Table 2 Overall occurrence and effects of treatment with estradiol cypionate (ECP) and/or equine chorionic gonadotropin (eCG) at onset of the proestrus on follicular and luteal development in an estradiol/progesterone-based synchronization protocol on anestrous suckled beef cows

Number of cows

43

44

43

42

–

–

–

BCS at onset of the synchronization²

3.1 ± 0.1

3.0 ± 0.1

2.9 ± 0.1

3.0 ± 0.1

0.12

0.71

0.43

DF diameter at insert removal, mm³

11.0 ± 0.4

11.2 ± 0.4

10.8 ± 0.4

11.3 ± 0.4

0.90

0.38

0.77

DF diameter at TAI, mm⁴

12.6 ± 0.4

13.6 ± 0.4

12.7 ± 0.4

13.4 ± 0.4

0.90

0.03

0.68

Daily DF growth, mm/d⁵

0.9 ± 0.1

1.3 ± 0.1

0.9 ± 0.1

1.1 ± 0.1

0.52

0.01

0.25

Occurrence of estrus, %⁶

37.2

52.3

55.8

73.8

0.008

0.03

0.77

Ovulation rate, %⁷

81.4

95.5

83.7

97.6

0.54

0.008

0.71

CL diameter at d 6 after TAI, mm

17.8 ± 0.6^b

20.1 ± 0.5^a

18.6 ± 0.6^ab

18.7 ± 0.6^ab

0.54

0.04

0.06

Plasma P4 at d 6 after TAI, ng/mL

3.8 ± 0.3

5.1 ± 0.3

4.1 ± 0.3

4.6 ± 0.3

0.94

0.001

0.18

Pregnancy per TAI, %

30.2

36.4

44.2

50.0

0.07

0.42

0.95