Time Of CIDR Removal Research Articles

PSI-5 Comparison of 7&7 Synch and 7-day Co-Synch + Cidr Protocols in a Fixed-Time ai System on Beef Cows Using Y-Sorted sex-Selected Semen

Abstract The 7&7 Synch and the 7-day CO-Synch+CIDR fixed-time estrous synchronization protocols were compared among mature and two-year-old lactating postpartum Angus and SimAngus cows (n=201). Mature (n=63) and two-year-old (n=36) cows treated with the 7&7 Synch received an injection of prostaglandin F2α (PGF; 25 mg dinoprost tromethamine) at the same time as insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) on Day -17, gonadotrophin-releasing hormone (GnRH; 100 μg gonadorelin) on Day -10, and PGF at time of CIDR removal on Day -3. Mature (n=65) and two-year-old (n=37) cows in the 7-day CO-Synch+CIDR groups received an injection of GnRH on Day -10 that coincided with CIDR insertion and received PGF at the time of CIDR removal on Day -3. Fixed-timed AI (FTAI) by a single technician using Y-chromosome-bearing sex-sorted semen (4x106 sperm/unit of SexedULTRA 4M) from one of two Charolais bulls occurred on Day 0, 70 hours after PGF injection. Seven days later bulls were pastured with cows for the remainder of the breeding season. Transrectal ultrasound was performed 77-83 days after AI and fetal size was used to differentiate AI and natural service pregnancies. Within the mature cows and two-year-old age groups, the GLIMMIX procedure in SAS was used to compare FTAI and breeding season pregnancy rates with estrous synchronization treatment and sire as main effects. No differences (P=0.41) were observed amongst mature cows in FTAI pregnancy rates between the 7&7 Synch (52.4%) and the 7-day CO-Synch+CIDR (44.9%) treatments. A greater (P=0.05) proportion of two-year-old cows were pregnant to FTAI following treatment with the 7-day CO-Synch+CIDR (56.7%) as compared to the 7&7 Synch (33.4%). A greater (P=0.02) proportion of two-year-old cows in the 7-day CO-Synch+CIDR treatment (91.9%) were pregnant at the conclusion of the breeding season as compared with the 7&7 Synch (69.7%).

Effect of PGF2α and GnRH administration on reproductive performance in Ghezel ewes

The main aim of the current study was to evaluate the effect of GnRH administration on day five after mating as well as PGF2α injection at the time of CIDR removal on the reproductive performance of Ghezel ewes. Estrus synchronization was performed using an intravaginal application of CIDR for 14 days and injection of 500 IU of PMSG at the time of CIDR removal. A total of 114 healthy fat-tailed ewes were randomly allotted into three groups as follow: control group (n = 35), did not receive any additional treatment; PG group (n = 44), each ewe received a dose of PGF2α at the time of CIDR removal; and PG+GnRH group (n = 35), the ewes received a dose of PGF2α at the time of CIDR removal and a single dose of GnRH, five days post-mating (post-conceptional day (PCD)− 5). Body condition score (BCS) of total ewes was determined at the time of CIDR insert. Blood samples were collected on PCD-19 for determining the serum progesterone levels. All the ewes were examined by transrectal ultrasonography 30–35 days after mating for pregnancy diagnosis. The serum values for P4 concentration were in control, PG and PG+GnRH groups 6.34 ± 1.17, 9.19 ± 2.55 and 10.57 ± 2.0 ng/mL respectively. The PG+GnRH treatment significantly increased the litter size compared to the control group (P = 0.04), but there were no significant differences in another reproductive indices between experimental groups. The multiple birth, twin, fecundity rates and litter size (P = 0.05, p = 0.03 and p = 0.003 respectively) were significantly higher in ewes with BCS > 2 compared to ewes with BCS ≤ 2. It is concluded that GnRH on PCD-5 treatment in addition to PGF2α injection at the time of CIDR removal could improve reproductive performance of Qezel ewes during non-breeding season.

Efficiency of hCG for Inducing Resumption of Ovarian Cyclicity and Synchronized Ovulations during the Seasonal Anestrous in Sheep.

Simple SummaryThe use of equine chorionic gonadotrophin (eCG) in protocols for estrus synchronization in sheep is currently challenged, so it is necessary to implement alternatives (i.e., human chorionic gonadotropin; hCG), mainly during the anestrous season. Therefore, we compared the reproductive outcomes, including estrus induction, ovulatory follicle dynamics, and pregnancy outputs in anestrus Dorper sheep treated with insertion of one intravaginal progesterone-loaded CIDR + either saline, eCG, or hCG. The administration of hCG at the time of CIDR removal was effective at inducing estrus, resume ovulations, and ovarian cyclicity, yet, in a narrow window of time, it is a scenario that may limit the implementation of an artificial insemination protocol.This research aimed to evaluate whether the administration of hCG at the time of removal of a progesterone device may be effective at inducing estrus and ovulations in sheep during the natural seasonal anestrous, by comparing reproductive outputs (induction and duration of estrus, follicle development, ovulation, ovulation rate, and pregnancy rates) in ewes treated with eCG or only saline solution at the time of CIDR removal. Whereas results demonstrated no response in the control non-treated group, the largest rate of narrowly synchronized estrus signs and ovulations occurred in the eCG-group. The administration of hCG was effective at inducing estrus, promote follicular growth and a delayed yet significant ovulation (>84%) on day 10 after CIDR removal; moreover, an increased embryonic implantation rate was also observed. Moreover, if the hCG ewes remain exposed to active males for some days, said strategy could be adopted, aiming to induce pregnancies by natural mating in a short period of time.

PSVII-26 Follicular growth in beef cows when using a low dose of FSH and hCG at the time of CIDR removal in a 7-day co-synch + CIDR protocol

Abstract The aim of the study was to compare the growth of the periovulatory follicle in crossbreed cows receiving either a low dose of hCG (150 IU; Chorulon®, Merck) or a low dose of FSH (20 mg)Folltropin®, Vetoquinol) vs. a control group when applied at CIDR removal during an estrus synchronization protocol. At d0, a CIDR (Eazi-Breed CIDR®, Zoetis) was placed, a dose of GnRH (Factrel®, Zoetis) was applied i.m. and transrectal ultrasound was conducted to evaluate cyclicity status. On d7, cows (n = 79) were randomly assigned to three treatments (Control n = 27, FSH n = 26, and hCG n = 26) according to body condition score (1 to 9 scale) and cyclicity status. On the same day, CIDR was removed, a dose of prostaglandin analog (Lutalyse HighCon Injection®, Zoetis) was administered i.m. and an Estrotect™ patch was placed between the hip and tail head. Transrectal ultrasound was conducted to evaluate the diameter of the preovulatory follicle (DPF) at d7 and every 12h from d8 until ovulation was detected. Five cows that did not ovulate were removed from the study. Data were analyzed using GLIMMIX and LIFETEST procedures (SAS). The diameter at ovulation was not different among treatments (Control: 13.02 ± 0.53 mm; FSH: 12.38 ± 0.54 mm; hCG; 11.69 ± 0.47 mm; P = >0.10). Also, the time to ovulation was not different among treatments (P = 0.65; Figure 1a). However, cows of the control group presented estrus signs earlier than FSH and hCG groups (P = 0.02, Figure 1b). In conclusion, the use of a low dose of hCG or FSH at the time of CIDR removal did not increase the DPF or the time to ovulation.

Effect of Dietary Fish Oil on Semen Quality and Reproductive Performance of Iranian Zandi Rams.

The current study was conducted to evaluate the effect of dietary fish oil on the semen quality and fertility potential of Zandi rams. For this purpose, a total of 15 Iranian Zandi rams were randomly assigned into three equal groups. The first group was a negative control and were fed without oil supplement. The second group was a positive control, and their diet contained palm oil, and the last group had a diet containing fish oil. All the diets were isocaloric and isonitrogenous. The rams were fed for 70 days, and the semen smaples were collected every 10 days. In experiment I, the evaluated parameters included semen volume, sperm concentration, motility, membrane integrity, and viability. In experiment II, 210 Iranian Zandi rams received CIDR for 12 days and 400 IU of equine chorionic gonadotropin at the time of CIDR removal. Then, they were assigned into three equal groups and artificially inseminated with semen samples. According to the obtained results, the supplementation of ram diet with fish oil as a source of omega-3 fatty acids improved the semen volume, sperm concentration, total motility, progressive motility, viability, membrane integrity, pregnancy rate, parturition rate, and lambing rate of the rams (P≤0.05). In conclusion, fish oil as a dietary supplement for rams could be an effective strategy to improve the semen quality of rams for artificial insemination and other goals.

Assessment of estrous synchronization protocols and pregnancy specific protein B concentration for the prediction of kidding rate in Lezhi black goats

• The onset of estrus is earlier in CIDR + cPGF 2α + eCG. • GnRH treated at CIDR removal showed similar reproductive performance as CIDR + eCG. • PSPB detected with ELISA can identify does carrying four fetuses. The objectives of this study were to assess the efficacy of estrous manipulation protocols and pregnancy specific protein B (PSPB) levels to determine kid number at birth in Lezhi black goats. Eighty-eight does were randomly allocated to three treatments. The PPe group (n = 29) was treated with Controlled Internal Drug Release devices (CIDR) for 7 days and 300 IU eCG and 0.2 mg PGF 2α at the time of CIDR removal. The PPG group (n = 28) was treated with a CIDR for 7 days and 0.2 mg PGF 2α at the time of CIDR removal and 15 μg GnRH at the onset of estrus. The GPG group (n = 31) was treated with 15 μg GnRH (day 0) and 0.2 mg PGF 2α on day 7, and a second GnRH treatment at the onset of estrus. Does at estrus were hand-mated using proven bucks. Estrous response ranged from 80.6%–89.7 %. The onset of estrus for the PPe, PPG and GPG groups was 38.4 ± 1.9, 45.6 ± 1.9 and 53.8 ± 1.4 h (P < 0.05), respectively. Mean kidding rates (205.9 %–227.8 %) and kidding percentages (112.9 %–146.4 %) were not different in the three treatments. At day 85 of gestation, does carrying quadruplets had a greater (P < 0.01) plasma PSPB level than does that delivered one to three kids. In conclusion, PPG may be a useful estrous synchronization protocol in goats. PSPB concentration at day 85 of gestation could be a potential diagnostic tool for predicting quadruplets.

Size and number of corpora lutea and serum progesterone concentrations when administering two doses of eCG in an estrous synchronization treatment regimen for dairy cattle

There was investigation of whether there were ovulations from co-dominant follicles following eCG administration. In all experiments, there was GnRH injection and CIDR insertion on day 0 (D0), CIDR withdrawal on D8, and cloprostenol administration on D8 (Exp. I and II) or D7 and D8 (Exp. III). Females in the control group were not administered any further treatment. Females in other group(s) were treated with eCG (500 IU) on Day 2 in Exp. I, Day 2 (eCG-2) or 8 (eCG-8) in Exp. II and Day 2 (eCG-2) or Days 2 and 6 (eCG-2-6) in Exp. III. Ovaries were examined using ultrasonography. In Experiments I and II, females had follicle emergence on Day 2. At the time of CIDR removal, more eCG-treated heifers (8/9; Exp. I) and cows (5/6; eCG-2; Exp. II) had co-dominant follicles compared to those in the control group (P < 0.05). Occurrence of ovulations from co-dominant for individual cows was minimal. In Experiment III, the time period from CIDR removal to estrus in cows treated with eCG-2 (68 ± 13 h) was longer compared to cows in the control (37±2 h) and eCG-2-6-treated group (38 ± 5 h; P < 0.05). There was a greater proportion of heifers having ovulations and thus greater progesterone concentration in the eCG-2-6 than eCG-2 group (P < 0.05). Administering eCG twice 4 days apart with the initial administration being two days after GnRH administration, at the time of follicle wave emergence, could induce growth of and ovulation from co-dominant follicles and enhance progesterone production in cattle.

Follicular dynamics, estrous response and pregnancy rate following GnRH and progesterone priming with or without eCG during non-breeding season in anestrous Beetal goats

Abstract Goats show seasonal reproductive behaviour under subtropical latitude; limiting the scope of the intensive farming system. Therefore, the objective was to evaluate the efficacy of GnRH plus short-term progesterone treatment with or without eCG on reproductive parameters of anestrous Beetal goats during the non-breeding season. We hypothesized that GnRH + short-term progesterone priming will be effective in inducing estrous response in anestrous Beetal goats during the non-breeding season. Anestrous goats (n = 48) were treated with GnRH and CIDR (Day 0), and randomly divided into eCG (400 IU; n = 27) and non-eCG (n = 21) groups on Day 7. All goats were administered PGF2α at the time of CIDR removal on Day 7. After the GnRH administration, eighteen goats were monitored daily for follicular dynamics. Of which 44% goat ovulated and had earlier emergence of new wave (P

Comparison of the effects of two shortened timed-AI protocols on pregnancy per AI in beef cattle

The objective was to compare pregnancy per AI (P/AI) between two shortened timed-AI (TAI) protocols in beef cattle. This study also determined whether administration of eCG in heifers and timing of AI in cows would affect P/AI. Cattle were submitted at random to either a modified 5-d Co-synch protocol (Day 0 = progesterone releasing device (CIDR); Day 5 = CIDR removal and 500 μg of cloprostenol (PGF); Day 8 = 100 μg GnRH concurrent with AI) or J-synch protocol (Day 0 = CIDR insertion and 2 mg of estradiol benzoate i.m.; Day 6 = CIDR removal and 500 μg PGF; Day 9 = 100 μg GnRH concurrent with AI). In Experiment 1, 1135 heifers (13–15 mo of age) received an estrus detection patch (Estrotect™) on Day 5 and 579 were selected at random to receive 300 IU of equine chorionic gonadotropin (eCG) at the time of CIDR removal. Patches were scored from 0 to 3 based on color change between initial application and AI; 0 = unchanged, 1 = ≤ 50% change, 2 = > 50% change, 3 = missing. Estrus was defined to have occurred when the patch was scored 2 or 3. In Experiment 2, 399 cyclic, non-lactating beef cows from 1 location were submitted to either the modified 5-d Co-synch or J-synch protocol and within each protocol cows were TAI at either 66 ± 1 (n = 199) or 72 ± 1 h (n = 200) following CIDR removal. Transrectal ultrasonography was used in both experiments to determine presence of a corpus luteum (CL) on Day 0, and to diagnose pregnancy 35 d after TAI. In Experiment 1, eCG increased estrus rate only in heifers without a CL on day 0 that were submitted to the modified 5-d Co-synch protocol (41.9 vs. 69.6%). Heifers submitted to the J-synch protocol had greater (P = 0.03) P/AI compared with those in the modified 5-d Co-synch (48.7 vs. 41.1%) and heifers that expressed estrus before AI had increased (P < 0.0001) P/AI compared to those that did not (53.6 vs. 36.5%). Administration of eCG and presence of a CL tended to affect P/AI (P = 0.13). In Experiment 2, cows submitted to the J-synch protocol tended (P = 0.07) to have greater P/AI compared to those in the modified 5-d Co-synch (74.1 vs. 66.5%). There was no association between P/AI and timing of AI. In summary, the J-synch protocol resulted in greater P/AI than the modified 5-day Co-synch protocol in heifers and cows. Administration of eCG increased estrus rate in heifers without a CL at the start of the protocol and tended to improve P/AI in all heifers. Timing of AI (66 vs. 72 h) had no effect on P/AI in cows subjected to either TAI protocol.

Evaluation of estrous synchronization protocols on ewe reproductive efficiency and profitability

A 2-year experiment was conducted to determine the effect of a single injection of prostaglandin after initiation of the breeding season on ewe estrous synchronization. Rambouillet ewes (n = 101; Year 1 = 52; Year 2 = 49) assigned to one of three treatments: untreated (CON); 12-d CIDR insert (CIDR); or 1 injection of prostaglandin at d 2.5 (1 PG) after rams were placed with ewes. Rams were placed with ewes at the time of CIDR removal (d 0) and remained with ewes during a 35-d breeding season. Both the CIDR- (94%) and 1 PG (73.5%) treatment groups had a larger number (P ≤ 0.01) of ewes bred in the first 5 d of the breeding season compared to ewes of the control (33%) group. As expected, CIDR-treated ewes had a shorter time to mating, than 1 PG-treated ewes and ewes of the control group had a longer interval to mating than both CIDR- and 1 PG-treated ewes (P ≤ 0.01). The number of lambs born per ewe and kg of lamb weaned per ewe was not different (P ≥ 0.31) among treatment groups. Additionally, there was no difference (P = 0.78) in net profit per ewe among treatment groups. Based on these data, utilizing a single injection of PG 2.5 d after initiation of the breeding season resulted in similar pregnancy rates at d 5 of the breeding season when compared with CIDR-treated ewes indicating the potential utilization of the 1PG protocol in a confinement setting as a viable method for estrous synchronization.

216 Effects of low doses of GnRH at CIDR removal on estrus expression and conception rates in beef heifers

Abstract Previous studies evaluating single and multiple GnRH injections at time of CIDR removal have reported decreased interval to estrus and increased expression of estrus, and increased conception rates, respectively. Thus, the objective of this study was to compare the effects of supplementing GnRH at CIDR removal on expression of estrus and conception rates in beef heifers following the 7-d CO-Synch + CIDR protocol. Heifers (n = 1,482) from 11 herds over two years were synchronized using the 7-d CO-Synch + CIDR fixed time AI (FTAI) protocol and were randomly assigned to receive one of three treatments at CIDR removal [0 µg GnRH (0); 5 µg GnRH (5); or 5 µg at CIDR removal and 5 µg 12 h later (5 + 5)]. Expression of estrus and conception rates were analyzed using the GLIMMIX procedure of SAS with treatment as an independent variable and herd as a random effect. There was no effect of treatment on expression of estrus (P = 0.38), or AI conception rates (P = 0.85). There was an effect of estrus (P &lt; 0.01) and a treatment × estrus interaction (P = 0.02). Animals that exhibited estrus prior to FTAI had increased (P &lt; 0.01) conception rates compared with those that did not. Animals that exhibited estrus had increased (P &lt; 0.01) conception rates compared with non-estrus animals in the 0 and 5 + 5 µg groups (54 ± 3% vs 34 ± 3%, and 52 ± 3% vs 36 ± 3%, respectively), but in the 5 µg group, there was no difference (P = 0.53) in conception rates between estrus and non-estrus animals (44 ± 3% vs 41 ± 3%, respectively). In conclusion, estrus expression increased pregnancy success, but supplementation with 5 or 5 + 5 µg of GnRH at CIDR removal did not improve estrus response or conception rates in beef heifers.

122 Effect of gonadotropin-releasing hormone plus 7-day progesterone (CIDR) with or without eCG on follicular dynamics, estrus response, and pregnancy rate in anestrous Beetal goats during nonbreeding season under subtropical conditions

Oestrus induction is a challenging task during the nonbreeding season in goats. Therefore, our objective was to evaluate the efficacy of gonadotropin-releasing hormone (GnRH) plus a 7-day CIDR-based protocol with or without eCG for the induction of oestrus and fertility in acyclic Beetal goats during the nonbreeding season under subtropical conditions. Based on the absence of corpus luteum via ultrasonography, goats (n=56; mean weight=32.8±0.5 kg; body condition scre=2.5±0.1) were inserted with a CIDR (300mg progesterone) along with GnRH (Day 0), and randomly treated either with eCG (400 IU; n=35) or without eCG (control; n=21) on Day 7. The CIDR was removed on Day 7 and all does were administered single dose of prostaglandin F2α (75µg cloprostenol; Fatro, Italy). Following CIDR insertion, ovarian follicular dynamics was monitored daily through a 7.5-MHz transrectal transducer (Honda HS 1500, Japan) until ovulation in a subset of eCG (n=11) and control goats (n=10). Oestrus was detected at every 12h after CIDR removal with aproned bucks and does were bred naturally. Pregnancy was detected 25 days after breeding by transrectal ultrasound. Data were analysed by t-test, ANOVA, and Chi-squared test using SPSS (version 20.0, SPSS Inc., Chicago, IL, USA). Oestrus occurred more often following CIDR removal in eCG v. control goats (94v. 57%; P&amp;lt;0.05). Similarly, onset of oestrus was earlier (36.0±2.1v. 54.2±4.7 h; P&amp;lt;0.05) and the duration of oestrus was longer in eCG v. control goats (i.e. 30.2±1.3v. 22.1±2.3 h; P&amp;lt;0.05). However, diameter of preovulatory follicles and interval to ovulation after CIDR removal were similar between eCG and control goats (P&amp;gt;0.05). In contrast, growth rate of preovulatory follicle after CIDR removal until ovulation in eCG goats was greater, and ovulation rate was higher than control goats (0.7±0.1v. 0.3±0.1 mm/day; 2.2±0.2v. 1.4±0.2, respectively; P&amp;lt;0.05). In eCG goats, the dominant follicle grew rapidly between Days 8 to 9 (P&amp;lt;0.05), whereas within control goats the dominant follicle grew at consistent rate (P&amp;gt;0.05). After CIDR removal, percentage of ovulating goats in eCG was higher as compared to the control group (100v. 44%; P&amp;lt;0.05). Within control goats, size of the dominant follicle in ovulatory goats was greater at the time of CIDR removal than anovulatory goats (5.7±0.3v. 5.0±0.15 mm; P&amp;lt;0.05), whereas wave emergence tended to be earlier after CIDR insertion in anovulatory goats (4.2±1v. 2.6±0.4 days; P=0.09). Pregnancy rate 25 days postbreeding did not differ between eCG and control goats [i.e. 49% (16/33) v. 25% (3/12); odds ratio 2.9/1; P&amp;gt;0.05]. In conclusion, the eCG protocol resulted in higher oestrus response, ovulation rate, and 3 times higher pregnancy rate in anestrous goats during the nonbreeding season.

Effects of different fat sources (saturated and unsaturated) on reproductive performance and biological indices of ewes during flushing period.

This study was conducted to evaluate the effect of feeding different sources of fat during flushing period on the reproductive performance, lambing percent, and twin numbers of Afshari ewes. A total of 84 ewes (mean weight 48±3kg; age: 3-4years) were divided into seven groups of 12 animals and received flushing-specific rations for 5weeks. The control group just received a basic ration (non-flushing). Lipid sources were calcium salt of palm oil (CaP), pure palm oil (PO), calcium salt of flaxseed (CaFL), calcium salt of sunflower oil (CaSF), flaxseed oil (FLO), and sunflower oil (SFO). Estrous cycles were synchronized in all ewes using 14-day CIDRs followed by 400-IU PMSG injection at the time of CIDR removal. Fertility and lambing percent were higher in ewes fed with diets containing calcium salts of flaxseed and SFO, as compared to other treatments. Total number of lambs in flushing treatments was significantly higher than that in the control group (p<0.01). Serum cholesterol and progesterone levels were significantly greater in omega-3 (CaFL) and omega-6 (CaSF) treatments relative to other treatments (p<0.01). It was concluded that supplementing the flushing diet with calcium salts of fatty acids (CSFA) increased blood metabolites and hormones related to reproductive performance; and improved fertility, lambing rate and ewes of CaFL treatment have the highest number of lambs (16 lambs) between different groups. Using saturated and unsaturated fatty acids, especially in their CSFA forms during flushing period, could improve the reproduction problems induced by progesterone deficiency, lack of durability of the fetus due to hormonal instability, and abortion control factors.

101 DOSE AND TIMING OF ADMINISTRATION OF PROSTAGLANDIN F2α DURING FIXED-TIME EMBRYO TRANSFER IN AN IN VITRO-PRODUCTION PROGRAM

Synchronization protocols for fixed-time embryo transfer (ET) contribute significantly to the overall cost of an in vitro-produced-ET program, primarily through the cost of drugs and the labour required. Optimization of synchronization protocols to reduce cost, while providing high fertility, have the potential to improve overall efficiency and profitability. The objective of the present study was to evaluate the effect of dose and schedule of administration of prostaglandin F2α (PGF) during a synchronization protocol for fixed-time ET. Holstein and cross-bred Holstein heifers (n = 3766) were synchronized using a modified 5-day CIDR Synch as follows: Day 0: CIDR inserted; Day 5: CIDR removed, PGF2α treatment; Day 8: gonadotropin-releasing hormone (GnRH; 100 μg of gonadorelin). On Day 5, at the time of CIDR removal, heifers were randomly assigned to a 2 × 2 factorial design to receive either a full or half dose of PGF (Cloprostenol; 500 v. 250 μg) and 1 (Day 5) or 2 (Day 6) administrations resulting in the following treatments: full dose Day 5 + Day 6 (n = 938); full dose Day 5 (n = 938); half dose Day 5 + Day 6 (n = 946); and half dose Day 5 (n = 944). Heifers were evaluated by ultrasonography 5 days after GnRH to determine presence and size of the corpus luteum. Heifers with a corpus luteum received a fresh in vitro-produced embryo 7 ± 1 days after GnRH administration, and pregnancy was determined by ultrasonography 32 and 60 days after GnRH. Fertility data were analysed by logistic regression and included the fixed effects of dose, time, and their interaction. Fertility results are shown in Table 1. Utilisation rate (transferred/treated) was not affected by dose (P = 0.66), time (P = 0.19), or their interaction (P = 0.17). The percentage of heifers detected in oestrus was not affected by dose (P = 0.13), time (P = 0.72), or their interaction (P = 0.89). There were no significant differences between doses of PGF (P = 0.32), time (P = 0.71), or their interaction (P = 0.80) on pregnancies per ET on Day 32. Similarly, no differences were found on pregnancies per ET on Day 60 between doses (P = 0.35), time (P = 0.96), or their interaction (P = 0.89). In addition, pregnancy loss between Day 32 and 60 was not affected by dose (P = 0.76), time (P = 0.66), or their interaction (P = 0.54). In conclusion, the use of a half dose of PGF once on Day 5 resulted in comparable utilisation rate and fertility as the observed with 2 full dose applications 24 h apart. As a result, the overall cost of the fixed-time ET program can be reduced by eliminating the need for a second PGF treatment and by decreasing the dose without compromising fertility. Table 1. Utilisation rate, oestrus expression, pregnancies per ET (P/ET), and pregnancy loss in recipients receiving either a full or half dose of prostaglandin F2α on Days (D) 5 and 6 or once on D 5

Expression of Na+/H+ exchanger isoforms 1, 2, 3, and 4 in bovine endometrium and the influence of uterine pH at time of fixed-time AI of pregnancy success

Cows that exhibit estrus prior to fixed-time AI had increased sperm transport to the site of fertilization, and improved embryo quality on d 6 after insemination. Sperm transport is influenced by uterine pH, and research has reported that uterine pH decreased at onset of estrus, but must return to normal prior to ovulation. Therefore, the objectives of these studies were to investigate a possible mechanism for the regulation of uterine pH around the onset of estrus, and to determine if uterine pH at time of fixed-time AI influenced pregnancy success. In experiment 1, Angus-cross beef cows (n=40 and 28 in rep. 1 and 2, respectively) were synchronized with the PG 6-day CIDR protocol (PGF2α on d -9, GnRH and insertion of a CIDR on d -6, and PGF2α and CIDR removal on d 0). Cows were blocked by follicle size at time of CIDR removal, and uterine biopsies were collected at 0, 12, 24, 36, 48, 60 (Rep. 1), 72, 84, or 96h (Rep2) after CIDR removal, and total cellular RNA was extracted from all biopsies. Estrus was monitored by the HeatWatch Estrous Detection System. In experiment 2, 223 postpartum beef cows in 2 herds were synchronized with a fixed-time AI protocol (herd 1: n=97; CO-Synch plus CIDR protocol; herd 2: n=126; Co-synch protocol). Uterine pH was determined at time of AI (n=80 and 63 for herd 1 and 2, respectively), and estrus was monitored by visual estrus detection with the aid of an ESTROTECT estrous detection patches, and pregnancy was determined by transrectal ultrasonography. In experiment 1, there was a significant (P<0.01), quadratic relationship in expression of Na+/H+ exchanger isoforms 1, 2, and 3 among animals that exhibited estrus, with expression greatest at time of CIDR removal, decreasing to the onset of estrus, and then increasing again following the onset of estrus. Among cows that did not exhibit estrus, the preceding relationship did not exist (P>0.46). In experiment 2, cows that had initiated estrus prior to fixed-time AI had decreased (P=0.01) uterine pH compared to cows that did not initiate estrus (6.78±0.03 and 6.89±0.03, respectively), and uterine pH at AI had an approximately linear effect on pregnancy success within the observed pH range. Furthermore, cows that initiated estrus prior to AI had increased (P=0.05) pregnancy success (52% vs. 38%) compared to cows that had not initiated estrus. In summary, expression of Na+/H+ exchanger isoforms 1, 2, and 3 decreased after CIDR removal among cows that exhibited estrus, but did not change among cows that did not exhibit estrus. Additionally, as uterine pH decreased pregnancy success tended to increase (P=0.076, logistics regression). Thus, Na+/H+ exchanger isoforms 1, 2, and 3 appear to be key regulators of uterine pH around the onset of estrus, and this change in uterine pH is critical for pregnancy success. Summary sentenceExpression of Na+/H+ exchanger isoforms 1, 2, and 3 decreased after CIDR removal among cows that exhibited estrus, but did not change among cows that did not exhibit estrus, and as uterine pH decreased, pregnancy success tended to increase.

154 EMBRYO RESPONSE OF SUPEROVULATED HOLSTEIN HEIFERS INSEMINATED WITH X-SORTED FROZEN SPERM

A study was conducted within a commercial embryo transfer program to assess the appropriateness of X-sorted semen in superovulated heifers. Commercial X-sorted semen frozen at a dose of 2 million sperm/straw and unsorted semen frozen at a dose of 20 to 30 million sperm/straw was used in donors according to the owner’s genetic criteria. One-hundred 15- to 18-month-old Holstein heifers were superovulated as follows: Animals received a CIDR device (Pfizer Animal Health, New York, NY, USA) for 13 days. At the time of CIDR insertion and 5 days later, heifers received 2 mL (0.15 mg) of d-cloprostenol (Veteglan, Laboratorios Calier, Spain). Gonadotropin-releasing hormone (GnRH), 200 mcg IM (Gonasyl, SIVA, Spain) was administered twice, 36 hours after the second prostaglandin (PGF) and 24 hours after CIDR removal. Superovulatory treatments with commercial FSH (Pluset, Laboratorios Calier) were initiated 36 hours after the first GnRH, with a total dose of 11.5 mL (575 IU), given twice daily in 10 daily decreasing-dose injections. Luteolysis was induced with 0.15 mg PGF given twice, 12 h before and at the time of CIDR removal. Heifers were randomly assigned to two groups for insemination in the uterine body: Group A (n = 31) heifers were inseminated with 5 straws of X-sorted semen in three inseminations (2 straws at 12 h, 2 straws at 18 h, and 1 straw at 24 h after the last GnRH); Group B (n = 69) heifers were inseminated twice with unsorted semen (one straw at each of 12 and 24 h after the last GnRH). A total of 614 embryos (153 in Group A and 461 in Group B) were collected and frozen. There were no significant differences between groups (Mann–Whitney rank sum test, SigmaStat, Systat Software Inc., San Jose, CA, USA) in the embryo production obtained (Table 1). Eighty-four embryos frozen with ethylene glycol were thawed and transferred; 34 from Group A, where all births were females and 50 from Group B with a 0.54 sex ratio. Pregnancy rates were 55 and 54% in Groups A and B, respectively. In conclusion, with the superovulation and AI schedule utilized in this experiment, the use of X-sorted semen in heifers can achieve reproductive outcomes similar to those obtained with unsexed semen, with the benefit of an increase in females offspring. Table 1.Mean number of recovered ova/embryos, transferable embryos, and unfertilized ova obtained in superovulated Holstein heifers inseminated with X-sorted (Group A) and unsorted (Group B) semen

18 PREGNANCY RATES IN LACTATING DAIRY COWS TREATED WITH GONADOTROPIN-RELEASING HORMONE-BASED SYNCHRONIZATION PROGRAMS AND INSEMINATED AT A FIXED TIME

An experiment was designed to compare pregnancy rates in lactating dairy cows synchronized with a 7-day CIDR-Synch or a 5-day CIDR-Synch program and to determine if the addition of a second prostaglandin F2α (PGF) injection to the 7-day CIDR-Synch program would improve pregnancy rates following fixed-time AI (FTAI). The experiments were performed on 2 dairy farms in Argentina, with year-round calving and a mixed feeding system (35% grazing plus 65% corn silage and grain). Cows (n = 621) were 39.3 ± 6.5 days in milk (DIM, mean ± SD) when they were enrolled in the program, had 2.4 ± 1.5 lactations and a body condition score (BCS) of 3.1 ± 0.2 (range: 2.7 to 4.0). All cows received a pre-synchronization treatment with 2 doses of prostaglandin (PGF, 25 mg of dinoprost, Lutalyse, Pfizer Animal Health, Argentina) 14 days apart, and 11 days after the second PGF (Day 0) received 10 µg of Buserelin (GnRH, Receptal, MSD-Intervet, Argentina) and a CIDR device (1.9 g of progesterone, Pfizer Animal Health). Cows were randomly allocated to 1 of 3 groups. The CIDR devices were removed and PGF was administered to cows in Groups 1 and 2 on Day 7. A second GnRH was given 56 h later and cows experienced FTAI 16 h after gonadotropin-releasing hormone (GnRH) injection (i.e. 72 h after CIDR removal). Cows in Group 2 also received a second PGF injection on the afternoon of Day 7. Cows in Group 3 had the CIDR removed and received 2 PGF injections 12 h apart on Day 5. A second dose of GnRH was given and FTAI was performed at the same time, on Day 8 (i.e. 72 h after CIDR removal). All cows were examined by ultrasonography (Aloka 500V, Aloka, Tokyo, Japan) on the day of the first PGF injection and at CIDR removal to determine the presence and number of corpora lutea (CL), and 30 days after FTAI to determine pregnancy status. Data were analyzed by logistic regression to determine the effects of treatment, parity, days postpartum, milk production, BCS, presence of a CL at enrollment, and number of CL at the time of CIDR removal on pregnancy rates. Overall pregnancy rates did not differ among groups: 32.9% (68/207), 38.2% (78/204), and 38.3% (80/209) for Groups 1, 2, and 3, respectively (P = 0.2). Although the number of CL present at CIDR removal did not significantly affect pregnancy rates (P = 0.4), pregnancy rates in cows with 1 CL in Groups 1 and 2 tended to differ [29.0% (11/38) v. 48.9% (21/43); P &lt; 0.07], but neither differed from that in Group 3 [37.2% (16/43)]. No differences were detected among groups in cows without a CL at CIDR removal [overall pregnancy rate: 29.4% (5/17)] and those with ≥2 CL [overall pregnancy rate: 36.1% (173/479)]. Among the other variables evaluated, first-parity cows had 1.96 (1.38–2.78) times more chance of getting pregnant than second-or-more-parity cows (P = 0.002) and cows with BCS &gt;3 had 1.63 (1.16–2.28) times more chance of getting pregnant than those with BCS &lt;3 (P = 0.003). Finally, herd, days postpartum, milk production, and presence of a CL at enrollment did not significantly affect pregnancy rates. We concluded that the 3 treatments resulted in similar pregnancy rates for lactating dairy cows and that the benefit of adding a second PGF injection to the 7-day protocol was only marginal in cows with 1 CL at CIDR removal.

162 FERTILITY OF BEEF RECIPIENTS FOLLOWING A FIXED-TIME EMBRYO TRANSFER PROTOCOL WHICH INCLUDED FOLLICLE STIMULATING HORMONE DILUTED IN HYALURONAN

This study was performed to test the viability of administering Folltropin-V® (FSH, Bioniche Animal Health) diluted in hyaluronan (MAP-5 50 mg, sodium hyaluronate, Bioniche Animal Health) to beef cows enrolled in a recipient synchronization protocol to evaluate its effect on recipient fertility. All recipients were administered an estradiol 17β (2.5 mg, IM) and progesterone (50 mg, IM) combination injection on Day 0, a CIDR® (progesterone 1.34 g, Pfizer Animal Health, Groton, CT, USA) was inserted for 7 days. Lutalyse® (dinoprost tromethamine, Pfizer Animal Health, 25 mg, IM) was administered at the time of CIDR removal on Day 7, and estradiol 17β (1 mg, IM) was administered on Day 8. On Day 16, the presence of at least one corpus luteum, detected via ultrasound, resulted in the recipient receiving an embryo (both fresh and frozen–thawed embryos were used). Embryos were not transferred into cows that did not show ultrasonic evidence of a CL. Dependent variables for which data were collected included circulating progesterone levels at the time of transfer and CL diameter, area, and circumference; measured in millimeters. The total study (n = 274) consisted of both wet (n = 85) and dry (n = 189) cows and included both Bos indicus (Brahman-influenced) crossbred (n = 93) and Bos taurus (Angus-based) cows (n = 181). The experiment consisted of cows being placed in either the treated or control groups, with treated cows receiving a single 40 mg (1 mL) IM injection of Folltropin-V in hyaluronan on Day 5 and control cows receiving no additional injections. Results are shown in Table 1. Transfer rate, conception rate, and pregnancy rate were tested for significance with chi-square analysis and remaining statistics were analyzed with a t-test: two-sample assuming equal variances. There were no significant differences found between the treated and control groups for transfer rate, conception rate, or pregnancy rate. Corpus luteum diameter was shown to be larger in control cows (P &lt; 0.05); however, CL area and circumference did not differ significantly. Folltropin-V given with hyaluronan at a 40-mg dose on Day 5 did not improve fertility, induce a larger CL, or increase circulating progesterone levels in synchronized beef recipients as hypothesized. Further work is needed with Folltropin-V in hyaluronan to determine if an alternative dose or timing of administration would be more appropriate for improving fertility in recipients. Table 1.Fertility data in beef recipients following synchronization for fixed-time embryo transfer with a protocol that included (Treated) or did not include (Control) FSH in hyaluronan

English

The present study considers the right versus the left ovarian responses to the different doses of eCG treatment in ewe. The estrous cycles of 32 adult Shall Iranian ewes were synchronized by CIDR during breeding period. At the time of CIDR removal, 0 (n = 8), 450 (n = 8), 550 (n = 8) and 650 (n = 8) IU of eCG (Intervet, Booxmer, Netherlands) was administered to ewes. The number of large follicles (&gt; 3 mm, LF) and CL in the right and left ovaries was monitored by transrectal ultrasonography on the day of estrus and 6 days later. In another analysing view, all ewes (n = 32) were set into 3 groups. Following superovulation, groups A and D ewes had at least one extra large follicle and CL, respectively, in their right ovary than that of the left one. Group B and E had the opposite position and group C and F had equal LF in their ovaries. The data were analysed by GLM procedure of SAS. The mean number of LF in the right (2.35 &plusmn; 0.14) was higher (P &lt; 0.001) in comparison to the left (1.42 &plusmn; 0.14) ovaries in all treatment groups. Also, the mean number of LF in the right was higher (P &lt; 0.05) than that in the left ovaries between every treatment group. In addition, the mean number of CL in the right (1.92 &plusmn; 0.47) was higher (P &lt; 0.05) in comparison to the left (1.33 &plusmn; 0.25) ovaries in all treatment groups. Furthermore, in the other analysis, we observed 62.5% of the ewes were in group A (n = 20) which was a higher (P &lt; 0.001) percentage compared to group B (n = 4, 12.5%) and group C (n = 8, 25%). Also, it is observed that 44% of the ewes were set into group D (n = 16) (the right ovary had at least one CL extra in comparison with the left ovary) which was a higher (P &lt; 0.05) percentage compared to groups E and F; and that both groups had equal number of ewes. The results suggest that the greater responses of follicular development occur in the right ovaries after eCG treatment in Shall Iranian ewes. &nbsp; Key words:&nbsp;Ewe, Shall, follicle, CIDR, eCG.

408 HOLSTEIN DONORS RESPONSE USING OR NOT USING ESTRADIOL 17-β IN THE SUPEROVULATORY TREATMENT

Because of new regulations banning the use of estradiol in the European Union and other countries, the present study was designed to determine the efficacy of an alternative to the use of estradiol 17-β in superovulation of Holstein cows and heifers. A total of 61 lactating cows and 49 heifers (15-18 months old) were divided into 2 groups: Group A (32 cows and 22 heifers) and Group B (29 cows and 27 heifers). Animals in Group A received a CIDR device (Pfizer, Madrid, Spain) for 13 days. At the same time of CIDR insertion and 5 days later, all animals received 2 mL (0.15 mg) of d-cloprostenol (PGF; Veteglan®, Calier, Spain). Gonadotropin-releasing hormone (0.5 mg of gonadorelin; Fertagyl®, Schering-Plough, Carbajosa de la Sagrada, Spain) was administered twice, 36 h after the second PGF and 24 h after CIDR removal. Superovulation treatments were initiated 36 h after the first GnRH, with a total dose of 15 mL (750 IU) of FSH (Pluset®, Calier, Spain) for cows and 11.5 mL (575 IU) for heifers, given in 10 twice-daily injections that decreased in dose. Luteolysis was induced with 0.15 mg of PGF given twice, 12 h before and also at the time of CIDR removal. Animals in Group B received a CIDR device for 7 days. Twenty-four hours after CIDR insertion, all animals received 100 mg of progesterone (Smithkline, Tres Cantos, Spain) and 5 mg of estradiol 17-β (Sigma, St. Louis, MO, USA). Beginning on Day 5, animals were superovulated with similar doses of FSH to those used in Group A. Luteolysis was induced with 0.15 mg of PGF given twice, 12 h before CIDR removal and also at the time of removal. Gonadotropin-releasing hormone (0.5 mg) was administered at the time of AI. Animals from both groups were inseminated with frozen-thawed semen at 12 and 24 h after the onset of standing estrus. Embryos were recovered nonsurgically 7 days later. A total of 299 frozen-thawed embryos (Freeze Control® CL5500, Bioniche, Belleville, Ontario, Canada) from both groups were transferred in synchronized Holstein heifers. Pregnancy was confirmed by rectal palpation on Day 40 to 45 of gestation. Data were analyzed by two-way ANOVA and results are shown in the table. No significant differences were found between cows and heifers, nor was there a difference between groups. These results showed that the previous superovulatory treatment using progesterone and estradiol can be successfully replaced with the treatment protocol described herein. Table 1.Mean number of recovered ova/embryos, transferable embryos, and pregnancy rates after embryo transfer (ET) in Holstein cows and heifers superovulated with 2 treatment protocols