Injection Of Prostaglandin F2α Research Articles

181 IN VITRO FERTILIZATION (IVF) USING SEMI-DEFINED CULTURE CONDITIONS FROM LOW OR HIGH ANTRAL FOLLICLE COUNT PUBERTAL BEEF HEIFERS

To compare the in vitro fertilization (IVF) and production (IVP) of embryos from low and high antral follicle count (AFC) heifers, AFC were determined on 106 heifers using transrectal ultrasonography. Ten heifers with the lowest AFC (avg. 13.2) and 10 heifers with the highest AFC (avg. 27.4) with evidence of oestrous cyclicity were synchronised with 2 injections of prostaglandin F2α (PGF2α); half were harvested on Days 5 to 6 and half on Days 15 to 16 of the oestrous cycle. The IVF procedures included protocols for semi-defined media and were as described (IVP Protocol, P. J. Hansen’s Laboratory, University of Florida, Gainesville, FL, USA). Cumulus-oocyte complexes (COC) from follicles less than 8 mm in diameter were cultured in maturation medium (5% CO2; 38.5°C) for 24 h. Matured COC were fertilised using thawed frozen semen from a crossbred bull that was purified using Percoll gradient separation procedures. Motile spermatozoa were added to COC in fertilization medium at a final concentration of 1 × 106 spermatozoa per mL. About 24 h later, presumptive zygotes were placed in microdrops of development medium under oil, and cultured (5% CO2, 5% O2, balance N2, 38.5°C). On Days 3 and 8 after fertilization, cleavage and blastocyst development rates, respectively, were assessed. Data were analysed using the mixed procedure of SAS (SAS Institute, Cary, NC, USA) and the model included the effects of collection day, group (high or low AFC), and their interaction. More COC (P < 0.0005) were collected from high than low AFC heifers (30.3 v. 9.3 ± 3.12 per heifer). Both the number and percentage of COC that cleaved had an interaction between collection day and group (P < 0.03). The interaction appeared to be due to low cleavage and development rates on 1 of 4 collection days (appeared not related to day of oestrous cycle). Although high compared to low AFC heifers had more COC that cleaved (18.7 v. 4.4 ± 1.84 per heifer), the percentage of cleaved COC did not differ (59.2 v. 49.8 ± 3.36%). There were no significant differences between high and low AFC heifers in the number of blastocysts (3.1 v. 0.6 ± 1.21 per heifer) or in the percentage of COC that developed to blastocysts (8.8 v. 5.2 ± 3.60%). In previous replicates (years), we reported that high AFC heifers had more COC collected, more COC that cleaved, and more COC that developed to blastocysts than low AFC heifers. In contrast, in this study numbers of COC that developed to blastocysts did not significantly differ between high and low AFC heifers. Additionally, the percentage of COC that cleaved, and that developed to blastocyst have been similar between high and low AFC heifers. Therefore, high compared to low AFC heifers may produce more IVP embryos; however, AFC does not appear to affect the competence of an oocyte to develop and mature to the blastocyst stage.

Fertility of Libyan Barbary Sheep Treated with Prostaglandin F2α (PGF2α) in Different Seasons

Bearing in mind the objectives of this study to investigate the Barbary sheep fertility under our climatic conditions and to evaluate the efficiency of the prostaglandin F2α (PGF2α) injection in induction of fertile estrus in different seasons. For these objectives some experiments were performed during the period from July 2008 to March 2009. A total number of 300 Libyan Barbary ewes (3 – 6 years old weight 40 – 60 Kg) was used in this experiment. Ewes were kept in privet farms fed and managed similarly. Ewes were divided to four season groups (summer, autumn, winter and spring groups) each season group was divided into treated and control. Animals in the treated groups were injected with double injection of 125μg of prostaglandin F2α intramuscularly (IM) 11days apart. While those in the control groups were injected with two injections of 1.0 ml of 0.9%NaCl saline solution simultaneously with the treated ewes. At the same day (day 11) rams wearing painted sponges on their briskets regions were introduced for natural mating. Treated groups showed shorter estrus response time than control groups in all seasons (P<0.05). Estrus duration was longer in winter and spring than in summer and autumn (P<0.001) but no difference was found between treated and control groups inside seasons. Treated group showed higher pregnancy rate (P<0.001) in winter season than control group. Percentage of ewes lambed in winter was significantly high (P<0.001) among treated ewes than control (80% Vs 38%). Lambing rate differed significantly (P<0.001) among treated groups in all seasons. Data were collected and calculated statistically using SPSS system for percentages, means, standard deviation (mean ±SD) analyses of variance (ANOVA), Chi squire and Duncan's test were used accordingly. Other values were measured, calculated and analyzed similarly.

Improved fertility of cows failing to respond to resynchronization of ovulation through presynchronization of ovulation or progesterone supplementation during Ovsynch

The most widely adopted Resynch program by US dairy herds consists of the initiation of Resynch at 32 d after a previous artificial insemination (AI) regardless of pregnancy status. Seven days later pregnancy status is determined so that non-pregnant cows continue in the protocol to receive their next timed AI (TAI). This program guarantees that cows not detected in estrus are re-inseminated within a specific timeframe after the previous AI (42 ± 3 d if groups of cows are enrolled weekly), reducing the interval between inseminations. Retrospective evaluation of pregnancy per AI (P/AI) for cows that complete the protocol and receive a TAI service has shown that cows without a corpus luteum (CL) at the time of Resynch initiation will have an approximate 50% reduction in fertility when compared with cows that do have a CL. Our objective was to evaluate treatments to increase fertility of TAI services of lactating dairy cows without a CL at the time of the prostaglandin F2α(PGF) injection of Resynch initiated 32 ± 3 d after AI.

Differential changes in luteinizing hormone secretion after administration of the investigational metastin/kisspeptin analog TAK-683 in goats

This study aimed to evaluate the hormonal and ovarian responses to the administration of a metastin/kisspeptin analog (TAK-683) under the endocrine environments of luteal and follicular phases in goats. Five estrous cycling goats received a prostaglandin F2α injection followed by 10 days of progesterone treatment by CIDR. The TAK-683 (35nmol) was intravenously administered (Hour 0) on 3 days after CIDR insertion (luteal phase condition; LC) and at 12h after CIDR removal (follicular phase condition; FC). Blood samples were collected at 10min (−2 to 6h), 2h (6–24h) or 6h intervals (24–48h). In the LC, small increases in the basal concentrations of LH were observed after TAK-683 administration from 0 to 6h, which were associated with an increase in estradiol concentration, followed by a surge-like release of LH with a peak at 12.5±1.0h (n=4) after TAK-683 administration. In the FC, a surge-like release of LH occurred immediately after TAK-683 administration with a peak at 6.0±3.5h (n=5), which was earlier than that in the LC (P<0.01). The peak concentration of estradiol did not differ between the two conditions, whereas the time interval from TAK-683 treatment to estradiol peak in the LC was longer than that in the FC (12.0±0.0 compared with 6.0±4.2h, P<0.05). These findings suggest that the timing of surge-like release of LH after TAK-683 administration is associated with blood estradiol concentration at the time of treatment.

Influence of glucogenic dietary supplementation and reproductive state of dairy cows on the composition of lipids in milk

We studied the effects of the frequently used glucogenic dietary supplementation in dairy herds and the hormonal changes occurring during the normal estrous cycle on the composition and concentration of milk lipid components. Holstein dairy cows were synchronized with two injections of prostaglandin F2α (estrus=day 0). Animals were held as controls or drenched for 11 days (day −3 to day 8 of the cycle) with 850 ml/day liquid propylene glycol (treatment, n=13 per group). Blood and milk samples were collected on day 1 and 8 of the cycle. In both groups, plasma progesterone concentration increased ∼10-fold between 1 and 8 days post-estrus. Milk fatty acid composition was associated primarily with estrous-cycle day: polyunsaturated fatty acids increased by 16%, n-6 by 15% and n-3 by 1% from day 1 to 8 post-estrus. Polar lipid composition was also altered by cycle day: phosphatidylethanolamine concentration was 2-fold and 1.5-fold higher on day 1 v. day 8 post-estrus in the control and treatment groups, respectively. Phosphatidylserine concentration in milk was also affected by cycle day by treatment interaction (P=0.04). A progesterone level by treatment interaction influenced the triglyceride-to-phospholipid ratio in the milk (P=0.02). The results suggest that progesterone plays a role in modulating milk lipid composition and structure. Therefore, strategies designed to alter milk lipid composition should consider the cow’s reproductive status.

Polyunsaturated Fatty Acids Combined with Equine Chorionic Gonadotropin to Enhance Reproductive Performance in Aged Rabbit Does

Sixty low-conception rate does aged 18 to 24 months (in four groups) were used to determine the effect of replacement of prostaglandin (PG) F2α (PGF2α) injection by oral administration with sunflower oil (Sun) (rich in omega 6) or linseed oil (Lin) (rich in omega 3) on reproductive and productive performance. Group 1 was injected with 20 U of equine chorionic gonadotropin (eCG), 54 h before artificial insemination (AI) and used as reference group. Group 2 was injected with 20 U of eCG+0.5 mg of PGF2α, 54 h before AI. Group 3 was orally given 3 mL of Sun/doe/day, for seven consecutive days before AI+20 U of eCG, 54 h before AI. Group 4 was treated like Group 3 except that the oil was Lin. Aged does treated with eCG+Sun had elevated blood 17-β estradiol concentration (P≤0.01) accompanied with a decrease of progesterone concentrations compared to the other experimental groups. Contrarily, no significant differences were found between eCG+Lin and eCG+PGF2α treatments on the previous two hormones. Likewise, aged does treated with eCG+Sun and eCG+Lin were statistically similar to those injected with ECG+synthetic PGF2α on blood prostaglandin profile, but still significantly higher than the control group. Treatment with eCG+Sun increased the percentage of fertile does (P≤0.01) and the litter size at birth compared to the other experimental groups. In conclusion, replacement of the PGF2α injection by oral administration of Sun or Lin to aged does improved sexual hormone synthesis and secretion, litter size and bunny body weight at birth.

Efficacy of a Cue-Mate Intravaginal Insert and Injection of Prostaglandin F2α for Synchronizing Estrus in Hanwoo Cattle

The present study was performed on farm animals to test the effectiveness of progesterone-releasing intravaginal device (Cue-Mate® 1.56 g) and injection of prostaglandin F2α (PGF2α) for synchronization estrus in Hanwoo cattle. The cattle were at random stage of the estrus cycle. The cows were artificially inseminated at day 7 after Cue-Mate withdrawal, using commercial semen from Korean native bulls. There was a season effect on the estrus synchronization rate. It was higher in spring (94.3%) followed by winter (93.3%), autumn (90.4%) and summer (67.2%). In summary, The results of this study revealed that season has influences on estrus behavior of cattle with no significant effect on pregnancy rate. In summary, we suggest summer reproductive management to alleviate the effects of heat stress. It should be based on intensive cooling combined with hormonal treatment. Given that different subgroups of cows benefit differently from the treatments, selective hormonal administration should be considered.

349 SUPEROVULATORY RESPONSE AND EMBRYO QUALITY RECOVERED FOLLOWING FLUSHING NGUNI HEIFERS AND COWS

Most of the South African indigenous cattle breeds are facing genetic degradation due to unselective crossbreeding and irregular matings especially in small scale farming. The aims of the study were to compare superovulatory (SO) response, fertilization rate and to evaluate embryo quality recovered from superovulated Nguni stud cows and heifers. Nguni stud cows (n = 15) and heifers (n = 10) aged 4–6 and 2 years, respectively, were used as embryo donors for ex situ conservation. Nine days following heat observation for the first oestrus synchronisation protocol, superstimulation of donor cows and heifers were administered with a total of 350 mg of FSH (Follotropin-V®, porcine pituitary glands extract) divided into 2 injections daily 12 h apart (6 a.m. and 6 p.m.) for 4.5 days on a decreasing dosage. Two injections of prostaglandin F2α were administered on Day 3 and 4 of FSH injections. Semen was collected from 2 Nguni bulls (bull 1 and 2) and assessed by computer aided sperm analysis before artificial insemination (AI). The AI was conducted with fresh semen 3 times, 12 h apart, and the first AI was performed at the onset of oestrus. Semen from bull 1 was used to inseminate the cows, and bull 2 was used for heifers. Embryos were flushed 7 days after AI using a nonsurgical technique. Embryos were evaluated under stereo microscope and classified according to IETS standard codes (code 1, good and excellent; code 2, fair). Recovered embryos were then vitrified and stored for future use. Superovulatory response was measured by counting number of corpus lutea in each ovary. Data were analysed using 1-way ANOVA (SAS, 2003, SAS Institute Inc., Cary, NC, USA). There was no statistical difference between bull 1 (93.7%) and bull 2 (83.5%) on total sperm motility rate. Furthermore, no significant differences were recorded on fertilization rate between cows (67.5%) and heifers (53.5%). There was also no significant difference on the proportion of Nguni cows (40%) and heifers (40%) that responded to superovulation treatment. There was a significant difference on the ovary reaction (number of corpus lutea) of cows (11.3 ± 1.41) and heifers (4.0 ± 0.57). There were no significant differences recorded on the embryo quality recovered between Nguni cows (code 1, 2.5 ± 1.00; code 2, 1.3 ± 0.59) and heifers (code 1, 0.8 ± 0.41; code 2, 1.0 ± 0.36). However, cows had higher numbers of unfertilized ova than heifers (5.5 ± 1.05 and 1.8 ± 0.47, respectively) and degenerate embryos (3.7 ± 1.00 and 1.3 ± 0.39, respectively). Although superovulatory response of both Nguni cows and heifers was low, Nguni cows had higher ovarian response than heifers. Moreover, the quality of embryos recovered was similar for both Nguni cows and heifers.

176 BLOOD FLOW TO THE CORPUS LUTEUM AND PREOVULATORY FOLLICLE AFTER OVULATION INDUCTION DURING FIRST VERSUS SECOND WAVE IN WATER BUFFALO

The objective of the study was to compare the blood flow to the corpus luteum (CL) and the preovulatory follicle in dairy buffalo (Bubalus bubalis) when ovulation was induced during the first (low to increasing progesterone levels) versus the second (luteal progesterone levels) follicular wave. We hypothesised that the wall of the first-wave dominant follicle will be less vascular compared with that of the second-wave follicle. The study was conducted during the summer months in Punjab, India. Ovulation was synchronized with prostaglandin F2α (PGF) IM followed by gonadotropin-releasing hormone (GnRH) IM 48 h later (Day 0) and buffaloes were randomised to first wave (FW; n = 6) and second wave (SW; n = 7) groups. FW group was given PGF on Days 6.5 and 7, and GnRH on Day 9.5 followed by AI (14–16 h after GnRH). The SW group was given GnRH on Day 7 (to induce ovulation of first-wave dominant follicle without luteolysis and synchronous emergence of next wave), PGF on Days 13.5 and 14, GnRH on Day 16.5 followed by artificial insemination. Transrectal colour Doppler ultrasonography (MyLab5 Vetwith 7.5 MHz transducer, Esaote S.p.A, Genoa, Italy) was performed daily and 20-s cineloops of each ovary were recorded under standardized gain controls. Images from the cineloops were processed using Fiji (ImageJ, National Institutes of Health, Bethesda, MD, USA) to calculate the area of blood flow (coloured area = vascular area, grey scale area = tissue area, and their ratio) for the preovulatory follicle (on the day before ovulation) and luteal tissue (on the day of PGF injection and 4 days post-ovulation). Data were analysed by t-test from the animals that ovulated one day before (n = 3) or the day of AI (n = 6) and had a functional CL at day 5 post-AI (FW n = 5, SW n = 4). FW follicles ovulated on 8.6 ± 0.3 days from wave emergence compared with SW follicles on 10.0 ± 0.6 days (P &lt; 0.05) but were similar in size (i.e. follicular area on the day before ovulation did not differ between groups; P = 0.5). There was no difference in the blood flow area in the wall of preovulatory follicles (P = 0.4). Vascular area of follicles was strongly correlated with their diameter (r = 0.87). Follicles &gt;13.5 mm in diameter had more blood flow in their wall than smaller follicles (P &lt; 0.01). FW had a tendency (P = 0.07) for smaller luteal area on the day of PGF treatment (FW = 171 ± 24 mm2; SW = 332 ± 81 mm2) and tended (P = 0.06) to have less vascular area in the CL compared to SW group (FW = 30 ± 6 mm2; SW = 67 ± 17 mm2). There was no difference (P = 0.5) between the groups for vascular to CL area ratio. The area of luteal tissue and blood flow to the CL at Day 4 post-ovulation did not differ between the groups (P = 0.4). The diameter of the preovulatory follicle (11.6–15.7 mm) was not correlated with the cross-sectional area of developing CL at Day 4 post-ovulation (r = 0.09). In conclusion, vascularity to preovulatory follicles originating from the first wave v. second wave did not differ and preovulatory follicles ≥13.5 mm were more vascular than smaller follicles. Research was funded by NSERC; the first author was funded by scholarships from WCVM and GADVASU.

Follicle Stimulating Hormone (FSH) Dosage Based on Body Weight Enhances Ovulatory Responses and Subsequent Embryo Production in Goats.

An experiment was conducted to evaluate the efficacy of porcine follicle stimulating hormone (pFSH) dosage based on body weight (BW) on ovarian responses of crossbred does. Thirty donor does were divided into 3 groups getting pFSH dosages of 3, 5, and 8 mg pFSH per kg BW, respectively, and were named as pFSH-3, pFSH-5 and pFSH-8, respectively. Estrus was synchronized by inserting a controlled internal drug release (CIDR) device and a single injection of prostaglandin F2α (PGF2α). The pFSH treatments were administered twice a day through 6 decreasing dosages (25, 25, 15, 15, 10, and 10% of total pFSH amount; decreasing daily). Ovarian responses were evaluated on Day 7 after CIDR removal. After CIDR removal, estrus was observed 3 times in a day and pFSH treatments were initiated at 2 days before the CIDR removal. All does in pFSH-5 and pFSH-8 showed estrus signs while half of the does in pFSH-3 showed estrus signs. No differences (p>0.05) were observed on the corpus luteum and total ovarian stimulation among the treatment groups, while total and transferable embryos were higher (p<0.05) in pFSH-5 (7.00 and 6.71) than pFSH-3 (3.00 and 2.80) and pFSH-8 (2.00 and 1.50), respectively. In conclusion, 5 mg pFSH per kg BW dosage gave a higher number of embryos than 3 and 8 mg pFSH per kg BW dosages. The results indicated that the dosage of pFSH based on BW is an important consideration for superovulation in goats.

The effects of intramuscular or intravenous injections of gonadotropin releasing hormone at fixed-time artificial insemination on pregnancy rates of Bos indicus beef cows

The effect of an intramuscular versus intravenous administration of gonadotropin releasing hormone (GnRH) at fixed-time AI (FTAI) on the pregnancy rates of crossbred Bos indicus beef cows was evaluated. Pluriparous nursing calv cows (n=120) were synchronized as follows: d 0 cows received a 2.0 mg injection of estradiol benzoate (EB) and insertion of a controlled intravaginal progesterone releasing device containing 0.558 g of progesterone, d 8 removal of the progesterone device , a 0.15 mg injection of prostaglandin F2α (PGF), a 1.0 mg injection of EB, and 400 IU injection of equine chorionic gonadotropin. Fifty-four hr after PGF, all cows were exposed to FTAI and a 0.084 mg injection of GnRH was administered either via Vena caudalis (n=60), or via Longissimus dorsi (n=60). Cows were inseminated with the same sire and by a single AI technician. Pregnancy was determined by the transrectal ultrasonography on d 40 after AI. Cows receiving the intravenous administration of GnRH had higher (P = 0.04) pregnancy rates than the cows receiving the intramuscular injection of GnRH (65 vs 46.6%, respectively). It was concluded that the intravenous administration of GnRH at the time of AI improved the pregnancy rates of crossbred Bos indicus beef cows submitted to FTAI.

Effect of mammary stimulation on dairy cows and heifers exposed to a lactation induction protocol

Cows (n = 21), dried off for a minimum of 45 days, and nulliparous heifers (n = 26), at ages > 18 months old, were placed on a 12-day Lactation Induction (LI) protocol. One group of animals (including both cows and heifers) received 3-minute mammary gland stimulation, along with the LI protocol. Another group, again including both cows and heifers, received no stimulation only the LI protocol This consisted of two injections of prostaglandin F2α (PGF2α; 25 mg) 11 days apart, followed by subcutaneous injections of 17β-estradiol (0.1 mg/kg BW/d) and progesterone (0.25 mg/kg BW/d) beginning 1 day later and continuing for seven (7) days. After this step, all animals received another injection of PGF2α on day 8, followed by intramuscular injections of reserpine (5 mg/d) and dexamethasone (20 mg/d) on each of days 9 to 12. All animals were milked, beginning on day 13, for a period of 154 days. For all animals, the success rate for lactation induction was 78% ± 6.3% and the mean weekly milk yield was 78.2 kg. Neither value was affected by mammary stimulation. Parity did not significantly impact on the success rate but it did affect the mean weekly milk yield. Milk yield varied significantly (p α = 0.05 level) affected by stimulation or by parity. However, heifers (at 8.2 weeks ± 1.0 week) tended (p = 0.1) to reach peak milk production earlier than cows (at 10.7 weeks ± 1.3). The milk produced was sold at a net profit per animal treated of $2206.31 TT. Hence, one can conclude that a Lactation Induction protocol can be a useful management tool to increase production and profitability of dairy operations in the tropics.

7 OESTRAL RESPONSE AND FERTILITY IN DAIRY COWS TREATED WITH PROGESTERONE FOR 6 DAYS PRIOR TO OESTRUS SYNCHRONIZATION WITH PROSTAGLANDIN F2α

The present study tested whether the increase in serum progesterone concentrations for 6 days before oestrus synchronization with prostaglandin F2α (PGF2) increases oestral response, pregnancy rate, and reduces the incidence of twin births in dairy cattle. Seven hundred and eighty-three first-service dairy cows were synchronized with 2 injections of PGF2 14 days apart, starting on Day 35 postpartum. Six days before the second PGF2 injection, cows were assigned to 2 groups: P4 and control. The P4 group (n = 387) received a progesterone-releasing intravaginal device and an intramuscular injection of 500 mg of progesterone. The control group (n = 396) did not receive the progesterone-releasing intravaginal device or progesterone injection. Cows were inseminated 12 h after exhibiting oestrus. Pregnancy diagnosis was performed 40 and 45 days after insemination by rectal palpation and the cumulative pregnancy rate on Day 90 postpartum was determined retrospectively through the individual records. The response to the progesterone treatment varied according to the parity of the cows (P &lt; 0.05). Thus, progesterone administration improved the percentage of cows detected in oestrus in multiparous [192/255 (75.2%) v. 161/267 (60.2%)] but not in primiparous [93/132 (70.4%) v. 90/129 (69.7%)] cows. Progesterone treatment increased pregnancy rate in multiparous [53/192 (27.6%) v. 27/161 (16.7%)] but not in primiparous cows [25/93 (26.8%) v. 29/90 (32.2%)]. Likewise, progesterone administration increased the cumulative percentage of pregnant cows on day 90 postpartum in multiparous [149/255 (58.4%) v. 129/267 (48.3%)] but not in primiparous cows [77/132 (58.3%) v. 82/129 (63.5%)]. The incidence of twin births was lower (P = 0.07) in cows treated with progesterone [1/74 (1%)] than in the control group [4/53 (7%)]. It is concluded that progesterone administration before oestrus synchronization with PGF2 in first service dairy cows improves oestral response, increases pregnancy rate, and percentage of pregnant animals on Day 90 postpartum in multiparous cows, but not in primiparous cows, and decreases the incidence of twin births. This research was supported by PAPIIT-UNAM research grant (IN219811-3).

9 EFFECT OF TIMING OF INSEMINATION WITH SORTED SEMEN ON SUBSEQUENT PREGNANCY RATE IN POSTPARTUM BEEF COWS SYNCHRONIZED WITH A MODIFIED 14-DAY PROGESTERONE PROTOCOL

A study investigated the effect of AI timing on pregnancy rate when using X sorted semen, and whether prostaglandin F2α (PGF2) injection on Day 7 of a modified 14-day progesterone (P4) protocol improved oestrous response in beef cows. Angus-based cows were allotted across treatment groups by cyclicity, parity, weight, body condition, and days postpartum. Treatment 1 (n = 132) cows received a CIDR P4 insert (Eazi-Breed CIDR, Pfizer Animal Health, Groton, CT, USA) on Day 0, with CIDR removal on Day 14, followed by 100 μg of gonadotropin-releasing hormone (GnRH; Factrel, Pfizer) on Day 16, and 25 mg of PGF2 (Lutalyse, Pfizer) on Day 23. Treatment 2 (n = 132) cows received the same synchronization treatment, except for an additional 25 mg dose of PGF2 given on Day 7 of CIDR treatment. Cows were observed for oestrus over an 84-h period and inseminated with X-sorted semen at 9 to 14, 15 to 17, 18 to 21 or 22 to 24 h after detected oestrus, followed 10 days later by exposure to fertile bulls for 45 days. Ultrasonography was used to determine pregnancy status ~45 days after AI and again 45 to 55 days after bull removal. Chi-squared analysis was used to determine the effects of treatment on oestrus response, AI pregnancy, and seasonal pregnancy rates, and the effect of AI timing on pregnancy rate. Analysis of variance was used to determine the effects of treatment on the interval from PGF2 dosing to detected oestrus. Oestrus response to synchronization treatment was similar (P = 0.33) at 76.5 and 71.2% for cows in Treatments 1 and 2, respectively. The mean interval from PGF2 to the onset of oestrus was extended (P = 0.03) ~3 h for cows in Treatment 2 (57.4 v. 54.3 h, respectively). About two-thirds of the cows in each treatment were cyclic at the start of synchronization. The extended interval from PGF2 to observed oestrus was due to an effect on cyclic, but not acyclic, cows in Treatment 2. Of the cows expressing oestrus, 69 and 89% expressed oestrus 48 to 72 h post-PGF2 in Treatments 1 and 2, respectively. Pregnancy rates after AI with sorted semen were similar (P = 0.64) at 63.3 and 66.7% for Treatments 1 and 2, respectively. No differences (P = 0.98) were detected in AI pregnancy rates for insemination intervals ranging from 9 to 24 h after detected oestrus. At the end of the breeding season, seasonal pregnancy rates were also similar (P = 0.74), at 83.3 and 84.9% for cows in Treatments 1 and 2, respectively. The addition of a PGF2 treatment on Day 7 of our 14-day CIDR-based protocol was expected to ensure all cows has sub-luteal P4 concentrations and would develop a persistent follicle capable of ovulation in response to GnRH given on Day 16. Whereas the Day 7 PGF2 treatment had no effect on oestrus response or pregnancy rate, it did result in a more synchronous oestrus within a 24-h period. Results indicate that acceptable pregnancy rates can be achieved in lactating beef cows when using sorted semen over a range of insemination times.

142 EFFECT OF HIGH AND LOW ANTRAL FOLLICLE COUNT IN PUBERTAL BEEF HEIFERS ON IVF

Pubertal heifers can be classified between those with high (n = 25) or low (n = 15) antral follicle counts (AFC). The objective of this study was to determine oocyte development and maturation (e.g. fertility) in an IVF system for high- and low-AFC heifers. From a pool of 120 heifers, 10 high- and 10 low-AFC heifers were determined by transrectal ultrasonography; all heifers with evidence of oestrous cyclicity (i.e. pubertal) were synchronized with two 5-mL injections of prostaglandin F2α 11 days apart. Heifers were euthanized over 4 days on Days 15 to 16 of the synchronized oestrous cycle. A total of 15 heifers (n = 7 high and n = 8 low AFC) were at the appropriate stage of the oestrous cycle. Ovaries were collected and transported to the laboratory. Follicles less than 8 mm in diameter were aspirated. The IVF procedures and media were as previously described (Miles et al. 2004. Biol. Reprod. 71, 1919–1926). Cumulus-oocyte complexes (COC) were identified and washed in oocyte collection medium and then in maturation medium and were cultured (5% CO2; 38.5°C) for 24 h. Following maturation, COC were transferred and washed in fertilization medium. Thawed frozen semen from a crossbred bull was subjected to the swim-up procedure. Motile spermatozoa were collected and added to COC to yield a final concentration of spermatozoa per milliliter of fertilization medium. About 24 h later, presumptive zygotes were washed in development medium, placed in microdrops of development medium, and cultured for 8 days. On Days 3 and 8 after fertilization, cleavage and blastocyst development, respectively, were assessed. Data were analysed using the Proc Mixed procedure of SAS (SAS Institute Inc., Cary, NC, USA) and the model included the effects of day of collection (n = 4), group (n = 7 high- or n = 8 low-AFC heifers), and the interaction. The interaction did not differ (P = 0.10). Day of collection influenced (P &lt; 0.05) the number of COC and the number of oocytes cleaved. High- compared to low-AFC heifers had the greater (P &lt; 0.05) numbers of COC (42.7 ± 4.66 v. 22.1 ± 4.59), oocytes that cleaved (28.1 ± 3.60 v. 15.9 ± 3.55), and developed to blastocysts (13.2 ± 1.71 v. 6.2 ± 1.69). However, there was no difference (P &gt; 0.10) in the percentage of COC that cleaved (65.3 ± 5.58 v. 66.2 ± 5.50%, high v. low, respectively) or that developed to blastocysts (46.7 ± 6.75 v. 42.2 ± 6.65%). In conclusion, AFC did not appear to affect oocyte maturation and development through the blastocyst stage.

Preliminary studies on synchronization of estrus with double injection of prostenol in dwarf does (Capra hircus) and role of macro minerals in estrus

A study was conducted to examine the efficacy of prostenol for synchronizing estrus in dwarf goats (Capra hircus) and role of concentration of macro minerals during estrus phase. A lot of goats (n=8) were selected from the flock maintained at Nuclear Institute for Agriculture and Biology (NIAB) Farm, Faisalabad on the basis of their post-partum period >2 months. Goats (n=5) were given 2 prostenol (an analogue of prostaglandin F2α (PGF2α) injections of 125 µg/animal), 12 days apart while 3 goats were kept as control. The does responded double injection at an interval of 15 days, because of immaturity of follicles. A teaser buck was introduced in the herd for estrus detection and visual symptoms were also observed. Blood sampling was carried out during estrus phase for sodium, potassium and phosphorus determination. Estrus was observed after 48 to 96 h with a mean time of onset of estrus at 72 ± 33 PGF2α injection. Estrus was observed in all treated goats (100% response) while no estrus was exhibited by any animal of the control group, because they were not injected by injection (PGF2α). Regarding macro-minerals, potassium in estrus was found to be higher (10.83 ± 1.89 ppm) in treated animals as compared to that of the control animals, while sodium and phosphorus levels were found to be the same in treated as well as control groups. It was concluded that double injection of prostenol (125 µg/animal) was efficient in synchronizing estrus in goats and potassium might have some important role during estrus phase in goats. Key words: Estrus synchronization, goats, prostaglandins, macro-minerals.

Effect of short‐term supplementation with rumen‐protected fat during the late luteal phase on reproduction and metabolism of ewes

This study was designed to study the effect of short-term supplementation with rumen-protected fat during the late luteal phase on reproduction and metabolism of sheep during breeding season. Seventy-six ewes (Rahmani, Barki and Awassi×Barki) were allocated to two groups considering genotype: the control ewes (C-group) received a maintenance diet, and the fat-supplemented ewes (F-group) received the maintenance diet plus 50g/head/day of rumen- protected fat (Megalac) for 9days during which oestrus was synchronized. The latter had been accomplished using double intramuscular injection of prostaglandin F2α (PGF2α ) 11days apart. Ovarian activity, serum concentration of cholesterol, glucose, insulin and reproductive performance variables were recorded. Data were analysed considering treatment (group) and genotype. Supplementation had positive effects on the overall mean serum concentrations of cholesterol (p<0.05), glucose (p<0.05) on day 6 of nutritional treatment and insulin (p=0.07) on day 8. Fat supplementation did not affect the total number of follicles, follicle populations and ovulation rate. However, fat-supplemented Rahmani ewes tended to have higher ovulation rate compared with other breeds (treatment×breed interaction, p=0.06). Treatment also did not affect the mean concentration of serum estradiol or progesterone. Supplemented ewes had higher conception (p=0.06) and lambing rates (p<0.05) compared with control. In conclusion, short-term supplementation with rumen-protected fat as a source of energy around breeding time improved metabolism, conception and lambing rates of ewes without effects on steroidogenic capacity and ovarian activity being apparent.

Daily or thrice weekly handling of eland antelope (Taurotragus oryx): Effects on serum cortisol level

We evaluated the cortisol response of adult female eland (n=8) that were handled in hydraulic chute daily or 3×/week. Females were divided into two groups and each group (n=4) successively received two estrous cycle synchronization treatments: (1) two injections of prostaglandin (PG–PG) F2α at 11day intervals and (2) oral administration of altrenogest for 7days and an injection of PGF2α on day 7 (Alt–PG). Blood samples were collected 3×/week during the synchronization (Synch) and expected luteal phase (Nonintensive) periods, and daily during the expected time of induced (Intensive 1) or natural (Intensive 2) estrus. Overall, mean cortisol levels were highest during Intensive 1, followed by Intensive 2, Synch and Nonintensive periods. Individual eland were the most significant source of variation for cortisol level. The frequency of handling and the synchronization treatment significantly affected cortisol levels in 3/8 and 4/8 females, respectively. In conclusion, in response to increased frequency of handling, eland cortisol levels rose transiently and returned to baseline within few days after more intensive handling. Thus, the eland females were tolerant to and recovered from the effects of repeated daily handling.

Concentrations of luteinizing hormone and ovulatory responses in dairy cows before timed artificial insemination (2013)

The objective of this study was to determine the incidence of spontaneous and gonadotropinreleasing hormone (GnRH)-induced surges of luteinizing hormone (LH) and ovulatory responses in lactating dairy cows enrolled in a timed artificial insemination (TAI) protocol. Cows (n = 70) in a single herd were assigned to one of two presynchronization protocols: Pre- 10 or PG-3-G. Cows assigned to the Pre-10 treatment received 2 injections of prostaglandin F2α(PGF2α) 14 days apart (Presynch), with the second injection administered 10 days before the onset of a TAI protocol. Cows assigned to the PG-3-G treatment received an injection of prostaglandin F2α(PGF2α), then 3 days later an injection of GnRH (GnRH-1) 7 days before the onset of a TAI protocol. All cows received the first GnRH injection (GnRH-2) of the Ovsynch protocol and a PGF2αinjection 7 days later, then cows received the breeding injection of GnRH (GnRH-3) at either 56 or 72 hours after PGF2α, with insemination occurring 12 to 16 hours after the second GnRH injection. Blood samples were collected during the study to monitor serum changes in LH, progesterone, and estradiol to determine why ovulatory responses to GnRH-induced LH release did not approach 100% when follicle dominance and adequate follicle size was achieved. Presynchronization administration of GnRH-1 increased the incidence of LH surges and ovulation rates in cows presynchronized with PG-3-G compared with Pre-10. Incidence of ovulation and occurrence of LH surges did not differ after GnRH-2, but more LH was released in Pre-10 than PG-3-G cows. Luteolysis, LH surge incidence, and ovulation rates were similar among the 4 treatment-time combinations after GnRH-3. Pregnancy per TAI was decreased in Pre-10 at 56 hours compared with Pre-10 at 72 hours and PG-3-G at 56 and 72 hours. We concluded that administration of GnRH 56 hours before breeding decreased pregnancy per TAI compared with administration of GnRH at 72 hours when cows were presynchronized with Pre-10. Presynchronization with PG-3-G resulted in acceptable pregnancy per TAI with GnRH administration occurring at either 56 or 72 hours before TAI. The flexibility of GnRH timing with the PG-3-G presynchronization protocol may be an advantage compared with the Pre-10 protocol for dairy cattle when programmed for a TAI at first service.; Dairy Day, 2013, Kansas State University, Manhattan, KS, 2013; Dairy Research, 2013 is known as Dairy Day, 2013

Periconceptional growth hormone treatment alters early uterine environment

We have shown that an injection of sustained release growth hormone (GH), given just prior to breeding, results in lambs that are 25% heavier at birth, with an altered body composition as evidenced by an increased abdominal girth, but no difference in crown rump length. The mechanisms by which these differences occur from a single periconceptional injection are not yet known. Therefore, the objective of this experiment was to determine the effect of an injection of GH given prior to breeding on the composition of the uterine luminal environment and the embryo at the time of blastocyst. Ewes were synchronized with two injections of prostaglandin F2α given eight days apart. On the day of the second injection, ewes were randomly assigned to be given an injection of sustained release GH or remain as controls and penned with a ram. On day 6.5 following breeding embryos were collected. Prior to surgery a jugular blood sample was taken to determine plasma progesterone and urea concentration. The uterine content of urea, prostaglandin F2α, prostaglandin E2, transforming growth factor β-1 (TGF β), and nitric oxide metabolites were measured. Collected embryos were differentially stained to calculate a trophectoderm to inner cell mass ratio. The concentration of progesterone in maternal plasma was greater in the treated group compare to controls, but blood urea nitrogen was not different between groups. The uterine content of urea in the GH group was lower than that of the control group. There was a trend for TGF β to be increased in the GH treated group compared to control (P = 0.07). There was no difference (P > 0.05) in the total uterine content prostaglandin F2α, prostaglandin E2 or nitric oxide metabolites. The trophectoderm to inner cell mass ratio was not different between treatment groups. Thus, we suggest that the observed difference in fetal development following periconceptional growth hormone administration just prior to breeding may be the result of an alteration in the uterine luminal environment, which may alter the cellular program of the conceptus and later development beyond the embryonic stage.