All ewe lambs showed signs of estrous 24 h after sponge withdrawal, though mating in clomiphene citrate groups lasted more till day 18 of experiment (individual data was not recorded). Ultrasound based pregnancy rate at the last trimester of expected pregnancy was significantly affected by synchronization methods (P<0.05). The highest pregnancy rate was observed in PS+eCG ewe lambs (90%), while PS+CC group indicated 10% pregnancy rate and CC+eCG and CC groups showed no pregnancy (0%), (Table 1).
Table 1
Impact of different estrus synchronization on reproductive performance of ewe lambs.
| | Treatments | |
Traits | PS+eCG1 | PS+CC2 | CC+eCG3 | CC4 | P value |
Ultrasound based-pregnancy No. (head) 6 | 9 | 1 | 0 | 0 | - |
Ultrasound based-pregnancy rate (%) 6 | 90.00 | 10.00 | 0.00 | 0.00 | 0.03 |
Lambs No. (head) | 13 | 1 | 0 | 0 | - |
Lambing rate (%) | 130.00 | 10.00 | 0.00 | 0.00 | 0.03 |
Twining rate (%) | 53.85 | 0.00 | - | - | 0.97 |
Prolificacy (%) | 144.44 | 100.00 | - | - | - |
1 Embedding progestogen sponge for 12 days+eCG injection (500 IU) at 12 days of experiment (n=10). |
2 Embedding progestogen sponge for 12 days+oral receiving of 100 mg CC during 7-12 days (n=10). |
3 Oral receiving of 100 mg CC during 7-12 days+eCG injection (500 IU) at 12 days of experiment (n=10). |
4 Oral receiving of 100 mg CC during 7-12 days (n=10). |
5 Pregnancy of ewe lamb's based on blood progesterone concentration at 40 days of experiment. |
6 Ewe lamb's pregnancy based on ultrasound at the last expected trimester of pregnancy. |
Lambing rate was significantly affected by estrus synchronization methods (P<0.05) and the highest lambing rate was observed in PS+eCG group with 130% lambing rate (Table 1). On the other hand, 10% lambing rate was observed in PS+CC group and 0% lambing rate was observed in CC+eCG and CC groups (Table 1).
The impact of estrus synchronization methods on twining rate was not significant (P>0.05); however, twining rate was higher in PS+eCG group (53.85%) compared with PS+CC group (0%), (Table 1).
Furthermore, prolificacy in PS+eCG and PS+CC groups was 144.44% and 100%, respectively.
Based on the results, estrus synchronization treatments had a significant effect on blood progesterone concentration (P<0.05), in which progesterone concentration was 1.68±0.32 ng/ml in PS+eCG group, 1.56±0.36 ng/ml in CC+eCG group, 1.03±0.32 ng/ml in PS+CC group, and 0.153±0.36 ng/ml in CC group. Although blood progesterone concentration was not affected by blood sampling times (P>0.05), the interaction effects of estrus synchronization treatments by sampling times on serum progesterone concentration was significant (P<0.01), (Fig. 1). Different treatments had a significantly different progesterone concentration on 0, 11, 14, and 40 days of experiment (P<0.05), (Fig. 1). On day 11 of the experiment, progesterone concentration was the highest in CC+eCG group as compared with other groups (P<0.05), (Fig. 1). Also, PS+eCG group had the highest progesterone concentration on day 40 of the experiment (P<0.05), (Fig. 1).
The impact of estrus synchronization treatments on blood estrogen concentration was significant (P<0.01). Serum estrogen concentration was 57.55±3.23 pg/ml in PS+eCG group, 52.38±3.61 pg/ml in CC+eCG group, 46.96±3.23 pg/ml in PS+CC group, and 38.41±3.61 pg/ml in CC group. Also, blood sampling times had a significant effect on blood estrogen concentration (P≤0.05), (Fig. 2). Furthermore, the interaction effects of treatments by times on estrogen concentration were significant (P<0.01), (Fig. 3). Estrogen concentration was significantly different among treatments on sampling times of 0, 11, 14, and 40 days (P<0.05), (Fig. 3). Estrogen concentration was higher in PS+eCG group than other groups on days 11, 14, and 40 of experiment (P<0.05), (Fig. 3).