Treatments 21 days Postpartum
4.6 Summary
GP-NCL(+) (d 38, p<0.05) in S2. In S1, 3rd luteal activity occurred earlier in the GP-CL(+) (d 60, p=0.06), GP-NCL(+) (d 57.2, p<0.05) and C-CL groups (d 65, p<0.05) when compared to the C-NCL group (d 77). Postpartum days to 3rd luteal activity did not differ among the different groups in S2 (overall, GP: d 61.6, C: d 62.5). The number of luteal phases by d 60 postpartum was increased in the GP-CL(+) (2.3 and 2.6), GP-NCL(+) (2.6 and 2.8) and C-CL groups (2.4 and 2.7) when compared to the C-NCL group (1.9 and 1.5) in S1 and S2, respectively. The proportion of cycles with normal length was greater in the GP than in the C group in both S1 (82 vs. 47%) and S2 (89 vs.
62%). The presence of active CL 28 days postpartum and CL regression and ovulation following the treatment protocol are critical factors that increase fertility.
In conclusion, the treatment of dairy cows with a GnRH-PGF2α protocol as early as 21 days postpartum induces ovulation, synchronizes the cyclic ovarian activity and is capable of improving fertility in both early ovulating cows and cows having the risk for a long postpartum anestrous period.
Figure 4.1 Time schedules for the two studies evaluating the ovulatory, the cyclic ovarian activity and the fertility responses of cows treated with a GnRH-PGF2α
protocol (GP) and control cows (C) during early postpartum (pp). Studies were carried out under a) research (study 1) or b) commercial conditions (study 2). GP cows received GnRH (10 μg buserelin) on pp d 21 and PGF2α (study 1: 500 μg cloprostenol; study 2: 5 mg etiproston tromethamine) on pp d 28. US: ultrasound scanning; striped bars: period for the confirmation of ovulation by US. Plasma P4
levels from samples collected throughout the pp (studies 1 and 2) were used to evaluate ovulation and the cyclic ovarian activity by the time of- and following the start of the protocol.
P4analysis
GP and C groups (studies1 and 2) US scan
Parturition
0 21 28 3rd P4rise
US scan GnRH PGF
GP group
a) Study 1
21 28 69
GnRH PGF GP group
Parturition
0
b) Study 2
P4analysis
GP and C groups (studies1 and 2)
P4analysis
GP and C groups (studies1 and 2) US scan
Parturition
0 21 28 3rd P4rise
US scan GnRH PGF
GP group
a) Study 1
US scan Parturition
0 21 28 3rd P4rise
US scan GnRH PGF GnRH PGF
GP group
a) Study 1
21 28 69
GnRH PGF GP group
Parturition
0
b) Study 2
21 28 69
GnRH PGF GnRH PGF
GP group
Parturition
0
b) Study 2
Table 4.1. Ovulatory response to the GnRH-PGF2α protocol started on day 21 postpartum under research conditions.
Group n
Ovulation to GnRH
n (%)
Ovulation to PGF2α
n (%)
GP-CL 4 4 (100) 4 (100)
GP-NCL 11 9 (82) 6 (55)
Total 15 13 (87) 10 (67)
GP: cows treated with GnRH on postpartum d 21 and with PGF2α on postpartum d 28.
-CL: cows having, and -NCL: cows not having spontaneous ovulation within 21 days postpartum.
Table.4.2 Plasma progesterone levels (ng/ml) during the synchronization protocol with GnRH and PGF2α in dairy cows managed under experimental (study 1) or commercial farming conditions (study 2).
Study 1 (postpartum day) Study 2 (postpartum day)
Group n 21 28 30 n 21 28 30
GP-CL(+) 4 2.9 ± 0.8 a 5.7 ± 1.5 0.4 ± 0.1 a 5 1.9 ± 0.6 a 4.9 ± 1.0 a 0.5 ± 0.1 a
GP-NCL(+) 6 0.4 ± 0.3b 2.7 ± 0.6 0.3 ± 0.0 a 5 0.1 ± 0.0 b 3.7 ± 1.0 ab 0.8 ± 0.4 ab
GP-NCL(-) 3 0.2 ± 0.1 b 2.8 ± 0.5 2.3 ± 0.4 b 11 0.1 ± 0.0 b 2.7 ± 0.4 b 2.0 ± 0.4 b
Non-synch† 2 0.1 ± 0.0 0.1 ± 0.0 0.5 ± 0.0 1 0.1 0.8 1.7
Inactive 0 --- --- --- 3 0.1 ± 0.0 0.1 ± 0.0 0.1 ± 0.0
GP: cows treated with GnRH on postpartum d 21 and with PGF2α on postpartum d 28.
-CL: cows having, and –NCL: cows not having spontaneous ovulation within 21 days postpartum.
(+): synchronized, and (-) non-synchronized ovulations after treatment with PGF2α.
† Cows without ovulation of the largest dominant follicle after 72 h following the treatment with GnRH were removed from analysis.
Means with different superscripts within a column differ significantly (p<0.05).
Inactive: Cows not showing luteal activity within the first 45 days postpartum, and which were removed from analysis.
Table 4.3 Frequency of luteal activity during postpartum in control cows and in cows induced to ovulate with a GnRH and PGF2α protocol started on day 21 postpartum in an experimental dairy farm.
Ovulation by / after Luteal activity (days postpartum)
Group day
21 GnRH PGF (n=) 1st 2nd 3rd Total by
60d
GP (overall) 13 24.0 ± 3.2 39.5 ± 2.9 a 59.9 ± 3.9 a 2.3 ± 0.1
GP-CL(+) + + + 4 19.8 ± 0.6 38.0 ± 0.7* 60.0 ± 1.0∬ 2.3 ± 0.3
GP-NCL(+) - + + 6 26.0 ± 0.3 37.0 ± 0.9* 57.2 ± 2.3* 2.6 ± 0.2∬
GP-NCL(-) - + - 3 25.7 ± 2.5 46.3 ± 5.0 66.5 ± 8.2 2.0 ± 0.0
C (overall) 32 29.1 ± 2.0 49.9 ± 1.8 b 73.2 ± 2.2 b 2.0 ± 0.1
C-CL + 11 17.9 ± 3.0 40.1 ± 2.5* 65.5 ± 3.4* 2.4 ± 0.2∬
C-NCL - 21 35.0 ± 2.0 55.1 ± 2.0 77.2 ± 2.5 1.9 ± 0.1
GP: cows treated with GnRH and PGF2α; C: untreated cows .
-CL: cows having, and –NCL: cows not having spontaneous ovulation within 21 days postpartum.
(+): synchronized, and (-) non-synchronized ovulations after treatment with PGF2α.
a, b Means within the same column differed significantly (p<0.01).
＊Means within a column differed significantly (p<0.05), or ∬tended to differ (p=0.07) from the control group negative in ovulation on day 21 postpartum (C-NCL).
Table 4.4 Characteristics of estrous cycles during postpartum in control cows and in cows induced to ovulate with a GnRH and PGF2α protocol started on day 21 postpartum in an experimental dairy farm.
Ovulation by / after Estrous cycle length, n (%)
Group d 21 GnRH PGF (n=) Short
(<18 d)
Normal (18-24d)
Long (>24d)
Length
GP (overall) 11 1(9.1) 9 (81.8) a 1 (9.1) x 21.2 ± 1.9
mean: 21.6 ± 0.6
range: 11 18-24 28
GP-CL(+) + + + 4 0 (0) 3 (75) 1 (25) 23.5 ± 1.6
mean: 22.0 ± 1.0
range: 21-24 28
GP-NCL(+) - + + 5 1 (20) 4 (80) 0 (0) 20.0 ± 2.3
mean: 22.3 ± 0.8
range: 11 21-24
GP-NCL(-) - + - 2 0 (0) 2 (100) 0 (0) 19.5 ± 4.5
mean:
range: 21 and 18
C (overall) 32 4 (12.5) 15 (46.9) b 13 (40.6) y 23.3 ± 1.1
mean: 13.8 ± 1.9 21.0 ± 0.2 28.8 ± 0.5
range: 10-17 18-24 25-46
C-CL + 11 1 (9.1) 6 (54.5) 4 (36.4) 25.3 ± 2.0
mean: 22.5 ± 0.7 31.8 ± 4.8
range: 17 21-24 25-46
C-NCL - 21 3 (14.3) 9 (42.8) 9 (42.8) 22.1 ± 1.4
mean: 12.7 ± 2.2 20.0 ± 0.7 27.4 ± 1.5
range: 10-17 18-24 25-38
GP: cows treated with GnRH and PGF2α; C: Untreated cows.
-CL: cows having, and –NCL: cows not having spontaneous ovulation within 21 days postpartum
a, b Means within the same column differed significantly (p<0.05).
x, y Means within a column tended to differ (p=0.05).
Table 4.5 Frequency of luteal activity in early postpartum dairy cows from four different commercial farms induced to ovulate with GnRH and PGF2α.
Ovulation by / after Luteal activity (days postpartum) Group day
21 GnRH PGF (n=) 2nd 3rd Total by
60days
GP (overall) 21 44.4 ± 1.5 61.6 ± 1.3 2.3 ± 0.1 a
GP-CL(+) + + + 5 39.6 ± 2.0∬ 61.8 ± 1.2 2.6 ± 0.2*
GP-NCL(+) - + + 5 38.4 ± 0.6* 57.6 ± 2.6∬ 2.8 ± 0.2*
GP-NCL(-) - + - 11 50.0 ± 1.4 65.4 ± 1.5 † 2.0 ± 0.1
C (overall) 19 45.6 ± 2.2 62.5 ± 1.6 1.9 ± 0.2b
C-CL + 6 41.0 ± 4.1∬ 61.0 ± 1.3 2.7 ± 0.2*
C-NCL - 13 48.2 ± 2.5 64.0 ± 3.0 1.5 ± 0.1
GP: cows treated with GnRH and PGF2α; C: Untreated cows.
-CL: cows having, and –NCL: cows not having spontaneous ovulation within 21 days postpartum
＊Means within a column differed significantly (p<0.05), or ∬tended to differ (p=0.05~0.1) from the control group negative in ovulation on day 21 postpartum (C-NCL).
a,bMeans within the same column differ (p<0.05)
† Comparison was performed using cows (n=6 / group) in which analysis was possible.
Excluded from analysis are: cows with inactive ovaries (GP, n=3; C, n=4) and non-synchronized cows (GP, n=1).
.
Table 4.6 Characteristics of estrous cycles in early postpartum dairy cows from four different commercial farms induced to ovulate with GnRH and PGF2α.
Ovulation by / after Estrous cycle length, n (%)
Group d 21 GnRH PGF (n=) Short
(<18 d)
Normal (18-24d)
Long (>24d)
Length
GP (overall) 18 2 (11) 16 (89) a 0 (0.0) x 21.0 ± 1.0
mean: 21.9 ± 0.5
range: 9 and 12 21-24
GP-CL(+) + + + 5 0 (0.0) 5 (100.0) 0 (0.0) 22.2 ± 1.0
mean: 22.2 ± 1.0
range: 18-24
GP-NCL(+) - + + 5 1 (20.0) 4 (80.0) 0 (0.0) 19.2 ± 2.8
mean: 21.8 ± 1.4
range: 9 18-24
GP-NCL(-) - + - 8 1 (12.5) 7 (87.5) 0 (0.0) 21.0 ± 1.0
mean: 21.9 ± 0.9
range: 12 18-24
C (overall) 13 2 (15) 8 (62)b 3 (23) y 21.0 ± 2.0
mean: 22.9 ± 0.5
range: 6 and 5 21-24 27
C-CL + 6 1 (16.6) 5 (66.6) 1 (16.6) 20.0 ± 3.0
mean: 21.8 ± 0.8
range: 6 21-24 27
C-NCL - 7 1 (14) 4 (57) 2 (29) 22.0 ± 3.0
mean: 24.0 ± 0.0
range: 5 24 27
GP: cows treated with GnRH and PGF2α; C: Untreated cows.
-CL: cows having, and –NCL: cows not having spontaneous ovulation within 21 days postpartum
a, b Means within a column tended to differ (p=0.08).
x, y Means within a column tended to differ (p=0.05).
Table 4.7 Fertility traits of dairy cows induced to ovulate with a 7-d GnRH-PGF2α protocol started from 21 days postpartum and cows spontaneously ovulating in four dairy farms.
Fertility parameters GP group C group
n= 25 23
Calving-first service (d) 82 ± 4.3 77 ± 4.5 Conception to 1st AI (%) 5/16 (31) 3/20 (15) 100-d submission (%) 22 (88) 18 (78) Calving-to-conception (d) 138 ± 13 120 ± 11
100-d conception (%) 24 30
150-d conception (%) 36 a 65 b
Services per conception 2.1 ± 0.2 2.5 ± 0.3
GP: cows treated with GnRH and PGF2α; C: Untreated cows.
a,b Means with different superscripts across columns differ significantly (p<0.05).
Table 4.8 Fertility traits of treated (GP) and control (C) cows without ovulation by 21 days postpartum. The study involved four commercial dairy farms.
Fertility parameters GP-NCL(+) GP-NCL(-) C-NCL
n= 5 15 17
Calving-first service (d) 84 ± 19 87 ± 23 75 ± 21 Conception to 1st AI (%) 2/3 (67) 1/9 (11) 3/15 (20) 100-d AI submission (%) 4 (80) 13 (87) 13 (77) Calving-to-conception (d) 103 ± 21 a 168 ± 14 b 124 ± 13 a 100-d conception (%) 2 (40) 1 (7) 5 (29)
150-d conception (%) † 3 (60) 2 (13) 11 (65)
Services per conception 1.3 ± 0.6 2.6 ± 1.0 2.5 ± 2.0
GP: cows treated with GnRH and PGF2α; C: Untreated cows.
-CL: cows having, and –NCL: cows not having spontaneous ovulation within 21 days postpartum.
(+): synchronized, and (-) non-synchronized ovulations after treatment with PGF2α. a,bMeans with different superscripts across columns differ significantly (p<0.05).
† Statistics for the contingency table revealed difference among groups: a) Likelihood ratio’s p>chisq= 0.0066, b) Pearson’s p>chisq= 0.0099.
Table 4.9 Fertility traits in dairy cows having GnRH-induced (GP) and/or spontaneous (C) CL by 28 days postpartum.
Fertility parameters GP(+) GP(-) C-CL
n= 10 11 8
Calving-first service (d) 74 ± 17 81 ± 12 79 ± 25 Conception to 1st AI (%) 4/7 (57) 1/7 (14) 1/6 (17)
100-d submission (%) 9 (90) 11 (100) 6 (75)
Calving-to-conception (d) 99 ± 13 a 165 ± 18 b 133 ± 20 ab
100-d conception (%) 5 (50) a 1 (9) b 0 (0) b
150-d conception (%) 7 (70) 2 (18) 4 (50)
Services per conception 1.4 ± 0.5 x 2.6 ± 1.0 y 2.8 ± 2.0 y
a,bMeans across columns differed significantly (p<0.05).
x, yMeans across columns tended to differ (p=0.06~0.08).
Fig.4.2 Representative P4 profiles during the postpartum period in cows treated with a 7-day GnRH and PGF2α protocol (GP) started 21 days postpartum and in control cows (C) in a research farm. Groups are subdivided based on the presence (-CL) or absence (-NCL) of ovulation within 21 days postpartum, and according to ovulation (+) or failure of ovulation (-) after treatment with PGF2α.
Progesterone (ng/ml)
P o s tp a r tu m d a y
0 1 2 3 4 5 6 7 8 9
1 0 C -C L
0 1 2 3 4 5 6 7 8 9 1 0
0 7 1 4 2 1 2 8 3 5 4 2 4 9 5 6 6 3 7 0 7 7 8 4
C -N C L
0 1 2 3 4 5 6 7 8 9
1 0 G P -C L (+ )
G n R H
P G F
0 1 2 3 4 5 6 7 8 9
1 0 G P -N C L (+ )
G n R H P G F
Progesterone (ng/ml)
P o s tp a r tu m d a y
0 1 2 3 4 5 6 7 8 9
1 0 C -C L
0 1 2 3 4 5 6 7 8 9
1 0 C -C L
0 1 2 3 4 5 6 7 8 9 1 0
0 7 1 4 2 1 2 8 3 5 4 2 4 9 5 6 6 3 7 0 7 7 8 4
C -N C L
0 1 2 3 4 5 6 7 8 9 1 0
0 7 1 4 2 1 2 8 3 5 4 2 4 9 5 6 6 3 7 0 7 7 8 4
C -N C L
0 1 2 3 4 5 6 7 8 9
1 0 G P -C L (+ )
G n R H
P G F
0 1 2 3 4 5 6 7 8 9
1 0 G P -C L (+ )
G n R H
P G F P G F
0 1 2 3 4 5 6 7 8 9
1 0 G P -N C L (+ )
G n R H P G F
0 1 2 3 4 5 6 7 8 9
1 0 G P -N C L (+ )
0 1 2 3 4 5 6 7 8 9
1 0 G P -N C L (+ )
G n R H G n R H
P G F P G F
Fig.4.3 Representative P4 profiles during the postpartum period in cows treated with a 7-day GnRH and PGF2α protocol (GP) started 21 days postpartum and in control cows (C) under field conditions. Groups are subdivided based on the presence (-CL) or absence (-NCL) of ovulation within 21 days postpartum, and according to ovulation (+) or failure of ovulation (-) after treatment with PGF2α.
0 2 4 6 8 1 0 1 2
0 7 1 4 2 1 2 8 3 0 3 3 3 6 3 9 4 2 4 5 4 8 5 1 5 4 5 7 6 0 6 3 6 6 6 9
0 2 4 6 8 1 0 1 2 0 2 4 6 8 1 0
1 2 G P -N C L (-)
C -C L
C -N C L
Progesterone (ng/ml)
P o s tp a rtu m d a y
G n R H 0
2 4 6 8 1 0
1 2 G P -C L (+ )
G n R H P G F
0 2 4 6 8 1 0
1 2 G P -N C L (+ )
G n R H P G F
P G F
0 2 4 6 8 1 0 1 2
0 7 1 4 2 1 2 8 3 0 3 3 3 6 3 9 4 2 4 5 4 8 5 1 5 4 5 7 6 0 6 3 6 6 6 9
0 2 4 6 8 1 0 1 2 0 2 4 6 8 1 0
1 2 G P -N C L (-)
C -C L
C -N C L
Progesterone (ng/ml)
P o s tp a rtu m d a y
G n R H G n R H 0
2 4 6 8 1 0
1 2 G P -C L (+ )
G n R H P G F
0 2 4 6 8 1 0
1 2 G P -C L (+ )
G n R H G n R H
P G F P G F
0 2 4 6 8 1 0
1 2 G P -N C L (+ )
G n R H P G F
0 2 4 6 8 1 0
1 2 G P -N C L (+ )
G n R H G n R H
P G F P G F
P G F P G F
Chapter 5
The Relation between Metabolism and Ovarian status on the Ovulatory Response in Dairy Cows Treated with GnRH and PGF2α
during Early Postpartum