split-time artificial insemination programs for beef cows · split-time artificial insemination...
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Split-time artificial insemination programs for beef cows
John R Jaeger
Western Kansas Agricultural Research Center - Hays
April 19, 2018
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Estrous Synchronization• Enhance the use of artificial insemination• Decrease / eliminate the time required for heat
detection• Maximize the number of cows conceiving to artificial
insemination
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Resources for estrous synchronization• Many estrous synchronization protocols to choose
from• Many different company brand name hormones
available for estrous synchronization• Beef Reproduction Task Force – Applied Reproductive
Strategies in Beef Cattle– https://beefrepro.unl.edu/
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Applied Reproductive Strategiesin Beef Cattle
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Applied Reproductive Strategiesin Beef Cattle
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Estrus Synchronization Hormones
Controlled internal drug release impregnated with progesterone
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Why add split-time breedingto a fixed-time protocol?
Hill et al., 2016
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Why add split-time breedingto a fixed-time protocol?
• Numerous studies have shown that ~30% of cows do not show estrus by 66 h post-CIDR.– First service conception rate is
• Delaying fixed-time insemination for those cows not displaying estrus by 66 h may improve conception rate among those cows.
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Estrous detection patches
CIDR
GnRH-1
-17 dBS
-7 dBS
PGF
PGF
PGF
PGF
TAI +GnRH-2
TAI
TAI
TAI
GnRH-2
0 65 h 84 h
E + G
E ‒ G
L + G
L ‒ G
Treatment protocol to establish theimportance of injecting GnRH
Active patch at 66 h
Non-active patch at 66 h
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Treatment protocol to establish theimportance of injecting GnRH
• E + G: Cows displayed estrus by 65 h, received GnRH and AI
• E – G: Cows displayed estrus by 65 h, received no GnRH and AI
• L + G: Cows did not display estrus by 65 h, received GnRH and inseminated at 84 h
• L – G: Cows did not display estrus by 65 h, received no GnRH and inseminated at 84 h
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First service conception rate to fixed-timeAI at 65 or 84 h after CIDR removal
61.9
41.7
60.4
30.8
0
10
20
30
40
50
60
70
80
Early (65 h) Late (84 h)
Firs
t ser
vice
con
cept
ion
rate
(%)
GnRHNo GnRH
a a
b
c
n = 385 n = 373 n = 226 n = 252
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Effect of estrus and GnRH on FSCR to fixed-timeAI at 84 h after CIDR removal
65.3
33.4
61.7
15.0
0
10
20
30
40
50
60
70
80
Estrus No Estrus
Firs
t ser
vice
con
cept
ion
rate
(%)
Cows bred at 84 hours after CIDR
GnRH
No GnRHa
a
b
n = 103 n = 97 n = 146 n = 128c
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Discussion• GnRH is not essential to achieve acceptable FSCR
(>60%) when cows express estrus before AI at 65 h.
• For cows not in estrus by 65 h – GnRH was only effective in improving FSCR for cows not displaying estrus by 84 h.– GnRH treatment of non-estrus cows increased
FSCR of those cows by 2×
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Conclusions
• GnRH injection at AI improved FSCR only in those cows that were not detected in estrus before AI.
• Cows that displayed estrus, regardless of GnRH treatment, had better FSCR than cows that did not display estrus.
• The split-time AI program serves as a compromise between conventional AI after detecting estrus and a standard one fixed-time AI program.
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Two split-time artificial insemination programs• Two split-time treatment groups
1. Cows in estrus bred at 55 h, non-estrus cows received GnRH and bred at 75 h. (55 – 75 h)
2. Cows in estrus bred at 65 h, non-estrus cows received GnRH and bred at 85 h. (65 – 85 h)
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Two split-time artificial insemination programs• Four treatment response groups
55 – 75 h1a. Cows in estrus at 55 h & AI (no GnRH)1b. Cows not in estrus at 55 h, received GnRH & AI
at 75 h.65 – 85 h 2a. Cows in estrus at 65 h & AI (no GnRH)2b. Cows not in estrus at 65 h, received GnRH & AI
at 85 h.
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Two split-time artificial insemination programs
CIDR
GnRH
Estrus + AI
No estrus+ GnRH
Estrus + AI
No estrus+ GnRH
‒7 d 0 d
PGF
55 h 65 h
TAI
75 h 85 h
TAI
Estrous detection patches
55 – 75 h
65 – 85 h
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Proportion of cows in estrus by 55, 65, 75 or 85 h after removal of CIDR and injection of PGF2α
28.5
65.3
53.5
74.8
45.5
61.468.3
77.2
0102030405060708090
100
55 65 75 85
Estr
us (%
)
Hours after PGF2α
PrimiparousMultiparous
224 328 309 201
Trt P < 0.001Parity P = 0.125T × P P = 0.006
Trt P < 0.001Parity P = 0.045T × P P = 0.137
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First service conception rate
46.0
64.5
43.3
53.5
70.564.9
49.456.4
0102030405060708090
100
55 65 75 85
Preg
nanc
y ra
te a
t 36
d (%
)
Hours after PGF2α
PrimiparousMultiparous
223 326 302 198
Trt P < 0.002Parity P = 0.067T × P P = 0.192
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Final (end of breeding) pregnancy rate
88.4 88.1
73.880.8
95.0 97.0 93.9 92.7
0102030405060708090
100
55 65 75 85
Fina
l pre
gnan
cy ra
te (%
)
Hours after PGF2α
Primiparous Multiparous
223 326 307 199
Trt P < 0.058Parity P = 0.001T × P P = 0.708
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First service conception and final pregnancy rate by treatment (55 + 75 vs. 65 + 85 h)
57.7
90.0
62.8
92.0
0102030405060708090
100
FSCR PR
Conc
eive
d, %
55 + 7565 + 85
525 524 530 525
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Summary• For cows in estrus by 55 or 65 h, pregnancy rate was
greater compared to cows not in estrus and bred at 75 or 85 h.
• For cows not in estrus by 55 or 65 h, but showed estrus by 75 or 85 h, pregnancy rate was greater for cows displaying estrus than for cows not showing estrus.
• Overall, (regardless of when estrus occurred) FSCR rate was greater for cows displaying estrus than for those not showing estrus (67.3 vs. 42.7%).
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Summary• FSCR was greater for cows assigned to the 65 + 85 h
treatment compared to cows assigned to the 55 + 75 h treatment (62.8 vs. 57.7%, respectively).
• Final pregnancy rate was not different between the 55 + 75 h and 65 + 85 h treatments (90.0 vs. 92.0 %, respectively).
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Summary – “Cowboy math” (100 cows)
FTAI at 65 h63 % in estrus at 65 h37 % not in estrus at 65 h63 estrus cows × 67% FSCR = 42 cows37 no estrus cows × 43% FSCR
= 16 cows
FSCR = 58 cows
FSCR: At 65/85 h Estrus – 67%; No estrus – 43%Split time AI at 65 + 85 h63 % in estrus at 65 h37 % not in estrus at 65 h63 estrus cows × 67% FSCR = 42 cows37 cows × 76% estrus @ 85 h= 28 cows28 cows × 67% FSCR = 19 cows9 no estrus cows × 43% FSCR @ 85 h
= 4 cows
FSCR = 65 cows
7% increase for FSCR
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Implications
• It is more economical to use estrus detection patches and reduce the number of GnRH injections required.
• Allows for choice of semen and sire selection (cost) for cows detected in estrus (greater PR)– Cows not detected in estrus are placed in a split-
time program and less expensive semen is utilized.
• Split-time insemination programs should result in a greater number of bred cows and recapture costs associated with estrus synchronization.
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J. R. Jaeger, PhD, PASBeef Cattle Scientist
Kansas State University Agricultural Research Center – Hays785-625-3425 [email protected]