Effects of excitable temperament and its physiological consequences on reproductive performance of Brahman-crossbred cows

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Effects of excitable temperament and its physiological consequences on reproductive performance of Brahman-crossbred cows
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2009 Florida Beef Report
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Cooke, R. F.
Araujo, D. B.
Lamb, G. C.
Arthington, J. D.
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Institute of Food and Agricultural Sciences, University of Florida
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Gainesville, Fla.
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Effects of Excitable Temperament and its Physiological Consequences on
Reproductive Performance of Brahman-crossbred Cows

R. F. Cooke1
D. B. Araujo
G. C. Lamb
J. D. Arthington



Measurements and physiologic responses associated with cow temperament, acute phase response, and
energy status influence the probability of Brahman-crossbred cows to become pregnant during the
breeding season


Summary
The objective of this experiment was to evaluate
the effects of cow temperament, acute phase
response, and energy status on the probability of
Brahman-crossbred cows to become pregnant
during the breeding season. Over two
consecutive yr, 160 Braford and 235 Brahman x
British cows were exposed to mature Angus
bulls during a 90-d breeding season. Prior to
the beginning of breeding, cows were evaluated
for body condition score (BCS) and
temperament, while blood samples were
obtained for determination of plasma
concentrations of insulin-like growth factor I
(IGF-I), cortisol, ceruloplasmin and
haptoglobin. During year 1, probability of
pregnancy during the breeding season increased
linearly (P<0.05) as temperament score and
concentrations of ceruloplasmin, haptoglobin,
and cortisol (Braford cows only) decreased,
whereas BCS and IGF-I concentrations affected
the probability of pregnancy quadratically
(P<0.05). During year 2, probability of
pregnancy increased linearly (P<0.05) as
concentrations of ceruloplasmin and
haptoglobin decreased, whereas BCS,
temperament score, and concentrations of
cortisol and IGF I affected the probability of


pregnancy quadratically (P<0.05). These
results s,,.,-,- ,t that measurements and
physiologic responses associated with
temperament, health, and energy status
influence the probability of cows to become
pregnant during the breeding season.

Introduction
The major objective of cow-calf production
systems is to produce one calf per cow annually.
Ovulation of a competent oocyte determines the
length of the postpartum interval and also the
fertility of beef cows during the breeding season
(Short et al., 1990). Follicle size and LH
pulsatility are major factors responsible for a
successful ovulation (Roche, 2006); therefore,
alternatives to stimulate GnRH delivery to the
pituitary, and anticipate/enhance the ovulatory
LH surge are options to maximize reproductive
performance of beef cows (Day, 1994).

Several factors are known to influence GnRH
and gonadotropin synthesis in cattle. Cattle with
excitable temperament often experience
stimulated secretion and circulating
concentrations of ACTH and cortisol (Curley et
al., 2008), and these hormones directly impair


2009 Florida BeefReport










synthesis and release of GnRH and
gonadotropins (Li and Wagner, 1983; Dobson et
al., 2000). Animals under inflammatory
processes, such as the acute phase response, may
also experience impaired GnRH and
gonadotropin production (Peter et al., 1989;
Battaglia et al., 2000; Williams et al., 2001).
Additionally, energy intake and level of body
reserves directly modulate circulating
concentrations of IGF-I (Wettemann et al.,
2003), which in turn may enhance GnRH and
gonadotropin synthesis, and also potentiate the
effects of gonadotropins in the ovary (Spicer and
Stewart, 1996; Wettemann et al., 2003).
Therefore, the objective of this study was to
determine the probability of cows to become
pregnant during the breeding season, according
to BCS, temperament score, and concentrations
of IGF-I, cortisol, and acute phase proteins
assessed at the beginning of breeding.

Materials and Methods
Over two consecutive years, 160 Braford and
235 Brahman x British cows were evaluated for
BCS (emaciated = 1, obese = 9; Wagner et al.,
1988) and plasma concentrations of IGF-I,
cortisol, ceruloplasmin, and haptoglobin at the
beginning of the breeding season. Cows were
exposed to mature Angus bulls for 90-d,
whereas bull to cow ratio was, respectively, 1:20
for both breed types.

Cow temperament was assessed by pen score,
chute score, and exit velocity. Chute score was
assessed by a single technician based on a 5-
point scale, where 1 = calm, no movement, and
5 = violent and continuous struggling. For pen
score assessment, cows exited the chute and
entered a pen containing a single technician, and
were assigned a score on a 5-point scale, where
1 =unalarmed and unexcited, and 5 = very
excited and aggressive toward the technician in a
manner that requires evasive action to avoid
contact between the technician and cow. Exit
velocity was assessed by determining the speed
of the cow exiting the squeeze chute by
measuring rate of travel over a 1.5-m distance
with an infrared sensor (FarmTek Inc., North
Wylie, TX). Further, cows were divided in
quintiles according to their exit velocity, and
assigned a score from 1 to 5 (exit score; 1 =


slowest cows;
temperament
averaging cow
score.


5 = fastest cows). Individual
scores were calculated by
chute score, pen score, and exit


Blood samples were collected via jugular
venipuncture into commercial blood collection
tubes (Vacutainer, 10 mL; Becton Dickinson,
Franklin Lakes, NJ) containing sodium heparin,
placed on ice immediately, and centrifuged at
2,400 x g for 30 min for plasma collection.
Plasma was frozen at -200C on the same day of
collection. Concentrations of cortisol were
determined using a Coat-A-Count solid phase
125I RIA kit (DPC Diagnostic Products Inc., Los
Angeles, CA). A double antibody RIA was used
to determine concentrations and IGF-I (Badinga
et al., 1991; Cooke et al., 2007). Concentrations
of ceruloplasmin were determined according to
procedures described by Demetriou et al. (1974).
Concentrations of haptoglobin were determined
by measuring haptoglobin/hemoglobin complex
by the estimation of differences in peroxidase
activity (Makimura and Suzuki, 1982).

The probability of cows to become pregnant
during the breeding season was determined with
the GLM and LOGISTIC procedures of SAS.
The GLM procedure was utilized to determine if
each individual measurement influenced
pregnancy rates linearly, quadratically, and/or
cubically. If multiple continuous order effects
were significant, the effect with the greatest F-
value was selected. The LOGISTIC procedure
was utilized to determine the intercept and
slope(s) values according to maximum
likelihood estimates from the significant effect
selected, and the probability of pregnancy was
determined according to the equation:
Probability = (e logc equahon) / (1 + e logi equahon).
Logistic curves were constructed according to
the minimum and maximum values detected for
each individual measurement.

Results
The probability of cows to become pregnant,
according to measurements obtained at the
beginning of the breeding season, was evaluated
within each year because mean days post-partum
across breeds at the onset of breeding differed
(P<0.01) from yr 1 to yr 2 (88 vs. 34 d,


2009 Florida BeefReport










respectively; SEM=1.5). Plasma IGF-I
concentrations and cow BCS affected
quadratically (P<0.01) the probability of
pregnancy during both yr (Figure 1). These
results indicate that reduced or excessive energy
status is detrimental to reproductive performance
of cattle, as reported by others (Armstrong et al.,
2001; Bilby et al., 2006; Cooke et al., 2008b).
Cow temperament score and plasma cortisol
concentrations affected the probability of
pregnancy linearly (P=0.03) during yr 1, and
quadratically (P<0.01) during yr 2 (Figure 2).
These results suggest that excitable temperament
and consequent elevated cortisol concentrations
(Curley et al., 2008) are detrimental to
reproductive function of cows. Concurring with
our findings, Plasse et al. (1970) reported that
excitable temperament influences negatively the
reproductive performance of beef females.
Additionally, as observed in yr 2, reduced
cortisol concentrations and temperament score
during the early postpartum period may denote
health disorders that negatively affect cattle
reproduction, such as lethargy, lameness
(Sprecher et al., 1997), and immunosuppresion
(Goff, 2006). Plasma concentrations of
ceruloplasmin and haptoglobin affected the
probability of pregnancy linearly during yr 1
(P<0.01 and =0.04, respectively) and yr 2
(P=0.01; Figure 3), suggesting and supporting
previous data indicating that the acute phase
response is detrimental to reproductive function
of livestock (Peter et al., 1989; Battaglia et al.,
2000; Williams et al., 2001).

In conclusion, results from this study indicate
that measurements and physiologic responses
associated with cow temperament, acute phase
response, and energy status influenced the
probability of cows to become pregnant during
the breeding season. Therefore, management
strategies that improve cow disposition, enhance
their immune status, and maintain the cowherd
at adequate levels of nutrition are required for
optimal reproductive performance of Brahman-
crossbred cows, and consequent productivity of
cow-calf operations containing these types of
cattle.


2009 Florida BeefReport











Literature Cited
Armstrong et al. 2001. Biol. Reprod. 64:1624-1632.
Badinga et al. 1991. J. Anim. Sci. 69:1925-1934.
Battaglia et al. 2000. Biol. Reprod. 62:45-53.
Bilby et al. 2006. J. Dairy Sci. 89:3360-3374.
Cooke and Arthington. 2008. Prof. Anim. Sci. 24:264-268.
Cooke et al. 2007. J. Anim. Sci. 85:2564-2574.
Curley et al. 2008. Horm. Behav. 53:20-27.
Day. 2004. Anim. Reprod. Sci. 82-83:487-494.
Demetriou et al. 1974. Clinical Chemistry 857-864
Dobson et al. J. Reprod. Fertil. 120:405-410.
Goff. 2006. J. Dairy Sci. 89:1292-1301.
Li and Wagner. 1983. Biol. Reprod 29:25-37.
Makimura and Suzuki. 1982. Jpn. J. Vet. Sci. 44:15-21.
Peter el al. 1989. Am. J. Vet. Res. 50:368-373.
Plasse et al. 1970. J. Anim. Sci. 30:63-72.
Spicer and Stewart. 1996. Biol. Reprod. 54:255-263.
Sprecher et al. 1997. Theriogenology 47:1179-1187.
Wagner et al. 1988. J. Anim. Sci. 66:603-612.
Wettemann et al. 2003. J. Anim. Sci. 81(E. Suppl. 2):E48-E59.
Williams et al. 2001. Endocrinology 142:1915-1922.













'R. F. Cooke, Former Graduate Student; D. B. Araujo, Graduate Student; G. C. Lamb,
Associate Professor, UF- IFAS North Florida Research and Education Center, Marianna FL;
J. D. Arthington, UF-IFAS Range Cattle Research and Education Center, Ona, FL


2009 Florida BeefReport












Year 1 ---Year 2


- - ~m ~


1 2 3 4 5 6 7 8 9


BCS


Year 1 --- Year 2


o N--mm


0 50 100 150


200 250


300 350


Plasma IGF-1, ng/mL



Figure 1. Effects of BCS (emaciated = 1, obese = 9; Wagner et al., 1988) and plasma IGF-I concentrations,
assessed at the beginning of the breeding season, on the probability of Brahman-crossbred cows
to become pregnant. A quadratic effect was detected during yr 1 and 2 for BCS (P<0.01) and
plasma IGF-I (P=0.02 and <0.01, respectively).


2009 Florida BeefReport


100

90

80

70

60

50

40

30

20

10

0


_










100
90
80
70
60
50
40
30
20
10
0


1





100
90
80
70
60
50
40
30
20
10
0


%









Year 1 --- Year 2


3
Temperament Score


,Vd


Year 1 ---Year 2


0 1 2 3 4 5 6 7 8 9
Plasma cortisol, pg/dL


Figure 2 Effects of temperament score and plasma cortisol concentrations, assessed at the beginning of the
breeding season, on the probability of Brahman x British and Braford cows to become pregnant.
For temperament score, a linear effect (P=0.03) and a quadratic effect (P<0.01) were detected for
both breeds during yr 1 and 2, respectively. For plasma cortisol, a linear effect was detected
(P=0.04) for Braford cows during yr 1, whereas a quadratic effect was detected (P=0.02) for both
breeds during yr 2.


2009 Florida BeefReport











100
to-

90

80

70

60

50

40

30


0 5


100

90

80

70

60

50


Year 1 - -Year 2


10 15 20


Plasma ceruloplasmin, mg/dL


Year -- Year




Year 1 ---Year 2


0 1 2 3 4 5 6 7 8 9 10

Plasma haptoglobin, 450 nm x 100


Figure 3. Effects of plasma ceruloplasmin and haptoglobin concentrations, assessed at the beginning of
the breeding season, on the probability of Brahman-crossbred cows to become pregnant. A
linear effect was detected during yr 1 and 2 for plasma ceruloplasmin (P<0.01 and =0.01,
respectively) and haptoglobin (P=0.04 and =0.01, respectively).


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26 2009 Florida BeefReport




Full Text

PAGE 1

Effects of E xcitable T emperament and its P hysiological Consequences on R eproductive P erformance of Brahman crossbred C ows R. F. Cooke 1 D. B. Araujo G. C. Lamb J. D. Arthington Summary The objective of this experiment was to evaluate the effects of cow temperament, acute phase response, and energy status on the probability of Brahman-crossbred cows to become pregnant during the breeding season. Over two consecutive yr, 160 Braford and 235 Brahman British cows were exposed to mature Angus bulls during a 90-d breeding season. Prior to the beginning of breeding, cows were evaluated for body condition score (BCS) and temperament, while blood samples were obtained for determination of plasma concentrations of insulin-like growth factor I (IGF-I), cortisol, ceruloplasmin and haptoglobin. During year 1, probability of pregnancy during the breeding season increased linearly (P<0.05) as temperament score and concentrations of ceruloplasmin, haptoglobin, and cortisol (Braford cows only) decreased, whereas BCS and IGF-I concentrations affected the probability of pregnancy quadratically (P<0.05). During year 2, probability of pregnancy increased linearly (P<0.05) as concentrations of ceruloplasmin an d haptoglobin decreased, whereas BCS, temperament score, and concentrations of cortisol and IGF I affected the probability of pregnancy quadratically (P<0.05). These results suggest that measurements and physiologic responses associated with temperament, health, and energy status influence the probability of cows to become pregnant during the breeding season. Introduction The major objective of cow-calf production systems is to produce one calf per cow annually. Ovulation of a competent oocyte determines the length of the postpartum interval and also the fertility of beef cows during the breeding season (Short et al., 1990). Follicle size and LH pulsatility are major factors responsible for a successful ovulation (Roche, 2006); therefore, alternatives to stimulate GnRH delivery to the pituitary, and anticipate/enhance the ovulatory LH surge are options to maximize reproductive performance of beef cows (Day, 1994). Several factors are known to influence GnRH and gonadotropin synthesis in cattle. Cattle with excitable temperament often experience stimulated secretion and circulating concentrations of ACTH and cortisol (Curley et al., 2008), and these hormones directly impair Measurements and physiologic responses associated with cow temperament, acute phase response, and energy status influence the probability of Brahman crossbred cows to become pregnant during the breeding season

PAGE 2

synthesis and release of GnRH and gonadotropins (Li and Wagner, 1983; Dobson et al., 2000). Animals under inflammatory processes, such as the acute phase response, may also experience impaired GnRH and gonadotropin production (Peter et al., 1989; Battaglia et al., 2000; Williams et al., 2001). Additionally, energy intake and level of body reserves directly modulate circulating concentrations of IGF-I (Wettemann et al., 2003), which in turn may enhance GnRH and gonadotropin synthesis, and also potentiate the effects of gonadotropins in the ovary (Spicer and Stewart, 1996; Wettemann et al., 2003). Therefore, the objective of this study was to determine the probability of cows to become pregnant during the breeding season, according to BCS, temperament score, and concentrations of IGF-I, cortisol, and acute phase proteins assessed at the beginning of breeding. Materials and Methods Over two consecutive years, 160 Braford and 235 Brahman British cows were evaluated for BCS (emaciated = 1, obese = 9; Wagner et al., 1988) and plasma concentrations of IGF-I, cortisol, ceruloplasmin, and haptoglobin at the beginning of the breeding season. Cows were exposed to mature Angus bulls for 90-d, whereas bull to cow ratio was, respectively, 1:20 for both breed types. Cow temperament was assessed by pen score, chute score, and exit velocity. Chute score was assessed by a single technician based on a 5point scale, where 1 = calm, no movement, and 5 = violent and continuous struggling. For pen score assessment, cows exited the chute and entered a pen containing a single technician, and were assigned a score on a 5-point scale, where 1 = unalarmed and unexcited, and 5 = very excited and aggressive toward the technician in a manner that requires evasive action to avoid contact between the technician and cow. Exit velocity was assessed by determining the speed of the cow exiting the squeeze chute by measuring rate of travel over a 1.5-m distance with an infrared sensor (FarmTek Inc., North Wylie, TX). Further, cows were divided in quintiles according to their exit velocity, and assigned a score from 1 to 5 (exit score; 1 = slowest cows; 5 = fastest cows). Individual temperament scores were calculated by averaging cow chute score, pen score, and exit score. Blood samples were collected via jugular venipuncture into commercial blood collection tubes (Vacutainer, 10 mL; Becton Dickinson, Franklin Lakes, NJ) containing sodium heparin, placed on ice immediately, and centrifuged at 2,400 g for 30 min for plasma collection. Plasma was frozen at -20C on the same day of collection. Concentrations of cortisol were determined using a Coat-A-Count solid phase 125 I RIA kit (DPC Diagnostic Products Inc., Los Angeles, CA). A double antibody RIA was used to determine concentrations and IGF-I (Badinga et al., 1991; Cooke et al., 2007). Concentrations of ceruloplasmin were determined according to procedures described by Demetriou et al. (1974). Concentrations of haptoglobin were determined by measuring haptoglobin/hemoglobin complex by the estimation of differences in peroxidase activity (Makimura and Suzuki, 1982). Th e probability of cows to become pregnant during the breeding season was determined with the GLM and LOGISTIC procedures of SAS The GLM procedure was utilized to determine if each individual measurement influenced pregnancy rates linearly, quadratically, and/or cubically. If multiple continuous order effects were significant, the effect with the greatest Fvalue was selected. The LOGISTIC procedure was utilized to determine the intercept and slope(s) values according to maximum likelihood estimates from the significant effect selected, and the probability of pregnancy was determined according to the equation: Probability = (e logistic equation ) / (1 + e logistic equation ). Logistic curves were constructed according to the minimum and maximum values detected for each individual measurement. Results The probability of cows to become pregnant, according to measurements obtained at the beginning of the breeding season, was evaluated within each year because mean days post-partum across breeds at the onset of breeding differed ( P<0.01) from yr 1 to yr 2 (88 vs. 34 d,

PAGE 3

respectively; SEM=1.5). Plasma IGFI concentrations and cow BCS affected quadratically ( P <0.01) the probability of pregnancy during both yr (Figure 1). These results indicate that reduced or excessive energy status is detrimental to reproductive performance of cattle, as reported by others (Armstrong et al., 2001; Bilby et al., 2006; Cooke et al., 2008b). Cow temperament score and plasma cortisol concentrations affected the probability of pregnancy linearly ( P =0.03) during yr 1, and quadratically ( P <0.01) during yr 2 (Figure 2). These results suggest that excitable temperament and consequent elevated cortisol concentrations (Curley et al., 2008) are detrimental to reproductive function of cows. Concurring with our findings, Plasse et al. (1970) reported that excitable temperament influences negatively the reproductive performance of beef females. Additionally, as observed in yr 2, reduced cortisol concentrations and temperament score during the early postpartum period may denote health disorders that negatively affect cattle reproduction, such as lethargy, lameness (Sprecher et al., 1997), and immunosuppresion (Goff, 2006). Plasma concentrations of ceruloplasmin and haptoglobin affected the probability of pregnancy linearly during yr 1 ( P <0.01 and =0.04, respectively) and yr 2 ( P =0.01; Figure 3), suggesting and supporting previous data indicating that the acute phase response is detrimental to reproductive function of livestock (Peter et al., 1989; Battaglia et al., 2000; Williams et al., 2001). In conclusion, results from this study indicate that measurements and physiologic responses associated with cow temperament, acute phase response, and energy status influenced the probability of cows to become pregnant during the breeding season. Therefore, management strategies that improve cow disposition, enhance their immune status, and maintain the cowherd at adequate levels of nutrition are required for optimal reproductive performance of Brahmancrossbred cows, and consequent productivity of cow-calf operations containing these types of cattle.

PAGE 4

Literature Cited Armstrong et al. 2001. Biol. Reprod. 64:1624 1632. Badinga et al. 1991. J. Anim. Sci. 69:1925 1934. Battaglia et al. 2000. Biol. Reprod. 62:45 53. Bilby et al. 2006. J. Dairy Sci. 89:3360 3374. Cooke and Arthington. 2008. Prof. Anim. Sci. 24:264 268. Cooke et al. 2007. J. Anim. Sci. 85:2564 2574. Curley et al. 2008. Horm. Behav. 53:20 27. Day. 2004. Anim. Reprod. Sci. 82 83:487 494. Demetriou et al. 1974. Clinical Chemistry 857 864 Dobson et al. J. Reprod. Fertil. 120:405 410. Goff. 2006. J. Dairy Sci. 89:1292 1301. Li and Wagner. 1983. Biol. Reprod 29:25 37. Makimura and Suzuki. 1982. Jpn. J. Vet. Sci. 44:15 21. Peter el al. 198 9. Am. J. Vet. Res. 50:368 373. Plasse et al. 1970. J. Anim. Sci. 30:63 72. Spicer and Stewart. 1996. Biol. Reprod. 54:255 263. Sprecher et al. 1997. Theriogenology 47:1179 1187. Wagner et al. 1988. J. Anim. Sci. 66:603 612. Wettemann et al. 2003. J. Anim. Sci. 81(E. Suppl. 2):E48 E59. Williams et al. 2001. Endocrinology 142:1915 1922. 1 R. F. Cooke, Former Graduate Student; D. B. Araujo Graduate Student; G. C. Lamb Associate Professor, UF IFAS North Florida Research and Education Center, Marianna FL ; J. D. Arthington, UF IFAS Range Cattle Research and Education Center, Ona, FL

PAGE 5

0 10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9 BCS Year 1 Year 2 0 10 20 30 40 50 60 70 80 90 100 0 50 100 150 200 250 300 350 Plasma IGF I, ng/mL Year 1 Year 2 F igure 1 Effects of BCS (emaciated = 1, obese = 9; Wagner et al., 1988) and plasma IGF I concentrations, assessed at the beginning of the breeding season, on the probability of Brahman crossbred cows to become pregnant. A quadratic effect was detected during yr 1 and 2 for BCS ( P <0.01) and plasma IGF I ( P =0.02 and <0.01, respectively). Probability of pregnancy, %

PAGE 6

0 10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 Temperament Score Year 1 Year 2 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 Plasma cortisol, g/dL Year 1 Year 2 Figure 2 Effects of temperament score and plasma cortisol concentrations, assessed at the beginning of the breeding season, on the probability of Brahman British and Braford cows to become pregnant. For temperament score, a linear effect ( P =0.03) and a quadratic effect ( P <0.01) were detected for both breeds during yr 1 and 2, respectively. For plasma cortisol, a linear effect was detected ( P =0.04) for Braford cows during yr 1 whereas a quadratic effect was detected ( P =0.02) for both breeds during yr 2. Probability of pregnancy, %

PAGE 7

0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 Plasma ceruloplasmin, mg/dL Year 1 Year 2 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 Plasma haptoglobin, 450 nm 100 Year 1 Year 2 Probability of pregnancy, % F igure 3 Effects of plasma ceruloplasmin and haptoglobin concentrations, assessed at the beginning of the breeding season, on the probability of Brahman crossbred cows to become pregnant. A linear effect was detected during yr 1 and 2 for plasma ceruloplasmin ( P <0. 01 and =0.01, respectively) and haptoglobin ( P =0.04 and =0.01, respectively).