Controlled Internal Drug Release Withdrawal Research Articles

Influence of repeated estrus synchronization treatment on hormone secretion, growth, and development of dairy goats.

In large-scale intensive farms, dairy goats often undergo frequent estrus synchronization (ES) treatment, which may result in a decline in reproductive performance; however, the underlying mechanism remains unclear. The present study aimed to investigate the effect of pregnant mare serum gonadotropin (PMSG) and progesterone (P4)-mediated ES treatment on fertility in dairy goats, while also identifying key metabolic and endocrine mechanisms that influence reproductive performance in does subjected to repeated ES treatment. Forty-eight Saanen does were randomly assigned to two groups (24 goats each) that received ES treatments either thrice fortnightly (3-PMSG) or once (1-PMSG) simultaneously with the third ES treatment of the 3-PMSG group during the breeding season. ES treatment was performed via the intravaginal insertion of a controlled internal drug release (CIDR) device impregnated with 300 mg P4, followed by 300 IU PMSG injections 48 h before CIDR withdrawal. Blood was collected to detect the level of hormones and blood biochemical indices. Additionally, estrus rate, fecundity rate, body weight, size, and lactation performance were measured. The results showed that repeated ES treatment markedly decreased the estrus rate and fecundity rate of goats. Among the does in all groups, there was no substantial difference in follicle stimulating hormone, luteinising hormone, gonadotropin-releasing hormone, melatonin, growth hormone, PMSG, total cholesterol, total protein, and glucose levels, as well as the body weight, body size, and lactation performance. Repeated ES treatment elevated estrogen (E2) levels 36, 48, and 72 h post-CIDR removal; increased P4 upon CIDR insertion; and raised PMSG antibody levels 24, 48, and 72 h post-CIDR removal. The results suggest that elevated anti-PMSG levels are the primary reason for the decline in ES efficiency, and that high E2 and P4 levels at some time points also impair reproductive performance. These findings provide novel insights into the metabolic effects of repeated PMSG stimulation in goats, guiding future reproductive hormone use in breeding practices.

Embryo yield and quality in superovulated Simmental donor cows following oral supplementation with different sources of omega-3 and omega-6 fatty acids

Owing to contradictory results with respect to the yield and quality of embryos after supplementation with omega-3 fatty acids, this study sought to determine the effect of an oral supplement containing sources of omega-3 and omega-6 fatty acids on the ovarian response and embryo quality after superovulation. Cows were allocated to receive one of three oral supplement regimens. In the control (CO) group (n = 9), cows were fed a control supplement without fatty acids. The cows in the soybean oil (SO) (n = 8) and linseed oil (LO) (n = 8) groups received supplements containing SO or LO, respectively. Supplements were administered for 28 days, commencing 7 days before the onset of estrus synchronization until the day of embryo collection. The estrous cycle of all cows was synchronized by inserting a controlled internal drug release (CIDR) device (progesterone 1.38 g), followed by the administration of estradiol benzoate 2.5 mg. The CIDR device was withdrawn 7 days after insertion, followed by intramuscular administration of dinoprost 25 mg. Superovulation was induced via the administration of 152 mg of follicle-stimulating hormone (Folltropin-V) in tapered doses, starting 72 h before CIDR withdrawal. The embryos were collected 6 days after artificial insemination. The estrous response, onset of estrus after CIDR withdrawal, and number of ovulations were similar among the experimental groups (p > 0.05). The mean number of transferable embryos (grades 1 and 2) was higher in the LO group compared to the CO group (9.0 vs 3.2; p < 0.05). Although the number of transferable embryos (grades 1 and 2) was greater in the LO group than that in the SO group, the difference was not statistically significant (9.0 and 4.4; p > 0.05). In conclusion, oral supplementation with LO for 28 days increased the yield of transferable embryos, which could potentially improve the profitability of embryo transfer programs in cattle.

Addition of equine chorionic gonadotropin in controlled internal drug-release-based synchronization improves reproductive performance of Nili-Ravi buffalo in the sub-tropics

This study evaluated the effect of equine chorionic gonadotropin (eCG) and factors such as body condition score (BCS), cyclicity, and breeding season in a controlled internal drug release (CIDR)-based oestrus synchronization protocol on ovarian follicle dynamics, oestrus expression, ovulation rate, and pregnancy per artificial insemination (AI) (P/AI) in Nili-Ravi buffalo. Adult buffaloes (n = 88), 6.69 ± 1.17 years, parity 3.36 ± 0.97, and BCS 2.76 ± 0.45, were randomly administered eCG or saline, concurrent with prostaglandin F2α (PGF2α) treatment on Day 6 in a CIDR synchronization protocol during the breeding season and low breeding season. Follicular dynamics and oestrus expression were recorded from eCG administration until ovulation. Fixed-time artificial insemination (FTAI) was performed at 48- and 60-hour intervals after CIDR withdrawal. On Day 35 post-AI, pregnancy was diagnosed with ultrasonography. There was no significant difference in the size of the ovulatory follicle between eCG-treated buffaloes (ETB) and saline-treated buffaloes (STB). The growth rate of the dominant follicle, oestrus response and intensity, ovulation, and P/AI were higher (P &lt;0.05) in eCG-treated buffaloes. It was concluded that eCG improved the growth rate of the dominant follicle, oestrus expression, and P/AI in a CIDR-based FTAI programme in Nili-Ravi buffalo. The deleterious effects of poor BCS, acyclicity, and low breeding season could be reduced with a progesterone-based fixed time AI protocol with the addition of eCG.

Role of aquaporin 3 in reproductive performance of dairy goats after repeated estrus synchronization stimulation.

This study explored the specific molecular mechanisms through which repeated estrus synchronization (ES) treatments reduce the reproductive performance of dairy goats. Ninety-six goats (n=24/group) were randomly assigned to two groups receiving ES treatments thrice every fortnight (3- equine chorionic gonadotropin [eCG] and 3-follicle stimulating hormone [FSH] groups) and two groups receiving one ES treatment (1-eCG and 1-FSH groups). ES treatments of 1- and 3-eCG goats were performed via the intravaginal insertion of a controlled internal drug release (CIDR) device containing 300 mg progesterone (P4), followed by 300 IU eCG injections 48 h before CIDR withdrawal. The 1- and 3-FSH goats received CIDR for 10 d, followed by 50 IU FSH and 100 μg PGF2α within 12 h of CIDR withdrawal. Ovaries of three goats in estrus from both groups were harvested for analysis. Subsequently, all the goats in estrus were artificially inseminated twice. Consequently, 3-eCG and 3-FSH goats showed a considerably reduced estrus rate and litter size than 1-eCG and 1-FSH goats. AQP3 mRNA and protein expression were significantly higher in the 3-eCG and 3-FSH groups than in the 1-eCG and 1-FSH groups. AQP3 overexpression led to cell apoptosis and decreased steroid hormone secretion ability of ovarian granulosa cells. Moreover, it resulted in a decrease in maturation and cleavage rates after parthenogenetic activation and in vitro fertilization, respectively. AQP3 gene was involved in reducing the reproductive performance of repeated ES-treated dairy goats. These findings provide a theoretical foundation for the effective use of reproductive hormones in breeding techniques for livestock.

Superovulatory response and embryo quality in Boer does following dietary supplementation with different sources of omega-3 and omega-6 fatty acids during the breeding season

The purpose of this study was to determine effects of various sources of omega-3 and omega-6 fatty acids on ovarian response and embryo quality in Boer does when there was a superovulation treatment regimen imposed. Pluriparous does were randomly assigned to be treated with 300 g of one of four experimental supplements containing linseed oil (LO), soybean oil (SO), palm oil (PO), or a control supplement without fatty acids (CO), for 15 days. Does were fitted with a controlled internal drug release (CIDR) device containing 0.3 g progesterone for 7 days. At 48 h before CIDR withdrawal, does were treated with 80 mg follicle-stimulating hormone (FSH) administered at 12 h intervals. Embryos were collected 7 days after the last natural mating. Estrous response and interval between CIDR withdrawals to estrous onset were similar between treatments (P > 0.05). Number of ovulations was similar for does in the different groups (10.0, 9.2, 7.0, and 7.0, in LO, SO, PO, and CO, respectively; P > 0.05). There was premature luteal regression in does of the SO, PO, and CO groups, except in LO group. The LO-treated does had a larger (P < 0.05) mean number of ova/embryos recovered than does of SO, PO, and CO groups (7.2, 2.0, 0.2, 0.2, respectively) and transferable embryos (5.1, 1.4, 0.2, 0.2, respectively). These results indicate that including LO in supplements may be a feasible strategy for preventing premature luteal regression and improving embryo quality in goats treated to induce follicular super-stimulation for induction of superovulation.

Investigation of ram effect and eCG usage in progesterone based oestrous synchronization protocols on fertility of ewes following fixed time artificial insemination

• Short term progesterone treatment in oestrous synchronization protocols improves conception rates. • Inclusion of male effect or eCG in a progesterone based oestrous synchronization protocol leads to similar response. • Male effect can replace eCG in a progesterone based synchronization protocols. Improving oestrus synchronization protocols is important, particularly to ensure that protocols which guarantee reduced hormonal use and environmental safety also result in acceptable reproductive efficiency. The aim of this study was to compare the effect of long and short-term progesterone (P4) treatment and their combination with either equine chorionic gonadotropin (eCG) or the ram effect (Ram) on oestrous response and fertility of ewes. Seventy-eight South African Mutton Merino ewes were randomly allocated to four treatment groups in a 2 × 2 factorial design and primed with controlled internal drug release (CIDR) for a 9 (short) or 14 d (long) period. At CIDR withdrawal, ewes in each group received either a single intramuscular injection of equine chorionic gonadotrophin (eCG; 300 IU) or exposure to the ram effect; eCGshort (n = 19), Ramshort (n = 21), eCGlong (n = 19) and Ramlong (n = 19). Oestrous behaviour was monitored from 12−84 h post CIDR withdrawal. Ultrasound was performed at 48 h post CIDR withdrawal to examine number and diameter of follicles. Artificial insemination (AI) was performed twice at 48 and 60 h post CIDR withdrawal with fresh undiluted semen using the cervical method. Pregnancy diagnosis was performed by transrectal ultrasound at 35 d post AI and confirmed by lambing data. Oestrous behaviour was observed in 98.7% of all synchronized ewes, with no significant difference among treatment groups. Overall, conception rate (CR) and the proportion of ewes lambing to synchronized oestrus were (74.4% and 52.6%, respectively). There was no significant difference among treatment groups in oestrous response, onset of oestrus, number of follicles, diameter of the largest follicle, CR and AI to lambing interval (P > 0.05). When data were pooled, CIDR-14 d protocols showed a significantly shorter interval to onset of oestrus (24.9 ± 1.6 vs 30.8 ± 2.1, P < 0.05) than CIDR-9 d protocols but there was no difference (P > 0.05) between eCG and Ram protocols when data were pooled. CIDR-9 d protocols resulted in a significantly higher CR (85.0% vs 63.2%, P < 0.05) than CIDR-14 d protocols when data were pooled, but CR between eCG and Ram protocols was not statistically different (P > 0.05). Mean AI to lambing interval was 158.2 ± 1.2 d, ranging from 147 to 154 d and 166 to 186 d post AI. Ewes lambing to synchronized oestrus per treatment group were 52.6% (eCGshort), 42.9% (Ramshort), 63.2% (eCGlong) and 52.6% (Ramlong), respectively (P > 0.05). In conclusion, the 4 protocols investigated were effective in synchronizing oestrus with similar response to synchronization of oestrus and fertility among treatment groups. Of the 4 protocols, the Ramlong protocol offers the benefit of being less costly because of reduced hormonal use in addition to the adequate fertility obtained.

Repeated pregnant mare serum gonadotropin-mediated oestrous synchronization alters gene expression in the ovaries and reduces reproductive performance in dairy goats.

This study aimed to elucidate the effects of repeated pregnant mare serum gonadotropin (PMSG) treatment for oestrous synchronization (ES) on ovarian gene expression and reproductive parameters in Xinong Saanen dairy goats, the dominant breed of dairy goat in China. The experiment was carried out at the Research Station of Northwest A&F University (NWAFU), China (34°16'N, 108°4'E). Forty-one does were randomly assigned to groups receiving ES treatments thrice every fortnight (3-PMSG group; n=19), or ES treatment only once simultaneously with the third ES treatment in the 3-PMSG group (1-PMSG group; n=22) during middle of the breeding season from late July (14hr light) until late September (12hr light). ES treatment was performed via intravaginal insertion of a controlled internal drug release (CIDR) device impregnated with 300mg progesterone (P4), followed by 300IU PMSG injections 48hr before CIDR withdrawal. Oestrus was monitored using vasectomized bucks. Ovaries of three goats in oestrus from both groups were harvested for morphological examination and RNA sequencing (RNA-Seq). Then, all the oestrous goats in the 1-PMSG (n=21) and 3-PMSG (n=11) groups were artificially inseminated twice. The 3-PMSG group showed reduced oestrous rate (57.89%), pregnancy rate (31.58%) and litter size (1.17) compared, respectively, with 95.45%, 68.18% and 1.67 for 1-PMSG group (p<0.05). However, no differences were found in the ovarian morphology between the 1-PMSG and 3-PMSG groups (p>0.05). RNA-Seq revealed 114 differentially expressed genes (DEGs) in the ovaries of the 3-PMSG group, among which GCG, FSTL3, TET3 and AQP3 were deemed novel and promising candidate genes for regulating fertility. The present study indicates that the three-time PMSG treatment dysregulated several ovarian genes, thereby reducing reproductive performance.

Ovarian follicular changes and hemodynamics in Egyptian buffaloes under CIDR-PGF2α and Ovsynch-CIDR estrus synchronization treatments

This study aimed at investigating the efficacy of two protocols of estrous synchronization on follicular changes and hemodynamics. Pluriparous Egyptian buffaloes (n = 36) were synchronized either with controlled internal drug release (CIDR)-PGF2α (7-days CIDR insert with PGF2α injected on the 6th day; n = 18) or Ovsynch-CIDR (Ovsynch protocol concurrent with 7-days CIDR insert; n = 18). Blood sampling and ovarian ultrasound examinations (Grayscale, color and power Doppler modes) were conducted on the Day of CIDR removal, estrus, and luteal phase. Mean follicle diameter (MFD), first (1st-LF) and second (2nd-LF) largest follicle diameters, and E2 levels significantly increased in the CIDR-PGF2α group at CIDR withdrawal. Ovsynch-CIDR markedly fortified higher follicle population, MFD, and 1st-LF diameter at estrus and corpus luteum (CL) volume at the luteal phase in concomitant with increases (P < 0.05) in E2 (at estrus) and P4 (at luteal phase). At CIDR removal, the blue pixels in the dominant follicle (DF) were higher (1.5 times; P = 0.054) in the Ovsynch-CIDR than in the CIDR-PGF2α. At estrus, total blood flow (TBF) and power Doppler pixels (PDP) to DF(s) were noticeably higher (seven and 1.6 times; respectively) in the Ovsynch-CIDR than in CIDR-PGF2α (5906 ± 237 vs. 830 ± 60 pixels, P < 0.01 and 5479 ± 322 vs. 3377 ± 19 pixels, P < 0.05; respectively). At the luteal phase, TBF and PDP to the CL increased in the Ovsynch-CIDR group than in the CIDR-PGF2α group (11060 ± 965 vs. 7963 ± 480 pixels, 1.4 times, P = 0.05 and 18900 ± 1350 vs. 13220 ± 568 pixels, 1.1 times, P = 0.005; respectively). In conclusion, based on the improvement in synchronized follicular activity and hemodynamics, the Ovsynch-CIDR regimen is persuaded in Egyptian buffaloes.

Effects of long-term controlled internal drug release reuse on reproductive performance, hormone profiles, and economic profit of sheep

ABSTRACT Fifty-seven multiparous Awassi ewes in the breeding season were used to compare the effects of controlled internal drug release (CIDR) reuse on hormone profiles, reproductive performance, and economic production. Ewes were randomly allotted to one of three CIDR treatments: new (control), once-used, and twice-used; treatment lasted 12 days. Blood samples were collected from all groups at the time of CIDR insertion, three and six days following insertion, at withdrawal time, and at insemination. Serum estradiol (E2) and progesterone (P4) concentrations were measured. Timed insemination was performed 48 h post CIDR withdrawal in all groups. Pregnancy was diagnosed by ultrasonography at day 23 post insemination. No significant differences were detected among groups in pregnancy rate/ewes in heat, twinning rate, fecundity, abortion rate, and prolificacy. However, estrus detection rate was significantly higher in control (100%) than in other groups. The P4 concentration was significantly higher in control than in other groups during treatment period; at insemination, P4 concentration was significantly higher in control than in other groups; at insemination time, E2 concentration was significantly higher in control than in the other groups; and the net profit was higher in once-used than in other groups. One-time reuse of CIDR for the long term (12 days) can synchronize estrus in ewes efficiently with higher net profit than the new or twice-used CIDR.

Efficacy of controlled internal drug release (CIDR) treatment durations on the reproductive performance, hormone profiles, and economic profit of Awassi ewes

This study was conducted using 80 multiparous Awassi ewes during the breeding season to compare the effects of controlled internal drug release (CIDR) treatment durations on ewe reproductive performance, hormone profiles, and economic production measures. Ewes were evenly allotted to one of various CIDR treatment durations (3, 6, 9, or 12 d) in four groups (CIDR3, CIDR6, CIDR9, and CIDR12 (control), respectively). The ewes in all groups were injected with 300 IU of equine Chorionic Gonadotropin (eCG) at the time of withdrawal. Blood samples were collected at the time of CIDR insertion and withdrawal, as well as at the time of insemination to measure serum estradiol (E2) and progesterone (P4) concentrations. Timed insemination was performed at 48 h post CIDR withdrawal. The heat detection rate was significantly (P < 0.05) highest in CIDR12 and CIDR9 (100% and 84.21%, respectively). The total pregnancy rate was significantly (P < 0.05) higher in CIDR9 and CIDR6 (68.4% and 60%, respectively) than in CIDR3. Additionally, fecundity was significantly (P < 0.05) lowest in CIDR3. At insemination, the P4 level was significantly (P < 0.05) lower in CIDR9 and CIDR12 than in the other groups. At insemination, the E2 level was higher (P < 0.05) in CIDR6 followed by that in CIDR3 and CIDR9, and then in CIDR12. The total variable cost, total cost, the return and net profit were higher in CIDR6 than in other groups. In conclusion, although use of CIDR for 6, 9, and 12 d is efficient to synchronize estrus in ewes with similar reproductive performance, CIDR use for 6 d provided higher return and net profit than that for 9 or 12 d. CIDR use for 3 d is inefficient for estrus synchronization in ewes.

23 THE EFFECT OF WITHDRAWAL TIMING OF CONTROLLED INTERNAL DRUG RELEASE (CIDR) ON EWE REPRODUCTIVE PERFORMANCE

This study was carried out using 80 multiparous Awassi ewes during breeding season to compare the effects of controlled internal drug release (CIDR) withdrawal time on ewe fertility. Ewes were equally and randomly allotted into 4 groups (n = 20/group). Ewes had a CIDR inserted for 3, 6, 9, or 12 days with intramuscular administration of 300 IU of equine chorionic gonadotropin (eCG) at withdrawal time. Oestrus was detected using vasectomized ram starting 12 h after CIDR withdrawal and repeated every 12 h up to 84 h. Blood samples were collected from all groups at the time of CIDR withdrawal for measuring of oestradiol (E2) and progesterone (P4) serum concentrations using commercial ELISA kits and micro-titrimetric plates. Timed insemination was performed 48 h post CIDR withdrawal in all groups. Pregnancy was diagnosed by ultrasonography at day 23 post-insemination and confirmed at day 35. Comparisons among groups were evaluated using Chi Square (χ2) test in all measured parameters except hormones levels, which analysed by repeated-measures analysis of variance (ANOVA), using SAS (SAS Institute Inc., Cary, NC, USA). A difference was considered significant at P &lt; 0.05 level. The results revealed that the retention, vaginal discharge and drawstring breakage rates after CIDR removal were insignificantly differed between all groups. On the other hand, pregnancy rate was significantly (P ≤ 0.05) higher in 9-d and 6-d groups (68.4 and 60%, respectively) than the 3-d group. While, no significant difference was detected between 12d group and other groups. The heat detection rate was significantly (P ≤ 0.05) higher in 12d group (100%) than 6-d and 3-d groups (80 and 45%, respectively). While, no significant difference was detected between 12-d and 9-d groups in heat detection rate. P4 was significantly higher in the 12-d group (13.4 ± 3.06 ng mL−1) than other groups. While E2 was significantly lower in the 12-d group (1.6 ± 0.06 pg mL−1) than other groups. These results indicated that withdrawal of CIDR devices after 9 days are efficient in synchronizing oestrus in ewes and provided higher pregnancy rate.

Manipulation of reproductive performance of lactating buffaloes using melatonin and controlled internal drug release device treatment during out-of-breeding season under tropical conditions

Twelve lactating Murrah buffalo, divided into control and treatment group of six animals each, were used to study the effect of melatonin and controlled internal drug release (CIDR) device treatment on the resumption of ovarian activity during out-of-breeding season (summer solstice). Treated group implanted with melatonin (18-mg melatonin/50-kg body weight) for 45 days and then animals of both groups received CIDR for 9 days. All animals received intramuscular 500 IU eCG, at day before CIDR removal, and 10-μg GnRH at day after CIDR withdrawal. All animals were subjected to estrus detection daily. Blood samples in conjunction with transrectal ultrasonography were performed once a week to determine serum concentrations of melatonin, progesterone, and antioxidant enzyme activities, as well as to monitor the ovarian activity. Melatonin treatment resulted in an increase (P < 0.01) in the overall mean superoxide dismutase activity. Melatonin and CIDR increased the diameter of CL (P < 0.01) and plasma progesterone concentration (P < 0.05). In addition, melatonin and CIDR exhibited superior ability to maintain presence of CL at Day 21 and Day 30 after artificial insemination and achieved higher percentage of conception rate than control. In conclusion, the CIDR treatment preceded by melatonin improved the reproductive performance in lactating buffaloes during out-of-breeding season under tropical conditions.

Peripheral Progesterone Level and Times to Estrus and Ovulation in Female Dromedary Camels Treated with CIDR-eCG-hCG Programs

This study was conducted to characterize serum progesterone (P4) profiles during CIDReCG- hCG superovulatory program and to investigate the effect of time of eCG administration on the superovulatory response in dromedary camels. Controlled internal drug release (CIDR) was inserted intravaginally for 14 days in eleven dromedary females. Two days before CIDR withdrawal, group 1 (n=6) received 3000 iu eCG im, group 2 (n=5) received the same dose at CIDR withdrawal. All received 1500 iu hCG two days after CIDR withdrawal (d+2). Animals were observed for estrus and mated with a fertile male. Serum was obtained for progesterone. The ovaries were examined using ultrasound. An increase in serum P4 was observed within 20min of CIDR insertion with peak level attained by 4h (P<0.0001). There were no differences in P4 between group 1 and 2. Estrus and ovulation occurred nonsignificantly earlier in group 1 (4.8±0.9d and 8.2±1d) than in group 2 (6±0.7d and 9±1d), respectively. Number of corpora lutea by d+14 did not differ between group 1 (4.6±0.7) and group 2 (5.2±1.5). In conclusion, early administration of eCG did not hasten estrus or ovulation or the function of the CLs in super-stimulated female dromedaries compared with its administration at the time of CIDR withdrawal. These data may help in designing fixed time superovulation programs in dromedary camels.

The efficacy of controlled internal drug release (CIDR) in synchronizing the follicular wave in dromedary camels (Camelus dromedarius) during the breeding season

The present study aimed to evaluate the efficacy of controlled internal drug release (CIDR) to synchronize the follicular wave in dromedary camels (Camelus dromedarius) during the breeding season through ovarian monitoring, evaluating sexual receptivity, and measuring progesterone (P4) and estradiol (E2) levels during and after CIDR treatment. Sixteen camels received a new CIDR containing 1.9 g of P4 for 14 days. Ultrasound ovarian monitoring was performed on the day of insertion and every 3 days until the CIDR was withdrawn. Ultrasound examinations were continued day in day out after the CIDR was withdrawn for 10 days. According to the ultrasound examinations, the percentages of camels in the breeding (follicles: 12–18 mm) and nonbreeding phases were calculated. Blood samples were collected day after day during the experimental period (24 days) from the day that the CIDR was inserted. The serum P4 and E2 concentrations were analyzed using ELISA kits. The sexual receptivity of the camels was tested daily during the course of the experiment. The results revealed that 2 and 4 days after the CIDR was withdrawn, the percentage of camels in the breeding phase (68.75% and 75.00%, respectively) was significantly (P < 0.05) higher than that in the nonbreeding phase (31.25% and 25.00%, respectively). The percentage of camels that were abstinent during CIDR treatment was significantly (P < 0.05) higher than that observed for those who were incompletely receptive or completely receptive. The P4 levels increased significantly (P < 0.05) 2 days after CIDR insertion (1.73 ng/mL) and reached maximum values (2.94 ng/mL) at Day 12. Significant (P < 0.05) decreases in the P4 levels were observed 2 to 4 days after CIDR withdrawal (1.01 and 0.80 ng/mL, respectively). The P4 levels reached minimum values (0.18–0.22 ng/mL) at Day 20 through the end of the experiment. The E2 levels differed insignificantly during and after CIDR treatment in dromedary camels. In conclusion, the treatment of dromedary camels with CIDR produced a uniform increase in serum concentrations of P4 that could completely prevent sexual receptivity but could not suppress the follicular wave. After CIDR withdrawal, the P4 levels fell and induced the emergence of a new follicular wave, and most of the camels were in the breeding (ovulatory) phase 2 to 4 days after withdrawal. Therefore, CIDR can be used to synchronize the follicular wave in dromedary camels.

Relationships among Feed Intake, Blood Metabolites, Follicle Size and Progesterone Concentration in Ewes Exhibiting or Not Exhibiting Estrus after Estrous Synchronization in the Tropics

Abstract The aim of this study was to determine the relationships among feed intake, blood metabolites, follicle size, and progesterone (P 4 ) concentration in ewes that did or did not exhibit estrus after estrous synchronization. Sixteen cycling, Merino ewes were synchronized for 12 days with a controlled internal drug release (CIDR) devices (300 mg P 4 ). Ewes were classified by estrous behavior as exhibited estrus (n=12) or did not exhibit estrus (n=4). Blood samples were collected at 0, 24, 48, and 72 h after CIDR removal to measure glucose, blood urea nitrogen (BUN), and P 4 concentrations. Follicular size was examined by transrectal ultrasonography on the day of CIDR removal. Ewes exhibiting estrus had greater concentrations of glucose at 24 and 48 h after CIDR withdrawal than ewes that did not exhibit estrus. Ewes exhibiting estrus had decreased concentrations of P 4 at 24 and 48 h after CIDR withdrawal compared with ewes that did not exhibit estrus. At the time of CIDR withdrawal, the diameter of largest follicle was observed greater in ewes exhibiting estrus than that in ewes not exhibiting estrus. By 48 h after CIDR removal, 91.7% of ewes that displayed estrous behavior had exhibited estrus. In all ewes, a significant positive relationship was observed between feed intake and glucose concentration. Follicle diameter was positively correlated with glucose and P 4 concentrations but was negatively correlated with time to onset of estrus in ewes exhibiting estrus. No relationship was detected between BUN and other parameters in all ewes. In conclusion, increased estrous activity in ewes synchronized to estrus may result from increased size of follicle, low P 4 levels, and sufficient production of glucose during the follicular development. Thus, these data highlight the importance of follicle diameter, glucose concentration, and time to onset of estrus in ewes exhibiting estrus under tropical conditions.

Comparison of 4-day vs 5-day controlled internal drug release (CIDR) + timed artificial insemination protocols in dairy heifers

Previous studies have demonstrated that during the application of a 5-day CIDR + Timed Artificial Insemination (TAI) protocol in dairy heifers, the initial GnRH at CIDR insertion and the second PGF2a 12h after CIDR removal are not essential to optimize pregnancy at TAI (P/TAI; J.Dairy Sci 2011 94:4997- 5004). A major factor limiting the development of these programs in dairy farms is to overlook the importance of applying the hormonal injections at the correct day and time according to the specific protocol. This situation becomes more critical when trying to avoid cattle management practices during weekends. The establishment of a 4-day CIDR+TAI protocol performed on a Monday-Friday schedule would simplify the routine reproductive management of heifers in dairy farms, since it would facilitate treatment administration (Monday: CIDR insertion; Friday: CIDR withdrawal+PGF2a; next Monday: GnRH+TAI). Moreover, in contrast to the 4-day CIDR protocol, both the 5-day and 7-day CIDR programs require handling of animals on three different days of the week. In a recent pilot study heifers treated with a 4-day CIDR+TAI protocol showed an optimal P/TAI (66.7%, 10/15) similar to that observed in the of 5-day CIDR+TAI protocol (46.7%, 7/15) or AI after PGF2a injection and heat detection (46.7%, 7/15). However; despite the numerical differences, in that study the sample size was not sufficient to show statistical differences among groups. The objective of this study was to evaluate the P/TAI in dairy heifers treated with a Monday-Friday 4-day CIDR+TAI protocol compared to that of heifers treated with a 5-day CIDR+TAI protocol.

Effectiveness of melatonin and controlled internal drug release device treatment on reproductive performance of buffalo heifers during out-of-breeding season under tropical conditions

Sixteen Murrah buffalo heifers, divided into control and treatment groups of eight animals each, were used to study the effect of melatonin and controlled internal drug release (CIDR) device treatment on the resumption of ovarian activity during out-of-breeding season (summer solstice). Treated group was implanted with melatonin (18 mg of melatonin per 50 kg of body weight) for 45 days and then heifers of both groups received CIDR for 9 days. All heifers received intramuscular 500 IU eCG on the day before CIDR removal and 10 μg GnRH on the day after CIDR withdrawal. All animals were subjected to estrus detection daily. Blood sampling in conjunction with transrectal ultrasonography were performed twice weekly to determine serum concentrations of melatonin, progesterone, LH, and antioxidant enzyme activities, as well as to monitor the ovarian follicular activity. Melatonin treatment resulted in an increase (P < 0.01) in serum melatonin and a decrease (P < 0.01) in serum progesterone and LH. In addition, melatonin had no significant effect on the frequency of LH pulses. Furthermore, melatonin treatment increased (P < 0.01) the diameter of the largest follicle and the number of large follicles between Days 0 and 35 of melatonin treatment. However, melatonin exhibited superior ability to maintain CL at 21 days after artificial insemenation (AI) and increased the percentage of conception to threefold higher than control. In conclusion, melatonin implantation successfully improved the diameter of largest follicles and the ability to maintain CL at 21 days after AI in buffalo heifers during out-of-breeding season under tropical conditions.

The Effect of Reduced Dose and Number of Treatments of FSH on Superovulatory Response in CIDR-Treated Korean Native Cows

The objective of this study was to investigate the effect of dosage and number of days of follicle stimulating hormone (FSH) treatment on superovulatory response in controlled internal drug release (CIDR)-treated Korean native cows. Forty cows underwent two superovulatory treatments with a crossover design. Cows, at random stages of the estrous cycle, received a CIDR together with injections of 1 mg estradiol benzoate and 50 mg progesterone, and gonadotropin treatment began 4 days later. The cows were divided into 2 groups based on the dosage and number of days of treatment with porcine FSH; a total of 28 mg FSH was given in twice daily intramascular injections in decreasing doses over 4 days (5, 5, 4, 4, 3, 3, 2 and 2 mg; T1 group, n=20) or a total of 24 mg FSH was given in twice daily decreasing doses over 3 days (5, 5, 4, 4, 3 and 3 mg; T2 group, n=20). This was followed by the alternate treatment in the subsequent superovulation. The cows were treated identically in all other respects. PGF(2alpha) (25 mg and 15 mg) was given with the 5th and 6th injections of FSH, CIDR were withdrawn at the 6th FSH injection and the cows received 200 microg GnRH 36 h after CIDR withdrawal. The cows were artificially inseminated twice, at 48 and 60 h after CIDR withdrawal, using commercial semen from four Korean native bulls, and embryos were recovered 6 or 7 days after the 2nd insemination. The numbers of corpora lutea (CL; 7.9+/-1.0 vs. 8.3+/-1.1) and large follicles (1.2+/-0.2 vs. 1.3+/-0.3) present at the time embryo recovery, as detected by ultrasonography, did not differ between the T1 and T2 groups (P>0.05). Similarly, the numbers of total ova/embryos (6.2+/-0.9 vs. 6.4+/-1.1), transferable embryos (3.4+/-0.8 vs. 3.2+/-0.7), degenerate embryos (0.8+/-0.2 vs. 1.0+/-0.3) and unfertilized ova (2.1+/-0.5 vs. 2.2+/-0.5) did not differ between the groups (P>0.05). These data indicate that a reduced dose (24 vs. 28 mg) and number of treatments (6 vs. 8) of FSH for superovulation of CIDR-treated Korean native cows does not affect the embryo yield.

Oestrus Induction, Plasma Steroid Hormone Profiles and Fertility Response after CIDR and eCG Treatment in Acyclic Sahiwal Cows

The study was conducted on 30 true acyclic Sahiwal cows (15 cows, ≥90 days postpartum; 15 postpubertal heifers, ≥30 months of age) and a similar 20 untreated controls (10 cows, 10 heifers). An 'Eazi' breed Controlled Internal Drug Release (CIDR) device (containing 1.38 g progesterone) was inserted intravaginally for 7 days (days 0 to 7) followed by 500 IU eCG i.m. at CIDR removal in all the treated animals. Heifers also received 5 mg oestradiol valerate i.m at CIDR insertion. The reproductive performance of these animals was recorded in terms of oestrus induction response, conception and pregnancy rates. Plasma progesterone (P4) and oestradiol-17β (E2) profiles of 4 representative animals from each treatment group before, during and after CIDR treatment were also monitored. An oestrus induction response of 100% was observed in treated cows and heifers. The majority of cows (53.3%) and heifers (60%) were induced to oestrus within 24-36 and 36-48 h, respectively after CIDR withdrawal; with mean intervals of 44±3.18 and 48±2.35 h, respectively. The conception rate at induced oestrus was higher in cows (40%) than heifers (20%). The final pregnancy rates after 2 subsequent oestruses were 80 and 60% in cows and heifers, respectively (overall 70% for all treated animals). In comparison, only 10% of control animals (2 cows only, 2/20) showed oestrus and become pregnant (10%) during theentire study period. The pretreatment (day 0) mean plasma P4 levels were statistically (p>0.05) similar in cows and heifers (0.40±0.04 and 0.49±0.11 ng/ml, respectively). The peak P4 levels were observed on day 1 in cows (13.94±1.41 ng/ml) and day 2 in heifers (19.15±3.30 ng/ml) with a progressive decline up to the day of CIDR withdrawal (3.35±0.92 and 8.79±1.71 ng/ml, respectively). Mean P4 levels on day 9 and 10 in cows and heifers did not differ significantly from their respective day 0 values and the lowest values were recorded on day 10 both in cows and heifers (0.13±0.03 and 0.14±0.02 ng/ml, respectively). Wide variations in individual pretreatment E2 levels were observed both in the cows (range = 4-26, mean = 13.00±4.65 pg/ml) and heifers (range = 10-14, mean = 11.50±0.96 pg/ml). Thereafter also, E2 levels in cows showed variation and reached a peak level (53.50±2.99 pg/ml) on day 8. In heifers, peak mean E2 level (111.25±39.81 pg/ml) was recorded on day 1, followed by a non-significant decline on day 2, a significant fall on day 6 and a non-significant increase on day 9 and 10. However, mean E2 levels on days 7 (p<0.05), 8 and 9 (p<0.01) were significantly higher in cows compared to heifers. The post-CIDR withdrawal mean highest P4 and lowest E2 levels coincided with the period when the majority of animals were induced to oestrus. CIDR and eCG treatment resulted in effective induction of oestrus with satisfactory pregnancy rates in true acyclic Sahiwal

Successful pregnancies with directional freezing of large volume buck semen

Artificial insemination with frozen-thawed buck semen shows variable results which depend on many factors related to semen quality and the cryopreservation processing. We conducted experiments based on a new freezing method, directional freezing, of large volumes (8 ml). In the first experiment semen from three Saanen bucks, ages 1–2-years-old and genetically selected for milk improvement, was frozen individually. Two to three-years-old Saanen females ( n = 164) were synchronized with controlled internal drug release (CIDR), pregnant mare serum gonadotrophin (PMSG) and prostaglandin. Double cervical inseminations were performed with frozen-thawed semen and fresh semen as control. In the second experiment we used pooled, washed frozen semen to examine the effect of washed seminal plasma. The motility after washing was 80–90% and after thawing was 55–65% for all bucks. The sperm concentration increased with the collections and the advance into the breeding season from 1.9 × 10 9 to 4.4 × 10 9 cell/ml average. Two inseminations were carried out at 8 h intervals. The first insemination was performed at 32 h after CIDR withdrawal with fresh and frozen-thawed semen. Pregnancy rates were assessed by ultrasonography conducted 40 and 90 days post-insemination (from three bucks). Results were 58, 67, 50% with fresh semen, and for frozen semen were 33, 37 and 53%; these results were significantly different in one of the three bucks ( P < 0.005). In the second experiment with pooled, washed semen the pregnancy rate was 41.6%, which compared with the average results of the frozen semen in the first experiment 38.9% no significant difference was found. We conclude that freezing buck semen in large volumes (8 ml) is possible. Cryobanking of buck semen will facilitate a genetic breeding program in goats and preservation of biodiversity. Washed semen did not improve the fertility of the semen when Andromed bull extender is used.