Day Of Sponge Removal Research Articles

The use of melatonin and progestagen–eCG to initiate reproductive activity in prepuberal Awassi ewe lambs

This experiment was conducted to evaluate the effect of administering hormonal treatments (melatonin and progestagen/equine chronic gonadotropin (eCG)) on advancing puberty in Awassi ewe lambs. Fifty-one 6-month-old ewe lambs of similar body weights (around 28kg) were randomly assigned into four treatment groups; control (CON; n = 14), melatonin (MEL; n = 13), melatonin plus progestagen-eCG (MELPP; n = 11), and progestagen-eCG (PP; n = 13). Ewe lambs in the PP and MELPP groups were fitted with intravaginal progestagen sponges containing 60mg medroxyprogesterone acetate for 14days; 400IU eCG were administered to each of these ewe lambs on the day of sponge removal. Ewe lambs in the MEL and MELPP groups received subcutaneous melatonin implants (Regulin®, 18mg melatonin) 36days before sponge insertion. Hormonal treatment had no effect on ewe lamb body weight change. Estrous behavior was greater (p < 0.001) in the PP and MELPP groups than in the CON and MEL ewe lambs. The duration from ram introduction to onset of estrus was shorter (p < 0.05) in the CON, PP, and MELPP than in the MEL ewe lambs. The number of ewe lambs showing luteal activity was greater (p < 0.001) in the MELPP and PP than in the CON and MEL groups. Lambing rate from mating during the first cycle following ram introduction differed significantly (p < 0.01) among treatments being greater in the MELPP and PP than in the CON and MEL groups. Based on these results, it can be concluded that progestagen-eCG appears to be more effective than melatonin in inducing reproductive activity. However, the majority of ewe lambs in the current study either failed to cycle or stopped cycling following the induced estrus. Such failure in advancing puberty may be related to body weight of ewe lambs at the time of mating.

Repeated administration of hCG on follicular and luteal characteristics and serum progesterone concentrations in eCG-superovulated does

The objective of this study was to evaluate the effect of repeated administration of hCG on the follicular and luteal charactristics and serum progesterone concentrations in eCG-superovulated Merghoz does. The estrous cycles of 40 adult does were synchronized following a 12-day treatment with intravaginal sponges (Chronogest ®), with 1000 IU eCG injected 2 days prior to sponge removal. On the day of sponge removal (day 0), the females were randomly assigned to 4 treatments. The first group (h1; n = 10), received an i.m. hCG injection (500 IU; Pregnyl ®) on the day 0. The second group (h2; n = 10), received an i.m. hCG (500 IU) injection on days 0 and 1, while the third group (h3; n = 10) received i.m. hCG (500 IU) on days 0–2. Does in the control group ( n = 10) did not receive any hCG treatment. Blood samples were taken on days 0, 1, 2, 5 and 8 and analysed for serum progesterone (P4) concentrations. Premature luteal regression was considered to have occurred if the P4 concentrations declined to less than 1 ng/mL by day 8 following sponge removal. On day 8 goats were slaughtered and ovaries recovered for evaluation. In each case the CL's were counted and classified according to their appearance – as normal or as regressing. According to the serum P4 concentration on day 8, 42.8% (3/7), 0% (0/8), 0% (0/7) and 0% (0/6) of the goats underwent premature luteal regression in the control, h1, h2 and h3 groups, respectively. The control group was the only group in which there was a significant increase in the number of regressing CL's on day 8 (5.1 ± 1.5; P < 0.05). The characteristics of the CL's, including the mean diameter and weight was greater ( P < 0.05) in the h2 and h3 groups, compared to the control group (10.9 ± 0.7, 11.0 ± 0.9 vs. 7.9 ± 1.1 mm and 640.0 ± 101.4, 691.7 ± 111.7 vs. 294.3 ± 143.7 mg, respectively). No differences ( P < 0.05) in the number of large follicles present on the ovaries were recorded on day 8 between the groups. However, the diameter of the large follicles present on the ovaries on day 8 was greater ( P < 0.05) in goats in the h2 and the h3 groups, compared to the control (15.3 ± 0.6 and 12.9 ± 0.3 vs. 8.6 ± 1.7 mm, respectively; P < 0.05). The serum P4 concentrations were higher in the h2 and the h3 groups than in the control group on days 2 and 8. The serum P4 concentrations on day 8 also recorded a positive correlation with the normal CL's, CL diameter and CL weight ( P < 0.001). These results indicate that the repeated administration of hCG post-sponge removal presumably prevents premature luteal regression and improves luteal function in goats after eCG-superovulatory treatment. However, neither the number of persistent follicles nor the diameter of the persistent follicles was reduced.

Estrus Synchronization in Sheep and Goats Using Combinations of GnRH, Progestagen and Prostaglandin F2α

The objective of this experiment was to evaluate the effect of GnRH, progestagen and prostaglandin F(2alpha) on estrus synchronization in sheep and goats. Sixty Awassi ewes and 53 Damascus does were used in the study. The experiment started at the beginning of the breeding season (June/July). The same treatments were applied to sheep and goats as follows: no treatment (CON), 14-day progestagen sponges and 600 IU equine chorionic gonadotropin (S), gonadotropin releasing hormone followed 5 days later by prostaglandin F(2alpha) (GP) and gonadotropin releasing hormone, progestagen sponges for 5 days and prostaglandin F(2alpha) on the day of sponge removal (GSP). None of the ewes in the S group lambed from mating during the induced cycle. A greater lambing rate (p < 0.05) was observed in the GSP group compared with the CON and S groups while the GP group was intermediate. The number of lambs born per lambed ewe was similar among the CON, GP and GSP groups. However, the number of lambs per exposed ewe was greater (p < 0.05) in the GSP than the remaining groups. The induced cycle kidding rate was 77% for all treatments combined. Similar kidding rate were observed among treatments. The numbers of kids born per kidded and exposed doe from mating during the induced estrus were also similar among treatments. Greater numbers of multiple births were observed in the GP and GSP than in the S group. In conclusion, a combination of GnRH, progestagen sponges and PGF(2alpha) can be effective in synchronizing estrus and improving fecundity in sheep and goats. Although the use of GnRH-PGF(2alpha) was effective, the addition of progestagen sponges at the time of GnRH administration appeared to improve reproductive parameters.

Effect of time of eCG administration on follicular response and reproductive performance of FGA-treated Ossimi ewes

Equine chorionic gonadotrophin (eCG) is commonly used to improve litter size and for synchronized lambing in ewes. The efficiency, however, may be influenced by the time of application. The aim of the present study was to test the hypothesis that the time of eCG treatment induces a change in follicular development and ovulation rate in progestagen—PGF 2α treated ewes. Eighteen Ossimi ewes were treated with 40 mg FGA sponges for 8 days. Two days prior to sponge removal ewes (G1) were injected with 500 IU eCG ( n = 6), the second group (G2) received eCG (500 IU) on the day of sponge removal ( n = 6), while the third group (G3) was not treated with eCG and acted as the control ( n = 6). PGF 2α was injected to all the ewes on the day of sponge removal. Follicular development was observed ultrasonographically twice daily from sponge withdrawal. Administration of eCG in the G1 group caused a rapid reduction in the number of small follicles and an early appearance of the medium and large follicles ( P < 0.05). Estrus and ovulation occurred in 100% of the ewes in G1 and in 83.3% of the ewes in the G2 and G3 groups. The interval from treatment to estrus and ovulation was shorter ( P < 0.05) in the G1 (32 ± 5.6 and 72 ± 0.0 h, respectively) than the G2 (69 ± 9.9 and 108 ± 11.1 h, respectively) and the control groups (80 ± 13.8 and 124 ± 15.4 h, respectively). Administration of eCG 2 days before sponge withdrawal synchronized the time of ovulation and all ewes in the G1 group ovulated at the same time − the time of ovulation was spread over a period of 48 h in G2 and 72 h in G3, respectively. The ovulation rate was higher ( P < 0.05) in the eCG-treated ewes than the controls (2.33 ± 0.2; 2.33 ± 0.5 and 1.0 ± 0.2 for the G1, G2 and G3 groups, respectively). Characteristics of ovulatory follicles, including the interval from follicle emergence to ovulation, follicular growth rate and maximum size before ovulation did not differ between the treatment groups. The administration of eCG increased the number of fetuses and the lambs born, compared to control group ( P < 0.05). Results demonstrate that eCG administration to FGA-treated Ossimi ewes in the subtropics stimulate follicular development and increase prolificacy. The administration of eCG before sponge removal resulted in a shorter interval to estrus and ovulation linked to earlier development of large follicles and could be beneficial in the use of fixed-time AI.

Uterine contraction patterns and fertility in early postpartum ewes

Three experiments were conducted to determine: (1) the direction of uterine contractions in Days 32 and 52 postpartum ewes (Experiment 1); (2) the effect of PGF 2 α on direction of uterine contractions (Experiment 2); and (3) the effect of PGF 2 α on fertility rates in Day 32 postpartum ewes (Experiment 3). In Experiment 1, non-lambing (>90 days postpartum) and lambing ewes (day of lambing=Day 0) received medroxyprogesterone acetate (MAP) vaginal sponges for 8 days and 500 IU of eCG at sponge withdrawal (Days 30 or 50 postpartum). At the time of eCG injection, ewes were divided into the following groups: (1) non-lambing (control; n=29); (2) Day 32 postpartum dry ( n=15) and lactating ( n=16); and (3) Day 52 postpartum dry ( n=14) and lactating ( n=16). At estrus or 60 h post-eCG, the uterus was exteriorized through a mid-ventral incision, and the origin and direction of uterine contractions were recorded for 10 min. In Experiment 2, ewes received MAP sponges on Day 16 postpartum followed by 500 IU of eCG on day of sponge removal (Day 30). At estrus, the ewes were divided into the following treatments: (1) two injections of saline 4 h apart ( n=10) and (2) 12.5 mg of PGF 2 α followed by another 12.5 mg 4 h later ( n=7). After the second injection, ewes were laparotomized and uterine contractions were counted. In Experiment 3, estrus was induced in postpartum ewes, and ewes were mated to two rams, then received the same two treatments as described in Experiment 2 (ram+saline; n=32 and ram+PGF 2 α ; n=28). Two days following mating, ewes were laparotomized and the oviducts flushed for recovery of ova. In Experiment 1, lactational status had no effect, therefore, the data were pooled. Control ewes had a greater percentage ( p<0.05) of uterine contractions (69%) moving towards the oviducts than did Day 32 (8%) or Day 52 (43%) ewes. In Experiment 2, PGF 2 α treatment increased the proportion of contractions ( p<0.05) moving toward the oviducts (controls 16%, PGF 2 α 42%). Number of PGF 2 α -treated ewes (Experiment 3) with fertilized ova were not significantly different from the control ewes (5/32 versus 2/28; respectively). In conclusion, it can be said that the direction of uterine contractions moving toward the oviducts increased as the postpartum interval progressed or if they received PGF 2 α injection. PGF 2 α treatment did not improve fertility rates in Day 32 postpartum ewes.

The effect of melatonin on lambing and litter size in milking ewes after advancing the breeding season with progestagen and PMSG followed by artificial insemination

To advance the breeding season in an indigenous sheep breed of Greece, 207 multiparous milking ewes were used and allocated randomly in two groups, group A of 114 and group B of 93 ewes, during the anoestrous period (spring). All ewes received intravaginal sponges impregnated with progestagen (60 mg, MAP) for 14 days and were injected with PMSG (500 IU) on the day of sponge removal. Ewes in group A received melatonin implants (18 mg) 35 days before inserting the sponges. Artificial insemination was carried out into both groups 48 and 60 h after sponge removal. Lambing rate at second oestrous was significantly higher in group A (60.4 vs. 32.6%, P<0.05). The overall lambing rate during two oestrous cycles was significantly higher in group A than in group B (83.3 vs. 68.8, P<0.05). The groups differed significantly in the mean litter size per lambing ewe that conceived during the first oestrus after sponge removal (1.52 vs. 1.32). The total mean litter size per lambing ewe was higher in group A than in group B (1.48 vs. 1.31) as a consequence of the difference in pregnancy rate.

Increasing lambing percentage by androstenedione immunoneutralization in synchronized ewes with or without PMSG

The present study was undertaken to determine the potential of active immunization against androstenedione to increase lambing percentage in dairy ewes synchronized with progestagen with or without PMSG. Ewes (n=200) which were milked twice daily by milking machine were alloted randomly to either the immunized or the nonimmunized (control) group. Ewes in the immunized group were given two injections of the immunogen Fecundin (2 ml) 3 wk apart. All ewes were synchronized with intravaginal sponges inpregnated with Cronolone (30 mg); then half of the ewes in each group (Ia and IIa) were given an injection of PMSG (330 IU) on the day of sponge removal. Ewes in groups Ib and IIb did not receive PMSG. Rams were introduced to all ewes the day after sponge removal, which in the immunized groups (Ia and Ib) was 21 after the second injection of Fecundin. The lambing percentage for immunized ewes that were given PMSG was significantly higher than for those not given PMSG (Ia vs Ib, P<0.05), and it was much higher for either of the control groups (nonimmunized, P<0.01). The lamb weight of control ewes was significantly higher than the immunized ewes (P<0.05), while the litter weight of immunized ewes was significantly higher than that of the controls (P<0.05).

The effect of the laparoscopic insemination technique on the oestrous cycle of the ewe

This investigation was designed to determine whether or not the technique of intrauterine insemination affects the length of the subsequent oestrous cycle. Dorper ewes (n = 31) were divided into treatment and control groups. All the ewes were synchronised using 40 mg fluorogestone acetate intravaginal sponges for 14 d and 300 IU pregnant mare serum gonadotrophin on the day of sponge removal. A standard semen diluent was deposited laparoscopically in each uterine horn of ewes in the treatment group. Teaser rams were used to detect oestrus. Progesterone profiles were used to confirm oestrus. The mean oestrous cycle length of 17.83 +/- 0.69 d for the group in which the diluent was deposited by laparoscopy did not differ significantly (P less than 0.1) from the 18.36 +/- 2.11 d of the control group. The technique of laparoscopic insemination did not influence the length of subsequent oestrous cycles.

The stimulation of fertile oestrus in anoestrous Romney ewes. II.

Summary. One hundred 6- and 7-year-old Romney ewes were treated for 13 days in January (mid-summer) with intra-vaginal sponges containing 40 mg of 6-methyl-17-acetoxyprogesterone (map). All ewes received 1000 i.u. pregnant mares serum gonadotrophin (pmsg) on the day of sponge removal and fifty ewes received a second 1000 i.u. pmsg 16 days later. The onset of oestrus was synchronized in both treatment groups and was apparently 2 weeks earlier than in twenty untreated ewes. Lambs born as percentage of ewes surviving was satisfactory in all groups being: one dose of pmsg, 94%; two doses of pmsg, 106%; controls 105%.