Controlled Internal Drug Release Research Articles

Reproductive Performance of Ongole Grade, Simmental, and Limousin Cattle Given Superovulation Treatment

Reproductive technologies have the potential to enhance livestock productivity, with superovulation being one such method aimed at increasing the number of ovulated oocytes per estrous cycle through hormonal stimulation. This study aimed to evaluate the reproductive performance of three cattle breeds—Ongole Grade (OG) (n=20), Simmental (n=18), and Limousin (n=20)—subjected to superovulation treatment. The cattle, aged 2.5 to 4 years with a body condition score of 3.5 to 4, were intensively managed. Superovulation was induced using CIDR (Controlled Internal Drug Release) for synchronization, followed by follicle-stimulating hormone (FSH) administration. Reproductive performance data, including age at first estrus, number of corpora lutea (CL), and embryo production, were collected over three estrous cycles. A quasi-experimental design was employed with breed as the primary treatment factor, and data were analyzed using analysis of variance (ANOVA). The results indicated that breed had a significant effect (P0.05) on the age of first estrus, with OG cattle reaching first estrus at 621.3±93.3 days, Simmental at 522.4±75.5 days, and Limousin at 570.4±88.1 days. However, no significant differences (P0.05) were observed among the breeds in terms of the number of CL, collected embryos, or transferable embryos across the superovulation cycles.

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.

100 Impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to embryo transfer

Abstract This study aimed to evaluate the impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to fixed-timed embryo transfer (FTET). Postpartum beef cows (n = 763) from 22 locations were exposed to a 7-d Select Synch + controlled internal drug releasing (CIDR) and breeding indicator patches were affixed upon CIDR removal. Estrus expression was assessed twice daily for 72 h and a 100-µg injection of gonadotropin-releasing hormone was administered to cows that failed to express estrus 72 h after CIDR removal. Brightness mode ultrasonography of the corpus luteum (CL) was conducted to select recipients for FTET 9 d after CIDR removal. Suitable recipients were assigned to receive a single fresh or frozen embryo derived from either in vitro (IVF) or in vivo (IVD) method. After embryo recipient selection, CL morphometries and blood perfusion (BP) were then assessed at the time of embryo transfer via transrectal ultrasonography. Embryo recipients were categorized according to CL area [small (< 3 cm²), medium (3 to 4 cm²), or large (> 4 cm²)] and based on the percentage of luteal area with blood perfusion signals [low (< 25%), medium (25 to 45%), or high (> 45%)]. Pregnancy diagnoses were performed between d 60 and 90 of gestation. Cows that failed to express estrus prior FTET had decreased (P ≤ 0.02) luteal area, luteal diameter, and pregnancy rates compared with cows that expressed estrus. Luteal area category had no effect (P = 0.61) on pregnancy rates. Embryo recipients that expressed estrus had similar (P = 0.12) luteal blood perfusion compared with recipients that failed to express estrus. Embryo recipients with high (P = 0.02) and medium (P = 0.05) BP had greater pregnancy rates compared with embryo recipients with low BP. There was no interaction between estrus expression and luteal BP (P = 0.84). In summary, estrus expression and luteal BP positively impacted pregnancy rates to embryo transfer and may be used to facilitate embryo recipient selection.

Study on the Technology of Laparoscopic Ovum Pick-Up and In Vitro Embryo Production in Chongming Goats.

The application of laparoscopic ovum pick-up (LOPU) and in vitro production of embryos (IVEP) technologies has opened up a new path for purebred breeding and breed improvement in goats. However, due to the complexity of the procedures and multiple influencing factors, these technologies have not been widely adopted in goat production. This study explores factors affecting the efficiency of LOPU in goats by comparing the use of controlled internal drug release (CIDR) for estrus synchronization, conventional FSH versus long-acting recombinant ovine FSH (R-FSH) for superovulation, and the timing of LOPU at 48 h, 60 h, and 72 h of follicular development. The metrics evaluated included the recovery rate of cumulus-oocyte complexes (COCs), the average number of ovarian follicles, the average number of COCs, and the average number of available COCs. The results demonstrated that the efficiency of LOPU was significantly higher with two doses of R-FSH compared to the conventional FSH superovulation protocol and the control group (p < 0.05), with two doses of R-FSH providing a higher LOPU efficiency than one dose (p < 0.05). Using CIDR for estrus synchronization showed no significant difference in LOPU efficiency compared to the non-CIDR group. Similarly, the efficiency of LOPU showed no significant difference between the hormone treatments at 48 h, 60 h, and 72 h. By exploring and optimizing the factors influencing LOPU, we ultimately established a LOPU technology system for goats that meets the production needs of small ruminants.

The effectiveness of different hormone protocols for improving ovarian function before ovum pick-up in crossbred Japanese black cattle.

Producing and transferring embryos in vitro are profitable for enhancing premium beef genetics. Reducing costs and enhancing the effectiveness of hormone protocols before ovum pick-up (OPU) yield advantages. This study aimed to confirm that estradiol benzoate (EB) treatment resulted in more medium- and large-sized follicles before OPU and of higher oocyte quality after OPU than non-hormonal treatments, comparable to those undergoing gonadotropin-releasing hormone (GnRH) with follicle-stimulating hormone (FSH) plus prostaglandin F2α (PGF2α) and progesterone-releasing controlled internal drug release (CIDR) or EB with progesterone-releasing CIDR hormonal treatments. 30 crossbred Japanese black cows were divided into five equal groups, which were either untreated or treated with different hormone protocols before OPU. Group 1 (cows in estrus) and group 2 (cows in diestrus) were the untreated controls. Cows in group 3 were treated with GnRH + FSH + CIDR + PGF2α. Cows in group 4 received EB, and those in group 5 received EB + CIDR + PGF2α. After administering the protocols, all cow follicles were examined through ultrasonography and categorized by size. Subsequently, all cows underwent OPU, and the oocytes were collected and graded from A to D according to standard criteria. Group 3 presented the highest large follicle numbers, and groups 3-5 had more medium follicle numbers, not different among groups but they had this parameter more than those of control groups 1 and 2. Moreover, groups 3-5 did not differ in combined grades A + B oocytes (good-quality oocytes). Groups 3 and 4 had more A + B oocytes than control groups 1 and 2, whereas group 5 was not different in this parameter from group 1. Among the three hormone protocols, EB treatment proved the most cost-effective and efficient, yielding more high-quality oocytes compared to the non-treatment protocols. To reduce the limitations of EB use in the future, this study suggests researching natural EB phytoestrogens as alternative treatments for improving ovarian function before OPU in other cattle breeds.

Effect of the feeding condition and number of dominant follicles on oestrus synchronization in Swamp buffalo

The research aimed to assess how feeding conditions and the number of the dominant follicles (DF) influence oestrus synchronization in swamp buffaloes. A total of 170 swamp female buffaloes raised in semi-grazing and housekeeping were included in the study. The synchronization used CIDR method and the follicles on the day of CIDR (Controlled Internal Drug Releasing) insert and removal were tracked by sonography. The results indicated that the age of first mating, age at first calving, and caving interval showed no significant differences in the two feeding conditions. The number of follicles at CIDR insertion and removal decreased in semi-grazing, but increased in housekeeping buffaloes. The percentage of buffalo without DF, one DF, and two DFs at CIDR withdrawal did not differ statistically. The percentage of estrus was 100% in both groups. Pregnancy rates were 53.18% in semi- grazing and 52.63% in housekeeping. The onset of oestrus was similar, but the duration of oestrus was longer in the buffaloes without DF than those with one or two DFs. The percentage of pregnant buffaloes in the group without DF was significantly lower than that in the other two groups. In summary, the efficiency of oestrus synchronization did not differ between semi-grazing and housekeeping methods. Buffaloes without DF displayed longer oestrus periods and lower pregnancy rates compared to those with one or two DFs in the ovarian system.

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.

Magnitude and persistence of higher estrus-associated temperatures in beef heifers and suckled cows.

Higher estrus-associated temperatures (HEAT) are a hallmark feature in sexually active females. The overarching aim of this study was to characterize the variability, magnitude, and persistence of HEAT in heifers and suckled beef cows as well as identify associated factors when occurring during thermoneutral conditions at the onset of the spring breeding season. In both heifers and cows, estrus was induced using a 7-d controlled internal drug release (CIDR)-PGF2α protocol. Vaginal temperature after prostaglandin F2α administration was recorded every 5min using a Thermochron iButton affixed to a blank CIDR (containing no progesterone). Estrus was defined as when a heifer first stood to be mounted or when a cow had an Estrotect patch score of 3 or 4. Level of HEAT varied among individual animals. When comparing common HEAT variables using a mixed model with date nested within a year, maximum HEAT (39.9 ± 0.1 and 40.0 ± 0.1 °C) and duration (15.5 ± 0.8 and 15.4 ± 0.7) were similar in heifers and cows, respectively. However, the magnitude and persistence of HEAT differed. Total area under the HEAT curve was 117.1 ± 13.5 and 158.7 ± 12.3 for heifers vs cows, respectively (P = 0.0571). Further, 42.9% of heifers and 49% of cows had maximum HEAT ≥ 40 °C which persisted up to 6.5 and 10h, respectively. When ambient conditions were predominantly thermoneutral, temperature humidity index had minimal impact on HEAT (mixed model, repeated measures over time). Toward identifying associated factors with different aspects of HEAT using best fit hierarchical linear regression models, baseline vaginal temperature and baseline duration were the most highly associated independent variables. Follicle size, estradiol and progesterone levels, and other available animal-related variables (e.g., age, weight, hair coat score) explained only a small amount of variation in HEAT. In summary, level of HEAT varies in estrus females even under thermoneutral conditions. Because HEAT can persist for an extended time, direct effects on fertility important components are unavoidable. Whether HEAT is a good or bad component of the periovulatory microenvironment is the basis of ongoing and future studies.

Pregnancy risk in beef and dairy cows after supplementing semen with transforming growth factor beta-1 at the time of artificial insemination.

Our objective was to determine if the addition of a concentrated human recombinant transforming growth factor beta-1 (TGF) to bovine semen at the time of AI would result in increased risk of pregnancy in beef and dairy cows. Suckled beef cows (n = 1,132) in 11 herds across 2 states and lactating dairy cows (n = 2,208) in one organic-certified herd were enrolled. Beef cows received fixed-time AI (FTAI) following a 7 d CO-Synch + controlled internal drug release estrous synchronization protocol. Dairy cows were inseminated following observation of natural estrus expression. Cows received either no treatment as a control (CON) or 10ng of TGF in 10 μL added through the cut-end of a thawed straw of semen immediately prior to AI. At the time of FTAI of beef cows, the mean ± SD age was 5.0 ± 2.4 yr, BCS was 5.3 ± 0.7, and days postpartum was 78.2 ± 15.5 d. The overall pregnancy risk (PR) in beef cows was 55.2% to AI and 90.5% season-long. PR in beef cows was not affected (P = 0.27) by the addition of TGF (53.1% vs. 58.1%). Furthermore, there was no difference (P = 0.88) for season-long PR in beef cows that received TGF (91.2% vs. 91.5%). At the time of insemination of dairy cows, the mean ± SD lactation was 3.0 ± 1.3 lactations, BCS was 2.9 ± 0.3, days in milk was 115.6 ± 56.6 d, and cows had received 2.4 ± 1.5 inseminations/cow. The overall pregnancy risk to AI in dairy cows was 23.1%. PR to AI for dairy cows was not affected (P = 0.32) by addition of TGF (22.0% vs. 23.8%). In conclusion, PR to AI was not affected by addition of TGF to thawed semen immediately prior to AI in beef or dairy cows.

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.

Follicular, luteal dynamics and effect of synchronization methods on reproductive responses in Cholistani cows.

The Cholistani cow is considered one of the milch breeds of Zebu cattle. Despite being heat and tick-resistant, it has not yet gained much popularity among Pakistan dairy farmers due to its long calving interval. This study aimed to understand the basic reproductive physiology of Cholistani cows using sonography and reproductive biotechnologies such as estrus synchronization and timed artificial insemination to improve reproductive efficiency. In experiment 1, six Cholistani cows with mixed parity 3.20 ± 1.30 and weighing 400 kg were selected to monitor ovarian dynamics on alternate days by the same sonographer from the onset of heat through ovulation until the next ovulation. Experiment 2 measured the effect of estrus synchronization methods, controlled internal drug release-gonadotropin-releasing hormone (CIDR-GnRH, n = 31) and Ovsynch (OVS, n = 32) on various reproductive parameters. The mean estrous cycle length was 19.81 ± 0.56 days with two follicular waves. The mean inter-ovulatory interval was 20.80 ± 0.52 days, with a preovulatory follicular size of 13.83 ± 2.37 mm. Estrus response was higher (p > 0.05) in controlled internal drug release (CIDR)-GnRH (93.54%) than in OVS (84.37%) cows. Similarly, ovulation and conception rates were higher in CIDR-GnRH (91.66% vs. 68.42%) than in OVS cows (41.37% vs. 33.33%), respectively. In conclusion, CIDR-GnRH results in a better estrus response, higher ovulation rate, and subsequently greater conception rate than OVS in Bos indicus dairy cows.

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.

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.

Timing of ovulation in the fat-tailed Qezel ewes after synchronization with vaginal devices containing endogenous or exogenous synthetic progestogens during out of the breeding season.

Wide range of ovulation distribution is the main restricting factor in establishing the pregnancy following oestrus synchronization (ES) and fixed time insemination (FTI) in sheep. Determining the ovulation time (OVT) following ES with two different vaginal devices, its relation to progesterone and conception upon FTI with frozen/thawed semen. Oestrus was synchronized using either controlled internal drug release (CIDR) (ewe, n=6; ewe lamb, n=5) or vaginal sponge (ewe, n=6; ewe lamb, n=5) insertion for 12 days, plus Equine chorionic gonadotropin (eCG) at devices removal (Day 0). Sizes of the ovarian follicles were measured using transvaginal probe at -12, 0 and 30-33, 53h and continued every 3-4h until 75h after eCG treatment. Serum progesterone amounts were measured at -12, 0, +2 and +11. Laparoscopic FTI was done at 60.5±0.5h. The CIDR-treated group initiated and completed ovulations earlier compared to sponge-treated females (median: 64 vs. 71h; p<0.05). Ewe lambs were ovulated earlier compared to ewes in the sponge-treated group (66.71 vs. 71.5; p=0.017). Mean sizes of ovulatory follicles and corpora lutea were not affected by device types. Higher amounts of progesterone were observed in CIDR group compared to sponge-treated group at device removal (2.68±0.12 vs. 0.30±0.01ng/mL; p<0.001). The conception was confirmed in 2/10, and 5/11 females of sponge and CIDR-treated females, respectively. Types of progestogens influence the OVT, and consequently the result of FTI with frozen/thawed semen. The optimum timespan for FTI should be chosen according to the device types during non-breeding season.

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.

55 Investigating the Potential Benefits of an Immunostimulant (Mycobacterium Cell Wall Fraction) Treatment on Increased Pregnancy Success of Embryo Transfer Recipients

Abstract Modulating the vaginal and uterine microbiome through the use of immunostimulants has the potential to improve fertility in cattle. The object of this study was to evaluate the potential benefits of an immunostimulant, mycobacterium cell wall fraction (MCWF), to increase pregnancy success of embryo transfer (ET) recipients. The three main objectives of this study were: determining if injecting ET recipient cows with MCWF increased proportion of cows with a corpus luteum (CL) on ET day, identifying differences in CL volume and progesterone concentration at the time of ET, and determining if ET recipients that received MCWF have greater pregnancy rate. A total of 926 beef cows at eight different locations were enrolled in this study. Primiparous and multiparous cattle were enrolled in a 7-day CO-Synch + CIDR estrous synchronization protocol. During this protocol, cows received an injection of GnRH (100-μg) at CIDR (controlled internal drug release) insertion [d -9], a prostaglandin F2α injection (25 mg), and CIDR removal [d-2] followed by another injection of GnRH (100 μg; d 0) within 60-66 hours after CIDR removal. At each location at (d 0), cows were sorted based on BCS and days post-partum and randomly assigned to one of two treatments: 1) MCWF- a single intramuscular injection (5 mL) of MCWF at (d 0; Amplimune, NovaVive Inc.; n = 452) or 2) Control- a single intramuscular injection (5 mL) of saline (n = 474). Seven days after (d 7), cows were examined by ultrasonography to determine if a CL was present. Recipient cows that had a CL received ET with a frozen or fresh in vivo or in vitro produced embryo in the ipsilateral uterine horn to the CL, with embryo type and grade balanced between treatments. Blood samples were collected in one location (n = 98) for analysis of plasma concentration of progesterone on (d 7) ET day. Pregnancy diagnosis was then performed by ultrasonography between 30 and 90 days of gestation. Data were analyzed using the GLIMMIX and MIXED procedures of SAS. Cow BCS and days postpartum were similar (P &amp;gt; 0.10) between treatments (5.5 ± 0.6 and 103 ± 14 days, respectively). Recipient cow utilization rate was similar between treatments (P = 0.49; 81.2 ± 0.42%). At the time of ET MCWF had larger CL than Control cows (5,768.6 ± 133.7 and 5,408.0 ± 128.5 mm3, respectively, P = 0.03). and increased progesterone concentration (2.68 ± 0.17 and 2.18 ± 0.14 ng/mL, respectively, P = 0.01). However, pregnancy rate to ET was similar (P = 0.922) between treatments (60.9 and 61.3 ± 0.05% for Control and MCWF, respectively). In conclusion, treatment of ET recipient cows with MCWF increased CL volume and concentration of progesterone at the time of ET but failed to generate greater pregnancy rates.

94 Changes in Vaginal Microbiome of Beef Cows Enrolled in an Estrous Synchronization Protocol

Abstract Vaginal pH and microbiome have been reported to influence fertility in women. In cattle, estrous synchronization protocols are a great tool to overcome infertility; however, the effects of the hormones administered in the protocol on vaginal microbiome and pH are unknown. A total of 24 cows were enrolled in the 7-d Co-Synch + controlled internal drug release (CIDR) protocol and had individual vaginal flushes collected during the handling events of the protocol on days 0, 7 and on day 10 at timed-artificial insemination (TAI). Flushes were used for pH analysis and DNA extraction. Extracted DNA was submitted to analysis by whole genome shotgun sequencing. Pregnancy status was assessed by ultrasonography 35 days after TAI. Firmicutes was the most abundant phylum, followed by Proteobacteria, and Actinobacteria for all collection days. Bacteria from the Clostridia genus were the most abundant in all samples. Greater alpha Shannon diversity (within sample diversity) was observed for pregnant animals on day -10 compared with non-pregnant animals at the phylum, class, and order (P &amp;lt; 0.01), as well as family, and genus level (P &amp;lt; 0.001). Overall, Shannon diversity was decreased on day 7 compared with day 0 (P &amp;lt; 0.05 at class and order level; P&amp;lt; 0.01 at genus and family level) and was greater at TAI compared with day 7 (P &amp;lt; 0.01 at the phylum, class, and order level; P &amp;lt; 0.001 at family and genus level). No differences were observed for Shannon diversity between samples from D0 and TAI (P &amp;gt; 0.05). No correlations between Shannon diversity were observed in relation to vaginal pH (P &amp;gt; 0.1). Bray-Curtis analysis (between sample diversity) revealed clustering by day (P &amp;lt; 0.05 at the order, family, and genus level) and a tendency (0.1 &amp;lt; P &amp;lt; 0.05) at the phylum and class level. In conclusion, greater fertility was observed for animals with greater within sample diversity prior to protocol initiation. Furthermore, vaginal bacterial diversity changes throughout the protocol, with decreased diversity observed on day 7 of the protocol, but restored diversity on day0 at TAI.

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.