Intravaginal Progestagen Research Articles

Patterns of Reproductive Management in Sheep and Goat Farms in Greece.

This paper reports findings regarding patterns of reproductive management in 325 sheep flocks and 119 goat herds throughout Greece. The objectives were to describe the patterns of reproductive management in sheep and goat farms, to highlight factors that were associated with these management patterns and the clinical application of the various reproductive management approaches in the farms and to establish potential associations with production outcomes. The median months of the start of the mating period for adult sheep and goats were May and June, respectively and for ewe lambs and replacement goats these were August and September, respectively. The median duration of the mating period was 2 months for adults and 1 month for replacements. The median ratio of female to male animals was 22:1 and 25:1 in sheep and goat farms, respectively. Control of reproduction was applied in 33.2% and 16.8% of sheep and goat farms, respectively, mostly by intravaginal progestagen sponges and less often by melatonin implants; multivariable analysis indicated five (availability of milking parlour, number of ewes in a farm, number of daily milkings, daily period spent by farmers at the farm, farming tradition in the family) and two (number of daily milkings, availability of milking parlour) predictors in sheep and goat farms, respectively. Pregnancy diagnosis ultrasonographically was performed in 36.6% and 16.8% of sheep and goat farms, respectively; multivariable analysis indicated as significant three (management system applied in farms, age of farmer, farming tradition in the family) and two (management system applied in farms, availability of milking parlour) predictors in sheep and goat farms, respectively. The control of reproduction and pregnancy diagnosis were associated with a higher number of vaccinations during pregnancy: 2.6 and 2.7, respectively, versus 2.2 and 2.1 in farms where they were not performed. The average per farm number of lambs/kids born per female animal was 1.33 ± 0.01 and 1.30 ± 0.02 for sheep and goat farms, respectively; five (control of reproduction, location of the farm, presence of working staff, collaboration with veterinary practice, breed of ewes) and two (control of reproduction, breed of female goats) predictors were identified in sheep and goat farms, respectively, for high numbers of lambs/kids. Lambs/kids were taken away from their dams at the age of 50 and 65 days, respectively. The average culling age (females, males) was 5.9 and 4.4 years and 6.9 and 4.9 years for sheep and goats, respectively. Farmers sourced animals to be used as replacements for those removed from the farm, mostly from the animals in their own farms, considering criteria related to milk production. Finally, the application of the control of reproduction was associated with increased milk production and the number of newborns, whilst an inverse correlation between the culling age of animals and milk production was seen.

Comparative Data about Estrus Induction and Pregnancy Rate on Lacaune Ewes in Non-breeding Season after Melatonin Implants and Intravaginal Progestagen

Backgroung: Seasonal anestrus in ewes reduces reproductive efficiency and hinders productivity. Exogenous hormones can be used to facilitate the induction and synchronization of estrus in the anestrus period. The aim of this study was to evaluate the pregnancy rate in ewes after the treatment with different hormones and fixed time artificial insemination. Methods: The ewes were randomly divided in 4 (n=4) groups: Melatonin group (Group 1), Melatonin and Medroxyprogesterone group (Group 2), Medroxyprogesterone group (Group 3) and control group (Group 4). Pregnancy rate, estrus induction rate and litter size were determined and compared. Result: The estrus induction rate in our study was 100% for the first 3 groups and 6.25% for the 4th group. The pregnancy rate was between 4.16% (group 4) and 95.83% (group 2). For the others groups the values were 89.58% for the first group and 91.67%, for the 3rd group. The prolificacy rate was between 1 (control group) and 1.71 (2nd group), with intermediate values for the other 2 groups: 1.21 for 1st group and 1.27 for the 3rd group.

Influence of Different Synchronization Protocols on Fertility Response in Surti Does

This study was carried out to assess the influence of different estrus synchronization Protocols on fertility response in Surti does based on litter size, fecundity and twining rate. Thirty does were selected and divided into five equal groups (n=6 in each). Does of G1 group were treated with intra-vaginal progestagen sponges (IVPS) for 11 days. Does of G2 group received the same IVPS sponge for 11 days and exposure of sexually active apronized buck during the treatment period. Does of G3 group were treated as per G1 group along with i/m injection of PGF2andalpha; analog (125 µg, Cloprostenol) at the time of sponge removal. Does of G4 group were subjected to the buck effect and exposed to a sexually active patronized buck for 11 days, and does of G5 group was kept as a control without any treatment for 11 days. It was found that, none of the synchronization Protocols had significant effect on litter size, fecundity, and incidence of multiple kid birth and sex ratio in Surti does.

110 Pregnancy rate and embryo viability in response to chorionic gonadotrophins given for oestrus induction and gonadotrophin-releasing hormone 5 days after timed laparoscope-aided insemination of lactating and non-lactating goats

Gonadotrophins are included in oestrous/ovulation synchronization (E/OS) regimens when breeding early in the transitional phase to promote follicular development. However, the time of use has been a matter of debate. Hence, the objective of this study was to determine whether equine and human chorionic gonadotrophins (eCG and hCG, respectively) given 24h before or 24h after concurrent removal of intravaginal progestagen (P4) and prostaglandin (PGF2α) delivery influences pregnancy rate (PR) and/or embryo viability (EV). Relatedly, the influence of gonadotrophin-releasing hormone (GnRH) 5 days post-breeding (dpb) on PR and/or EV was also considered. A prospective randomised control trial was conducted using lactating and non-lactating Alpine breed goats of different parity, average±s.e. age, and bodyweight (3.7±2.6), and (52.5±7), respectively. Goats were time-bred at 48h after P4 removal by laparoscopy (LAI; n=75) or by natural service (NS; n=29) during the early transitional breeding phase in mid-September through mid-December (corresponding to 12:12h daylight/darkness). E/OS used an intravaginal device containing 300mg of P4 for 12±1d. At P4 removal, 2mL of PGF2α was administered IM. Twenty-four hours before (E) or 24h after (L) P4 removal, an IM dose of 1.5mL containing 120IU of eCG and 60IU of hCG was given. A third control (C) group (n=38) was not exposed to gonadotrophins. GnRH analogue was given (n=51) 5 days after insemination, and the remaining goats (n=53) received an IM dose of 2mL of saline solution. PR was evaluated at 18 to 24 (dpb) by non-return to oestrus (NRE), at 30 dpb by pregnancy-specific protein B (PSPB), and at 40 dpb by ultrasound imaging (UI). EV was determined from the difference between pregnancy outcomes for NRE and PSPB, and PSPB and UI. Statistical analysis (JMP/SAS vs.11; SAS Institute Inc.) were obtained using logistic regression. All concomitant variables (i.e. parity, bodyweight, days of P4 exposure, and lactation were not influenced by PR or EV; P>0.07). The overall PR was 71% for LAI and 69% for NS and, as shown in Table 1, was similar (P>0.49) at all times (at 18 to 24, 30, and 40 dpb). Likewise, the breeding procedure did not influence the levels of EV at 30 or 40 dpb. E/OS protocol or the use of GnRH 5 dpb did not affect PR or EV at any of the time points evaluated. Table 1. Main effect mean comparisons and logistic model probabilities for pregnancy rate (PR) and embryo viability (EV) by main treatment effect Response variable (days post-breeding) Breeding procedure E/OS Protocol Gonadotrophin LAI NS P> Control Early Late P> GnRH Placebo P> PR at 18–24 77 72 0.49 76 73 78 0.83 78 74 0.49 PR at 30 68 66 0.65 66 65 70 0.82 71 64 0.43 PR at 40 69 69 0.78 66 69 73 0.77 73 66 0.43 EV at 30 89 90 0.94 86 94 90 0.65 92 87 0.46 EV at 40 88 95 0.42 86 89 94 0.73 92 87 0.43

10.4314/sajas.v40i5.65265

This study was conducted to evaluate the effect of breed types and lactation status on reproductive performance of hormonally-treated Awassi ewes. A total of 282 ewes were treated with intravaginal progestagen sponges and equine chorionic gonadotropin. Ewes were mated with fertile rams following sponge removal. Lambing rate was similar between brown- and black-faced ewes, while the percentage of multiple births, fecundity and prolificacy were greater in black-faced ewes. Lambing rate and the percentage of multiple births were similar between lactating and dry ewes. Fecundity tended to be greater in lactating ewes, while prolificacy was similar regardless of lactation status. Results of the present study indicate that black-faced Awassi ewes respond better to hormonal treatment than brown-faced ewes while the lactation status does not appear to influence the ewes’ response to hormonal treatment.

Effects of short-term intravaginal progestagen treatment on fertility and prolificacy after natural breeding in sheep at different reproductive seasons

ABSTRACT The present study indicates that short-term progestagen-based protocols for synchronization of estrus and ovulation in sheep involving 7 days of progestagen insertion with administration of prostaglandin F2α at either insertion or removal of the progestagen sponge resulted in 80–90% fertility during the breeding season, while a classical long-term protocol of 14 days of progestagen insertion resulted in 77% fertility. During the non-breeding season, fertility was significantly higher for the 7-day protocol with prostaglandin administration at sponge insertion (79.2%) and for the 14-day protocol (80%) than for the 7-day protocol with prostaglandin administration at sponge removal (59.1%; P = 0.018). Prolificacy, in contrast, varied significantly with genotype, being higher in prolific breeds, but it did not vary with progestagen protocol or breeding season. These results suggest that short-term progestagen-based treatments can provide similar reproductive efficiency as long-term treatments, which may help practitioners reduce welfare and health issues while maintaining productivity.

Effects of short-term intravaginal progestagens on the onset and features of estrus, preovulatory LH surge and ovulation in sheep

In the present study, there was a comparison among classical long-term progestagen (fluorogestone acetate) protocols for synchronization of estrus and ovulation (14 days; group FGA14, n = 9 ewes) and short-term protocols based on 7 days of progestagen treatment plus a dose of prostaglandin F2α at either insertion (PG-FGA7, n = 11) or removal (FGA7-PG, n = 12). There were no significant differences in the ovulation rate and progesterone secretion among treatments. The FGA7-PG group, however, had a similar percentage of ewes expressing estrous behavior than the group FGA14 (90.9 and 100%, respectively, with a trend for a lesser percentage in the PG-FGA7 group, 63.6%) and about 90% of the ewes in the FGA7-PG group had the preovulatory surge release of LH 8 h after the onset of estrous behavior. These features may be related to a greater number of preovulatory follicles during growing phases (P < 0.05) and a greater plasma estradiol concentration (P < 0.05) in this group than in the classical 14-day group, which suggest these are more functional preovulatory follicles. In conclusion, therefore, the use of the FGA7-PG treatment may favor efficiency of progestagen-based protocols for reproductive management.

Effects of subcutaneous melatonin implants and short-term intravaginal progestagen treatments on estrus induction and fertility of Kivircik ewes on seasonal anestrus.

The aim of this study was to compare the efficacy of estrus induction and fertility by using subcutaneous melatonin (MEL, T1) and short-term intravaginal medroxyprogesteronacetate plus pregnant mare serum gonadotropin treatments (sMAP+eCG, T2) in ewes on seasonaly anestrus. In this study, 105 mature clinically healthy Kivircik ewes in anestrus season and 4 rams were used. After synchronization applications, ewes exhibiting estrus signs were hand-mated with rams known to be fertile. Blood samples were collected at different times in order to determine progesterone (P4) concentrations. Results showed that estrus manipulation protocols induced significant improvement in pregnancy rate. All the fertility results obtained with the sMAP+eCG or MEL groups were similar, in seasonal anestrus. The efficacy duration of P4 in the MEL group was longer than that in short-term progestagen group. Plasma P4 concentrations was significantly different between the first (I) and last (III) measurement days (p0.01). Increase in P4 concentration in T2 group was faster than that in T1 group, and blood P4 concentrations at higher levels could successfully be achieved by using any of the protocols in this study during the seasonal anestrus. In conclusion, according to the results obtained, the hormone application groups received very high estrus response. In addition, the twin ratio was found to be higher in T1 group compared to those determined in the other groups (T2 and Control group). Furthermore, plasma P4 concentrations and high birth rates were obtained in ewes in T1 and T2 groups. These procedures can be considered a good alternative to traditional procedures due to its flexibility under field conditions.

The effects of short-mid-long term intravaginal sponge application on reproductive performance of karacabey Merino ewes in the anestrous season

The aim of the present paper was to investigate the efficiency of different progestagen treatment methods in combination with Pregnant Mare Serum Gonadotrophin (PMSG) in Merino ewes outside the breeding season. A total of 78 ewes (2 to 4 years old) with a mean bodyweight of 58.4 kg and an average body condition score (BCS) of 3.5 were used in the trial. The ewes were randomly divided into 3 equal groups [n= 26]. Intravaginal progestagen sponges containing Fluorogestone Acetate (FGA; 30 mg) were inserted intravaginally for different periods (7_days: short-term; 10_days: mid-term, 14_days: long-term). In all cases, 500 IU PMSG was administered intramuscularly at sponge withdrawal. The oestrus response, lambing rate, multiple birth rate, fecundity and litter size were [65.4, 61.5, 18.8 %, 0.77 and 1.25] in the short-term group; 80.8, 88.5, 34.8 %, 1.31 and 1.48 in the mid-term group; and 96.2, 92.3, 62.5 %, 1.50 and 1.63 in the long-term group, respectively. Oestrus manifestation and multiple birth rate were greater in long-term than in mid- and short-term groups, whereas for lambing rate, fecundity and litter size, better results were obtained in long- and mid-term than in short-term protocol. In conclusion, in Merino ewes, oestrus synchronisation outside the breeding season with long and mid-term progestagen treatment was found to be more effective than short-term treatment.

The effect of the intracervical administration of FSH or LH on the levels of hyaluronan, COX2, and COX2 mRNA in the cervix of the nonpregnant ewe

During the periovulatory period, the cervix relaxes in response to changes in circulating concentrations of reproductive hormones. The present study investigated the role of gonadotrophins in cervical function by examining the expression of cyclooxygenase-2 (COX2) and COX2 mRNA and the concentration of hyaluronan (HA) in the cervix, after intracervical treatment with either FSH or LH. Eighteen ewes were assigned to four groups. They were then treated with commercial intravaginal progestagen sponges and eCG to synchronize their estrous cycles. Intracervical treatments were given 24 hours after removal of the sponges as follows: group 1: FSH, 2 mg; group 2: LH, 2 mg; group 3: vehicle; and group 4: control. Cervices were collected 54 hours after sponge removal and then divided into three regions. The expression of COX2 and COX2 mRNA was determined by immunohistochemistry and in situ hybridization and those of HA by ELISA. The levels of expression of COX2, COX2 mRNA, and HA were compared in six tissue layers (luminal epithelium, subepithelial stroma, circular, longitudinal and transverse muscle, and serosa) and in three cervical regions (vaginal, mid, and uterine). The results showed that both FSH and LH significantly increased the levels the COX2 mRNA and COX2 in the cervix, but the effects of the gonadotrophins were selective. The effects of both FSH and LH were most evident at the vaginal end of the cervix and least at the uterine end of the cervix. Furthermore, their effects were confined to the stroma and smooth muscle layers of the cervix in the case of FSH and to smooth muscle only in the case of LH. Neither FSH nor LH affected the concentration of HA in the cervix although FSH but not LH reduced the concentration of HA in cervical mucus. These findings suggest that the gonadotrophins regulate the expression of COX2 in the cervix and that they may have a role facilitating relaxation of the cervix during estrus in the ewe.

Effect of natural mating or laparoscopic artificial insemination in superovulated Santa Inês ewes on superovulatory response, fertility and embryo viability

This study evaluated the effect of two mating methods (GNM: natural mating or GAI: laparoscopic artificial insemination) on superovulatory response, fertility and embryo yield in superovulated ewes. Fifteen non-pregnant Santa Inês ewes were superovulated and either mated by GNM or GAI in a crossover design. Oestrus was synchronised using intravaginal progestagen sponges for 6 days and on Day 5, 300 IU eCG and 0.0375 mg d-cloprostenol were given. Twelve hours after sponge removal, 0.025 mg gonadotropin-releasing hormone was administered. Superovulation started 48 h after gonadotropin-releasing hormone treatment, using 5 IU/kg follicle-stimulating hormone (pFSH). At the first pFSH dose, new sponges were inserted. At the fifth dose, 0.0375 mg cloprostenol was administered and the sponges were removed. The GNM was mated with rams every 12 h, until the end of oestrus. The ewes of GAI were laparoscopic inseminated with frozen–thawed semen 36 and 48 h after sponge removal. Ultrasonography was performed every 24 h from the beginning of oestrus synchronisation treatment and every 12 h from the second sponge removal to 2 days after the last pFSH dose. Six to seven days after mating, the number of corpora lutea (CL) was evaluated by laparoscopy and the females with &gt; 4 CL were subjected to embryo collection. The interval from sponge removal to ovulation was shorter (P &lt; 0.05) in the GNM. The overall superovulatory response was 63.3% (19/30), with 60.0% and 66.7% in GNM and GAI, respectively (P &gt; 0.05). The number of recovered structures (6.4 ± 2.4 vs 4.5 ± 3.0), recovery rate (74.0 ± 16.0 vs 52.3 ± 26.5%), number of transferable embryos (3.0 ± 2.9 vs 3.6 ± 2.0) and viability rate (47.2 ± 45.3 vs 77.4 ± 37.1%) did not differ between GAI and GNM (P &gt; 0.05). However, the GAI group showed a higher (P &lt; 0.05) number of unfertilised oocytes (3.1 ± 3.1) and a higher non-fertilisation rate (47.1 ± 45.3%) than the GNM (0.9 ± 2.1 and 11.5 ± 21.5%). The mating method did not affect the superovulatory response, and production of viable embryos although the non-fertilisation rate has been inferior for the AI group.

Use of fluorogestone acetate sponges or controlled internal drug release for estrus synchronization in ewes: Effects of hormonal profiles and reproductive performance

This study was carried out using 300 multiparous Najdi ewes during breeding season to compare the effects of fluorogestone acetate (FGA) sponges and controlled internal drug release (CIDR) dispensers to synchronize estrus on reproductive performance and hormonal profiles. Ewes were equally and randomly allotted into group A (FGA) and group B (CIDR); intravaginal progestagen was administered for 14-day period with intramuscular administration of 600-IU eCG at withdrawal time. Estrus was detected using a vasectomized ram starting 12 hours after progestagen withdrawal and repeated every 12 hours up to 84 hours. Blood samples were collected at the time of progestagen withdrawal (0 hour), 24 hours, and 48 hours. Follicle-stimulating hormone, LH, estradiol, and progesterone serum concentrations were measured using commercial ELISA kits and microtitrimetric plates. Timed laparoscopic insemination was performed 48 hours after progestagen withdrawal. Pregnancy and the number of fetuses were diagnosed by ultrasonography on Day 23 after insemination and confirmed on Days 35 and 60. The results revealed that the retention, vaginal discharge, and drawstring breakage rates after progestagen removal were significantly (P ≤ 0.05) higher in the FGA group (94.00, 98.58, and 9.22, respectively) than those in the CIDR group. On the other hand, pregnancy, fertility, twinning rates, and fecundity were significantly (P ≤ 0.05) higher in the CIDR group (77.86, 75.57, 34.34, and 1.02, respectively) than in the FGA group. Estrus responses in FGA and CIDR groups increased gradually to attain their significantly (P ≤ 0.05) higher percentages after 48 hours of progestagen withdrawal (91.49 and 92.37, respectively); thereafter, they decreased. The overall estrus responses and prolificacy did not differ between the FGA and CIDR groups. Follicle-stimulating hormone was significantly higher in the FGA group at 24 and 48 hours after progestagen withdrawal, whereas LH was significantly higher in the CIDR group at 48 hours after progestagen withdrawal. Estradiol and progesterone were significantly higher in the CIDR group at 0, 24, and 48 hours after progestagen withdrawal. These results indicated that although FGA and CIDR devices are efficient in synchronizing estrus in ewes, CIDR provided higher pregnancy, fertility, twinning rates, and fecundity than FGA.

The timing of oestrus, the preovulatory LH surge and ovulation in Blanca Andaluza goats synchronised by intravaginal progestagen sponge treatment is modified by season but not by body condition score

The aim of this study was to determine whether a seasonal pattern of reproductive events is followed after synchronisation by intravaginal progestagen sponge treatment in female Blanca Andaluza goats, and whether the timing of these events is affected by body condition score (BCS). During seasonal anoestrus (March), and again during the breeding season (November), the same 32 does were distributed into four subgroups according to their BCS: ≤2.25, =2.50, =2.75, and ≥3.00 (n=8 in all cases). They were then synchronised using a commercial intravaginal sponge treatment. Every 4h over the 72h following sponge removal, oestrous activity, the LH concentration and each doe's number of follicles were followed by transrectal ultrasonography. The does synchronised during seasonal anoestrus produced more follicles than those synchronised during the breeding season (P<0.01). The time elapsed between sponge removal and the onset of oestrus, the LH surge and time of ovulation, was also shorter in these does (P<0.001). The BCS only modified the number of follicles present in the ovary just before ovulation; this number was significantly lower in the =2.50 BCS subgroup than in the other subgroups (P<0.05). The present results show that the time to ovulation, and all events around it, are modified by the season in which Blanca Andaluza does are synchronised, but not by BCS.

Effect of nutrition on plasma lipid profile and mRNA levels of ovarian genes involved in steroid hormone synthesis in Hu sheep during luteal phase1

Ovarian steroid hormones regulate follicular growth and atresia. This study aims to determine whether key ovarian sterol-regulatory genes are differentially expressed in Hu sheep under different short-term nutritional regimens. Estrus was synchronized using intravaginal progestagen sponges. The ewes were assigned randomly to 3 groups. On d 6 to 12 of their estrous cycle, the control (CON) group received a maintenance diet (1.0×M), the supplemented (SUP) group received 1.5×M, and the restricted (R) group received 0.5×M. On d 7 to 12, blood samples were taken. The sheep were slaughtered at the end of the treatment, and their organs and ovaries were collected. The plasma concentrations of urea (P<0.01), total cholesterol (P<0.01), low-density lipoprotein cholesterol (P<0.01), NEFA (P<0.01), FSH (P<0.05), and estradiol (P<0.05) increased with decreasing dietary intake, whereas plasma triglyceride (P<0.01) and triiodothyronine (T3) concentrations decreased (P<0.05). The ewes in the R group had higher spleen weight and percentage of spleen to BW and lower liver and small intestine weights and percentage of liver/stomach to BW than the SUP group ewes (P<0.05). Nutritional restriction decreased the cytochrome p450 (CYP17A1) and estrogen receptor 1 (ESR1) mRNA expression (P<0.05) and increased the cytochrome p450 aromatase (CYP19A1) mRNA expression (P<0.05) in follicles>2.5 mm. Follicle size affected the mRNA expression of very low density lipoprotein receptor (VLDLR), estrogen receptor 2 (ESR2), FSH receptor (FSHR), CYP17A1, and CYP19A1 (P<0.05). In conclusion, we suggest that a potential mechanism by which short-term negative energy balance inhibits follicular growth may involve responses to disrupted reproductive hormone concentrations and influenced the intrafollicular expression of CYP17A1, CYP19A1, and ESR1. This result may be due to increased plasma urea and lipid concentrations.

The effect of estrus synchronization on the reproductive characteristics of Turkish Saanen goats and growth characteristics of kids under extensive conditions

The aim of this study was to determine the effect of oestrus synchronization on the growth characteristics of the Turkish Saanen kids under extensive production. In this study, 70 goats undergoing estrus cycles were synchronized and mated by 10 Turkish Saanen bucks, and together with the produced 124 Turkish Saanen kids, provided the animal material of the study. As a result, 204 animals were used as a material in this study. The estrus cycles of goats were synchronized with intra-vaginal progestagen sponges impregnated with 45 mg cronolone. Ten day after the application, 0.5 ml prostaglandin F2α (PGF2α) (A°liren®) were injected. After 12 days, sponges were removed and the females received an intramuscular injection 400 IUPMSG (pregnant mare serum gonadotrophin) and each goat was mated by Turkish Saanen bucks. It was observed that the effects of FGA/PGF2α /PMSG on fertility and litter size were significant (P 0.05). In conclusion, the use of intravaginal sponges impregnated with 45 mg FGA and 0.5 ml PGF2α, in combination, is convenient for estrous synchronization of Turkish Saanen goat in Turkey during the breeding season. Key words: Estrus synchronization, fluorogestone acetate (FGA), pregnant mare serum gonadotrophin (PMSG), Turkish Saanen goat, fertility, litter size.

Effects of oestrus induction with progestagens or prostaglandin analogues on ovarian and pituitary function in sheep

The aim of the current study was to determine possible differences in ovarian and pituitary features explaining lower fertility rates in sheep with oestrus induced with intravaginal progestagens or prostaglandin analogues (group FGA and PGF, n = 8 in both) when compared to a control group (group C, n = 8). The growth profiles and the mean individual sizes of preovulatory follicles were similar between groups; however, the number of preovulatory follicles per ewe and, consequently, the number of ovulations were higher in groups FGA and PGF (2.3 ± 0.3 and 2.0 ± 0.1, respectively) than in group C (1.4 ± 0.1, P < 0.05). However, plasma oestradiol concentrations were similar between groups suggesting a defective function in some preovulatory follicles of groups FGA and PGF. In group FGA, the basal LH levels during the follicular phase were lower (0.21 ± 0.0 ng/mL, P < 0.005) than in groups C (0.41 ± 0.1 ng/mL) and PGF (0.55 ± 0.1 ng/mL); the onset of preovulatory discharge being later (21.0 ± 2.3 h vs. 12.8 ± 1.5 in C and 14.5 ± 1.5 in PGF; P < 0.05 for both). Finally, luteal activity was also found to be affected in group FGA; the rate of progesterone secretion per total luteal tissue was lower (range: 0.46–0.65 ng/mL/cm 2) than in ewes treated with cloprostenol (2.1–3.3 ng/mL/cm 2) and control sheep (2.0–3.4 ng/mL/cm 2).

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.

Growth characteristics in lambs of estrus synchronized ewes in grower conditions

The aim of this study was to determine the growth characteristics of lambs of estrus-synchronized ewes in an extensive production system during 2 different periods. The animal material of this study was composed of 325 head Chios × Kıvırcık cross breeds. These lambs were provided by mating 124 Kıvırcık sheep on 2 farms with 8 Chios rams provided by the Adnan Menderes University, Faculty of Agriculture, Sheep Research Unit. The estrus cycles of the ewes were synchronized with intra-vaginal progestagen sponges impregnated with 30 mg of cronolone. After 12-14 days the sponges were removed, the females received an intramuscular injection of 500 IU PMSG, and 5 or 6 ewes were mated with Chios rams. This research lasted for 3 years, and detailed flock records were kept. The average birth weight, average weight of 100-day-old lambs, and average marketing weight of Kıvırcık × Chios F1 were 3.18 kg, 19.71 kg, and 29.10 kg, respectively. Lambing season, birth type, and the sex of the lambs were found to significantly affect birth weight, which is an important factor in lamb production (P < 0.01). In this study daily gains in the live-weight of 100-day-old lambs and daily gains in the live-weight during the marketing period were 163.07 g and 167.48 g, respectively. Year of birth, lamb sex, and growing methods were significant in determining the characteristics mentioned (P < 0.01). In addition, the 100th day performances indicated significant changes according to the farms, and the performances during the marketing period varied significantly according to the ages of the ewes. The survival rates of lambs up to 100 days of age and the marketing period were 66.81% and 63.57%, respectively. The effect of year was also significant (P < 0.01). The results of this study indicate that, with respect to lamb development and marketing, more advantageous results can be achieved by synchronizing estrus and having earlier births than traditional production methods allow.

The effect of breed type and lactation status on reproductive performance in

This study was conducted to evaluate the effect of breed types and lactation status on reproductive performance of hormonally-treated Awassi ewes. A total of 282 ewes were treated with intravaginal progestagen sponges and equine chorionic gonadotropin. Ewes were mated with fertile rams following sponge removal. Lambing rate was similar between brown- and black-faced ewes, while the percentage of multiple births, fecundity and prolificacy were greater in black-faced ewes. Lambing rate and the percentage of multiple births were similar between lactating and dry ewes. Fecundity tended to be greater in lactating ewes, while prolificacy was similar regardless of lactation status. Results of the present study indicate that black-faced Awassi ewes respond better to hormonal treatment than brown-faced ewes while the lactation status does not appear to influence the ewes’ response to hormonal treatment.

The effect of the absence or presence of a corpus luteum on the ovarian follicular population and serum oestradiol concentrations during the estrous cycle in Sanjabi ewes

The aim of this study was to determine if the presence or absence of a corpus luteum (CL) during estrous synchronization in ewes can affect the ovarian follicular population and the serum oestradiol concentrations. The estrous cycles of 197 Sanjabi ewes were synchronized using a 12-day treatment with intravaginal progestagen sponges (Chronogest ®). Estrus was detected in 144 ewes, 27–39 h after sponge removal. Blood samples were taken daily from day 2 and continued for 19 days and analyzed for serum oestradiol concentration. Nine ewes were slaughtered on each experimental day (days 1–16 after estrus) for ovary collection. The ovaries per ewe were classified as those without, or with one or two CL's, for each slaughter day. Visible follicles on the surface of the ovaries were classified, based on their diameter, into (i) very small (<2 mm), (ii) small (2–3.4 mm), (iii) medium (3.5–5 mm) and (iv) large (>5 mm) categories, and the respective numbers recorded. Results indicated, the number of ovarian follicles to decrease ( P < 0.01) from days 1 to 5 of the cycle and showed a significant increase on day 7. Numbers were high again on day 11 and decreased ( P < 0.01) on day 16 of the estrous cycle. The serum oestradiol concentrations were significantly higher ( P < 0.001) in the double than in the single ovulating animals (one or two CL's, respectively) on days 2–0. However serum levels were also significantly higher ( P < 0.001) in single, than twin ovulating animals on days 4–5 and 12–16 of the estrous cycle. There were no significant differences in the total number of very small follicles between animals without and those with two CL's. The number of small, medium and large follicles in ewes, with or without a CL on the ovary was significantly higher ( P < 0.01) than ewes with two ovulations at certain stages of the estrous cycle. The present study provides evidence of differences in the follicular ovarian population in ovaries without CL's and double ovulations. The existence of an intraovarian effect of the CL numbers on follicular population is demonstrated.