifers of Bos indicus x Bos taurus breeding.


Summary
Bos indicus x Bos taurus suckled postpartum
cows (n=324) and yearling heifers were utilized
over two breeding seasons (n=218 and 137) in
an experiment comparing two progestogen
based synchronization protocols and two
prostaglandins. On d 0, the 7-10 treatment
received an autoclaved once used Eazi breed
CIDR progesterone insert (CIDR) that was
removed on d 7 concomitant with Dinoprost
tromethamine (Prostamate) followed by
gonadotropin releasing hormone (GnRH) on d
10. On d 17, 7-10 treatment received one of two
prostaglandins, Prostamate or Cloprostenol
sodium (Estrumate). Also on d 10, the Select
Synch/CIDR+timed-artificial insemination (AI)
treatment received a new CIDR concomitant
with GnRH with CIDR removal on d 17 where
cows received either Prostamate or Estrumate.
Estrus was visually detected twice daily (0700
and 1600 h) for 72 h after prostaglandin F2a
(PGF2a) and cows were AI 6 to 12 h after a
detected estrus. Non-responders were timed-AI
+ GnRH 72 to 76 h post PGF2a.

For the cows, estrous response, conception rate,
and synchronized pregnancy rate synchronized
pregnancy rate were affected (P < 0.05) by
synchronization treatment but not (P > 0.05)
PGF2 treatment. The synchronized pregnancy
rates were 45.5% and 31.2 for the Select


Synch/CIDR+timed-AI and 7-10 treatments,
respectively. As body condition score (BCS)
increased from < 4.5 to > 5.5, estrous response,
conception rate, synchronized pregnancy rate,
and 30-d pregnancy rates increased (P < 0.05).

For the heifers, estrous response, conception
rate, timed-AI pregnancy rates, synchronized
pregnancy rate, and 30-d pregnancy rates were
similar (P > 0.05) between the synchronization
and PGF2, treatments, with the mean estrous
response, conception rate, timed-AI pregnancy
rates, synchronized pregnancy rate, and 30 d
pregnancy rates being 66.8, 65.0, 16.1, 48.7,
and 76.3%, respectively.


Introduction
One of the most consistent synchronization
protocols in suckled cows and yearling heifers of
Bos taurus breeding includes administration of a
7 d Eazi-BreedT CIDR with GnRH at CIDR
insertion and PGF2, at CIDR removal, followed
by 3 d of estrous detection and AI with a timed-
AI plus GnRH for cattle not exhibiting estrus by
72 h after PGF2,. This protocol is known as the
Select Synch/CIDR+timed-AI protocol.
Previous reports indicated pregnancy rates were
similar for suckled cows and yearling heifers of
Bos indicus x Bos taurus breeding compared to


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cattle of Bos taurus breeding. Therefore,
additional experiments are needed in cattle of
Bos indicus x Bos taurus breeding to evaluate
CIDR synchronizations treatments when GnRH
is administered at CIDR insertion and at timed-
AI for induction of ovulation in cows not
expressing estrus.

The 7-11 synchronization protocol is another
short-term progestogen synchronization protocol
that is frequently used in cattle of Bos taurus
breeding. The 7-11 protocol consists of a 7 d
melengestrol acetate (MGA) treatment with
PGF2, on the last day of MGA followed by
GnRH 4 d later. Seven-d after GnRH, PGF2, is
administered to synchronize estrus. The 7-11
synchronization protocol is effective in Bos
taurus cattle but no research has been conducted
to evaluate the effectiveness of the 7-11 protocol
in yearling heifers of Bos indicus x Bos taurus
breeding and one study has been conducted in
suckled cows of Bos indicus x Bos taurus
breeding.

As production costs increase, producers seek to
implement new management practices that either
reduce their operating costs and (or) increase
productivity. Therefore, there has been
considerable interest in using a once-used CIDR
in estrous synchronization protocols. Previous
reports indicate utilization of a once-used CIDR
for 7 d suppresses estrus in beef females and
autoclaving a once-used CIDR increases
circulating progesterone concentrations
compared to a non-autoclaved once-used CIDR.
Autoclaving also reduces the risk of disease
transmission. Therefore, there appears to be
potential for incorporating a once-used CIDR
into some estrous synchronization protocols.

Additionally, a minimal amount of research has
been conducted evaluating the effectiveness of
prostaglandin type; Prostamate compared to
Estrumate, when used in GnRH+PGF2, estrous
synchronization protocols in cattle of Bos
indicus x Bos taurus breeding. Additionally, no
direct comparisons have been made between
Prostamate and Estrumate in yearling Bos
indicus x Bos taurus heifers synchronized with
GnRH+PGF2, synchronization protocols.


Therefore, the objectives of these experiments
were to evaluate the effectiveness of Prostamate
compared to Estrumate when used in a modified
7-11 protocol and a Select Synch/CIDR+timed-
AI protocol in yearling heifers and suckled cows
of Bos indicus x Bos taurus breeding.

Procedure
Suckled cows of Bos indicus x Bos taurus (n
324) in 2007, and yearling heifers in 2006 and
2007(n = 218 and 137) from Bar-L Ranch in
Marianna, FL, were used for the experiments.
Genotypes for the animals utilized ranged from
approximately 7 to 38% Bos indicus with the
remainder being Bos taurus genotype.

At the start of the experiment (d 0), cows were
equally distributed by body condition score
(BCS; 1 = emaciated, 5 = moderate, 9 = very fat)
and days post partum (DPP) to one of two
progestogen based synchronization treatments
and one of two PGF2a treatments (Figure 1).
The synchronization treatments included a
modified 7-11 treatment, (7-10) and the Select
Synch/CIDR+timed-AI treatment. Within each
synchronization treatment, half the cows
received one of two PGF2~ treatments:
Prostamate (25 mg i.m.; Agrilabs) or Estrumate
(500 ig i.m.; Schering-Plough Veterinary
Corp.). On d 0, the 7-10 treatment received an
autoclaved once-used CIDR (Eazi-BreedT
CIDR, 1.38 g progesterone, Pfizer Animal
Health) that was removed on d 7 concomitant
with Prostamate followed by GnRH (500 Gg;
Cystorelin, Merial Animal Health) on d10. The
once-used autoclaved CIDR was used in place of
MGA to test its effectiveness as a low cost
alternative progestogen source in the 7-10
protocol. On d17, 7-10 cows received either
Prostamate or Estrumate. Also on d 10, the
Select Synch/CIDR+timed-AI treatment
received a new CIDR concomitant with GnRH
followed by CIDR removal on d 17 where cows
received either Prostamate or Estrumate.

To aid in estrous detection, all cows received
EstrotectTM estrous detection patches (Rockway,
Inc.) on d 18 of the experiment. Estrus was
visually detected twice daily (0700 and 1600 h)
for 72 h after PGF2, and cows were inseminated


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6 to 12 h after detection of estrus. Non-
responders were timed-AI + GnRH 72 to 76 h
post PGF2a. Seven-d after the timed-AI, natural
service sires were placed with cows. Pregnancy
was diagnosed approximately 55 d after AI by
transrectal ultrasonography.

Estrous response was defined as the number of
cows displaying estrus for 3 d after
prostaglandin and AI divided by the total
number of cows treated. Conception rate was
defined as the number of cows that became
pregnant to AI divided by the number of cows
that displayed estrus and were AI. Timed-AI
pregnancy rate was the number of cows that
failed to display estrus, were timed-AI, and
became pregnant divided by the total number of
cows that were timed-AI. Synchronized
pregnancy rate was the number of cows pregnant
to AI divided by the total number of cows
treated. Thirty-d pregnancy rate was the number
of cows pregnant during the first 30 d of the
breeding season divided by the total number of
cows treated.

Yearling heifers were randomly assigned to the
same treatments and estrous detection and AI
were administered in the same manner as for the
cows.

Results and Discussion
For the cows, estrous response, conception rate,
and synchronized pregnancy rate was affected
(P < 0.05) by synchronization treatment (Table
1). Body condition score also affected (P <
0.05) estrous response, conception rate, and
synchronized pregnancy rate, and 30 d
pregnancy rates. Days postpartum tended to (P
= 0.1) effect timed-AI pregnancy rate and had an
effect (P < 0.05) on synchronized pregnancy
rate. Prostaglandin treatments were similar (P >
0.05) for estrous response, conception rate,
timed-AI pregnancy rate, synchronized
pregnancy rate, and 30 d pregnancy rate (Table
1).


In both years, heifers had similar (P > 0.05)
estrous response, conception rate, timed-AI
pregnancy rate, synchronized pregnancy rate,
and 30 d pregnancy rate between 7-10 vs. Select
Synch/CIDR+timed-AI (Table 2) and Estrumate
vs.Prostamate (Table 3). Across treatments, the
mean estrous response, conception rate, timed-
AI pregnancy rate, synchronized pregnancy rate
and 30 d pregnancy rate were 66.8, 65.0, 16.1,
48.7, and 76.3% respectively. The mean
synchronized pregnancy rate for the Prostamate
and Estrumate treatments were 45.5 and 52.0%,
respectively. At 48 h after PGF2a, treatments
had a similar (P > 0.05) conception rate. At 60
h, Select Synch/CIDR+timed-AI treatment
tended (P = 0.10) to have a decreased
conception rate. Inversely, at 72 h, Select
Synch/CIDR+timed-AI treatment had an
increased (P < 0.05) conception rate compared
to the 7-10 treatment.

In summary, the Select Synch/CIDR+timed-AI
had increased conception and synchronized
pregnancy rates compared to the 7-10 treatment
in suckled cows of Bos indicus x Bos taurus
breeding. The effectiveness of the treatment
was influenced by BCS, as BCS increased, the
estrous response, conception rate, and
synchronized pregnancy rates increased. Days
postpartum also influenced effectiveness of the
synchronization treatments, as time from calving
to start of synchronization increased,
synchronized pregnancy rates increased. There
was no effect of prostaglandin treatment on
estrous response, conception rate, timed-AI
pregnancy rate, synchronized pregnancy rate, or
30 d pregnancy rate. There were no
synchronization or prostaglandin treatment
effects on any of the reproductive responses
measured in the yearling heifers of Bos indicus
x Bos taurus breeding for either year.


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


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a) 7-10 treatment with Prostamate or Estrumate PGF2, on d 17


Prostamate GnRH


Prostamate or
Estrumate


GnRH +
timed-AI


SI

Estrus detect & Al


Once-used CIDR


b) Select Synch/CIDR+timed-AI treatment with Prostamate or Estrumate PGF2, on d 17


GnRH


Prostamate or
Estrumate


New CIDR Estrus detect & AI


GnRH +
timed-AI


Day of experiment


Experimental design evaluating the effects of two progestogen and two PGF2, treatments in Bos
indicus x Bos taurus suckled cows and yearling heifers a) 7-10 treatment: on d 0 received a once-
used CIDR that was removed on d 7 concomitant with Prostamate (25 mg i.m.) followed by
GnRH (500 ig i.m.) on d 10. On d 17, females received either Prostomate or Estrumate (500 Ig
i.m.). b) Select Synch/CIDR+timed-AI treatment: on d 10 received a new CIDR (1.38 g)
concomitant with GnRH. Day 17 CIDR was removed and females received either Prostomate or
Estrumate. For all four treatments estrus was detected for 3 d and females were inseminated 6 to
12 h after detected estrus. Females not exhibiting estrus by 72 h were timed-AI and received
GnRH.


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Figure 1.


















Table 1. Effect of synchronization treatment and prostaglandin treatment on estrous response,
conception rates and pregnancy rates in suckled cows of Bos indicus x Bos taurus breeding
synchronized with either a modified 7-11 (7-10) or Select Synch/CIDR+timed-AI (SSC+TAI)
treatment with either Estrumate or Prostamate.a

Timed-AI
Estrous Conception pregnancy rate, Synchronized
Variable response, %b rate, % %d pregnancy rate, %e

Synchronization

7-10 49.0 (77/157) 45.5 (35/77) 17.5 (14/80) 31.2 (49/157)

SSC+TAI 59.9 (100/167) 62.0 (62/100) 20.9 (14/67) 45.5 (76/167)

P-value < 0.05 < 0.05 > 0.05 < 0.05




Prostaglandin

Estrumate 57.0 (94/165) 48.9 (46/94) 23.9 (17/71) 38.2 (63/165)

Prostamate 52.2 (83/159) 61.5 (51/83) 14.5 (11/76) 39.0 (62/159)

P-value > 0.05 > 0.05 > 0.05 > 0.05

a See Figure 3-1 for details of treatments.
b Percentage of cows displaying estrus 72 h after PGF2, 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 synchronized breeding of the total treated.


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Table 2. Estrous response, conception, and pregnancy rates by synchronization treatment of yearling
heifers of Bos indicus x Bos taurus genotype synchronized with either a modified 7-11 (7-10) or Select
Synch/CIDR+timed-AI (SSC+TAI) treatment with either Estrumate or Prostamate for years 1 and 2.1

Estrous response, Conception rate, Timed-AI Synchronized
%0b %c pregnancy rate %d pregnancy rate, %e
Variable

7-10 65.2 (116/178) 62.1 (72/116) 14.5 (9/62) 45.5 (81/178)

Yr 1 71.6 (78/109) 65.4 (51/78) 9.68 (3/31) 49.5 (54/109)

Yr2 55.1 (38/69) 55.3 (21/38) 19.4 (6/31) 39.1 (27/69)

SSC+TAI 68.4 (121/177) 67.8 (82/121) 17.9 (10/56) 52.0 (92/177)

Yr 1 64.2 (70/109) 71.4 (50/70) 20.5 (8/39) 53.2 (58/109)

Yr 2 75.0 (51/68) 62.7 (32/51) 11.8 (2/17) 50.0 (34/68)




P-value

Snc > 0.05 > 0.05 > 0.05 > 0.05

Yr > 0.05 > 0.05 > 0.05 > 0.05

Sync xYr <0.05 > 0.05 > 0.05 > 0.05

a See Figure 3-1 for details of treatments.
b Percentage of heifers displaying estrus 72 h after PGF2, of the total treated.

c Percentage of heifers pregnant to AI of the total that exhibited estrus and were AI.
d Percentage of heifers pregnant to timed-AI of the total that were timed-AI.

e Percentage of heifers pregnant during the synchronized breeding of the total treated.


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Table 3. Estrous response, conception and pregnancy rates by prostaglandin treatment of yearling
heifers of Bos indicus x Bos taurus genotype synchronized with either a modified 7-11 (7-10) or Select
Synch/CIDR + timed-AI (SSC+TAI) treatment with either Estrumate or Prostamate for yr 1 and 2.'

Timed-AI
Estrous Conception rate, pregnancy rate, Synchronized
Variable response, %b %c %d pregnancy rate, %e

Estrumate 68.7 (123/179) 67.5 (83/123) 17.9 (10/56) 52.0 (93/179)

Yr 1 70.6 (77/109) 71.4 (55/77) 18.8 (6/32) 56.0 (61/109)

Yr 2 65.7 (46/70) 60.9 (38/46) 16.7 (4/24) 45.7 (32/70)

Prostamate 64.8 (114/176) 62.3(71/114) 14.5 (9/62) 45.4 (80/176)

Yr 1 65.1 (71/109) 64.8 (46/710 13.2 (5/38) 46.8 (51/109)

Yr 2 64.2 (43/67) 58.1 (25/43) 16.7 (4/24) 43.3 (29/67)




P-value

Prostaglandin > 0.05 > 0.05 > 0.05 > 0.05

Yr > 0.05 > 0.05 > 0.05 > 0.05

Prostaglandin x > 0.05 > 0.05 > 0.05 > 0.05
Yr

a See Figure 3-1 for details of treatments.
b Percentage of heifers displaying estrus 72 h after PGF2, of the total treated.

c Percentage of heifers pregnant to AI of the total that exhibited estrus and were AI.
d Percentage of heifers pregnant to timed-AI of the total that were timed-AI.

e Percentage of heifers pregnant during the synchronized breeding of the total treated.


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Full Text

PAGE 1

Comparison o f Two Progestogen Based Estrous Synchronization Protocols a nd Cloprostenol Sodium v s. Dinoprost Tromethamine i n Suckled Post Partum Cows a nd Yearling Heifers o f B os Indicus Bos Taurus Breeding Erin McKinniss 1 Regina Esterman Steaven Woodall Brad Austin Joel Yelich Summary Bos indicus Bos taurus suckled postpartum cows (n=324) and yearling heifers were utilized over two breeding seasons (n=218 and 137) in an experiment comparing two progestogen based synchronization protocols and two prostaglandins. On d 0, the 7-10 treatment received an autoclaved once used Eazi breed CIDR progesterone insert (CIDR) that was removed on d 7 concomitant with Dinoprost tromethamine (Prostamate) followed by gonadotropin releasing hormone (GnRH) on d 10. On d 17, 7-10 treatment received one of two prostaglandins, Prostamate or Cloprostenol sodium (Estrumate). Also on d 10, the Select Synch/CIDR+timed-artificial insemination (AI) treatment received a new CIDR concomitant with GnRH with CIDR removal on d 17 where cows received either Prostamate or Estrumate. Estrus was visually detected twice daily (0700 and 1600 h) for 72 h after prostaglandin F (PGF and cows were AI 6 to 12 h after a detected estrus. Non-responders were timed-AI + GnRH 72 to 76 h post PGF 2a For the cows, estrous response, conception rate, and synchronized pregnancy rate synchronized pregnancy rate were affected (P < 0.05) by synchronization treatment but not (P > 0.05) PGF2 treatment. The synchronized pregnancy rates were 45.5% and 31.2 for the Select Synch/CIDR+timed-AI and 7-10 treatments, respectively. As body condition score (BCS) conception rate, synchronized pregnancy rate, and 30-d pregnancy rates increased (P < 0.05). For the heifers, estrous response, conception rate, timed-AI pregnancy rates, synchronized pregnancy rate, and 30-d pregnancy rates were similar (P > 0.05) between the synchronization and PGF treatments, with the mean estrous response, conception rate, timed-AI pregnancy rates, synchronized pregnancy rate, and 30 d pregnancy rates being 66.8, 65.0, 16.1, 48.7, and 76.3%, respectively. Introduction One of the most consistent synchronization protocols in suckled cows and yearling heifers of Bos taurus breeding includes administration of a 7 d Eazi-Breed CIDR with GnRH at CIDR insertion and PGF at CIDR removal, followed by 3 d of estrous detection and AI with a timedAI plus GnRH for cattle not exhibiting estrus by 72 h after PGF This protocol is known as the Select Synch/CIDR+timed-AI protocol. Previous reports indicated pregnancy rates were similar for suckled cows and yearling heifers of Bos indicus Bos taurus breeding compared to Synch/CIDR+timed AI had increased conception and synchronized pregnancy rates compared to the 7 10 treatment in suckled cows of Bos indicus Bos taurus breeding. Body condition score and days postpartum influenced the effectiv eness of the synchronization treatments. There were no synchronization or prostaglandin treatment effects on any of the reproductive responses measured in the yearling heifers of Bos indicus Bos taurus breeding.

PAGE 2

cattle of Bos taurus breeding. Therefore, additional experiments are needed in cattle of Bos indicus Bos taurus breeding to evaluate CIDR synchronizations treatments when GnRH is administered at CIDR insertion and at timedAI for induction of ovulation in cows not expressing estrus. The 7-11 synchronization protocol is another short-term progestogen synchronization protocol that is frequently used in cattle of Bos taurus breeding. The 7-11 protocol consists of a 7 d melengestrol acetate (MGA) treatment with PGF on the last day of MGA followed by GnRH 4 d later. Seven-d after GnRH, PGF is administered to synchronize estrus. The 7-11 synchronization protocol is effective in Bos taurus cattle but no research has been conducted to evaluate the effectiveness of the 7-11 protocol in yearling heifers of Bos indicus Bos taurus breeding and one study has been conducted in suckled cows of Bos indicus Bos taurus breeding. As production costs increase, producers seek to implement new management practices that either reduce their operating costs and (or) increase productivity. Therefore, there has been considerable interest in using a once-used CIDR in estrous synchronization protocols. Previous reports indicate utilization of a once-used CIDR for 7 d suppresses estrus in beef females and autoclaving a once-used CIDR increases circulating progesterone concentrations compared to a non-autoclaved once-used CIDR. Autoclaving also reduces the risk of disease transmission. Therefore, there appears to be potential for incorporating a once-used CIDR into some estrous synchronization protocols. Additionally, a minimal amount of research has been conducted evaluating the effectiveness of prostaglandin type; Prostamate compared to Estrumate, when used in GnRH+PGF estrous synchronization protocols in cattle of Bos indicus Bos taurus breeding. Additionally, no direct comparisons have been made between Prostamate and Estrumate in yearling Bos indicus Bos taurus heifers synchronized with GnRH+PGF synchronization protocols. Therefore, the objectives of these experiments were to evaluate the effectiveness of Prostamate compared to Estrumate when used in a modified 7-11 protocol and a Select Synch/CIDR+timedAI protocol in yearling heifers and suckled cows of Bos indicus Bos taurus breeding. Procedure Suckled cows of Bos indicus Bos taurus (n = 324) in 2007, and yearling heifers in 2006 and 2007(n = 218 and 137) from Bar-L Ranch in Marianna, FL, were used for the experiments. Genotypes for the animals utilized ranged from approximately 7 to 38% Bos indicus with the remainder being Bos taurus genotype. At the start of the experiment (d 0), cows were equally distributed by body condition score (BCS; 1 = emaciated, 5 = moderate, 9 = very fat) and days post partum (DPP) to one of two progestogen based synchronization treatments and one of two PGF treatments (Figure 1). The synchronization treatments included a modified 7-11 treatment, (7-10) and the Select Synch/CIDR+timed-AI treatment. Within each synchronization treatment, half the cows received one of two PGF treatments: Prostamate (25 mg i.m.; Agrilabs) or Estrumate (500 g i.m.; Schering-Plough Veterinary Corp.). On d 0, the 7-10 treatment received an autoclaved once-used CIDR (Eazi-Breed CIDR 1.38 g progesterone, Pfizer Animal Health) that was removed on d 7 concomitant with Prostamate followed by GnRH (500 g; Cystorelin Merial Animal Health) on d10. The once-used autoclaved CIDR was used in place of MGA to test its effectiveness as a low cost alternative progestogen source in the 7-10 protocol. On d17, 7-10 cows received either Prostamate or Estrumate. Also on d 10, the Select Synch/CIDR+timed-AI treatment received a new CIDR concomitant with GnRH followed by CIDR removal on d 17 where cows received either Prostamate or Estrumate. To aid in estrous detection, all cows received Estrotect estrous detection patches (Rockway, Inc.) on d 18 of the experiment. Estrus was visually detected twice daily (0700 and 1600 h) for 72 h after PGF and cows were inseminated

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6 to 12 h after detection of estrus. Nonresponders were timed-AI + GnRH 72 to 76 h post PGF Seven-d after the timed-AI, natural service sires were placed with cows. Pregnancy was diagnosed approximately 55 d after AI by transrectal ultrasonography. Estrous response was defined as the number of cows displaying estrus for 3 d after prostaglandin and AI divided by the total number of cows treated. Conception rate was defined as the number of cows that became pregnant to AI divided by the number of cows that displayed estrus and were AI. Timed-AI pregnancy rate was the number of cows that failed to display estrus, were timed-AI, and became pregnant divided by the total number of cows that were timed-AI. Synchronized pregnancy rate was the number of cows pregnant to AI divided by the total number of cows treated. Thirty-d pregnancy rate was the number of cows pregnant during the first 30 d of the breeding season divided by the total number of cows treated. Yearling heifers were randomly assigned to the same treatments and estrous detection and AI were administered in the same manner as for the cows. Results and Discussion For the cows, estrous response, conception rate, and synchronized pregnancy rate was affected ( P < 0.05) by synchronization treatment (Table 1). Body condition score also affected ( P < 0.05) estrous response, conception rate, and synchronized pregnancy rate, and 30 d pregnancy rates. Days postpartum tended to ( P = 0.1) effect timed-AI pregnancy rate and had an effect ( P < 0.05) on synchronized pregnancy rate. Prostaglandin treatments were similar ( P > 0.05) for estrous response, conception rate, timed-AI pregnancy rate, synchronized pregnancy rate, and 30 d pregnancy rate (Table 1). In both years, heifers had similar ( P > 0.05) estrous response, conception rate, timed-AI pregnancy rate, synchronized pregnancy rate, and 30 d pregnancy rate between 7-10 vs. Select Synch/CIDR+timed-AI (Table 2) and Estrumate vs.Prostamate (Table 3). Across treatments, the mean estrous response, conception rate, timedAI pregnancy rate, synchronized pregnancy rate and 30 d pregnancy rate were 66.8, 65.0, 16.1, 48.7, and 76.3% respectively. The mean synchronized pregnancy rate for the Prostamate and Estrumate treatments were 45.5 and 52.0%, respectively. At 48 h after PGF treatments had a similar ( P > 0.05) conception rate. At 60 h, Select Synch/CIDR+timed-AI treatment tended ( P = 0.10) to have a decreased conception rate. Inversely, at 72 h, Select Synch/CIDR+timed-AI treatment had an in creased ( P < 0.05) conception rate compared to the 7-10 treatment. In summary, the Select Synch/CIDR+timed-AI had increased conception and synchronized pregnancy rates compared to the 7-10 treatment in suckled cows of Bos indicus Bos taurus breeding. The effectiveness of the treatment was influenced by BCS, as BCS increased, the estrous response, conception rate, and synchronized pregnancy rates increased. Days postpartum also influenced effectiveness of the synchronization treatments, as time from calving to start of synchronization increased, synchronized pregnancy rates increased. There was no effect of prostaglandin treatment on estrous response, conception rate, timed-AI pregnancy rate, synchronized pregnancy rate, or 30 d pregnancy rate. There were no synchronization or prostaglandin treatment effects on any of the reproductive responses measured in the yearling heifers of Bos indicus Bos taurus breeding for either year. 1 Erin McKinniss Graduate Student; Regina Esterman Gra duate Student; Steaven Woodall Former Graduate Student; Brad Austin, Graduate Student, Department of Animal Sciences, Gainesville, FL; Joel Yelich Professor, UF IFAS Departme nt of Animal Sciences, UF, Gainesville, FL

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GnRH GnRH a) 7 10 treatment with Prostamate or Estrumate PGF on d 17 b) Select Synch/CIDR+timed AI treatment with Prostamate or Estrumate PGF on d 17 0 7 10 17 20 Day of experiment Figure 1. Experimental design evaluating the effects of two progestogen and two PGF treatments in Bos indicus Bos taurus suckled cows and yearling heifers a) 7 10 treatment: on d 0 received a once used CIDR that was removed on d 7 concomitant with Prostamate (25 mg i.m.) followed by GnRH (500 g i.m.) on d 10. On d 17, females received either Prostomate or Est rumate (500 g i.m.). b) Select Synch/CIDR+timed AI treatment: on d 10 received a new CIDR (1.38 g) concomitant with GnRH. D a y 17 CIDR was removed and females received either Prostomate or Estrumate. For all four treatments estrus was detected for 3 d a nd females were inseminated 6 to 12 h after detected estrus. Females not exhibiting estrus by 72 h were timed AI and received GnRH. Prostamate GnRH + timed AI Estrus detect & AI Once used CIDR Prostamate or Estrumate New CIDR Estrus detect & AI Prostamate or Estrumate GnRH + timed AI

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Table 1. Effect of synchronization treatment and prostaglandin treatment on estrous response, conception rates and pregnancy rates in suckled cows of Bos indicus Bos taurus breeding synchronized with either a modified 7 11 (7 10) or Select Synch/CIDR+timed AI (SSC+TAI) treatment with either Estrumate or Prostamate. a Variable Estrous response, % b Conception rate, % c Timed AI pregnancy rate, % d Synchronized pregnancy rate, % e Synchronization 7 10 49.0 (77/157) 45.5 (35/77) 17.5 (14/80) 31.2 (49/157) SSC+TAI 59.9 (100/167) 62.0 (62/100) 20.9 (14/67) 45.5 (76/167) P value < 0.05 < 0.05 > 0.05 < 0.05 Prostaglandin Estrumate 57.0 (94/165) 48.9 (46/94) 23.9 (17/71) 38.2 (63/165) Prostamate 52.2 (83/159) 61.5 (51/83) 14.5 (11/76) 39.0 (62/159) P value > 0.05 > 0.05 > 0.05 > 0.05 a See Figure 3 1 for details of treatments. b Percentage of cows displaying estrus 72 h 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 synchronized breeding of the total treated

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Table 2. Estrous response, conception, and pregnancy rates by synchronization treatment of yearling heifers of Bos indicus Bos taurus genotype synchronized with either a modified 7 11 (7 10) or Select Synch/CIDR+timed AI (SSC+TAI) treatment with either Estrumate or Prostamate for years 1 and 2. a Variable Estrous response, % b Conception rate, % c Timed AI pregnancy rate % d Synchronized pregnancy rate, % e 7 10 65.2 (116/178) 62.1 (72/116) 14.5 (9/62) 45.5 (81/178) Yr 1 71.6 (78/109) 65.4 (51/78) 9.68 (3/31) 49.5 (54/109) Yr 2 55.1 (38/69) 55.3 (21/38) 19.4 (6/31) 39.1 (27/69) SSC+TAI 68.4 (121/177) 67.8 (82/121) 17.9 (10/56) 52.0 (92/177) Yr 1 64.2 (70/109) 71.4 (50/70) 20.5 (8/39) 53.2 (58/109) Yr 2 75.0 (51/68) 62.7 (32/51) 11.8 (2/17) 50.0 (34/68) P value Sync > 0.05 > 0.05 > 0.05 > 0.05 Yr > 0.05 > 0.05 > 0.05 > 0.05 Sync Yr < 0.05 > 0.05 > 0.05 > 0.05 a See Figure 3 1 for details of treatments. b Percentage of heifers displaying estrus 72 h after PGF 2 of the total treated. c Percentage of heifers pregnant to AI of the total that exhibited estrus and were AI. d Percentage of heifers pregnant to timed AI of the total that were timed AI. e Percentage of heifers pregnant during the synchronized breeding of the total treated.

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Table 3. Estrous response, conception and pregnancy rates by prostaglandin treatment of yearling heifers of Bos indicus Bos taurus genotype synchronized with either a modified 7 11 (7 10) or Select Synch/CIDR + timed AI (SSC+TAI) treatment with either Estrumate or Prostamate for yr 1 and 2. a Variable Estrous response, % b Conception rate, % c Timed AI pregnancy rate, % d Synchronized pregnancy rate, % e Estrumate 68.7 (123/179) 67.5 (83/123) 17.9 (10/56) 52.0 (93/179) Yr 1 70.6 (77/109) 71.4 (55/77) 18.8 (6/32) 56.0 (61/109) Yr 2 65.7 (46/70) 60.9 (38/46) 16.7 (4/24) 45.7 (32/70) Prostamate 64.8 (114/176) 62.3(71/114) 14.5 (9/62) 45.4 (80/176) Yr 1 65.1 (71/109) 64.8 (46/710 13.2 (5/38) 46.8 (51/109) Yr 2 64.2 (43/67) 58.1 (25/43) 16.7 (4/24) 43.3 (29/67) P value Prostaglandin > 0.05 > 0.05 > 0.05 > 0.05 Yr > 0.05 > 0.05 > 0.05 > 0.05 Prostaglandin Yr > 0.05 > 0.05 > 0.05 > 0.05 a See Figure 3 1 for details of treatments. b Percentage of heifers displaying estrus 72 h after PGF 2 of the total treated. c Percentage of heifers pregnant to AI of the total that exhibited estrus and were AI. d Percentage of heifers pregnant to timed AI of the total that were timed AI. e Percentage of heifers pregnant during the synchronized breeding of the total treated.