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    Effect of delaying the time of insemination with sex-sorted semen on pregnancy rate in Holstein heifers
    (Blackwell Publishing Ltd, 2020) Guner, Baris; Erturk, Melih; Yilmazbas-Mecitoglu, Gulnaz; Keskin, Abdulkadir; Karakaya-Bilen, Ebru; Cakircali, Rabia; Serim, Enes
    The objective of the study was to evaluate the interval from onset of oestrus to time of artificial insemination (AI) to obtain the optimum pregnancy rate with sex-sorted semen in Holstein heifers. Heifers in oestrus were detected and inseminated only by using heat–rumination neck collar comprised electronic identification tag at the age of 13–14 months. Heifers (n = 283) were randomly assigned to one of three groups according to the timing of insemination at 12–16 hr (G1, n = 97), at 16.1–20 hr (G2, n = 94) and at 20.1–24 hr (G3, n = 92) after reaching the activity threshold. The mean duration of oestrus was 18.6 ± 0.1 hr, and mean peak activity was found at 7.5 ± 0.1 hr after activity threshold. The mean interval from activity threshold to ovulation was 29.4 ± 0.4 hr. The overall pregnancy per AI (P/AI) was 53.0% at 29–35 days and 50.9% at 60–66 days after AI. There was a significant reduction between G1 (13.8 ± 1.4 hr) and G3 (7.9 ± 1.4 hr) related to the intervals from AI to ovulation time. Sex-sorted semen resulted in significantly higher P/AI at 29–35 days when heifers inseminated in G3 (60.9%) after oestrus than those inseminated in G1 (49.5%) and G2 (48.9%). In terms of fertility, when the temperature–humidity index (THI) was below the threshold value (THI ?65) at the time of AI, there was a tendency (?65; 57.2% vs. > 65; 47.1%) for high pregnancy rate. There was no effect of sire on P/AI. In addition, the interaction of the technician with the time of AI was found significant, and three-way interaction of technician, sire and time of AI was tended to be significant on pregnancy rate. Thus, in addition to delaying the time of insemination (between 20.1 and 24 hr) after oestrous detection, THI and experienced technician were also found to be critical factors in increasing fertility with the use of sex-sorted semen in Holstein heifers. © 2020 Wiley-VCH GmbH
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    Fertility of lactating dairy cows inseminated with sex-sorted or conventional semen after Ovsynch, Presynch-Ovsynch and Double-Ovsynch protocols
    (Wiley, 2019) Karakaya-Bilen, Ebru; Yilmazbas-Mecitoglu, Gulnaz; Keskin, Abdulkadir; Guner, Baris; Serim, Enes; Santos, Jose E. P.; Gumen, Ahmet
    Contents 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.
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    The effect of supplementation of follicle-stimulating hormone (FSH) into the Ovsynch protocol to increase the pregnancy rate in cyclic lactating dairy cows
    (Veterinarni A Farmaceuticka Univerzita Brno, 2022) Yilmazbas-Mecitoglu, Gulnaz; Keskin, Abdulkadir; Karakaya-Bilen, Ebru; Tasdemir, Umut; Gumen, Ahmet
    The aim of this study was to determine the effects of the follicle stimulating hormone (FSH) supplemented in the Ovsynch protocol on pregnancy per timed artificial insemination (P/TAI) in cyclic dairy cows. All cows (n = 383) included in the study received the Ovsynch protocol. The cows in FSH3 (n = 92), FSH4 (n = 88), and FSH3&4 (n = 91) were administered 20 mg FSH on day 3, or day 4, or both on days 3 and 4 of the protocol, respectively, whereas the control group (n = 112) did not receive any FSH treatment. The mean follicle number at TAI and ovulation number after TAI were similar among the FSH groups. However, the mean follicular size was smaller (similar to 14.9 mm, P = 0.02) in FSH4 compared to the other groups (similar to 15.9 mm). Pregnancy/TAI of the FSH4 group on day 31 (59.1%) and day 62 (53.4%) was higher than those of other groups on day 31 (45.5% in control, 45.7% in FSH3, and 46.2% in FSH3&4) and day 62 (42.9% in control, 43.5% in FSH3, and 40.7% in FSH3&4), but the difference was non-significant. Likewise, FSH4 (62.7%) had more (P = 0.05) P/TAI than the other groups (48.6% in control, 47.7% in FSH3, and 49.4% in FSH3&4) in synchronized cows. The cows which responded to the first gonadotropin-releasing hormone (GnRH) of Ovsynch in the FSH4 group (64.8%) had higher (P < 0.02) P/AI rate than the responding control cows (44.6%). We concluded that application of FSH on day 4 in cyclic cows which were responsive to the Ovsynch protocol can yield higher pregnancy rates, but more studies are needed to better demonstrate this potential effect.
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    The ovulatory response to human chorionic gonadotropin administration on day 4 post timed artificial insemination improved fertility in repeat breeder cows
    (Veterinarni A Farmaceuticka Univerzita Brno, 2021) Yilmazbas-Mecitoglu, Gulnaz; Gumen, Ahmet; Karakaya-Bilen, Ebru; Keskin, Abdulkadir; Guner, Baris; Cakircali, Rabia
    This study focused on determining the success of inducing endogenous progesterone source (by formation of accessory corpus luteum) by human chorionic gonadotropin (hCG) administration on day 4 post timed artificial insemination (TAI) and on evaluating the effect of the day of hCG administration (day 4 or 5 post TAI) on pregnancy rates in repeat breeder cows according to their responses to hCG administrations. Non-pregnant cyclic lactating Holstein dairy cows with more than three services despite no clinical reproductive abnormalities were enrolled in the study. All cows (n = 192) received the Ovsynch protocol (GnRH-7d-PGF(2 alpha)-56h-GnRH-16/18h-TAI) and hCG administration (1500 IU, i.m.) was performed in group hCG4 (n = 64) on day 4 and in group hCG5 (n = 68) on day 5 post TAI. The control group (CON, n = 60) did not receive any hCG treatment. The responses (ovulation rate) to hCG (similar to 64%) were similar on days 4 and 5 post TAI. Pregnancy per AI (P/AI) at 31 days was similar among the groups (48.3% in CON, 48.4% in hCG4, and 42.6% in hCG5). Regardless of the day of the treatment (hCG4 + hCG5), the cows had an ovulatory response to hCG (54.1%), and a greater P/AI (P = 0.007) at 31 days than those without a response (29.8%). The administration of hCG on either day 4 or 5 post TAI did not increase overall pregnancy rates, however, the ovulatory response to the post TAI hCG administration on day 4 improved fertility in repeat breeder cows. Further studies are needed with a larger number of animals to reveal this potentiallly beneficial effect.