Internal Drug Release Device Research Articles

Estrus syncrhonization in ewes with prostaglandins at dif-ferent days post CIDR insertion

Objective: To evaluate the effect of prostaglandin F2α (PGF2α) application on days 0, 3 and 6 of the synchronized luteal phases on reproductive perfomance and its effect on progesterone concentrations of multiparous ewes. Design/methodology/approach: The experimental design was a completely randomized. Seventy-five ewes synchronized with control internal drug release devices (CIDR) for six days and 250 UI of equine chorionic gonadotropin (eCG) were used at device removal. The ewes were randomly distributed in three treatments in relation to the days of application of PGF2α (125 μg sodium cloprostenol): in the first group of ewes, PGF2α was applied at the time of insertion of the CIDR (D0, n=25); in the second group PGF2α was applied on day three of insertion of the CIDR (D3, n=25) and in the third group it was applied on day six, at the time of the withdrawal of the CIDR (D3, n=25). The presentation of estrus and the gestation rate were analyzed through the c2 test. The onset of estrus and prolificacy by a Tukey analysis of variance and comparison of means. The concentration of P4 was carried out using the mixed design procedure, which included fixed effects of treatment and day, and interaction of both. Results: Presentation and onset of estrus were different (P<0.05) between treatments due to the effect of the interval in the days of PGF2α application. The progesterone (P4) concentrations in blood serum showed differences during the synchronized luteal phase (D0: 4.8 ng mL-1; D3: 6.0 ng mL-1, D6: 8.8 ng mL-1). However, no differences were found in gestation rate and prolificacy due to the main effects. Limitations on study/implications: The application of 125 µg of PGF2α on different days of the synchronized luteal phase does not affect gestation rate and prolificacy. Nevertheless, presentation and onset of estrus were different, so it must be considered in laparoscopic artificial insemination programs. Findings/conclusions: The application of PGF2α during the synchronized luteal phase at short intervals showed better results at the end of treatment. The corpus luteum (CL) and CIDR increase P4 concentrations; which modifies the estrus response, and it has a positive effect in reproductive performance.

Conception Rate in Dairy Cows Receiving a First or Repeatedly Used Controlled Internal Drug Release Devices in Timed Artificial Insemination Protocol

Controlled internal drug release (CIDR) devices for releasing progesterone have been used for reproductive management in dairy cattle. In order to minimize the cost, the devices can be reused upon disinfection after being used for 7-8 days. Therefore, the aim of this research is to compare the conception rate of dairy cows after the first, second, and third-use of CIDR devices timed following artificial insemination (TAI) protocol. A total of 783 cows receiving short-term hormonal protocol (9.5 days) by inserting CIDR for 7 day. At the initiation of the TAI protocol, cows were randomly assigned into three groups, (1st CIDR; n = 312), (2nd CIDR; n = 233), and (3rd CIDR; n = 238). Moreover, in each CIDR group, cows were subdivided into two types (primiparous and multiparous cows). Cows in all groups were inseminated on day 9.5 of the TAI protocol. Diagnosis of pregnancy was performed using ultrasound on days 30 and 60 after insemination. From the results, the 1st, 2nd and 3rd used CIDR devices did not significantly change the conception rates on days 30 (28.8% vs. 25.3% vs. 28.2%, respectively) and 60 (26.9% vs. 24.5% vs. 27.7%, respectively) post-TAI in dairy cows (P > 0.05). The embryonic loss did not differ among cows receiving the 1st, 2nd and 3rd used CIDR devices (6.7% vs. 3.4% vs. 1.5%, respectively) (P > 0.05). For each CIDR group, parity (primiparous and multiparous) did not alter conception rates on days 30 and 60 post-TAI and embryonic loss in dairy cows (P > 0.05). Our findings indicate that the CIDR device could be used for at least three times in the TAI protocol in primiparous and multiparous dairy cows.

Vaginal cytology during the estrous cycle and early pregnancy of ewes

Changes in vaginal epithelial cells and blood progesterone and estrogen concentrations were compared between estrous cycle and early pregnancy in multiparous Sanjabee ewes. Twenty non-pregnant ewes were synchronized with intravaginal insertion of a controlled internal drug release (CIDR) device which was in place for 7 days, intramuscular administration of a GnRH analog (Alarelin acetate; 12.5 µg) at the time of CIDR insertion (Day -7), a PGF2α analog (D-cloprostenol sodium; 125 µg) and 500 I.U. of human chorionic gonadotropin (hCG) at the time of CIDR removal (Day 0). At Day 0, all ewes were introduced to four fertile rams and observed for estrous signs. Ewes exhibiting estrous signs were divided into two groups: MATED (confirmed pregnant with transrectal ultrasound scanning at Day 35) and NOT-MATED (confirmed non-pregnant with transrectal ultrasound scanning at Day 35). Vaginal smears and blood samples were taken daily and every other day, respectively, from the beginning of estrus for 20 days for cytology and hormone assay. Based on the results, during days 0 and 1 of the estrous cycle, only the percentages of intermediate cells differed between the groups (P < 0.05). During days 2 to 4, there was no difference in the cell populations between the groups (P ≥ 0.05). During days 5 to 16, the percentages of all cell types except the parabasal cells differed between the groups (P < 0.05). During days 17 to 20, the percentages of all types of vaginal epithelial cells differed between the groups (P < 0.05). Progesterone concentrations increased gradually from days 0 to 14 of the estrous cycle in both groups, however, they decreased significantly afterward in the NOT-MATED group. Estrogen concentrations changes showed an opposite pattern to that of progesterone in the study groups. Collectively, vaginal cytology can be used as a useful tool in assessing hormonal and physiological characteristics of the female reproductive system and thus provides a more accurate understanding of the physiology of estrous cycle and early pregnancy in ewes, which can be used to improve reproductive management.

389 Impact of a Controlled Internal Drug Release device on circulating and local concentrations of progesterone

Abstract Controlled Internal Drug Release (CIDR) devices have become an important component of reproductive management programs in many beef herds. When a CIDR is inserted into a cow, circulating concentrations of progesterone mimic a functional corpus luteum. Some data, however, suggest that concentration of progesterone following insertion of a CIDR might have negative consequences on fertility in Bos indicus animals. Therefore, the objective of this study was to determine the impact of a CIDR device on circulating and uterine tissue concentrations of progesterone. A blood sample and a uterine biopsy were collected from non-suckled postpartum cycling Brahman cows (n = 10; Cycling) during the midluteal stage. A blood sample and a uterine biopsy were also collected from non-suckled postpartum cycling Brahman cows (n = 9; CIDR) after a CIDR had been in place for 5 d. To collect uterine biopsies from CIDR cows, the uterine biopsy tool was placed inside a plastic covering, both were passed into the cervix of the cow before the tool was extended through the covering and into the uterus. After the biopsy was collected, the tool was carefully removed to prevent sample contamination. Blood samples were centrifuged, and serum was collected to determine concentrations of progesterone. Uterine biopsies were snap frozen until extraction. Biopsies were weighted, thawed, and homogenized in assay buffer. Samples were then extracted with methyl tert-butyl ether and resuspended in assay buffer. Serum concentrations are reported as ng/mL and uterine concentrations are reported as ng/g. Statistical analysis was performed using the GLM procedure in SAS with treatment (CIDR vs Cycling), tissue type (uterine vs serum) and their interaction included in the model. There was a significant effect of treatment (P = 0.0062), tissue (P = 0.0063) and a treatment by tissue interaction (P = 0.0068). Animals with a CIDR had greater concentrations of progesterone than Cycling animals (274.77 vs 4.37 ng, respectively). Uterine samples had greater concentrations of progesterone than serum samples (274.40 vs 4.74 ng, respectively). These increased concentrations of progesterone were mainly from CIDR uterine samples (543.24 ng/g) which had greater (P < 0.001) concentrations of progesterone compared with all other samples, which did not differ from each other (P > 0.98; CIDR Serum 6.29 ng/mL, Cycling Serum 3.2 ng/mL, and Cycling Uterus 5.54 ng/g). In summary, CIDRs increased circulating concentrations of progesterone sufficient to keep animals from exhibiting estrus, and were not different from cows in the midluteal stage of their cycle. Local concentrations in uterine tissue; however, were significantly greater when a CIDR was in place compared with uterine tissue collected during the midluteal phase. The implications of these significantly greater concentrations of progesterone in uterine tissue warrant further investigation.

242 Comparison of GnRH administration day in the 7&7 Synch versus 8&6 Synch Protocol for fixed-timed artificial insemination in beef heifers

Abstract The research aimed to investigate the impact of reducing the time interval for progesterone exposure on the ovulatory follicle just before performing fixed-timed artificial insemination (FTAI). This was achieved by adjusting the timing of administering a gonadotropin-releasing hormone agonist (GnRH; specifically, 100 µg gonadorelin, known as Cystorelin). The study assessed the effectiveness of two estrous synchronization protocols, the “7 & 7 Synch” and a modified protocol, by examining estrus expression (EE) and the resulting pregnancy rates (PR) following FTAI. The research utilized frozen conventional Angus semen from Select Sires, Inc. (Plain City, OH), and involved 66 Angus-cross heifers from the beef cattle research unit near Fayetteville at the University of Arkansas. To ensure consistency, the heifers were divided into two treatment groups based on their cyclicity status (CYC) and age. CYC status was determined by assessing a reproductive tract score (RTS) 1 wk before the synchronization process. RTS scores ranged from 1 to 5, with RTS 1-3 indicating pre- or peripubertal status and scores of 4 and 5 indicating cycling. Heifers with an RTS of 1 and 2 were excluded from the study before synchronization commenced. Both treatment groups involved the insertion of a controlled internal drug-releasing device (CIDR; specifically, Eazi-breed, containing 1.38 g of progesterone) into the vagina on d -14. Simultaneously, a prostaglandin F2α analogue (PGF; 500 µg cloprostenol sodium, known as Synchsure) was administered. In the first treatment group (7&7), GnRH was administered on d -7, while in the second group (8&6), GnRH was given on d -6. In both cases, PGF was administered on d 0 when the CIDR was removed, precisely 72 ± 1 h before FTAI, along with another dose of GnRH. Estrus expression (EE) was assessed during FTAI by examining Estrotect patches (Rockway Inc., Spring Valley, WI). EE was considered present when a patch had 50% or more of its color rubbed off, and it was deemed absent when less than 50% of the color had worn off. Pregnancy rates (PR) were determined through ultrasound examination on d 55. EE and PR were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC). Statistical differences were declared at α ≤ 0.05 and tendencies declared between 0.05 < P ≤ 0.1. Heifers on the 8&6-d protocol had greater rectal temperatures at breeding compared with 7&7-d heifers (P < 0.0001). AI pregnancy rates were greater in heifers on the 8&6-d protocol compared with the heifers on 7&7-d protocol (P = 0.625) with average pregnancy rates of 39.4% and 30.3%, respectively. Overall, pregnancy rate was greater as well for the 8&6-d heifers compared with the 7&7-d heifers (P = 0.044), with mean overall pregnancy rates of 78.8% and 54.5%, respectively.

52 Evaluation of linseed meal on ovarian follicular development after synchronization in preovulatory small ruminants during seasonal anestrus

Abstract Seasonal estrous of small ruminants can hinder overall reproductive efficiency of holistic management strategies involving sheep and goats. The objective of this study was to quantify the effect of increased melatonin containing feed ingredients on ovarian function during seasonal anestrus. Ovarian follicle number and follicle sizes were evaluated on Spanish × Boer cross does and Rambouillet ewes amounts of lineseed meal in the treatment diet (P30DIET) or an isocoloric and isonitrogenous control diet (CON). The P30DIET contained 2.5% linseed meal which contained increased melatonin (Manchester et al. 2000). At d -18 ewes and does were stratified by age into treatment groups and the P30DIET and CON diets were supplemented (0.91 kg and 0.68 kg per animal per day for sheep and goats, respectively). Synchronization protocols were administered at d 0 for both groups and ovarian ultrasound measures were collected 48 h after the removal of the controlled internal drug release device (CIDR). Mixed model procedures of SAS were used to analyze the number of dominant follicles that were present following the synchronization protocols. The number of dominant follicles observed in the P30DIET goats was significantly greater than the CON consuming goats (P < 0.05). Least Squares Means estimates (LSMEANS) in the P30DIET were 1.5 ± 0.20 as compared with CON goats (0.91 ± .21). These data suggest that flushing small ruminants with greater linseed meal during the seasonal anestrus period can increase the number of dominant follicles therefore implying an improvement in reproductive efficiency in holistic management strategies of small ruminants.

Differing planes of nutrition alter serum and histotroph amino acid composition in nonpregnant, multiparous beef cows on day 3 of the estrous cycle.

Endometrial-derived uterine histotroph is a critical component of nutrient supply to a growing conceptus throughout gestation; however, the effect of nutritional plane on histotroph nutrient composition remains unknown in multiparous cows. We hypothesized that differing planes of nutrition would alter histotroph and serum nutrient composition in beef cattle. Thus, we evaluated serum and histotroph amino acid and glucose composition, and serum non-esterified fatty acids (NEFA) and blood urea nitrogen (BUN) in cows individually fed to maintain body weight (BW; 0 kd/d, n = 9; CON) compared with those losing moderate BW (-0.7 kg/d, n = 9; NEG). After 49 d of differing nutritional planes, cows were subjected to the 7-d CoSynch + controlled internal drug release device estrus synchronization protocol and then slaughtered on day 62. Blood serum (days 0 and 62) and uterine histotroph [day 62; from uterine horns ipsilateral and contralateral to the corpus luteum (CL)] were collected and analyzed for concentrations of amino acids, glucose, and NEFA. Performance characteristics, body composition via ultrasound (days 0 and 62), and carcass characteristics were collected. Body condition score, change in BW, average daily gain, dry matter intake, and gain:feed were decreased (P ≤ 0.05) in NEG vs. CON cows. There were no differences in body composition or carcass characteristics, except an increase (P ≤ 0.05) in dressing percentage in NEG cows due to differences in gut fill, consistent with study design. Serum NEFA increased (P ≤ 0.05) in the NEG group, but there were no differences between NEG vs. CON in glucose or BUN. Serum histidine increased (P ≤ 0.05) and alanine, isoleucine, and tryptophan decreased (P ≤ 0.05) in NEG vs. CON cows. Compared with that of the uterine horn ipsilateral to the CL, histotroph from the uterine horn contralateral to the CL had increased (P ≤ 0.05) isoleucine, asparagine, and proline concentrations in NEG cows, and decreased (P ≤ 0.05) tryptophan as a proportion of essential and total amino acids. There were no differences in glucose concentrations of histotroph contralateral or ipsilateral to the CL. Cow nutritional plane does alter serum and histotroph amino acid composition, although the presence of an embryo may be necessary to fully elucidate these changes. Differences in serum and histotroph tryptophan should be given consideration in future studies due to its importance as an essential amino acid in protein synthesis and bioactive affects.

Ovarian dynamics in progesterone tablet-induced superovulation in goats assessed by magnetic resonance imaging.

Controlled internal drug-releasing (CIDR) devices are commonly used for superovulation in goats. However, such devices are unavailable in some countries, including Japan. In this technical note, we aimed to explore the efficacy of an alternative superovulation protocol using progesterone tablets in goats. We employed intravaginal progesterone tablets (LUTINAS® Vaginal Tablet 100 mg) following a standard superovulation protocol. Additionally, we assessed the ovarian dynamics using 3T-magnetic resonance imaging (MRI) 1day preceding the progesterone treatment (Day "-1") and 3days before the end of treatment (Days 11-13). The ovarian monitoring was successfully performed in the short tau inversion recovery T2-weighted images of MRI, and ovulation was confirmed by the disappearance of follicles on Day 13 post-administration of the tablets. Immediately after ovulation, oviduct flushing yielded a substantial number of oocytes (13.5 ± 1.8 oocytes per animal). These findings provide evidence that the administration of progesterone tablets can serve as a viable alternative for inducing. Additionally, our findings suggest that 3T-MRI is a promising alternative to conventional ultrasonography for monitoring ovarian dynamics following superovulation in experimental goats.

Application of bovine progesterone intravaginal controlled-release formulation for estrus synchronization treatment in goats

Progesterone (P<inf>4</inf>)-impregnated controlled internal drug-releasing device for goats and sheep (CIDR-G) is used in the estrus synchronization protocol; however, it is not commercially available in Japan. In this study, we investigated whether a modification of CIDR-B, designed for cattle, could be used as a P<inf>4</inf> release device for synchronizing estrus in goats. An in vitro analysis showed that the dissolution rate was not significantly different between CIDR-G and modified CIDR-B (CIDR-M). The administration of CIDR-G or CIDR-M to dairy goats resulted in plasma P<inf>4</inf> concentrations being maintained at the functional luteal phase levels (>2 ng/ml) in both groups for 12 days after administration. However, P<inf>4</inf> concentrations at 2, 4, and 8 days after the administration of CIDR-G were significantly higher than those after the administration of CIDR-M. These results suggest that the CIDR-M examined in this study can maintain P<inf>4</inf> levels for 12 days after its administration as a P<inf>4</inf> release device.

Relationship between higher estrus-associated temperatures and the bovine preovulatory follicular fluid metabolome

IntroductionA higher estrus-associated temperature (HEAT) is a hallmark feature in sexually active females; however, its functional importance is unclear. Our objective was to examine the relationship between HEAT and the preovulatory follicular fluid metabolome. It was hypothesized that HEAT is functionally important as it affects fertility-related components in the preovulatory follicle.MethodsEstrus was synchronized in non-lactating Jersey cows. A Thermochron iButton temperature data logger was affixed to blank controlled internal drug release (CIDR) devices and intravaginally inserted after CIDR device removal. The follicular fluid was aspirated 14.9 h + 3.3 h after an animal first stood to be mounted. Regression models were performed using metabolite abundance and HEAT variables. Best-fit models were determined using backward manual selection (p &amp;lt; 0.05).ResultsA total of 86 metabolites were identified in cow follicular fluid samples. The vaginal temperature at first mount and when it was expressed as a change from baseline was positively related to the abundance of four metabolites (i.e., taurine, sn-glycerol 3-phosphate, glycine, and cysteine) and negatively related to one metabolite (i.e., serine). The vaginal temperature at the first standing mount was related to the differential abundance of two metabolites (i.e., jasmonate and N-carbamoyl-L-aspartate). Three metabolites were related to the maximum vaginal temperature (i.e., N-carbamoyl-L-aspartate, uracil, and glycodeoxycholate). When expressed as a change from baseline, the maximum vaginal temperature was related to the differential abundances of uracil, uric acid, and 6-phospho-D-gluconate. The time taken to reach maximum vaginal temperature was related to N-carbamoyl-L-aspartate, glycodeoxycholate, jasmonate, and tricarballylic acid. Pertaining to the combination of HEAT and its duration, the area under the curve associated with the time between the first increase in vaginal temperature and the maximum vaginal temperature was related to 6-phospho-D-gluconate, sulfolactate, guanidoacetic acid, and aspartate. The area under the curve associated with the time between the initial vaginal temperature increase and up to 10 h after a cow first stood to be mounted or when a cow’s temperature returned to baseline was related to the differential abundances of uracil, sn-glycerol 3-phosphate, methionine sulfoxide, and taurodeoxycholate.DiscussionOur findings support the notion that HEAT is related to changes in the preovulatory follicular fluid metabolites involved in energy metabolism, thermoregulation, and oxidative stress management.

291 Impact of Early Resynchronization in Combination with Color Doppler Ultrasonography on Cumulative Pregnancy Rates in Postpartum Beef Cows

Abstract The objective of this study is to evaluate a GnRH and progesterone-based early resynchronization strategy combined with color Doppler ultrasonography for early pregnancy diagnosis. Postpartum Bos taurus beef cows (n = 375) from four locations were enrolled in a completely randomized design, where cows were randomly assigned to 1 of the 2 treatments: 1) Natural Service (NS), cows were exposed to a 7-d CO-Synch + CIDR protocol followed by fixed-time artificial insemination (day 0). On day 15, cows were exposed to natural service for the remainder of the study; or 2) Early Resynchronization (ER), cows were exposed to a 7-d CO-Synch + CIDR protocol followed by fixed-time artificial insemination (day 0). On day 15, a controlled internal drug release (CIDR) device was inserted. On day 20, CIDR was removed, and pregnancy was estimated based on luteal blood perfusion using color Doppler ultrasonography. Non-pregnant cows received a 25-mg injection of prostaglandin F2α at CIDR removal and were fixed-timed-AI concurrently with a 100-μg injection of GnRH 60 to 66 h later. Pregnancy diagnosis and fetal aging were performed on day 53 using conventional ultrasonography. Pregnancy rate to the first AI was greater (P = 0.03) for NS compared with ER (70.25% vs 59.29%, respectively). Pregnancy rates for the second service were also greater (P = 0.01) for NS compared with ER (65.67 vs 42.93%, respectively). Cumulative pregnancy rates to AI did not differ between treatments (P = 0.38); however, cumulative pregnancy rates (first and second service) were greater (P &amp;lt; 0.01) for NS compared with ER (90 vs 77.73%, respectively). In conclusion, the proposed early resynchronization strategy using color Doppler ultrasonography resulted in fewer pregnancies compared with natural service as the second service strategy. Moreover, the proposed ER decreased pregnancy rates to the first insemination, indicating a detrimental effect of ER on pregnancy establishment.

PSIII-7 Effect of Time of Estrus on Conception Rate for a Sexed Semen Artificial Insemination Protocol in Multiparous Beef Cows

Abstract Sexed semen artificial insemination is a breeding technique that allows producers to shorten breeding seasons, optimize genetics through use of superior semen, create calves based on sex preference, and increase profitability. Sexed semen is a technology that sorts semen by differences in DNA content between X (female) and Y (male) bearing sperm. However, sexed semen practices have yet to be widely used in beef cows due to reduced sperm numbers, low conception rates, and increased costs. The objective of this study was to determine the effect of time of estrus upon fixed-time artificial insemination (FTAI) of sex-sorted semen on conception rate using two different estrous synchronization protocols. Multiparous commercial beef cows (n = 73) were randomized by age, body condition score (BCS), and days post-partum at the University of Arkansas Livestock and Forestry Research Station in Batesville. Both synchronization treatments (TRT) used a controlled internal drug releasing device (Eazi-breed CIDR; 1.38g progesterone) inserted intravaginally on d -14 of the protocol simultaneous to administration of prostaglandin F2α (PGF; 500µg cloprostenol sodium; Estrumate). In the first treatment (TRT 1; 7&amp;7 Synch), gonadotropin-releasing hormone (GnRH; 86µg gonadorelin; Fertagyl) was administered on d -7. In the second treatment (TRT 2; 8&amp;6 Synch), GnRH was administered on d -6. Both treatments were then administered PGF simultaneous to CIDR removal on d 0, 66 ± 2h before FTAI and administration of GnRH. Standing heat (estrus) was visually detected every 3 h for 30 min intervals between CIDR removal and FTAI. Heat detection patches were used in conjunction with visual detection of estrus. Time of estrus was signified as time of standing immobile when mounted in combination with presenting a patch score of 4 (&amp;gt;75% color removed). Time of estrus (TD) was deviated from time of FTAI and categorized into three equal time groups (Grp 1 = 0 to 11.0 h; Grp 2 = 11.01 to 22.0 h; and Grp 3 = 22.01 to 33.0 h). Conception rate (CR) was determined via ultrasound 37 ± 2 d after FTAI. Data were analyzed using the GLIMMIX procedure of SAS 9.4. CR did not differ by age of dam (P = 0.58), BCS (P = 0.48), or TRT (P = 0.83). However, TD had an effect on CR (P = 0.002); and resulted in CR of 45% (Grp 1), 87% (Grp 2), and 42% (Grp 3). In conclusion, these results indicate artificially inseminating cows with sexed semen between 11.01 and 22.0 h after time of standing estrus will increase pregnancy rates for multiparous commercial beef cattle.

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.

A single dose of FSH or hCG during a split-time AI program did not enhance follicular growth or pregnancy per artificial insemination in beef heifers

ABSTRACT The objective of this study was to evaluate the effect of a low dose of hCG or FSH on follicle growth and pregnancy per artificial insemination (AI) in crossbreed beef heifers subjected to a split-time AI program. All heifers (n = 386) were subjected to a 7-d Co-synch protocol and an intravaginal controlled internal drug release (CIDR) device (GnRH and CIDR insertion; 7 days later PGF2α, CIDR removal, and application of a tail head estrus detection patch; 36 hours later AI of heifers detected in estrus, 24 hours later timed AI of remaining heifers). At CIDR removal, heifers were randomly assigned to receive either 150 IU of hCG, 20 mg of FSH, or remained as untreated controls. The diameter of the preovulatory follicle and the pregnancy per AI did not differ among treatments. A smaller (P = 0.035) proportion of heifers in the hCG group were detected in estrus compared with control. Additionally, the incidence of premature ovulation was greater (P < 0.01) among heifers treated with hCG compared with control. In conclusion, using a low dosage of hCG or FSH at the time of device removal did not affect pre-ovulatory follicle growth or the proportion of pregnant heifers.

73 Comparison of GnRH Administration day in the 7 &amp; 7 Synch Versus 8 &amp; 6 Synch Protocol for Fixed-Timed Artificial Insemination in Beef Heifers

Abstract The study was conducted to identify effects of a decreased interval of progesterone on the ovulatory follicle before fixed-timed artificial insemination (FTAI) by altering the day of a gonadotropin-releasing hormone agonist (GnRH;00µg gonadorelin; Cystorelin) administration. Evaluation of the 7 &amp; 7 Synch and altered estrous synchronization protocols was done using estrus expression (EE) and FTAI pregnancy rates (PR). Using frozen conventional Angus semen (Select Sires, Inc. Plain City, OH), Angus-cross heifers (n = 68) from the University of Arkansas beef cattle research unit near Fayetteville were stratified into two treatment groups by cyclicity status (CYC) and age. Cyclicity status was determined by using a reproductive tract score (RTS) taken one week prior to beginning synchronization. Scores ranged from 1-5, where RTS 1-3 were considered pre- or peripubertal while scores 4 and 5 were considered cycling. Heifers with a RTS of and 2 were culled prior to synchronization. Each treatment used a controlled internal drug releasing device (CIDR; Eazi-breed; 1.38g progesterone) inserted intravaginally on –14 d simultaneous to the administration of a prostaglandin F2α analogue (PGF; 500 µg cloprostenol sodium; Synchsure). In the first treatment (7 &amp; 7), GnRH was administered on –7 d. In the second treatment (8 &amp; 6), GnRH was administered on –6 d. Both treatments were then administered PGF simultaneous to CIDR removal on 0d, 72 ±h prior to FTAI and the administration of GnRH. Estrus expression was recorded at the time of FTAI using an Estrotect patch (Rockway Inc., Spring Valley, WI). Estrus expression was determined as a patch with 50% or more of the color rubbed off. On the contrary, a patch with less than 50% of the color rubbed off, was not. Pregnancy rates was determined via ultrasound on 58 d. Estrus expression and PR were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC) with CYC as a fixed effect for EE; CYC and EE as fixed effects for PR. Statistical differences were determined with α ≤ 0.05 and tendencies were observed between 0.06-0.1. There was an effect of CYC on EE (P = 0.001) and a tendency to affect PR (P = 0.088). There was no treatment effect on EE (P = 0.892) or PR (P = 0.708). In conclusion, the altered time of GnRH administration in the 7 &amp; 7 synch at 72 ± hours did not affect EE or PR; however, research will continue to investigate adjusting length of time from PGF injection to FTAI to evaluate the effects.

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.

Effect of progesterone infused controlled internal drug releasing (CIDR) device and timing of gonadotropin stimulation using P.G. 600 on reproductive success in ewes bred out of season.

Objectives of this study were to determine effects of exogenous progesterone (via controlled internal drug releasing devices; CIDR) in combination with exogenous gonadotropins (PMSG/hCG) use either at CIDR removal or 1 d before CIDR removal to induce estrus and cyclicity and subsequently enhance the proportion of ewes lambing, lambing rate, prolificacy, and days to lambing in ewes bred out of season. Multiparous ewes (n = 414) were randomly assigned to one of four treatments: untreated (U, n = 122), 7 d CIDR (C, n = 97), 7 d CIDR plus P.G. 600 (240 IU pregnant mare serum gonadotropin [PMSG] and 120 IU human chorionic gonadotropin [hCG]) at CIDR removal (CPG0, n = 97), and 7 d CIDR plus P.G. 600 (240 IU PMSG and 120 IU hCG) 1 d before CIDR removal (CPG-1, n = 98). Rams (n = 15) were joined with ewes immediately after CIDR removal and remained with ewes for a 21 d breeding period. Lambing data were summarized for the first 10 days of the lambing season and overall. Categorical data were analyzed using the GLIMMIX procedure of SAS whereas non-categorical data were analyzed using the mixed procedure. Proportion of ewes lambing in the first 10 d was greater (P < 0.05) for CPG0 and CPG-1 ewes compared with C ewes, which was greater (P < 0.0001) compared with U ewes. Overall proportion of ewes lambing was greater (P ≤ 0.0001) in all treatments utilizing CIDR compared with U ewes, but no differences (P ≥ 0.84) due to P.G. 600 were detected compared with C. Lambing rate in the first 10 d was greater (P < 0.05) for CPG-1 than C, with CPGO being intermediate, and all CIDR-treated ewes being greater than U (P < 0.0001). Overall lambing rate increased (P ≤ 0.0001) in all treatments utilizing CIDR compared with U ewes, but no differences (P ≥ 0.76) due to P.G. 600 were detected compared with C. Prolificacy was similar among all treatments both for the first 10 d of the lambing season (P = 0.86) and overall (P = 0.80). Day of lambing in the lambing season was reduced (P ≤ 0.03) for CPG0 and CPG-1 compared with CIDR-treated ewes, which was reduced (P < 0.0001) compared with U ewes (days 10.6, 9.0, 13.4, and 24.4 ± 0.9 for CPG0, CPG-1, CON, and U, respectively). Though timing of P.G. 600 did not influence results, the combination of CIDR and P.G. 600 enhanced the proportion of lambs born earlier in the lambing season, and incorporating a CIDR with or without P.G. 600 enhanced the overall proportion of ewes lambing and lambing rate in out-of-season breeding scenarios.

Therapeutic Management of Anovulatory Follicle using CIDR Based protocol in a Repeat Breeder Heifer

A Controlled internal drug releasing device (CIDR)- Prostaglandin F2α (PGF2α) based estrus synchronization protocol and post-insemination CIDR application led to successful conception and parturition in a repeat breeder anovulatory heifer.

Effects of additional gonadotropin-releasing hormone and prostaglandin F2α treatment to an estradiol/progesterone-based embryo transfer protocol for recipient lactating dairy cows

This study was designed to evaluate whether the utilization of a second PGF2α treatment at the end of an estradiol/progesterone (E2/P4)-based protocol with or without GnRH at the beginning of the protocol would improve pregnancy rates of lactating Holstein cows assigned to timed embryo transfer. A total of 501 lactating Holstein cows in 5 farms were enrolled in the experiment. Within farm, cows were blocked by parity and, within block, were assigned randomly to (1) insertion of an intravaginal P4 device (controlled internal drug-releasing device; CIDR) and estradiol benzoate on d -11, PGF2α on d -4, CIDR withdrawal and an injection of estradiol cypionate on d -2, and timed embryo transfer on d 7 (1-PGF; n = 164); (2) the same treatments as 1-PGF, but with PGF2α administered on d -4 and -2 (2-PGF; n = 171); and (3) 2-PGF with the addition of a GnRH treatment on d -11 (GnRH+2-PGF; n = 166). Ovaries were scanned by transrectal ultrasonography on d -11, -4, and 7, and blood samples were collected on d -11, -4, 0, and 7 for P4 determination. Treatment comparisons were performed using contrasts. The proportion of cows with a new corpus luteum on d -4 was greater in GnRH+2-PGF cows. Cows in 1-PGF had a greater P4 concentration on d 0 but lesser P4 on d 7 compared with cows in the other groups. Cows assigned to receive 2-PGF (2-PGF and GnRH+2-PGF) had greater estrus expression, and a greater proportion of cows ovulated to estradiol cypionate. No further contrast effects were observed for follicle diameter, double ovulation rate, pregnancy per embryo transfer (P/ET) on d 32 and 60, or pregnancy loss. As P4 concentration on d -4 increased, P/ET on d 60 tended to increase. Cows with P4 ≥3.66 ng/mL on d -4 had greater P/ET on d 32 and 60 than those with P4 below that threshold. Regardless of treatment, cows with P4 concentration ≥3.66 ng/mL also had a greater pregnancy per synchronized protocol (P/SP) on d 60. Also, a P4 concentration on d -4 (low or high) × follicle diameter (continuous) interaction tendency was observed when evaluating P/ET. Although P/ET did not differ among cows with different follicles sizes with reduced P4 concentration on d -4 (<3.66 ng/mL), it increased in cows with larger follicles exposed to increased P4 concentration (≥3.66 ng/mL). When P4 on d 0 was evaluated, P/ET on d 32 and 60 was greater for cows with low (≤0.09 ng/mL) versus high (>0.21 ng/mL) P4; as P4 concentration on d 0 increased, P/ET linearly decreased. In summary, cows with increased P4 concentrations during growth of the ovulatory follicular wave had improved P/ET. Administering a second PGF2α dose reduced P4 concentration on d 0 and increased ovulatory response to the protocol, but no benefits were observed on P/ET or P/SP.

PSIII-5 Evaluation of Gnrh Administration day in the 7 &amp; 7 Synch Protocol for Fixed-Timed Artificial Insemination in Multiparous Beef Cows

Abstract The objective was to determine the effects of a decreased interval of progesterone on the ovulatory follicle prior to fixed-timed artificial insemination (FTAI) in a 7 &amp; 7 Synch estrous synchronization protocol using estrus expression (EE), FTAI pregnancy rates (AIPR) on 37±2d, and overall pregnancy rates (OPR) after a 60d bull exposure 90±2d determined via ultrasound. Using conventional Angus semen, multiparous Angus-cross cows (n=201) from two locations were randomized by age and days post-partum into two treatments. Both treatments used a controlled internal drug releasing device (Eazi-breedTM CIDR; 1.38g progesterone) inserted intravaginally –14d of the protocol simultaneous to administration of prostaglandin F2α (PGF; 500µg cloprostenol sodium; Estrumate®). In the first treatment (7&amp;7), gonadotropin-releasing hormone (GnRH; 86µg gonadorelin; Fertagyl®) was administered on –7d. In the second treatment (8&amp;6), GnRH was administered on –6d. Both treatments were then administered PGF simultaneous to CIDR removal on 0d, 66±2h prior to FTAI and administration of GnRH. EE was determined at the time of artificial insemination using an EstrotectTM patch (Rockway Inc., Spring Valley, WI). EE was signified as a patch with 50% or more of the color rubbed off or missing. Subsequently, a patch with less than 50% of the color rubbed off, was not. AIPR, OPR and EE were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC.). There was a significant effect on EE (P=0.01), a tendency on PR (P=0.08), and no effect on OPR (P=0.53) by treatment. EE, AIPR, and OPR for 7&amp;7 were 95±2.1%, 82±3.7% and 96.7±1.7% and for 8&amp;6 were 86±4.0%, 91±3.1% and 98±1.5%, respectively. In conclusion, the altered timeframe of GnRH administration affected EE and tended to affect PR in multiparous beef cows, suggesting that GnRH administration may improve PR when administered 6d, instead of 7d, prior to CIDR removal.