Effect of eCG on fertility to
GnRH-based TAI protocols in
beef cows (Bos Taurus)
Dr. Marcos G Colazo Research Scientist, Alberta Agriculture & Rural
Development
Edmonton, Alberta, Canada E-mail: [email protected]; [email protected]
Cow’s study (Experiment 1)
Suckled crossbred beef cows (n=292)
2X2 factorial; presynchronization (used CIDR for 15 d) and eCG treatment (400 IU)
53.4 53.443.8
64.4
0
20
40
60
80
100
%
eCG (-) eCG (+) eCG (-) eCG (+)
All cows
P=0.08
Presynch No Presynch
Cow’s study (Experiment 2)
Suckled crossbred beef cows (n=411)
2X2 factorial; presynchronization (used CIDR for 7d plus PG) and eCG treatment (400 IU)
66.760.7
24.1
55.6
0
20
40
60
80
100
%
eCG (-) eCG (+) eCG (-) eCG (+)
Primiparous cows
P<0.01
Presynch No Presynch
Heifer’s study (Experiment 1)
Crossbred beef heifers (n=128)
presynchronization with MGA for 15 d
eCG treatment (300 IU)
53.148.4
0
10
20
30
40
50
60
70
80
90
100
eCG (-) eCG (+)
%
NS
Heifer’s study (Experiment 2)
Crossbred beef heifers (n=450)
presynchronization with a CIDR
eCG treatment (300 IU)
26.3
59.1 60
28.4
44.4
55
0
10
20
30
40
50
60
70
80
90
100
HERD A HERD B* HERD C
%
eCG (-) eCG (+)
* P<0.05
Take home message
Treatment with eCG improved pregnancy rate to TAI, especially in primiparous beef cows that are not presynchronized.
Treatment with eCG did not improve prenancy rate in heifers.
