Effects of temporary calf removal prior to fixed time AI on pregnancy rate and calf performance in suckled beef cows

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Title:
Effects of temporary calf removal prior to fixed time AI on pregnancy rate and calf performance in suckled beef cows
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Book
Creator:
Marquezini, Guilherme
Mercadante, Vitor
Bird, Scott
Funnell, Bethany
Lamb, G. Cliff
Publisher:
Institute of Food and Agricultural Sciences, University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:
Copyright Date:
2011

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University of Florida Institutional Repository
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University of Florida
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All rights reserved by the source institution and holding location.
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AA00000422:00001


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Effects of Temporary Calf Removal Prior To Fixed Time AI On Pregnancy
Rate And Calf Performance In Suckled Beef Cows



Guilherme Marquezini1, Vitor Mercadante1, Scott Bird2, Bethany Funnell2, G. Cliff Lamb1



Temporary calf removal between prostaglandin and fixed time artificial insemination on CO-Synch +
CIDR protocol enhances pregnancy rates; however, calf removal had a negative impact on calf
performance during the calf removal period, but variable effects on weaning weight, depending on the
location.


Summary
We determined whether 72 h calf removal (CR)
prior to fixed-time artificial insemination (TAI)
would increase pregnancy rates or alter
subsequent calf performance in suckled,
crossbred beef cows. Cows at three locations
where stratified by days postpartum and parity
and randomly assigned to one of two treatments:
1) received 100 pg gonadotropin releasing
hormone (GnRH) and a CIDR insert (d -7),
followed in seven d by 25 mg prostaglandin F2a
(PGF2a) and CIDR removal (d 0), followed in 72
h by GnRH and AI (d 3); (Control; n 158), 2)
same as control but calves were removed from
their dams for 72 h between d 0 and d 3 (CR; n
169). Transrectal ultrasonography was used
to follow follicle and corpus luteum development
on d 0, 3, and 10 and to determine pregnancy
status on d 28. Blood samples were collected on
d -14, -7, 0, 3, 10, and 28 to determine
concentrations of progesterone. Calf weights
were determined on d 0, 3, and at weaning. Calf
removal did not affect dominant follicle
diameter at d 3. Concentrations of progesterone
were greater (P 0.03) for CR than Control
group (3.53 0.16 vs 2.71 0.22 ng/ml
respectively) on d10. At -, ,n, calf weights
did not differ between treatments, but there was
a location affect. At one location weaning
weights were significantly reduced by CR,
whereas weaning weights at the remaining two
locations were not adversely affected by CR.


We conclude that 72 h of calf removal between
PGF and AI improve pregnancy rate, however it
has gontw'c impact on calf performance at the
time of CR.

Introduction
Estrous synchronization protocols that allow the
use of fixed-time artificial insemination (TAI)
have been developed to diminish labor and
increase pregnancy rates (Larson et al., 2006).
One of the negative effects of this protocol is the
intense work during the protocol and the price of
the estrous synchronization products. Temporary
calf removal (CR) between prostaglandin and
TAI has resulted in improved on pregnancy rates
(Geary et al., 2001), when calf removal occurred
for 48 h. However, no research has been
completed to determine the effects of 72-h CR
on fertility or the impact that CR could cause on
calf performance during or after CR. Calf
removal could potentially have a positive impact
on cow reproductive performance because
suckling stimulation causes the release of
endogenous opioids as P-endorphins that
decrease the release of hormones necessary for
ovulation, such as GnRH and luteinizing
hormone (LH; Carter et al., 1980; Myer et al.,
1989). Temporary CR may decrease the negative
impact on these reproductive hormones
improving pregnancy rates at TAI; however,
temporary CR may have a negative impact on
calf performance.


'North Florida Research and Education Center, University of Florida, Marianna, FL
2University of Minnesota, NCROC, Grand Rapids, MN










Therefore, it is important to determine whether
72-h CR would increase pregnancy rates and
have a negative impact on calf performance.

Materials and Methods
Three hundred thirty one cow/calf pairs were
stratified by days postpartum, body condition
score, and parity at three different locations and
assigned to one of two treatments; 1) received
100 ig GnRH and a CIDR insert (d -7),
followed in 7 d by 25 mg PGF2, and CIDR
removal (d 0), followed in 72 h by GnRH and AI
(d 3); (Control; n = 158); 2) same as Control but
calves were removed from their dams for 72 h
between d 0 and d 3 (CR; n = 169; Figure 1).
Calves removed from their dams were housed
under a covered shelter with ad libitum water
and perennial peanut hay. Two blood samples
were collected at 10 d apart prior to initiation of
estrous synchronization to assess cycling status
of the cows. Transrectal ultrasonography was
performed on the day of the PGF (d 0), at TAI (d
3) and seven d after TAI (d 10) to evaluate
follicle diameter, whether ovulation occurred,
and corpus luteum (CL) volume. Blood samples
also were collected on d -7, d 0, d 3 and d 10 to
evaluate concentration of progesterone in serum.
Pregnancy diagnosis was performed by
transrectal ultrasonography 30 d after AI. Calves
were weighed on d 0, 3 and at weaning to
evaluate growth performance.

At the time of statistical analyses of calf
performance data, calves were blocked by age as
young (less than 70 d; averaging 49.2 1.4 d of
age) and old (more than 70; averaging 83.5 0.9
d of age) to evaluate whether temporary CR had
different impact on young and old calves. The
MIXED procedure of SAS was used to
determine if differences existed for continuous
variables: calf performance data, follicle
diameter, and corpus luteum volume, whereas
the GLIMMIX procedure of SAS was used to
determine difference in binary data of
pregnancy and conception rates.

Results
Follicle diameter on d 3 did not differ (P > 0.05)
between Control and CR (13.4 0.6 vs 13.3
0.3 mm, respectively) and tended to be greater
(P = 0.06) for multiparous than primiparous


cows (14.0 + 0.3 vs 12.8 0.6 mm,
respectively). Concentrations of progesterone in
serum on d 10 was greater (P = 0.03) for the CR
than Control group (3.53 0.16 vs 2.71 0.22
ng/ml, respectively). Corpus luteum volume did
not differ (P > 0.10) between Control and CR on
d 10 (4.9 0.8 vs 5.1 0.4 cm3, respectively;
Table 1) and was greater (P = 0.04) for
multiparous than primiparous cows on d 10
(6.02 0.39 vs 4.1 0.86 cm3, respectively).
Vasconcelos et al. (2001) reported that follicles
with greater diameters form a CL greater in
volume and produce more progesterone. Our
study concurs and we observed that multiparous
cows had larger follicles than primiparous cows
and also formed a larger CL with greater
concentrations of progesterone on d 10. Overall
pregnancy rates tended to be greater (6%) for
CR than the Control group (42 vs 48 % for
Control and CR respectively). Temporary CR
seems to improve pregnancy rate in primiparous
cows (38.5 vs 51.0 % for Control and CR
respectively) and cows with younger calves
(32.3 vs 45.8 % for Control and CR,
respectively). Primiparous cows with younger
calves in the Control treatment had the lowest
pregnancy rates (26.6 %) compared to 45.2% for
primiparous cows in the CR treatment.

Calf performance was negatively affected by
temporary weaning. On average, during the 72-h
CR period, calves in the CR treatment lost
approximately 7.0 lb of weight (Table 2). As a
percent of body weight (amount of weight
gained or lost during 72 h divided by the initial
weight) the percentage weight loss for younger
calves was greater (P < 0.001) than older calves
(10.1 + 1.1 vs. 4.4 0.9 % loss in percent of
body weight for young and old calves,
respectively). However at weaning, calf weights
did not differ between treatments, but there was
a location affect. At one location weaning
weights were significantly reduced by CR,
whereas weaning weights at the remaining
locations were not adversely affected by CR.

Conclusion
We conclude that temporary CR for 72 h
between PGF and TAI improved pregnancy rate.
Temporary CR had a negative impact on calf
performance. Younger calves lost a greater









percentage of body weight than older calves
during 72 h of CR; however, the difference in
body weight between treatments at weaning was
greater for older than younger calves.




































Literature Cited
Geary et al. 2001. J. Anim. Sci. 79(1): 1.
Larson et al. 2006. J. Anim. Sci. 84:332.
Myers et al. 1989. Domest. Anim. Endocrinol. 6(3): 183.
Vasconcelos et al. 2001. Theriogenology. 56(2): 307.


Acknowledgements
We thank Pfizer Animal Health (New York, NY) for contributions of prostaglandin F2n(Lutalyse) and CIDR
inserts and IVX Animal Health (St. Joseph, MO) for donation of gonadotropin-releasing hormone
(OvaCyst). Appreciation also is expressed to Olivia Helms, Don Jones, Mary Maddox, Harvey Standland,
and David Thomas for their assistance with data collection and laboratory analysis.















Table 1. Concentrations of progesterone (P4), follicle diameter, corpus luetum (CL) volume, and
pregnancy rates in cows receiving either Control or calf removal (CR) treatment between d 0 and
3.
Treatment'
Item Control Calf Removal
P4 on d 10, ng/ml 2.71 0.22y 3.53 + 0.16x
CL volume on d 10, cm3 4.9 +0.8 5.1+ 0.4
Follicle diameter d 3, mm 13.4+ 0.6 13.3 + 0.3
Overall pregnancy rates, % 66/158(41.7%) 81/169(47.9%)
'Cows were assigned to receive no calf removal or calf removal between d 0 and 3.
yx Concentrations differ (P < 0.05).










Table 2. Evaluation of calf performance during temporary calf removal and at weaning.
Treatment'
Item Control Calf removal
Calf weight on d 0, lbs 224.4 + 5.7 224.8 + 3.7
Calf weight on d 3, lbs 233.4 + 5.9x 217.1 + 3.7y
Body weight change, % of d 0 body 3.3 0.5 3.4 0.3
weight2
Mean weaning weight, lbs 452.5 + 6.3 447.2 6.1
Weaning weight location 1, lbs 523.3 + 11.9z 490.3 + 11.4w
Weaning weight location 2, lbs 424.3 10.7z 427.3 10.5w
Weaning weight location 3, lbs 409.8 + 10.3 423.9 10.2
'Cows were assigned to be separated from their dams (Calf removal) or not (Control) between d 0
and 3.
2Calculated from the weight gained or lost during CR divided by initial weight on d 0.
yx Weight differ (P < 0.05).
z,w Tendence for weight to differ (P < 0.10)












GnRH


Control ___
n= 158


Control
n= 169


Days of -14
treatment


PGF TAI &
GnRH



us us us


0 IDRO7I2BE


0 3

wW


- p-


10 30 205

W W


us = Ultrasound


9 Blood sample


W = calf weight


CR = Calf removal


Figure 1. Schematic of experimental design for cows treated with or without calf removal
(CR) between d 0 and 3.




Full Text

PAGE 1

Summary We determined whether 72 h calf removal (CR) prior to fixed time artificial insemination (TAI) would increase pregnancy rates or alter subsequent calf performance in suckled, crossbred beef cows. Cows at three locations where stratified by days postpartum an d parity and randomly assigned to one of two treatments: 1) received 100 g gonadotropin releasing hormone (GnRH) and a CIDR insert (d 7), followed in seven d by 25 mg prostaglandin F (PGF ) and CIDR removal (d 0), followed in 72 h by GnRH and AI (d 3) ; (Control; n = 158), 2) same as control but calves were removed from their dams for 72 h between d 0 and d 3 (CR; n = 169). Transrectal ultrasonography was used to follow follicle and corpus luteum development on d 0, 3, and 10 and to determine pregnancy status on d 28. Blood samples were collected on d 14, 7, 0, 3, 10, and 28 to determine concentrations of progesterone. Calf weights were determined on d 0, 3, and at weaning. Calf removal did not affect dominant follicle diameter at d 3. Concentrations o f progesterone were greater (P = 0.03) for CR than Control group (3.53 0.16 vs 2.71 0.22 ng/ml respectively) on d10. At weaning, calf weights did not differ between treatments, but there was a location affect. At one location weaning weights were sign ificantly reduced by CR, whereas weaning weights at the remaining two locations were not adversely affected by CR. We conclude that 72 h of calf removal between PGF and AI improve pregnancy rate, however it has negative impact on calf performance at the time of CR. Introduction Estrous synchronization protocols that allow the use of fixed time artificial insemination ( TAI ) have been developed to diminish labor and increase pregnancy rates (Larson et al., 2006). One of the negative effects of this protocol is the intense work during the protocol and the price of the estrous synchronization products. Temporary calf remo val (CR) between prostaglandin and TAI has resulted in improved on pregnancy rates (Geary et al., 2001), when calf removal occurred for 48 h. However, no research has been completed to determine the effects of 72 h CR on fertility or the impact that CR co uld cause on calf performance during or after CR. Calf removal could potentially have a positive impact on cow reproductive performance because suckling stimulation causes the release of endorphins that decrease the release of hormo nes necessary for ovulation, such as GnRH and luteinizing hormone (LH; Carter et al., 1980; Myer et al., 1989). Temporary CR may decrease the negative impact on these reproductive hormones improving pregnancy rates at TAI; however, temporary CR may have a negative impact on calf performance. Effects of Temporary Calf Removal Prior To Fixed Time AI On Pregnancy Rate And Calf Performance In Suckled Beef Cows Guilherme Marquezini 1 Vitor Mercadante 1 Scott Bird 2 Bethany Funnell 2 G. Cliff Lamb 1 Temporary calf removal between prostaglandin and fixed time artificial insemination on CO Synch + CIDR protocol enhances pregnancy rates; however, calf removal had a negative impact on calf performance during the calf removal period, but variable effects on weaning weight, depending on the location. 1 North Florida Research and Education Center, University of Florida Marianna, FL 2 University of Minnesota, NCROC, Grand Rapids, MN

PAGE 2

Therefore, it is important to determine whether 72 h CR would increase pregnancy rates and have a negative impact on calf performance. Materials and Methods Three hundred thirty one cow/calf pairs were stratified by days postpartum, body condition score, and parity at three different locations and assigned to one of two treatments; 1) received 100 g GnRH and a CIDR insert (d 7), followed in 7 d by 25 mg PGF and CIDR removal (d 0), followed in 72 h by GnRH and A I (d 3); (Control; n = 158); 2) same as Control but calves were removed from their dams for 72 h between d 0 and d 3 (CR; n = 169; Figure 1). Calves removed from their dams were housed under a covered shelter with ad libitum water and perennial peanut hay. Two blood samples were collected at 10 d apart prior to initiation of estrous synchronization to assess cycling status of the cows. Transrectal ultrasonography was performed on the day of the PGF (d 0), at TAI (d 3) and seven d after TAI (d 10) to evalua te follicle diameter, whether ovulation occurred, and corpus luteum (CL) volume. Blood samples also were collected on d 7, d 0, d 3 and d 10 to evaluate concentration of progesterone in serum. Pregnancy diagnosis was performed by transrectal ultrasonograp hy 30 d after AI. Calves were weighed on d 0, 3 and at weaning to evaluate growth performance. At the time of statistical analyses of calf performance data, calves were blocked by age as young (less than 70 d; averaging 49.2 1.4 d of age) and old (more than 70; averaging 83.5 0.9 d of age) to evaluate whether temporary CR had different impact on young and old calves. The MIXED procedure of SAS was used to determine if differences existed for continuous variable s: calf performance data, follicle diame ter, and corpus luteum volume, whereas the GLIMMIX procedure of SAS was used to determine difference in binary data of pregnancy and conception rates. Results Follicle diameter on d 3 did not differ ( P > 0.05) between Control and CR (13.4 0.6 vs 13.3 0.3 mm, respectively) and tended to be greater ( P = 0.06) for multiparous than primiparous cows (14.0 0.3 vs 12.8 0.6 mm, respectively). Concentrations of progesterone in serum on d 10 was greater ( P = 0.03) for the CR than Control group (3.53 0.16 vs 2.71 0.22 ng/ml, respectively). Corpus luteum volume did not differ ( P > 0.1 0 ) between Control and CR on d 10 (4.9 0.8 vs 5.1 0.4 cm 3 respectively; Table 1) and was greater ( P = 0.04) for multiparous than primiparous cows on d 10 (6.02 0.39 vs 4.1 0.86 cm 3 respectively). Vasconcelos et al. (2001) reported that follicles with greater diameters form a CL greater in volume and produce more progesterone. Our study concurs and we observed that multiparous cows had lar ger follicles than primiparous cows and also formed a larger CL with greater concentrations of progesterone on d 10. Overall pregnancy rates tended to be greater (6%) for CR than the Control group (42 vs 48 % for Control and CR respectively). Temporary CR seems to improve pregnancy rate in primiparous cows (38.5 vs 51.0 % for Control and CR respectively) and cows with younger calves (32.3 vs 45.8 % for Control and CR, respectively). Primiparous cows with younger calves in the Control treatment had the lowes t pregnancy rates (26.6 %) compared to 45.2% for primiparous cows in the CR treatment. Calf performance was negatively affected by temporary weaning. On average, during the 72 h CR period, calves in the CR treatment lost approximately 7.0 lb of weight (Ta ble 2). As a percent of body weight (amount of weight gained or lost during 72 h divided by the initial weight) the percentage weight loss for younger calves was greater ( P < 0.001) than older calves (10.1 1.1 vs. 4.4 0.9 % loss in percent of body weig ht for young and old calves, respectively). However at weaning calf weights did not differ between treatments, but there was a location affect. At one location weaning weights were significantly reduced by CR, whereas weaning weights at the remaining loc ation s were not adversely affected by CR. Conclusion We conclude that temporary CR for 72 h between PGF and TAI improved pregnancy rate. Temporary CR had a negative impact on calf performance. Younger calves lost a greater

PAGE 3

percentage of body weight than older calves during 72 h of CR; however, the difference in body weight between treatments at weaning was greater for older than younger calves. Literature Cited Geary et al. 2001. J. Anim. Sci. 79(1): 1. Larson et al. 2006. J. Anim. Sci. 84:332. M yers et al. 1989. Domest. Anim. Endocrinol. 6(3): 183. Vasconcelos et al. 2001. Theriogenology. 56(2): 307. Acknowledgements We thank Pfizer Animal Health (New York, NY) for contributions of prostaglandin F (Lutalyse) and CIDR inserts and IVX Animal Health (St. Joseph, MO) for donation of gonadotropin releasing hormone (OvaCyst). Appreciation also is expressed to Olivia Helms, Don Jones, Mary Maddox, Harvey Standland, and David Thomas for their assistance with data collection and laboratory analysis.

PAGE 4

Table 1. Concentrations of progesterone (P4), follicle diameter, corpus luetum (CL) volume, and pregnancy rates in cows receiving either Control or calf removal (CR) treatment between d 0 and 3. Treatment 1 Item Control Calf Removal P4 on d 10, ng/ml 2.71 0.22 y 3.53 0.16 x CL volume on d 10, cm 3 4.9 0.8 5.1 0.4 Follicle diameter d 3, mm 13.4 0.6 13.3 0.3 Overall pregnancy rates, % 66/158(41.7%) 81/169(47.9%) 1 Cows were assigned to receive no calf removal or calf removal between d 0 and 3. y,x Concentrations differ ( P < 0.05). Table 2. Evaluation of calf performance during temporary calf removal and at weaning. Treatment 1 Item Control Calf removal Calf weight on d 0, lbs 224.4 5.7 224.8 3.7 Calf weight on d 3, lbs 233.4 5.9 x 217.1 3.7 y Body weight change, % of d 0 body weight 2 3.3 0.5 3.4 0.3 Mean weaning weight, lbs 452.5 6.3 447.2 6.1 Weaning weight location 1, lbs 523.3 11.9 z 490.3 11.4 w Weaning weight location 2, lbs 424.3 10.7 z 427.3 10.5 w Weaning weight location 3, lbs 409.8 10.3 423.9 10.2 1 Cows were assigned to be separated from their dams (Calf removal) or not (Control) between d 0 and 3. 2 Calculated from the weight gained or lost during CR divided by initial weight on d 0. y,x Weight differ ( P < 0.05). z,w Tendence for weight to differ ( P < 0.1 0 )

PAGE 5

Figure 1. Schematic of experimental design for cows treated with or without calf removal (CR) between d 0 and 3