Sex-sorted Semen Research Articles

Corpora lutea affect in vitro maturation of bovine cumulus-oocyte complexes and embryonic development after fertilization with sex-sorted or conventional semen.

Influence of both the presence of a corpus luteum on the ovary and semen sex-sorting on development following in vitro fertilization is not yet conclusive. To determine the effect of these factors, 376 bovine oocytes were processed in vitro according to luteal presence on the ovary (CL+ and CL-) and type of semen used (sexed or conventional). Maturation rate was higher (P < 0.01) in CL- (136/138; 98.6%) than in CL+ (217/238; 91.2%). Cleavage rate was lower (P < 0.01) in CL+ with sexed semen (60/172; 34.9%) than in CL- with sexed semen (42/71; 59.1%), CL+ with conventional semen (47/66; 71.2%), and CL- with conventional semen (54/67; 85.1%). Compaction was similar (P = 0.69) in CL- (49/99; 49.4%) and CL+ (50/107; 46.7%). Blastulation rate was higher (P < 0.01) in CL- (26/99, 26.2%) than in CL+ (13/107; 12.1%) group. Expansion rate was higher (P = 0.01) in CL- (22/99; 22%) than in CL+ (11/107; 10.2%) group. Compaction rates were similar (P = 0.78) in sex-sorted (50/102; 49.0%) or conventional semen (49/104; 47.1%) groups. Blastulation was also similar (P = 0.91) with sex-sorted semen (19/102; 18.6%) and conventional semen (20/104; 19.2%). The rate of expanded blastocysts was similar (P = 0.89) in sex-sorted (16/102; 15.6%) and conventional (17/104; 16.3%) semen groups. In conclusion, the presence of CL can compromise maturation of the oocytes and their development, as a higher proportion of cleavage-stage embryos can be obtained with non-sexed semen with oocytes from ovaries without a CL.

Remote monitoring system as a tool for calving management in Mediterranean Buffalo heifers (Bubalus bubalis).

Buffalo breeding is common in Southern Italy. Dystocia compromises dam's and newborn health and welfare. Difficult parturition could be solved through prompt calving assistance, even if the identification of the beginning of delivery is challenging. Herein, we aimed to evaluate a remote calving alarm system in 15 Mediterranean buffalo heifers. An intravaginal probe was placed close to the external cervical os once premonitory signs of delivery were observed. No vaginal discharge nor signs of discomfort were notified in the days following the insertion of the probe. Heifers calved from 48 to 72hr after the alarm was activated. The system correctly warned the farm personnel at the beginning of stage II of parturition, except for 2 cases. In the former, the intravaginal probe was expelled but the poor carrier network coverage negatively affected phone's signal quality; in the latter, recurrent vaginal prolapse was responsible for non-retention of the probe. Overall median expulsive phase was 68±8min, while the expulsion of a female calf took 54±22.0min and 90±34.0min in males, with significant difference (p=.02). Deliveries were homogeneously distributed across a 24-hr interval. No retention of foetal membranes nor metritis was identified at postpartum clinical examination. The calving alarm system used in this work was well tolerated in buffalo heifers. The introduction of smart technology in buffalo farming could contribute to the overall farm net return by reducing calf losses, especially for calves born from sexed-sorted semen, and by increasing animal welfare through quick resolution of dystocia. Further studies will be necessary to evaluate the net return in buffalo farms which will implement a remote calving alarm system on a wider population.

In Memoriam: Duane L. Garner, PhD.

In Memoriam: Duane L. Garner, PhD.

Performance and optimization of an ear tag automated activity monitor for estrus prediction in dairy heifers

The objectives of this study were to evaluate the performance of the SCR eSense ear tag automated activity monitor (AAM) to detect estrus behavior in Holstein heifers and to determine the optimal time from estrus alert to artificial insemination (AI) using sex-sorted or conventional semen. In total, 281 heifers were fitted with the AAM once eligible for breeding (>13.5 m of age). For the first AI, estrus was synchronized using 500 μg of cloprostenol (PGF), given 14 d apart, and heifers were given estrus detection patches (Estrotect™) after the second PGF. Heifers were inseminated at randomly attributed times after high activity alert from the AAM system or if the estrus patch had ≥ 50% colour change. Most heifers received sex-sorted semen for the first AI and conventional semen for subsequent inseminations. Pregnancy diagnosis was performed at 30 d post AI and heifers had four opportunities to become pregnant. In a subset of heifers (n = 149), ovaries were scanned every 12 h from the time of AI until ovulation (OV). The system recorded a heat index (measure of estrus strength), maximum activity change, maximum rumination change and duration of high activity. The sensitivity was 91.0%, with a false positive and false negative rate of 8.0%, and the positive predictive value to detect true estrus events was 83.5%. Pregnancy per AI to first AI was 67.6% and 97.9% of heifers become pregnant after four inseminations. Most false positive estrus events had a heat index < 45 and a rumination change < -20, while false negative events had a rumination change ≥ -20. Odds of pregnancy was not associated with any estrus characteristics measured by the system. However, pre-ovulatory follicle diameter had a weak correlation (r < 0.25) with all estrus characteristics. The average (range) interval of onset of high activity, peak activity and end of high activity to OV was 28 h (16–46 h), 22 h (10–40 h) and 16 h (0–36 h), respectively. For conventional semen, each hour increase in interval from activity onset or peak activity to AI reduced the predicted probability of pregnancy by 3.8 and 4.2%, respectively. For sex-sorted semen, the relationship between activity onset or peak activity to AI and predicted probability of pregnancy was quadratic, but not significant. Overall, the SCR eSense ear tag AAM performed well and strategies to identify false positive and false negative estrus events, along with optimization of timing of AI, should further improve performance in Holstein heifers.

Adoption of Breeding and Calf Rearing Practices in Modern Dairy Farms of Gujarat

A study was carried out to compare the breeding and calf rearing practices of modern specialized dairy farms of north and south Gujarat. The data was collected from ten specialized dairy farms, each from the north and south Gujarat. The study revealed that farms of the southern region mostly reared buffaloes, which relied on natural service, whereas northern farms mostly reared cows, and AI was more popular. Around 22.2 and 16.7% of dairy farms preferred pedigreed and sex-sorted semen from the private sector, respectively. Most of the dairy farms (60%) purchased frozen semen doses from the co-operative sector. About 20% of dairy farms used sex-sorted semen at the price of Rs. 2100-3000 per dose. One farm from the north and another one from south were using Delaval® heat detector system. The majority (75%) of the dairy farms adopted the practice of colostrum feeding by allowing for natural suckling. The majority (70%) of the dairy farms provided first colostrum feeding within 2 to 4 hours of calf birth. Some dairy farms (20%) possessed individual calf boxes. From the research finding, it can be concluded that artificial insemination was more famous in north Gujarat. Many specialized dairy farms of north Gujarat were adopting most advanced breeding practices by the use of sex-sorted and pedigreed semen of private companies to produce an offspring of the desired sex, high milk yielding potential and healthy one.

Optimization of timing of insemination of dairy heifers inseminated with sex-sorted semen

We hypothesized that delaying by approximately 12 h the artificial insemination (AI) of heifers with sex-sorted semen increases pregnancy per AI (P/AI). Holstein heifers (n = 1,207) were fitted with a collar containing an automated estrus-detection device (HR-LDn tags, SCR Engineers Ltd., Netanya, Israel) at 10.7 ± 0.02 mo of age. Once they reached 330 kg, heifers were enrolled in an ovulation synchronization protocol (5-d Cosynch + controlled internal drug release; Zoetis, Parsippany-Troy Hills, NJ). Study personnel recorded the heifers that were in estrus according to the DataFlow II software (SCR Engineers Ltd., Netanya, Israel) twice daily at 0500 and 1500 h from the day of the first PGF2α (Estrumate; Merck Animal Health, Madison, NJ) injection to 72 h later. Heifers enrolled in the conventional (CONV) and early sex-sorted (SSEarly) semen treatments detected in estrus at 0500 and 1500 h were AI at 0600 and 1600 h of the same day, respectively. Heifers enrolled in the late sex-sorted (SSLate) semen treatment detected in estrus at 0500 and 1500 h were AI at 1600 h of the same day and 0600 h of the following day, respectively. All heifers not detected in estrus by 72 h after the first PGF2α injection received a GnRH (Fertagyl; Merck Animal Health, Madison, NJ) injection at 0500 h. Heifers in the CONV and SSEarly treatments were AI at fixed time at 0600 h, whereas heifers in the SSLate treatment were AI at fixed time at 1600 h. Among heifers detected in estrus, the ranges of the interval from the onset of estrus to AI were 3.6 to 28.5 h, 0.0 to 25.5 h, and 9.4 to 36.8 h for the CONV, SSEarly, and SSLate treatments, respectively. Among heifers AI at fixed time, the ranges of the interval from the GnRH injection to AI were 0 h for heifers in the CONV and SSEarly treatments and 8.5 to 11.7 h for heifers in the SSLate treatment. The P/AI at 62 ± 1 d after the first AI was greater for CONV (63.1 ± 2.6%) compared with SSEarly (43.3 ± 2.6%) and SSLate (44.8 ± 2.7%). A greater percentage of heifers enrolled in the SSEarly (65.8 ± 2.5%) and SSLate (70.0 ± 2.5%) treatments produced a live female calf compared with the CONV treatment (40.5 ± 2.7%). When the values of 1-d-old female and male calves were USD $0 and the cost of replacement heifers was $750, the cost of raising heifers from enrollment to calving was lesser for the CONV treatment than the SSEarly treatment, but SSLate treatment did not differ from CONV and SSEarly treatments. When the values of a 1-d-old female calf ≥$130 and 1-d-old male calf ≥$30 and the cost of replacement ≥$1,000, no differences were observed among treatments in the cost from enrollment to calving. We conclude from this experiment that the P/AI with sex-sorted semen is not improved when insemination is delayed by approximately 12 h.

102 The National Center for Applied Reproduction and Genomics (NCARG) in Beef Cattle: supporting improvements in reproductive management

Abstract Limited transfer of existing and emerging reproductive technologies to beef cattle enterprises precludes those enterprises from reaching their economic potential and places them at a competitive disadvantage relative to livestock enterprises where such technologies are being implemented more aggressively. On the other hand, and until now, the beef cattle sector has never had the reproductive tools available to facilitate widespread successful adoption of these technologies within the industry. Hence, the need for increased efforts to transfer technology to the industry has never been greater. The National Center for Applied Reproduction and Genomics (NCARG) in Beef Cattle will serve as a new model for research and technology transfer wherein industry participants at all levels and from across the US are afforded the opportunity to access information and acquire new skills that will improve reproductive management and resulting genetic makeup of our nation’s beef cattle industry. Comprehensive educational training programs will be developed for practicing veterinarians, extension livestock specialists, allied industry, producers, and students that will enable various segments of the beef cattle sector to acquire (through face-to-face and distance-learning applications) new knowledge and skills that will aid in the successful adoption of reproductive procedures/biotechnologies. Curriculum modules designed to support improvements in reproductive management will be comprised of the following: 1) Heifer development programs including reproductive tract scoring, fetal aging and sexing; 2) Breeding management, including estrus synchronization, artificial insemination, sex-sorted semen, and embryo transfer; 3) higher education student internships in reproductive management; and 4) on-farm beef heifer development and marketing programs patterned after the Missouri Show-Me-SelectTM Replacement Heifer Program. In addition, a graduate certificate program will be offered, entitled “Bovine Reproductive Management and Genomic Technologies.” Collectively, NCARG will serve as a new model for research and technology transfer intent on improving reproductive management and genetic makeup of our nation’s beef industry.

378 Awardee Talk - Impact of fetal versus maternal contributions of Bos indicus and Bos taurus genetics on embryonic and fetal development

Abstract To evaluate how the inclusion of Bos indicus genotype influences early fetal development in cattle, a reciprocal embryo transfer approach was used in a completely randomized design with a 2×2×2 factorial arrangement of treatments in order to generate 55 pregnancies (n = 55). Recipient cows were randomly assigned to 1) a diet that met daily energy maintenance requirements (MAINT), or 2) a diet that restricted intake to 70% of the energy maintenance requirements (RESTR). Angus (AN) and Brangus (BN) embryo donors were superovulated and artificially inseminated with female sexed-sorted semen from the same breed. Embryos were then randomly transferred to either AN or BN recipients fed their respective diets for 28d. Recipients remained on the dietary scheme until d91 of gestation, and were then comingled and fed a common diet that met their requirements. Measurements included pregnancy establishment at d28 of gestation, pregnancy-associated glycoproteins (PAG; using 2 commercial [A1 and A2] and 1 in-house assay), and fetal size (CRL). Recipients in the RESTR diet had lower BW and BCS (diet×day; P &amp;lt; 0.01) than MAINT recipients. Energy-restricted AN recipients experienced greater (recipient breed×diet, P &amp;lt; 0.01) pregnancy failure by d28 than the other recipient breed × diet combinations. Restricted recipients that received AN embryos experienced greater pregnancy failure than RESTR recipients receiving BN embryos (embryo breed×diet; P = 0.03). Brangus embryos resulted in greater plasma concentrations of PAG in both A1 (embryo breed×day, P &amp;lt; 0.01) and A2 (embryo breed P &amp;lt; 0.01). Alternatively, recipients that received AN embryos had greater plasma concentrations of PAG for the in-house assay (embryo breed×day; P &amp;lt; 0.01). In addition, fetuses from AN recipients had greater CRL on d91 (breed×day, P &amp;lt; 0.01). In summary, Bos taurus cows experienced greater pregnancy failure when nutrient restricted. Furthermore, fetal size and profile of PAG production during early gestation differed between Bos indicus-influenced and Bos taurus cattle.

173 Pregnancy rates in suckled beef cows synchronised with progesterone/oestradiol-based protocol and inseminated with conventional or sexed-sorted semen

An experiment was designed to evaluate pregnancy rates per AI (P/AI) in suckled beef cows synchronised with a progesterone (P4)/oestradiol-based protocol and AI with non-sexed (conventional) semen and with a sexed-sorted semen with 65% X-bearing sperm and 35% Y-bearing sperm that was named SuperConventionalTM. Angus and Hereford suckled cows (n=558), 60-90 days postpartum, with a body condition score of 2 to 3.5 (1-to-5 scale) and 48% (269/558) with a corpus luteum, were randomly allocated to be AI with non-sexed (conventional) or SuperConventional semen. The experiment was performed on 3 farms using straws with sexed-sorted SuperConventional semen containing 6 or 8 million sperm and non-sorted conventional semen with 25 million sperm per straw. Semen was from split ejaculates from two Angus bulls. All cows received a P4 device with 0.6g of P4 (Pluselar, Calier) and 2mg of oestradiol benzoate (Calier) on Day 0. All P4 devices were removed on Day 8, and all cows received 400IU of equine chorionic gonadotrophin (Vetegon, Calier), 150µg of d+cloprostenol (Veteglan, Calier), and 1mg of oestradiol cipionate (Calier) at the same time. All cows were also tail-painted and observed for signs of oestrus. Cows with &amp;gt;30% of the tail paint rubbed off by 48-50h after P4 device removal were AI at that time with either SuperConventional or conventional semen. Those not showing oestrus by 48-50h received 10µg of buserelin (Pluserelina, Calier) at that time and were AI with either SuperConventional or conventional semen 50-52h after P4 device removal. Pregnancy was diagnosed using ultrasonography 60 days after AI, and all pregnancies were sexed to determine the proportion of female pregnancies. Data were analysed using GLM for binary data. The P/AI were different between cows showing or not showing oestrus (P&amp;lt;0.01) but did not differ among the three types of semen used (Table 1). The percentage of cows pregnant with female fetuses was 51% (50/98) for cows AI with conventional semen and 65.5% (55/84) and 65.3% (51/78) for those AI with SuperConventional semen with 8 million or 6 million sperm per straw, respectively. In conclusion, sexed-sorted semen with 65% of X-bearing sperm and 6 or 8 million sperm per straw can be successfully used to inseminate suckled beef cows. Furthermore, results confirm those of previous studies that cows in oestrus at the time of fixed-time AI have higher pregnancy rates than cows not in oestrus in P4/oestradiol-based synchronisation programmes. Table 1.Effect of semen type and oestrus expression on pregnancy rates per AI in suckled beef cows synchronised with a progesterone/oestradiol-based protocol Semen type In oestrus,% (n) Not in oestrus,% (n) Total,% (n) Conventional (25 million sperm) 59.8 (82/137)a 32.0 (16/50)b 52.4 (98/187) SuperConventional (8 million sperm) 53.7 (73/136)a 20.0 (10/50)b 44.6 (83/186) SuperConventional (6 million sperm) 50.4 (63/125)a 26.7 (16/60)b 42.7 (79/185) Total 54.8 (218/398)a 26.3 (42/160)b a,bDifferent superscripts denote differences in pregnancy rates per AI between cows in oestrus and not in oestrus by the time of fixed-time AI (P&amp;lt;0.01). Research was supported by Fondo Nacional de Ciencia y Tecnología (FONCYT PICT 2017-4550) and UNVM.

Global transcriptomic response of bovine endometrium to blastocyst-stage embryos.

The aims of this study were (i) to investigate changes in the global transcriptome of bovine endometrial explants induced by exposure to blastocysts, (ii) to investigate if male and female blastocysts elicit a differential response in the endometrial transcriptome in vitro and (iii) to determine whether bovine endometrium responds to the presence of murine embryos. In Experiment 1, endometrial explants from the same uterus were cultured for 6 h with or without 20 in vitro-produced bovine blastocysts. In Experiment 2, endometrial explants were cultured with male or female bovine blastocysts produced in vitro by IVF either using sex-sorted semen or conventional unsorted semen followed by embryo sexing based on a biopsy. In Experiment 3, endometrial explants were cultured alone or in the presence of bovine blastocysts (n = 25) or murine blastocysts (n = 25). Following culture, explants were snap frozen and stored at -80°C until RNA extraction, qPCR or RNA-Seq. Culture with bovine blastocysts increased endometrial expression of 40 transcripts, all of which were interferon-tau induced. Culture with male or female bovine blastocysts increased transcript abundance of five classic interferon-stimulated genes (MX1, MX2, ISG15, OASY1, RSAD2) in explants; however, there was no difference in abundance of transcripts previously reported to be related to embryonic sex (IFNAR1, IFNAR2, CTGF, ARTN, SLC2A1, SLC2A5). Exposure to murine blastocysts did not elicit any detectable change in transcript abundance. These findings, coupled with our previous data, indicate that very local, interferon-tau-induced changes in endometrial gene expression occur in response to blastocysts; whether such changes play any role in subsequent pregnancy recognition remains to be established.

Fertility of fresh and frozen sex-sorted semen in dairy cows and heifers in seasonal-calving pasture-based herds

Our objective in this study was to evaluate the reproductive performance of dairy heifers and cows inseminated with fresh or frozen sex-sorted semen (SS) in seasonal-calving pasture-based dairy herds. Ejaculates of 10 Holstein-Friesian bulls were split and processed to provide (1) fresh conventional semen at 3 × 106 sperm per straw (CONV); (2) fresh SS at 1 × 106 sperm per straw (SS-1M); (3) fresh SS semen at 2 × 106 sperm per straw (SS-2M); and (4) frozen SS at 2 × 106 sperm per straw (SS-FRZ). Generalized linear mixed models were used to evaluate the effect of semen treatment and other explanatory variables on pregnancy per artificial insemination (P/AI) in heifers (n = 3,214) and lactating cows (n = 5,457). In heifers, P/AI was greater for inseminations with CONV (60.9%) than with SS-FRZ (52.8%) but did not differ from SS-1M (54.2%) or SS-2M (53.5%). Cows inseminated with CONV had greater P/AI (48.0%) than cows inseminated with SS, irrespective of treatment (SS-1M, SS-2M, and S-FROZEN; 37.6, 38.9, and 40.6%, respectively). None of the SS treatments differed from each other with regard to P/AI in either heifers or cows. The relative performance of SS compared with CONV was also examined [i.e., relative P/AI = (SS P/AI)/(CONV P/AI) × 100]. Frozen SS achieved relative P/AI >84%. Bull affected P/AI in both heifers and cows, but no bull by semen treatment interaction was observed. In heifers, P/AI increased with increasing predicted transmitting ability for milk protein percentage. In cows, P/AI increased with increasing Economic Breeding Index (EBI) and with days in milk (DIM) at AI but decreased with increasing EBI milk subindex, parity and with DIM2. Cows in parity ≥5 had the lowest P/AI and differed from cows in parities 1, 2, or 3. Dispatch-to-AI interval of fresh semen did not affect P/AI in lactating cows, but a dispatch-to-AI interval by bull interaction was detected whereby P/AI was constant for most bulls but increased with greater dispatch-to-AI intervals for 2 bulls. In conclusion, frozen SS achieved greater P/AI relative to conventional semen than was previously reported in lactating cows. Fresh SS did not achieve greater P/AI than frozen SS, regardless of whether the sperm dose per straw was 1 × 106 or 2 × 106. A bull effect for all semen treatments, as well as a dispatch-to-AI interval by bull interaction for fresh semen, highlights the importance of using a large team of bulls for breeding management.

Effect of presynchronization with prostaglandin F2α before the 5-d timed AI protocol on ovarian responses and pregnancy in dairy heifers

The objectives were the determine the effects of presynchronization with PGF2α 2 days before the 5-d timed artificial insemination (AI) protocol on ovarian responses and pregnancy per AI (P/AI) in dairy heifers. The hypothesis was that PGF2α would induce responsive heifers to be in proestrus at the initiation of the timed AI protocol, which was expected to improve ovulatory responses and P/AI. Weekly cohorts of Holstein heifers were blocked by age and, within block, randomly assigned to remain as control (CON; n = 255) or receive PGF2α on experiment Day −10 (PG; n = 255). All heifers were subjected to the 5-d timed AI protocol (Day −8, GnRH + intravaginal progesterone controlled internal drug release insert; Day −3, PGF2α and insert removal; Day −2, PGF2α; and Day 0, GnRH and AI). A subset of 22 blocks of heifers (n = 43) had their ovaries scanned by ultrasonography on experiment Days −8, −3, 0, and 2 and blood was sampled and analyzed for concentrations of progesterone on experiment Days −8, −7, −5, and −3. Pregnancy was diagnosed on experiment Days 32 and 60. On the day of the first GnRH of the timed AI protocol, PG heifers had smaller concentration of progesterone in plasma (CON = 4.5 ± 0.5 vs. PG = 0.5 ± 0.5 ng/mL), but larger follicular diameter (CON = 9.1 ± 0.5 vs. PG = 11.0 ± 0.5 mm), and a greater proportion of them had a follicle with at least 8.0 mm in diameter (CON = 61.9 vs. PG = 90.9%) than CON heifers, which resulted in increased ovulation to GnRH (CON = 19.0 vs. PG = 86.3%). Ovulation to the initial GnRH of the protocol increased as the concentration of progesterone in plasma decreased, from less than 20% when progesterone was greater than 5.0 ng/mL to more than 65% when progesterone was less than 1.0 ng/mL. More CON than PG heifers spontaenously ovulated before the day of timed AI. Detection of estrus on the day of timed AI did not differ between treatments (CON = 50.9 vs. PG = 46.6%), but P/AI on Days 32 (CON = 52.9 vs. PG = 61.1%) and 60 (CON = 49.0 vs. PG = 57.1%) after insemination tended to be greater for PG than CON; however, the benefit to presynchronization was observed in heifers inseminated with conventional (CON = 54.7 vs. PG = 67.4%), but not in heifers inseminated with sex-sorted semen (CON = 50.9 vs. PG = 52.8%). Administration of PGF2α 2 days before initiating the timed AI protocol induced heifers to be in proestrus, which enhanced ovulation to the initial GnRH and favored pregnancy per AI, particularly in heifers inseminated with conventional semen.

Superovulation protocols for dairy cows bred with SexedULTRA™ sex-sorted semen.

The objective was to compare embryo yield and quality in lactating dairy cows superovulated (SO) with varying amounts of gonadotropins and FSH:LH ratios and inseminated with SexedULTRA™ sex-sorted semen. The SO treatments (n=77) involved 3 protocols: groups F700 and F1000 were given total doses of 700 and 1,000IU of Folltropin (FSH:LH ratio 49:1), respectively, whereas group F700P300 was given 700IU of Folltropin+300IU of Pluset (FSH:LH ratio 1:1). Cows were artificially inseminated 3 times over a 10-hr interval with frozen-thawed SexedULTRA™ sex-sorted semen (total of 10×106 sex-sorted sperm), starting 18hr after onset of oestrus, with embryos/ova recovered 7 d after oestrus. Total number of recovered structures and transferable embryos were lower (p<0.05) in F700 (4.7±3.0 and 1.9±1.7, respectively; mean±SD) compared to F1000 (8.1±3.8 and 4.4±2.6) and F700P300 (8.5±6.4 and 4.5±3.3). Percentage of cows ovulating >50% of follicles ≥0.8cm in diameter was lower (p<0.05) in F700 (35.5%) than in F1000 (82.4%) and F700P300 (73.1%). Percentage of unfertilized oocytes was higher (p<0.05) in F700 (45.0% vs. 27.7% for F1000 and 29.0% for F700P300) whereas percentage of morulae was higher (p<0.05) in F1000 (19.3% vs. 8.7% for F700 and 12.2% for F700P300). Embryo quality was similar among groups (p>0.05). In conclusion, embryo production in lactating dairy cows was improved by increasing total dose of gonadotropins from 700 to 1,000IU, with SexedULTRA™ sex-sorted semen yielding satisfactory fertilization rates and embryo quality.

Impact of fetal vs. maternal contributions of Bos indicus and Bos taurus genetics on embryonic and fetal development1

To evaluate how the inclusion of Bos indicus genotype influences early fetal development in cattle, a reciprocal embryo transfer approach was used in a completely randomized design with a 2 × 2 × 2 factorial arrangement of treatments to generate 55 pregnancies over 2 consecutive years (n = 55). Recipient cows were randomly assigned to (i) a diet that met daily energy maintenance requirements (MAINT) or (ii) a diet that restricted intake to 70% of the energy maintenance requirements (RESTR). Angus (AN) and Brangus (BN) embryo donors were superovulated and artificially inseminated with female sexed-sorted semen from the same breed. Embryos were then randomly transferred to either AN or BN recipients fed their respective diets for 28 d. Recipients remained on the dietary scheme until day 91 of gestation and were then comingled and fed a common diet that met their energy requirements until calving. Measurements included pregnancy establishment at day 28 of gestation, interferon-stimulated genes (ISG) expression in peripheral blood leukocytes, pregnancy-associated glycoproteins (PAG; using two commercial [A1 and A2] and one in-house assay), and fetal crown-to-rump length (CRL). Recipients in the RESTR diet had lower BWs and BCS (diet × day; P < 0.01) than MAINT recipients. Energy-restricted AN recipients experienced greater (recipient breed × diet, P < 0.01) pregnancy failure by day 28 than the other recipient breed × diet combinations. Restricted recipients that received AN embryos experienced greater pregnancy failure than RESTR recipients receiving BN embryos (embryo breed × diet; P = 0.03). No relevant differences were observed in ISG expression (P > 0.10). Recipients that received BN embryos had greater plasma concentrations of PAG in both A1 (embryo breed × day, P < 0.01) and A2 (embryo breed; P < 0.01). Alternatively, recipients that received AN embryos had greater plasma concentrations of PAG for the in-house assay (embryo breed × day; P < 0.01). In addition, fetuses from AN recipients had greater CRL on day 91 (breed × day, P < 0.01). In summary, Bos taurus cows experienced greater pregnancy failure when nutrient restricted. Furthermore, fetal size and the profile of PAG production during early gestation differed between B. indicus-influenced and B. taurus cattle.

Perspectives on the development and incorporation of assisted reproduction in the equine industry.

Marked changes in equine breeding technologies have occurred over the past 25 years. Although there have been numerous reviews on assisted reproduction techniques for horses, few publications include the acceptance and impact of these techniques on the horse industry. In this review, several techniques are discussed, with an emphasis on how they developed in the horse industry and altered equine reproductive medicine. Embryo transfer has become a widely used technology, allowing multiple foals to be produced per year. Embryos can be collected, cooled or frozen, and shipped to a distant facility for transfer into recipient mares. Failure to obtain embryos from some mares stimulated the development of oocyte collection and transfer. Oocyte technologies became more practical when intracytoplasmic sperm injection was developed in the early 2000s. There are now facilities across the world that routinely produce embryos invitro. Cryopreservation of oocytes has lagged because of limited success, but embryo cryopreservation is commonplace. Techniques such as sex-sorted semen, superovulation and genetic diagnosis of embryos are not widely used, and they will require more development before they are established in the horse industry in a cost-efficient manner.

128 Evaluation of SexedULTRA sex-sorted semen in timed artificial insemination programs for mature beef cows.

128 Evaluation of SexedULTRA sex-sorted semen in timed artificial insemination programs for mature beef cows.

7 Pregnancy rates in suckled beef cows synchronized with a shortened progesterone/oestradiol-based protocol (J-synch) and inseminated with conventional or sexed-sorted semen

An experiment was designed to evaluate pregnancy rates (P/AI) in suckled beef cows synchronized with a progesterone (P4)/oestradiol-based protocol (J-Synch) and inseminated (AI) with sexed or nonsexed (conventional) semen. Angus or Angus crossbred cows (n=877), 60 to 90 days postpartum, with a body condition score of 2.5 to 3.5 (scale of 1 to 5) and a corpus luteum or a follicle &amp;gt;8mm in diameter detected by ultrasonography, were randomly allocated to be AI with sexed-sorted or nonsexed (conventional) semen. The experiment was performed in 4 farms, and the sexed-sorted (SexedUltra™ 4M, with 4 million sperm; ST Genetics, Navasota, TX, USA) and conventional (25 million sperm) semen were from split ejaculates from 5 Angus bulls. All cows received a P4 device (DIB 0.5, Zoetis, Villa Adelina, Argentina) and 2mg of oestradiol benzoate (Gonadiol, Zoetis) on Day 0. On Day 6, cows received 400IU of eCG (Novormon 5000, Zoetis) and 500µg of cloprostenol (Ciclase DL, Zoetis) and DIB was removed. All cows were also tail painted and observed for signs of oestrus (i.e. &amp;gt;30% of the tail paint rubbed off) at 60, 72, and 84h after DIB removal. Cows with the tail paint rubbed off by 60 or 72h after DIB removal were artificially inseminated at 72h with either sexed or conventional semen. Those not showing oestrus by 72h received 100µg of gonadorelin acetate (Gonasyn GDR, Zoetis) at that time and were artificially inseminated with either sexed-sorted or conventional semen 12h later (i.e. 84h). Pregnancy was diagnosed by ultrasonography 30 days after AI. Data were analysed by general linear model for binary data with a logit link. Overall, 76.4% (678/877) of cows showed oestrus 60 to 84h after DIB removal, and there were differences in P/AI between sexed-sorted and conventional semen (P&amp;lt;0.01; Table 1); however, there was no farm effect (range: 52-59%) and no interactions. Fertility differed (P&amp;lt;0.05) among bulls and ranged from 25.8 to 55.3% for sexed-sorted semen and from 53.1 to 73.9% for conventional semen. In cows artificially inseminated with sexed-sorted semen, P/AI was the highest in cows showing oestrus and AI at 84 h; however, no differences were detected among cows artificially inseminated with conventional semen (Table 1). Although P/AI was lower for sexed-sorted than conventional semen, tail painting for oestrus detection can be successfully applied to AI beef cows with sexed-sorted semen synchronized with a shortened P4/oestradiol-based protocol. Table 1.Effect of semen type (sexed-sorted or conventional) and time of oestrus and AI on P/AI in suckled beef cows synchronized with a shortened P4/oestradiol-based protocol Research was supported by Fondo Nacional de Ciencia y Tecnología (FONCYT PICT 2017-4550) and UNVM.

29 Development and survival of bovine vitrified sexed IVF-derived embryos in vitro matured with pituitary or human recombinant follicle-stimulating hormone

Improving in vitro production efficiency involves the development of effective oocyte in vitro maturation conditions. Although &amp;gt;80% of cumulus-oocyte complexes (COC) undergo nuclear maturation, only approximately 30 to 35% of immature bovine COC develop to the blastocyst stage. Also, animal-sourced FSH is typically used in IVF, so an effective alternative using recombinant DNA technology is desirable. The aim of this study was to compare the effect of porcine (p) and recombinant human (rh)FSH concentrations on in vitro performance and post-thaw survival. Ovaries were collected from an abattoir and oocytes were aspirated from 2- to 6-mm follicles. The COC with compact and complete cumulus cell layers were selected and matured in groups of 25 COC in 200µL of M199 medium supplemented with alanyl-glutamine (0.1mM), Na pyruvate (0.2mM), gentamicin (5µg mL−1), epidermal growth factor (50ng mL−1), pLH (5µg mL−1), cysteamine (0.1mM), and 10% FBS for 22 to 24h in humidified air and 5% CO2. Oocytes were divided into the following groups: 1× pFSH (2µg mL−1), 1× rhFSH (0.01 UI mL−1), 1× pFSH+1× rhFSH, 2× pFSH, and 2× rhFSH. After 22 to 24h, fertilization (Day 0) was carried out using female sexed-sorted semen selected with a mini single-continuous 80% layer (PureSperm, Nidacon International AB, Mölndal, Sweden) and diluted to 1×106 sperm mL−1. The SOF-FERT medium was supplemented with fructose (90µg mL−1), penicillamine (3µg mL−1), hypotaurine (11µg mL−1), and heparin (20µg mL−1). After 18h, presumptive zygotes were denuded and cultured under low oxygen tension in groups of 15 to 20 in 50-µL drops of SOF-BSA for 7 days. Also, 2% FBS was added post-fertilization on Day 3.5. Expanded blastocysts were selected based on IETS standards at Day 6.5 to 7 of culture. Only grade 1 expanded blastocysts were vitrified (Cryotop, Kitazato, Tokyo, Japan). Vitrification medium was 15% (vol/vol) ethylene glycol+propylene glycol. Vitrified embryos were thawed in a solution of H199+20% FBS and 0.25M sucrose at 39°C. Thawed embryos were cultured in SOF-BSA+10% FBS under cumulus/granulosa cell monolayer co-culture. Embryo assessment involved post-thaw survival (0h), re-expansion and development progress (24-48h), and hatching of the zona pellucida (72h). A minimum of 4 replicates were performed. Data were analysed using a generalized linear mixed model with logit-link binomial distribution. Media treatment differences were determined using Fisher’s least significant difference test with the Bonferroni correction (α-level=0.05). The FSH origin affected cleavage and embryo development rate but not cryotolerance (Table 1). The results support previous research on low dose versus high dose rhFSH effectiveness and interspecies interaction of FSH on follicular receptors. Table 1.Cleavage, embryo development rate, and cryotolerance of FSH of various origins

A simulation model to evaluate the economic consequences of insemination programs in dairy herds: timed artificial insemination and sex-sorted semen

ABSTRACT The objective of this study was to develop a simulation model to analyse the technical, economic, and financial performance of using different reproductive strategies in dairy herds. Strategies simulated were: artificial insemination (AI) using conventional semen after oestrus detection (AIC), AI using sex-sorted semen after oestrus detection (AIS), timed artificial insemination (TAI) using conventional semen (TAIC), and TAI using sex-sorted semen (TAIS). The total time horizon analysed corresponded to 25 years, divided into 425 periods of 21 days. The [...]

Fertility of lactating dairy cows inseminated with sex‐sorted or conventional semen after Ovsynch, Presynch–Ovsynch and Double‐Ovsynch protocols

The objective was to compare pregnancy per artificial insemination (P/AI) with conventional (CS) or sex-sorted semen (SS) in dairy cows subjected to one of the three timed AI protocols. Cows (n=356) were randomly assigned to synchronization with Ovsynch (OVS), Presynch-Ovsynch (PO) or Double-Ovsynch (DO) and inseminated on Day 77±3 postpartum with either frozen-thawed SS (n=182) or CS (n=184) of the same bull. More cows were cyclic at the beginning of breeding Ovsynch increased (p<0.01) with presynchronization and it was greater for DO than PO (OVS=78.5%, PO=85.1%, DO=95.6%). Overall, P/AI for SS and CS increased with presynchronization (p<0.05) on Days 31 (OVS=35.5%, PO=47.1%, DO=48.3%) and 62 (OVS=30.1%, PO=43.8%, DO=43.9%). Regardless of synchronization treatments, insemination with SS reduced P/AI (p<0.02) on Days 31 (38.1% vs. 50.6%) and 62 (34.5% vs. 45.6%) compared with CS. No interaction was observed between synchronization treatment and type of semen for P/AI, although in cows receiving CS, P/AI was numerically greatest for PO (OVS=42.0%, PO=59.3%, DO=49.0%), and in cows receiving SS, it was numerically greatest for those inseminated following DO (OVS=27.9%, PO=35.5%, DO=47.6%). Thus, presynchronization improved P/AI in cows inseminated with sex-sorted or conventional semen.