Comparative efficiency of oestrus synchronization in sheep with progesterone/eCG and progesterone/GnRH during breeding and non-breeding season

The present study compared the occurrence of oestrus behaviour and ovulation in response to the insertion of CIDR devices plus a classical treatment with equine chorionic gonadotrophin (eCG; single dose at CIDR removal) or alternative treatments with gonadotrophin-releasing hormone (GnRH, either in a single dose at 56 hr after CIDR removal, or in one dose at CIDR insertion and another dose at 56 hr after CIDR removal). The appearance of oestrus behaviour during reproductive season ranged between 84% and 95% and all females showing oestrus signs had subsequent ovulations. The response, during seasonal anoestrus, was similar in the group treated with eCG, but less than half of the females in the groups treated with GnRH showed oestrus signs in response to the treatment, although more than 80% of them showed resumption of ovulatory activity after the treatment. In conclusion, protocols based on GnRH administration offer similar yields to eCG-based protocols during the reproductive season but occurrence of oestrus in response to GnRH-based treatments is highly compromised during seasonal anoestrus.     

Effect of Weaning to Oestrus Interval and Equine Chorionic Gonadotropin on Vaginal Electrical Impedance During Peri‐oestrus in Sows

The influence of weaning to oestrus interval, its interaction with parity and equine chorionic gonadotropin (eCG) on changes of vaginal impedance in sows after weaning was examined. The impedance measurements were carried out by a four‐terminal method. Sows were monitored for oestrus via exposure to a sexually mature boar. The interval from weaning to oestrus was longer in primiparous than multiparous sows (p < 0.01). A significant negative correlation was found between the interval from weaning to oestrus and parity. Repeated measures analysis showed that the interval from weaning to oestrus and parity and their interactions had a significant effect on the vaginal impedance in peri‐oestrus. The vaginal impedance during pro‐oestrus gradually decreased in all groups of sows with the weaning to oestrus interval from 4 to 8 days (p < 0.05). In the subsequent period, the vaginal impedance increased and was significantly lower from 1 to 3 days after oestrus onset in sows with the weaning to oestrus interval 7–8 days than 4–6 days. Similarly, the vaginal impedance during pro‐oestrus gradually decreased in all groups of sows with parity 1–5 (p < 0.01). In the next period, the vaginal impedance increased and was significantly lower from 2–3 days after oestrus onset in sows of parity 1 than parity 2–5. Repeated measures analysis showed that eCG treatment had a significant effect on the vaginal impedance in peri‐oestrus. Sows treated with eCG displayed the decrease and increase of vaginal impedance due to oestrus onset earlier than untreated sows. The results indicate that the weaning to oestrus interval, its interaction with parity and eCG markedly affect the vaginal impedance in sows during peri‐oestrus.     

GnRH and prostaglandin‐based synchronization protocols as alternatives to progestogen‐based treatments in sheep

The study investigated, for cycling sheep, synchronizing protocols simultaneously to the standard “P” protocol using progestogens priming with intravaginal devices and gonadotropin. In November 2014, 90 adult Menz ewes were assigned to either the “P” protocol, “PGF” treatment where oestrus and ovulation were synchronized using two injections of prostaglandin 11 days apart or a “GnRH” treatment where the ewes had their oestrus and ovulation synchronized with GnRH (day 0)–prostaglandin (day 6)–GnRH (day 9) sequence. The ewes were naturally mated at the induced oestrus and the following 36 days. Plasma progesterone revealed that 92% of the ewes were ovulating before synchronization and all, except one, ovulated in response to the applied treatments. All “P” ewes exhibited oestrus during the 96‐hr period after the end of the treatments in comparison with only 79.3% and 73.3% for “PGF” and “GnRH” ewes, respectively (p < .05). Onset and duration of oestrus were affected by the hormonal treatment (p < .05); “GnRH” ewes showed oestrus earliest and had the shortest oestrous duration. Lambing rate from mating at the induced oestrus was lower for “P” than for “PGF” ewes (55.6% and 79.3%, respectively; p < .05). The same trait was also lower for “P” than for “PGF” and “GnRH” ewes (70.4%, 89.7% and 86.7%, respectively; p < .05) following the 36‐day mating period. Prostaglandin and GnRH analogue‐based protocols are promising alternatives for both controlled natural mating and fixed insemination of Menz sheep after the rainy season when most animals are spontaneously cycling.     

Fixed‐time Insemination in Pasture‐based Medium‐sized Dairy Operations of Northern Germany and an Attempt to Replace GnRH by hCG

A field study was conducted aimed at (i) evaluating the practicability of a fixed‐time insemination regime for medium‐sized dairy operations of north‐western Germany, representative for many regions of Central Europe and (ii) substituting hCG for GnRH as ovulation‐inducing agent at the end of a presynch or ovsynch protocol in an attempt to reduce the incidence of premature luteal regression. Cows of two herds synchronized by presynch and two herds synchronized by ovsynch protocol were randomly allotted to three subgroups; in one group ovulation was induced by the GnRH analog buserelin, in another by hCG, whereas a third group remained untreated. The synchronized groups were fixed‐time inseminated; the untreated group bred to observed oestrus. Relative to untreated herd mates, pregnancy rate in cows subjected to a presynch protocol with buserelin as ovulation‐inducing agent was 74%; for hCG it was 60%. In cows subjected to an ovsynch protocol, the corresponding relative pregnancy rates reached 138% in the case of buserelin and 95% in the case of hCG. Average service interval was shortened by 1 week in the presynch and delayed by 2 weeks in the ovsynch group. It may be concluded that fixed‐time insemination of cows synchronized via ovsynch protocol with buserelin as ovulation‐inducing agent is practicable and may help improve efficiency and reduce the work load involved with herd management in medium‐sized dairy operations. The substitution of hCG for buserelin was found to be not advisable.     

Effect of Modified Eros Centre on Some Reproductive Parameters of the Sow

The effect of a modified eros centre on weaning to oestrus interval, follicle size, ovulation and farrowing rate and total born litter size was investigated. In modified eros centre 94.4% and in group housing 79.1% of the sows (p < 0.01) expressed oestrus within 10 days post‐weaning. Weaning to oestrus interval was shorter (p < 0.001) for sows kept in modified eros centre. The interval from onset of oestrus to the time of ovulation was longer for sows in group housing (p=0.05). The time of ovulation was negatively correlated (r=?0.50) with the interval from weaning to oestrus (p=0.005). The time of ovulation after onset of oestrus was significantly (p < 0.05) shorter for sows expressing oestrus within 2–4 days of weaning, compared with the animals that expressed oestrus between days 5 and 6 post‐weaning and was shortest for sows expressing oestrus after day 6 post‐weaning. Farrowing rate was not affected by a modified eros centre. Litter size tended to be smaller in group‐housed weaned sows (p=0.10). The timing of last artificial insemination relative to time of ovulation did not affect litter size (p > 0.10). The implication of these results is that a modified eros centre may improve some of the post‐weaning oestrous parameters of the sow.     

Effect of estradiol cypionate and GnRH treatment on plasma estradiol‐17β concentrations,synchronization of ovulation and on pregnancy rates in suckled beef cows treated with FTAI‐based protocols

Two experiments were conducted to evaluate the effect of different ovulation inducers on E‐17β plasma concentrations, synchronized ovulations and pregnancy rates. In Experiment 1, cows received a progesterone intravaginal device (PID) with 1 g of progesterone (P4) plus 2 mg of estradiol benzoate (EB) (day 0). At PID removal (day 8), cows received 0.150 mg of D‐cloprostenol and were randomly assigned to four treatment groups (n = 10/treatment): Group ECP: 1 mg of estradiol cypionate at PID removal, Group EB: 1 mg of EB 24 hr after PID removal, Group GnRH: 10 μg of GnRH 48 hr after PID removal, Group ECP‐GnRH: 1 mg of ECP at PID removal plus 10 μg of GnRH 48 hr later. Ultrasonographic examinations were performed to detect the dominant follicle and ovulation. GnRH‐treated cows ovulated later (p < .05) compared to ECP‐ and ECP+GnRH‐treated cows. There were effects of treatment, time and their interaction on E‐17β concentrations (p < .05). ECP treatment affected plasma E‐17β concentration, which increased earlier and decreased later compared to treatments without ECP. In Experiment 2, cows received (i) ECP: n = 126; (ii) EB: n = 126; (iii) GnRH: n = 136; (iv) ECP+GnRH: n = 139; FTAI was performed 48–50 hr after PID removal. Pregnancy rates did not differ among ovulation inducers (p > .05; ECP: 54.0%, 68/126; EB: 49.2%, 62/126; GnRH: 40.4%, 55/136; ECP+GnRH: 43.9%, 61/139). In conclusion, ECP administration (ECP and ECP+GnRH treatments) affected E‐17β concentrations, determining its earlier increase and later decrease compared to treatments without ECP (EB and GnRH treatments). ECP+GnRH‐treated cows achieved the best distribution of ovulations without affecting pregnancy rates.     

Ovsynch Plus protocol improves ovarian response in anovular Murrah buffaloes in low‐breeding season

The objective of the study was to evaluate the efficacy of ovarian response and pregnancy rate in anovular buffaloes following Ovsynch and Ovsynch Plus protocols. Buffaloes (n = 55) were divided into two groups: Ovsynch group (n = 26): GnRH (10 μg, GnRH1) on Day 0, PGF₂α (25 mg) on Day 7, GnRH (10 μg, GnRH2) on Day 9; Ovsynch Plus group (n = 29): 500 IU equine chorionic gonadotropin (eCG) 72 hr (day ?3) prior to Ovsynch protocol, followed by fixed timed artificial insemination (FTAI) 6 and 24 hr after GnRH2 injection in bot groups. Transrectal ultrasonography was performed daily, that is, from day 0 and ?3 in Ovsynch and Ovsynch Plus group, respectively for ovarian response and pregnancy diagnosis at day 30 post‐insemination. In Ovsynch Plus group, administration of eCG prior to GnRH1 increased (p < .001) the diameter (mm) of dominant follicle (DF) from 10.15 ± 0.26 to 12.23 ± 0.34 within 72 hr of treatment resulting higher ovulatory response to GnRH1. Ovulation after GnRH1 was higher (p < .01) in Ovsynch Plus group (96.6%) than Ovsynch group (61.5%). However, ovulation rate to GnRH2 was similar (p > .05) between groups (Ovsynch group: 76.9% vs. Ovsynch Plus group: 70.0%). Mean DF diameter (mm) that ovulated to both GnRHs was higher (p < .01) than non‐ovulated counterparts in both groups (Ovsynch group: 10.80 ± 0.27 vs. 8.47 ± 0.53; Ovsynch Plus group: 11.99 ± 0.24 vs. 9.5 ± 0.63). Pregnancy was established in buffaloes which responded to both GnRHs, irrespective of groups, being higher (p = .52) in Ovsynch Plus group (34.5%) than Ovsynch group (23.1%), though non‐significant. In summary, this study showed that eCG inclusion prior to Ovsynch regimen improves ovulatory response in anovular buffaloes during low‐breeding season.     

Improving ovulation in gilts using anti-inhibin serum treatment combined with fixed-time artificial insemination

For successful batch farrowing, porcine oestrus and ovulation must be synchronized using fixed-time artificial insemination (FTAI). However, exogenous gonadotropins, which are currently used in FTAI, negatively affect gilt ovulation. Here, we aimed to improve sexually mature gilt superovulation efficiency using passive immunization against inhibin during FTAI. Altrenogest-treated gilts were challenged with 10 ml anti-inhibin serum (AIS group, n = 6), 1,000 IU pregnant mare serum gonadotropin (PMSG group, n = 6), or 10 ml goat serum (control group, n = 6). Gilts in the AIS and PMSG groups were inseminated according to the FTAI protocol, and gilts in the control group were inseminated during natural oestrus. When PMSG was replaced by AIS during FTAI of gilts, ovulation rate and embryos recovered were significantly greater in the AIS group as compared to the other two groups (p < .05). Especially the average number of 6–8-cell embryos in the AIS group was significantly higher than that in the PMSG group (p < .01). Moreover, the blastocyst number in the AIS group was significantly higher than that in the PMSG group and the control group (p < .05). But there was no significant difference in the blastocyst number between the PMSG group and the control group (p > .05). Besides, plasma levels of estradiol-β (E2) and progesterone (P4) were significantly greater in the AIS group as compared to the other two groups on Day 23 and D 27, respectively (p < .01). In summary, we devised an improved high-yield FTAI protocol for sexually mature gilts using AIS; this protocol had a greater superovulation efficiency than the FTAI using PMSG.     

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14‐day CIDR protocol

This study compared artificial insemination pregnancy rate (AI‐PR) between 14‐day CIDR‐GnRH‐PGF2α‐GnRH and CIDR‐PGF2α‐GnRH synchronization protocol with two fixed AI times (56 or 72 hr after PGF2α). On day 0, heifers (n = 1311) from nine locations assigned body condition score (BCS: 1, emaciated; 9, obese), reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic) and temperament score (0, calm; and 1, excited) and fitted with a controlled internal drug release (CIDR, 1.38 g of progesterone) insert for 14 days. Within herd, heifers were randomly assigned either to no‐GnRH group (n = 635) or to GnRH group (n = 676), and heifers in GnRH group received 100 μg of GnRH (gonadorelin hydrochloride, IM) on day 23. All heifers received 25 mg of PGF2α (dinoprost, IM) on day 30 and oestrous detection aids at the same time. Heifers were observed for oestrus thrice daily until AI. Within GnRH groups, heifers were randomly assigned to either AI‐56 or AI‐72 groups. Heifers in AI‐56 group (n = 667) were inseminated at 56 hr (day 32 PM), and heifers in AI‐72 group (n = 644) were inseminated at 72 hr (day 33 AM) after PGF2α administration. All heifers were given 100 μg of GnRH concurrently at the time AI. Controlling for BCS (p < .05), RTS (p < .05), oestrous expression (p < .001), temperament (p < .001) and GnRH treatment by time of insemination (p < .001), the AI‐PR differed between GnRH treatment [GnRH (Yes – 60.9% (412/676) vs. No – 55.1% (350/635); p < .05)] and insemination time [AI‐56 – 54.6% (364/667) vs. AI‐72 – 61.8% (398/644); (p < .01)] groups. The GnRH treatment by AI time interaction influenced AI‐PR (GnRH56 – 61.0% (208/341); GnRH72 – 60.9% (204/335); No‐GnRH56 – 47.9% (156/326); No‐GnRH72 – 62.8% (194/309); p < .001). In conclusion, 14‐day CIDR synchronization protocol for FTAI required inclusion of GnRH on day 23 if inseminations were to be performed at 56 hr after PGF2α in order to achieve greater AI‐PR.     

Onset of oestrus and periovulatory events in sheep exposed to 5 and 14 days of CIDR treatment with and without eCG

The present study supports that 5‐day short‐term CIDR treatments without administration of eCG are equally effective for inducing oestrus behaviour, preovulatory LH discharge and ovulation in sheep than classical protocols based on 14‐day treatments plus eCG at CIDR withdrawal. However, the implementation of a 5‐day protocol without eCG for fixed‐time artificial insemination would be adapted to a later timing of ovulation (p < .05).     

The Effect of Intravaginal Applied GnRH-agonist on the Time of Ovulation and Subsequent Reproductive Performance of Weaned Multiparous Sows

In order to prove the effect of 'fixed time insemination' and insemination at standing oestrus after post-weaning application of GnRH, in a Croatian large breeding unit, 502 sows were assigned to three groups and were artificially inseminated (AI) at their first post-weaning oestrus as many times as they stand, in 24-h intervals. The groups were treated as follows: group 1 (control, n = 160) were AI during their standing reflex; group 2 ['GnRH-fixed time insemination' (GnRH-FT-AI), n = 175] were AI, independent of detection of oestrus and following administration of GnRH-agonist at 96 h post-weaning; group 3 [GnRH insemination at standing oestrus (GnRH-OE-AI), n = 167] the animals were GnRH-agonist treated as group 2 and were AI at their standing reflex. Pre-trial daily average lactational feed intake, average daily feed intake from weaning to oestrus, oestrus within 6 days post-weaning (%), ovulation within 6 days post-weaning (%), weaning-to-oestrus interval (h), duration of oestrus (h), follicle size (mm), interval from oestrus to ovulation (h), subsequent day 24 pregnancy rate (%), farrowing rate (%) and total pigs born were evaluated. Pre-trial average daily lactational voluntary feed intake was 7.1 +/- 0.08 kg in group 1, 7.0 +/- 0.07 kg in group 2 and 7.1 +/- 0.17 kg in group 3 (p > 0.05). Average voluntary daily feed intake from weaning to oestrus was 5.1 +/- 0.3 kg in group 1, 5.2 +/- 0.5 kg in group 2 and 5.2 +/- 0.19 kg in group 3 (p > 0.05). Oestrus was detected within 6 days post-weaning in 134 (83.8%) in control, 164 (93.7%) in GnRH-FT-AI and 155 (92.8%) animals in GnRH-OE-AI groups (p = 0.05). Follicle size did not differ (p > 0.05) among the groups. In control 82.8%, in GnRH-FT-AI 91.5% and in GnRH-OE-AI 91.0% of the sows ovulated within 6 days post-weaning (p = 0.04), and had 80.6, 90.9 and 89.7% 24-day pregnancy rates (p = 0.16), respectively. In GnRH-FT-AI group 90.2%, in GnRH-OE-AI sows 89.7%, in control animals 79.9% farrowing rates were recorded (p = 0.17). Weaning to oestrus interval was 113.1 h in control, 114.1 h in GnRH-FT-AI and 112.6 h GnRH-OE-AI (p > 0.05). Duration of oestrus was significantly shorter in GnRH-FT-AI (44.9 h) and GnRH-OE-AI (48.1 h) animals, compared with the control (62.9 h) sows (p = 0.001). Similarly, the interval from oestrus to ovulation revealed significant (p = 0.004) differences between the groups (control 44.1 h, GnRH-OE-AI 34.1 h and GnRH-FT-AI 32.9 h). GnRH-FT-AI (12.5) and GnRH-OE-AI (12.6) sows had significantly higher (p = 0.01) number of total pigs born (n = 10.4) compared with control sows. GnRH-agonist-gel treatment to the sow shortens duration of oestrus, the interval from oestrus to ovulation, and may eliminate the need for oestrus detection in the hands of skilled personnel.     

Ultrasonographic and Endocrine Evaluation of Three Regimes for Oestrus and Ovulation Synchronization for Sheep in the Subtropics

This study aimed to evaluate three regimes for oestrus and ovulation synchronization in Farafra ewes in the subtropics. During autumn, 43 ewes were assigned to (i) controlled internal drug releasing (CIDR)‐eCG group, treated with CIDR for 12 days and eCG at insert withdrawal, n = 13; (ii) PGF₂α‐PGF₂α group, treated with two PGF₂α injections at 11 days interval, n = 14; and (iii) GnRH‐PGF₂α‐GnRH group, treated with GnRH, followed 5 days later with PGF₂α and 24 h later with a second GnRH, n = 16. Oestrus‐mating detection was carried out at 4 h intervals starting on day 0 [the day of CIDR withdrawal (CIDR‐eCG group), the day of second PGF₂α treatment (PGF₂α‐PGF₂α group) and the day of PGF₂α treatment (GnRH‐PGF₂α‐GnRH group)]. Ovarian dynamics was monitored by ultrasound every 12 h beginning on day 0 and continued for 4 days. Blood samples were obtained daily for progesterone (P₄) and oestradiol 17β (E₂) estimation starting on day 0 and continued for 4 days. The obtained results showed that, oestrus expression, ovulation and conception were greater (p < 0.05) in CIDR‐eCG and PGF₂α‐PGF₂α groups than in GnRH‐PGF₂α‐GnRH group. All ewes of PGF₂α‐PGF₂α group presented, on day of second PGF₂α injection with mature CL (P₄ > 2.0 ng/ml), compared to 42.9% in GnRH‐PGF₂α‐GnRH group (p = 0.01). The peak of oestrus occurred 32–52, 48–60 and 28–96 h after the end of treatment in CIDR‐eCG, PGF₂α‐PGF₂α and GnRH‐PGF₂α‐GnRH groups, respectively. Ovulation started 48 h after treatment in all groups and extended for 24, 36 and 48 h for CIDR‐eCG, PGF₂α‐PGF₂α and GnRH‐PGF₂α‐GnRH groups, respectively. Results demonstrated that oestrus and ovulation synchronization could be efficiently achieved in Farafra ewes using either CIDR‐eCG or PGF₂α‐PGF₂α regimes; however, the GnRH‐PGF₂α‐GnRH treatment induced a more spread oestrus and ovulation that may make the protocol inadequate for timed artificial insemination.     

Effect of the administration of GnRH or hCG on time of ovulation and the onset of estrus-to-ovulation interval in sows in Thailand

The aim of the present study was to evaluate the control of ovulation by the administration of human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) at the onset of estrus. Thirty-three multiparous sows housed under tropical conditions and showing standing estrus within 5 days after weaning were included. The sows were allocated to three groups, spontaneous ovulation (control group, n = 10), induced ovulation using 750 IU hCG (hCG group, n = 10), and induced ovulation using 50 μg GnRH (GnRH group, n = 13). The hormones were given at the onset of estrus and the occurrence of ovulation was monitored every 6 h by transrectal ultrasonography. Data for weaning-to-estrus interval, onset of estrus-to-ovulation interval (EOI), and the length of estrus were recorded. All sows in the control and hCG groups ovulated, while 3 out of 13 sows treated with GnRH developed cystic ovaries (did not ovulate). Of those sows ovulating, the EOI of the hCG (40.2 ± 1.7 h) and GnRH (37.5 ± 3.3 h) groups were shorter than that of the control group (63.6 ± 9.6 h; P < 0.05). In conclusion, the administration of either hCG or GnRH at the onset of estrus can control time of ovulation but, at the dose employed, sows receiving GnRH may develop ovarian cysts.     

Oxytocin increases pregnancy rates after fixed time artificial insemination in Kazak ewes

It is probable that reduced pregnancy rates in ewes after fixed time artificial insemination (FTAI) is attributable, in part, to the reduced number of normal spermatozoa that colonize the oviduct. Administration of oxytocin stimulates both cervical dilation and uterine/oviductal contractility. The hypothesis that oxytocin can enhance sperm transport into the uteri and the oviducts, and thereby increase pregnancy rates, was tested in the present study. Oestrus was synchronized in 199 multiparous Kazak ewes using intravaginal flurogestone-impregnated sponge. The sponge was left in the vagina for 12 days followed with an injection of 330 IU of eCG at sponge removal. Each ewe was intracervically inseminated twice at 50 hr and 62 hr after the removal of sponges using an insemination catheter containing 0.25 ml of diluted semen. Semen was collected from seven Texel rams and all the ejaculates were pooled and diluted in ultra-high temperature-treated commercial skimmed milk without (Control group, 0.05 ml of saline per mL milk, n = 144) or with oxytocin supplement (Oxytocin group, 0.5 U of oxytocin per ml milk, n = 55). Pregnancy status was determined by transabdominal ultrasound examination 45 days after insemination. Lambing performance was recorded at delivery. Significant differences were observed between the Oxytocin group and the Control group in terms of the pregnancy rate and the fecundity rate (85.5% and 92.7% versus 68.8% and 72.9%, respectively). In conclusion, low dose oxytocin supplementation of semen extender significantly increased pregnancy and fecundity rates in oestrus-synchronized Kazak ewes after FTAI.     

Expression of Progesterone Receptor in the Utero‐tubal Junction After Intra‐uterine and Deep Intra‐uterine Insemination in Sows

The aim of this study was to investigate the expression of progesterone receptor (PR) in the utero‐tubal junction (UTJ) of sows at 24 h after intra‐uterine insemination (IUI) and deep intra‐uterine insemination (DIUI) compared with conventional artificial insemination (AI) in pigs. Fifteen multiparous sows were used: AI (n = 5), IUI (n = 5) and DIUI (n = 5). The sows were inseminated with a single dose of diluted semen during the second oestrus after weaning at 6–8 h prior to ovulation (AI: 3000 × 10⁶ spermatozoa, IUI: 1000 × 10⁶ spermatozoa and DIUI: 150 × 10⁶ spermatozoa). The UTJ was collected and subject to immunohistochemical staining using avidin‐biotin immunoperoxidase technique with mouse monoclonal antibody to PR. In the oviductal part of the UTJ, the intensity of PR in the tunica muscularis and the proportion of PR‐positive cells in the surface epithelium after DIUI were lower than AI (p < 0.05). The intensity and the proportion of PR‐positive cells between AI and IUI in all compartments of the UTJ did not differ significantly (p > 0.05). When comparing between tissue compartments, prominent staining was observed in the muscular layer of the UTJ. It could be concluded that the expression of PR in the UTJ prior to fertilization after DIUI with a reduced number of spermatozoa was lower than that after AI. This might influence sperm transportation and the fertilization process.     

Evaluation of different hormonal treatments on oestral and ovarian responses in Moroccan Beni Arouss goats during anoestrus and breeding season

The efficacy of eight combinations of fluorogestone acetate (FGA, 20 or 40 mg as intravaginal device during 11 days), equine chorionic gonadotropin (eCG, 300 or 500 UI injected 48 hr before FGA removal) and prostaglandin F_2α (cloprostenol, 0 or 50 μg injected 48 hr before FGA removal) aiming at induction and synchronization of oestrus and ovulation was evaluated during the anoestrus season in spring and during the breeding season in autumn in adult Beni Arouss goats. Oestrous behaviour was recorded between 12 and 60 hr after FGA removal. Blood samplings allowing to assess onset of the pre‐ovulatory LH surge and increase of progesterone as sign of an active corpus luteum were performed, respectively, between 20 and 60 hr and 3, 5, 8 and 15 days after FGA removal. No season‐related differences (spring vs. autumn) were observed for oestrous response (95% vs. 93%), pre‐ovulatory LH surge (94% vs. 84%) and luteal response after 3–8 and 11–15 days post‐treatment (respectively 92% vs. 66% and 92% vs. 98%). The onset of oestrus (21 [13–53] vs. 32 [12–54] hr) and LH surge (26 [20–60] vs. 38 [22–60] hr) occurred significantly later in autumn. FGA (40 vs. 20 mg) in autumn significantly delayed the onset of oestrus (36 [16–54] vs. 23 [12–47] hr) and LH surge (44 [26–58] vs. 33 [22–60] hr). Significant treatment‐related differences were recorded for onset of LH surge (earliest for 20 mg FGA, 300 IU eCG, 50 μg PGF_2α) and onset of luteal phase (latest for 40 mg FGA, 300 IU eCG, 50 μg PGF_2α). In conclusion, the hormone combinations tested appeared equally effective in terms of oestrous and ovulation rates. Season has influenced significantly the onset of oestrus and LH surge, and the high dose regimen of FGA delayed the ovarian response in autumn.     

Pregnancy and offspring sex ratio following insemination with SexedULTRA and conventional semen in cows in a commercial beef operation

Pregnancy rate per AI (PR/AI) and breeding season pregnancy rates between insemination with sexed semen (SS; at 18 hr after the onset of oestrus) and conventional semen (CS; at 12 hr after the onset of oestrus,) and offspring gender ratio between two groups were compared. Angus cross cows (n = 686, during 2019 and 2020 breeding seasons) were oestrus-synchronized using Select-Synch + CIDR protocol and were observed thrice daily for oestrus until 72 hr after PGF2α administration. Cows expressed oestrus (n = 513) were inseminated with either SS (n = 246; SexedULTRA 4M™; y chromosome-bearing sperm) or CS (n = 267). Cows (n = 173) that failed to express oestrus at 72 hr after PGF2α received 100 μg of GnRH and CS insemination concomitantly. Two weeks later, cows were penned with natural service sires (bull:cow ratio 1:25) for 45 days. Pregnancy was diagnosed 30 days after bull removal. Calves' gender was determined at birth. For cows that expressed oestrus, PR/AI did not differ (p > .1) between SS (65.0%) and CS (66.7%) groups. The overall PR/AI differed (p < .05) between SS (65.0%) and CS (56.4%) groups. The natural service PR differed (p < .001) but breeding season PR (p > .05) did not differ between SS vs. CS groups. Bull:heifer gender ratio following AI was 88:12 and 52:48 for SS and CS groups, respectively, with an overall 66:34 ratio. Bull:heifer gender ratio for the two breeding seasons was 79:21 and 52:48 for SS and CS groups, respectively, with an overall 62:38 ratio. In conclusion, the fertility of SS insemination at 18 hr after onset of oestrus was 97% of CS insemination at 12 hr after onset of oestrus. Though breeding season pregnancy did not differ between SS and groups, preferred calf gender was 25 percentage points greater for SS over CS application. The gender accuracy was 88%.     

The Post‐Cervical Insemination does not Impair the Reproductive Performance of Primiparous Sows

The study evaluated the reproductive performance of primiparous sows submitted to post‐cervical insemination (PCAI) compared with cervical artificial insemination (CAI). Difficulty with catheter introduction, the occurrence of bleeding or semen backflow during insemination, and volume and sperm cell backflow up to 60 min after insemination were also evaluated. Sows were homogenously distributed, according to body weight loss in lactation, lactation length, weaned piglets, weaning‐to‐oestrus interval and total born in previous farrowing, in two treatments: PCAI (n = 165) with 1.5 × 10⁹ sperm cells in 45 ml (2.4 ± 0.04 doses per sow) and CAI (n = 165) with 3 × 10⁹ sperm cells in 90 ml (2.5 ± 0.04 doses per sow). During PCAI, sows were inseminated in the absence of boars. Transabdominal real‐time ultrasonography was performed at oestrus onset, immediately before the first insemination and at 24 h after last insemination. There was no difference (P > 0.05) between treatments in farrowing rate (91.5% × 89.1%) and litter size (12.5 × 11.9 piglets born, respectively for PCAI and CAI sows). Successful passage of the intrauterine catheter in all the inseminations was possible in 86.8% (165/190) of sows initially allocated to PCAI treatment. Difficulty of introducing the catheter in at least one insemination did not affect the reproductive performance of PCAI sows (P > 0.05). Bleeding during insemination did not affect (P > 0.05) the farrowing rate in both treatments, but litter size was reduced in CAI and PCAI sows (P ≤ 0.06). Percentage of spermatozoa present in backflow within 1 h after insemination was greater in CAI than PCAI sows (P < 0.01). More than 85% of primiparous sows can be successfully post‐cervical inseminated with doses containing 1.5 × 10⁹ sperm cells in the absence of the boar during insemination without impairing the reproductive performance.     

Effect of delaying the time of insemination with sex-sorted semen on pregnancy rate in Holstein heifers

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.     

Use of Porcine Luteinizing Hormone at Oestrous Onset in a Protocol for Fixed‐Time Artificial Insemination in Gilts

The aim of this study was to evaluate the effect of porcine luteinizing hormone (pLH) given at oestrous onset in gilts, by different routes and doses, on the interval between onset of oestrus and ovulation (IOEO) and reproductive performance using a single fixed‐time artificial insemination (FTAI). A total of 153 gilts were submitted to oestrous detection at 8‐h intervals and assigned to three groups: control – without hormone application and inseminated at 0, 24 and 48 h after oestrous onset; VS2.5FTAI – 2.5 mg pLH by the vulvar submucosal route at oestrous onset and a single FTAI 16 h later; IM5FTAI – 5 mg pLH by the intramuscular route at oestrous onset and a single FTAI 16 h later. More VS2.5FTAI gilts (47.1%; p < 0.05) ovulated within 24 h after oestrous onset than control gilts (25.5%) whereas IM5FTAI gilts had an intermediate percentage (31.4%; p > 0.05). The IOEO tended to be shorter (p = 0.06) in VS2.5FTAI (30.2 ± 1.4 h) than in control (34.7 ± 1.4 h) gilts, but there was no difference (p > 0.05) between control and IM5FTAI (32.8 ± 1.4 h) gilts. Farrowing rate was not different (p > 0.05) among treatments. Total born piglets (TB) was lower (p < 0.05) in VS2.5FTAI (12.3 ± 0.4) than in control gilts (14.1 ± 0.4), whereas intermediate TB was observed in IM5FTAI gilts (13.3 ± 0.4). Due to the advancement of ovulation, reduction of the hormonal dose and the ease of application, the vulvar submucosal route would be the best option for FTAI protocols, but their negative impact on litter size remains to be elucidated. Taking into account the good fertility results obtained in IM5FTAI gilts whose ovulation was not advanced, the possibility of a single FTAI without any hormonal treatment should be further investigated, to establish reliable FTAI protocols for gilts.