Comparison of prostaglandin- and progesterone-based protocols for timed artificial insemination in sheep

The objective was to compare the reproductive performance of a new PGF_2α-based timed artificial insemination (TAI) protocol in sheep (Synchrovine®: two doses of PGF_2α, 7 d apart) to a traditional progesterone-eCG (P4-eCG) protocol, considering the effects of seminal state, AI-times, and AI-pathway. Three experiments involving 1297 multiparous Australian Merino ewes were done during the physiologic breeding season (location 32 °S-57 °W). Reproductive performance was assessed as non-return rate to service 21 d after AI (NRR21d), based on detection with androgenized wethers, as well as Fertility (pregnant/inseminated ewes), Prolificacy (fetuses/pregnant ewe), and Fecundity (fetuses/inseminated ewe), which were based on transabdominal ultrasonography 50 d after TAI. In Experiment 1, Synchrovine® treated ewes TAI cervically with fresh semen at 42, 48, or 54 h had similar NRR21d (0.51, 0.46, 0.57), Fertility (0.27, 0.31, 0.26), and Fecundity (0.29, 0.32, 0.27), all of which were lower (P < 0.05) than in a control P4-eCG group inseminated at 54 h (0.61, 0.48, 0.52, NRR21d, Fertility and Fecundity respectively). In Experiment 2, using chilled semen and cervical TAI, Synchrovine® treated ewes inseminated at 42 h yielded lower (P < 0.05) NRR21d, Fertility and Fecundity (0.28, 0.06, 0.06) compared to 48 (0.43, 0.24, 0.24) and 54 h (0.44, 0.22, 0.23). In Experiment 3 with chilled semen, Synchrovine® treated ewes TAI into the cervix at 51 or 57 h were similar in NRR21d (0.16 vs 0.20), Fertility (0.12 vs 0.14), and Fecundity (0.12 vs 0.15), respectively; but lower (P < 0.05) than P4-eCG treated ewes TAI at 54 h (0.34, 0.28, and 0.33 for NRR21d, Fertility and Fecundity respectively). Synchrovine® treated ewes intrauterine TAI at 51 or 57 h yielded similar NRR21d (0.51 vs 0.58), Fertility (0.43 vs 0.51), and Fecundity (0.45 vs 0.56) respectively, but lower (P < 0.05) results compared to P4-eCG treated ewes (0.75, 0.71, and 0.88 for NRR21d, Fertility and Fecundity respectively). In conclusion, AI-time in Synchrovine® treated ewes with fresh semen might be extended (42 to 54 h after the second PGF_2α), but should be delayed to 48-54 h with chilled semen and cervical AI. Independent of the seminal state, AI-time or AI-pathway, Synchrovine® yielded lower reproductive results than a conventional P4-eCG protocol.     

Estrus synchronization and artificial insemination of hair sheep ewes in the tropics

Hair sheep ewes (St. Croix White and Barbados Blackbelly) were used to evaluate 3 methods of estrus synchronization for use with transcervical artificial insemination (TAI). To synchronize estrus, ewes (n = 18) were treated with PGF2alpha (15 mg, im) 10 d apart, with controlled internal drug release (CIDR) devices containing 300 mg progesterone for 12 d (n = 18), or with intravaginal sponges containing 500 mg progesterone for 12 d (n = 18). On the day of the second PGF2alpha injection or at CIDR or sponge removal, sterile rams were placed with the ewes. Jugular blood samples were collected from the ewes at 6-h intervals until the time of ovulation, and daily for 16 d after estrus (Day 0). Plasma was harvested and stored at -20 degrees C until LH, and progesterone concentrations were determined by RIA. There was no difference (P>0.10) in time to estrus among the CIDR-, PGF2alpha- or sponge-treated ewes. All of the ewes in the CIDR group and 94.4% of the sponge treated ewes exhibited estrus by 36 h after ram introduction, while only 72.2% of PGF2alpha-treated ewes showed signs of estrus by this time (P<0.06). The time from ram introduction to ovulation was not different (P>0.10) among the CIDR-, PGF2alpha- or sponge-treated ewes. The time to the preovulatory LH surge was similar (P>0.10) among CIDR, PGF2alpha and sponge treated ewes. Progesterone levels through Day 16 after the synchronized estrus were not different (P>0.10) among treatment groups. Hair sheep ewes (n = 23) were synchronized using PGF2alpha and bred by TAI using frozen-thawed semen 48 h after the second injection. The conception rate to TAI was 2/23 (8.7%) and produced 3 ram lambs. In a subsequent trial, 17 ewes were synchronized with CIDR devices and bred by TAI using frozen-thawed semen 48 h after CIDR removal, resulting in a conception rate of 52.9% (9/17). It is possible to synchronize estrus in hair sheep using either CIDRs, sponges or PGF2alpha. Even though there were no significant differences in the timing of ovulation or the LH surge among the treatment groups, a higher conception rate was achieved in ewes synchronized with CIDR devices during the second trial. This may reflect an increase in the skill level of the TAI technician.     

Profitability of a dairy sheep genetic improvement program using artificial insemination

This simulation study investigated the farm-level economic benefits of a genetic improvement scheme using artificial insemination (AI) with fresh ram semen in dairy sheep of the Chios breed in Greece. Data were collected from 67 farms associated with the Chios Sheep Breeders' Cooperative 'Macedonia', describing the percentage of ewes that would be artificially inseminated in the flock, pregnancy rate, annual ram costs that could be saved using AI rather than natural mating, expected improvement in milk production, annual costs of semen and feed, milk price and number of years of AI usage. The study considered 77 760 possible scenarios in a 3 × 4 × 4 × 3 × 3 × 3 × 4 × 15 factorial arrangement. Analysis of variance was used to investigate the effect of each factor on farm profitability. All factors considered were statistically significant (P < 0.001), but their effect varied. The number of years using AI had the greatest effect on profitability and farmers should become aware that using AI is a long-term investment. Semen price, pregnancy rate and improvement in milk production also had substantial effects. The price of milk and feed had a considerably lower effect on profitability, as did the annual cost of maintaining rams that would be replaced by AI. A positive annual and cumulative return was achieved in the model within the first 6 years. The cost of semen was estimated at 8€ to 10€ per dose for the first 5 years. Where the annual improvement in milk production was 1% of annual phenotypic mean (e.g. 3.0 kg) profitability of the scheme was improved greatly.     

Alternatives to improve a prostaglandin-based protocol for timed artificial insemination in sheep

The objective was to improve the reproductive performance of a prostaglandin (PG) F_2α-based protocol for timed artificial insemination (TAI) in sheep (Synchrovine®: two doses of 160 μg of delprostenate 7 d apart, with TAI 42 h after second dose). Three experiments were performed: Experiment 1) two doses of a PGF_2α analogue (delprostenate 80 or 160 μg) given 7 d apart; Experiment 2) two PGF_2α treatment intervals (7 or 8 d apart) and two times of TAI (42 or 48 h); and Experiment 3) insemination 12 h after estrus detection or TAI with concurrent GnRH. Experiments involved 1131 ewes that received cervical insemination with fresh semen during the breeding season (32/34 °S–58 °W). Estrous behaviour, conception rate, prolificacy, and fecundity (ultrasonography 30–40 d), were assessed. In Experiment 1, ewes showing estrus between 25 and 48 h or at 72 h after the second PGF_2α did not differ between 80 and 160 μg of delprostenate (73 vs 86%, P = 0.07; and 92 vs 95%, P = NS, respectively). Conception rate and fecundity were lower (P < 0.05) using 80 vs 160 μg (0.24 vs 0.42, and 0.27 vs 0.47, respectively). In Experiment 2, giving PGF_2α 7 d apart resulted in higher (P < 0.05) rates of conception (0.45 and 0.51) and fecundity (0.49 and 0.53) than treatments 8 d apart (conception: 0.33 and 0.29; fecundity: 0.33 and 0.34) for TAI at 42 and 48 h, respectively. In Experiment 3, rates of conception, prolificacy and fecundity were similar (NS) between Synchrovine® with TAI at 42 h (0.50, 1.13, and 0.56) and AI 12 h after estrus detection (0.47, 1.18, and 0.55), and Synchrovine® plus GnRH at TAI (0.38, 1.28, and 0.49). However, all TAI treatments had lower (P < 0.05) prolificacy and fecundity compared to AI following detection of spontaneous estrus (1.39 and 0.83, respectively). In conclusion, the Synchrovine® protocol was: a) more successful using 160 vs 80 μg delprostenate; b) more successful with a 7 d than 8 d PGF_2α interval; c) similarly effective for TAI versus AI 12 h after estrus detection; and d) not improved by giving GnRH at TAI.     

Environmental and genetic variation factors of artificial insemination success in French dairy sheep

Artificial inseminations (n = 678 168) recorded during 5 years in five French artificial insemination (AI) centres (2 'Lacaune', 1 'Manech tête rousse', 1 'Manech tête noire' and 1 'Basco béarnaise') were analysed to determine environmental and genetic factors affecting the insemination results. Analyses within centre-breed were performed using a linear model, which jointly estimates male and female fertility. This model combined four categories of data: the environmental effects related to the female, those related to the male, the non-sex-specific effects and finally the pedigree data of these males and females. After selection, the environmental female effects considered were age, synchronisation (0/1) on the previous year, total number of synchronisations during the female reproductive life, time interval between previous lambing and insemination, already dry or still lactating (0/1) when inseminated, and milk quantity produced during the previous year expressed as quartiles intra herd * year. The environmental male effects were motility and concentration of the semen. The non-sex-specific effects were the inseminator, the interaction herd * year nested within the inseminator, considered as random effects and the interaction year * season considered as a fixed effect. The main variation factors of AI success were relative to non-sex-specific effects and to female effects. Heritability estimates varied from 0.001 to 0.005 for male fertility and from 0.040 to 0.078 for female fertility. Repeatability estimates varied from 0.007 to 0.015 for male fertility and from 0.104 to 0.136 for female fertility. These parameters indicate that genetic improvement of AI results through a classical polygenic selection would be difficult. Moreover, in spite of the large quantity of variation factors fitted by the joint model, a very large residual variance remained unexplained.     

Transcervical artificial insemination in sheep: effects of a new transcervical artificial insemination instrument and traversing the cervix on pregnancy and lambing rates

Cervical anatomy limits the use of transcervical intrauterine artificial insemination (TC AI) in sheep. We have developed an instrument to cope atraumatically with the cervix; although this instrument has not affected fertilization rate or pregnancy rate through Day 3, the effects on sperm transport and pregnancy after Day 3 are not known. The objective of the present study was to determine whether our TC AI instrument affected sperm transport, pregnancy rates, or lambing rate. In Experiment 1, ewes were assigned to two treatments: TC AI using the new TC AI instrument (n=10) or AI via laparotomy using a laparoscopic AI instrument (n=10). Twenty hours after artificial insemination, the uterine horns and oviducts were recovered and flushed to collect spermatozoa. Sperm transport did not differ (P>0.05) between the two treatments. In Experiment 2, ewes were assigned to three treatments: TC AI using the new TC AI instrument+sham intrauterine AI via laparotomy (n=29); sham TC AI+intrauterine AI via laparotomy using a laparoscopic AI instrument (n=29); and sham TC AI+intrauterine AI via laparotomy using the new TC AI instrument (n=30). On Day 14 after AI, uteri were collected and flushed to recover blastocysts. Transcervical deposition of semen reduced (P<0.05) Day 14 pregnancy rate (17.2% versus 61%), but intrauterine deposition of semen using the TC AI instrument via midventral laparotomy increased (P<0.05) Day 14 pregnancy rate (76.6% versus 44.8%). In Experiment 3, ewes were assigned to two treatments: sham cervical manipulation (n=40) or cervical manipulation to mimic TC AI (n=40). Immediately after treatment, each ewe was mated with a ram and watched until the ram mounted and ejaculated into the ewe. Treatment did not affect Day 30 or 50 pregnancy rate (67.5 and 66.2%, respectively), determined ultrasonically, or lambing rate (62.5%). The differences between Days 30 and 50 pregnancy rates and lambing rate were not significant. In Experiment 4, ewes were assigned to two treatments: TC AI (n=99) or laparoscopic AI (n=99). Transcervical AI reduced (P<0.01) Day 30 (TC AI versus laparoscopic AI; 5.0% versus 46.0%) and Day 50 pregnancy rates (4.0% versus 41.0%), determined ultrasonically, and lambing rate (4.0% versus 41.0%). Although the TC AI procedure significantly reduced pregnancy and lambing rates, large numbers of spermatozoa deposited at natural insemination seemed to compensate. Because our TC AI procedure has all but eliminated any visual evidence of trauma, and because the procedure does not seem to affect sperm transport or embryonal survival until Day 3, we speculate that cervical manipulation associated with TC AI may activate pathways that interrupt pregnancy between Days 3 and 14.     

Ram-induced ovulation to improve artificial insemination efficiency with frozen semen in sheep.

Ram effect, defined as shortening of seasonal anestrus in ewes by exposure to the ram, is now well recognized but the underlying mechanisms are still unclear. Little information also exists whether the ram is able to influence the estrus cycle and ovulation. Three experiments were conducted to investigate endocrine response, time of ovulation and pregnancy rate of ewes in proestrus, exposed to the ram (treated) or an adult ewe (control). In the first experiment, ewes (n = 20) were treated with fluorgestone acetate pessaries for 12 days and were given eCG and cloprostenol one day before withdrawal of pessaries. On the day after removal of the pessaries ewes in the treated group (n = 10) were exposed to the ram and those in the control group (n = 10) were exposed to an adult ewe. Blood samples were taken for LH assay every 20 min from 2 h before to 24 h after ram exposure. In the second experiment, ewes (n = 120) were induced into proestrus and on the day after removal of the pessaries were exposed to either a ram (n = 60) or a ewe (n = 60) as described above and were laparoscoped 50, 60 or 70 h after pessary withdrawal (n = 20 at each time interval). In the third experiment ewes (n = 90) were induced and exposed to the ram (n = 45) or an adult ewe (n = 45) and inseminated via a laparoscope whit frozen-thawed semen at 50 or 60 h after pessary removal, respectively. Exposure to the ram was followed in 2 h by a marked rise in LH, equivalent to a preovulatory surge in duration and amplitude. It was also followed by concentrated ovulation within 25 to 30 h and by an increased pregnancy rate in exposed ewes (73.3 vs. 53.3%).     

Further development of a transcervical technique for artificial insemination in sheep using previously frozen semen

A transcervical technique (the Guelph System for transcervical AI) was used to inseminate 2060 ewes on 65 farms (average 31 ewes, range 5 to 107) in Ontario, Canada, from October 1990 to September 1992, using previously frozen semen. Estrus was synchronized using progestagen pessaries and PMSG with median inseminations done at 54 h from pessary removal. Maiden ewes were not included. Only ewes in which the cervix could be penetrated were inseminated with 150 million spermatozoa per insemination. A total of 1809 were penetrated and inseminated (penetration rate 87.8%). Success of penetration increased from 76.3% in the first 500 ewes to 97.9% in the last 500 (P=0.01). Cervical penetration was more successful in ewes in the accelerated lambing program (92.3%, average 3.1 mo since the previous lambing) than those in the annual lambing program (82.4%, average 7.0 mo since the previous lambing; P=0.06). The lambing rate for ewes bred during the combined traditional breeding seasons (Fall of 1990, 1991, 1992) was 50.7% compared to 24.4% for ewes bred at other periods (P=0.00001). The average time required for handling and insemination decreased from 8.62 min in the first 500 ewes to 3.62 min in the last 500 ewes. The Guelph System for Transcervical AI was found to be successful for cervical penetration in most ewes. Penetration success was affected by period since the last lambing and by inseminator experience. The lambing rate was higher for ewes bred during the traditional Fall breeding seasons than during other times of the year.     

Caffeine and artificial insemination

We studied the reactivation of cells and the repair of photomutagenic damage induced by xanthotoxin and visnagin plus NUV in arg-1 cells of Chlamydomonas reinhardii. Maintenance of liquid cultures in the dark resulted only in a slight reactivation of cells, even after 24 h. Repair of photomutagenic damage was more efficient: within 24 h the number of Arg⁺ revertants was reduced by 50% in cells cultured in the dark at 20°C. The repair was more efficient at 30°C. At the beginning of dark cultivation an after-effect could be observed. Cultivation in standard white light instead of dark after treatment resulted in a very strong after-effect. Therefore it was not possible to detect any photoreactivation.After treatment with xanthotoxin plus standard white light (24 h) neither reactivation of cells nor repair of photomutagenic damage was found. The after-effect was higher than after xanthotoxin plus NUV. It is possible that a small amount of repair could be masked by the after-effect.Treatment with visnagin yielded similar results. The photomutagenic effect of visnagin is described for the first time in this paper. The drug is a much less effective photomutagen than xanthotoxin. The photomutagenesis of visnagin may be attributable to photoproducts similar to those formed after treatment with furocoumarins.No definite conclusion can be drawn from the present results regarding the basis for the observed lack of repair (or reduced repair) after standard white light treatment; a possible cause might be a preferential formation of bi-adducts under these conditions.     

Development of a new transcervical artificial insemination method for sheep: effects of a new transcervical artificial insemination catheter and traversing the cervix on semen quality and fertility

The difficulty of traversing the cervix severely limits transcervical artificial insemination (TC AI) in sheep. Cervical trauma and poorly designed instruments can reduce fertility after AI. To overcome problems associated with TC AI, we developed a new TC AI catheter. Three bench experiments were conducted to determine the effects of the new TC AI catheter on semen quality independent of the effects of moving the catheter through the cervix. In each of the three bench experiments, the standard laparoscopic instrument for intrauterine AI in sheep was used as the control for the TC AI catheter. In Experiment 1, the total volume of semen extender expelled and void volumes for both types of AI instrument (TC versus laparoscopic) were determined. In Experiment 2, the effects of each type of AI instrument (TC versus laparoscopic) on semen quality, estimated as percentage motility and percentage forward progressive motility, of frozen-thawed semen was determined. In Experiment 3, the effects of both types of AI instrument (TC versus laparoscopic) on number of spermatozoa expelled was determined. The type of AI instrument affected neither semen quality nor the number of spermatozoa expelled. However, void volume differed (P < 0.01) between the two instruments. After differences in void volume were taken into account, an in vivo experiment was conducted to determine whether using our new TC AI catheter for TC or surgical intrauterine AI affected fertilization and pregnancy rates. For this, ewes were assigned to one of three treatments: (1) TC AI using the new TC AI catheter + sham AI via laparotomy (n = 9); (2) sham TC AI + AI via laparotomy using a laparoscopic AI instrument (n = 8); and (3) sham TC AI + AI via laparotomy using the new TC Al catheter (n = 10). To synchronize estrus, progestogenated pessaries were inserted and left in place for 12 days. On Day 5 after pessary insertion, PGF2alpha (15 mg) was given i.m. At pessary removal, 400 IU of eCG were administered i.m. Ewes were inseminated 48-52 h after pessary removal using fresh diluted semen (200 x 10(6) to 350 x 10(6) spermatozoa per 0.2 ml) pooled from the same four rams each day during the experiment. At 72 h after AI, uteri were collected postmortem and flushed. Oocytes and embryos were recovered and evaluated. Treatments did not affect (P > 0.01) ovum and embryo recovery rate (mean = 87.3%), fertilization rate (59.3%), or Day 3 pregnancy rate (mean = 66.6%). We conclude from these data that the use of our new TC AI catheter for TC AI or intrauterine AI should not impair the success of AI in sheep.     

Fixed-time artificial insemination in beef cattle

Background  

The study was designed to test the effect of fixed-time artificial insemination (fixed-AI) after the slightly modified Ovsynch protocol on the pregnancy rate in beef cattle in Finnish field conditions. The modification was aimed to optimize the number of offsprings per AI dose.     

Bio-economic and operational feasibility of introducing oestrus synchronization and artificial insemination in simulated smallholder sheep breeding programmes

Low selection intensity due to few selection candidates available at any one time due to thinly spread year-round lambings in villages and prohibitively large nucleus requirements to provide sufficient improved rams to the production tier are the major challenges for designing effective village-based and central nucleus-based breeding programmes, respectively, for smallholder sheep farmers. To tackle these challenges, we used deterministic simulation to design three schemes in village-based programmes introducing hormonal oestrus synchronization (natural oestrus (VNE), single oestrus synchronization (VSE1) and double oestrus synchronization (VSE2)) and three schemes in central nucleus programme introducing artificial insemination (AI) (natural mating with nucleus sizes of 5% (CNM1) and 1% (CNM2) of the total ewe population and natural mating in breeding tier and AI in production tier (CAI)). The schemes were evaluated for their bio-economic and operational feasibility, taking Bonga sheep of Ethiopia as a case study. The selection intensities achieved in VNE, VSE1 and VSE2 were 2.0, 2.3 and 2.4, respectively, for selecting rams for the breeding tier and 0.0, 0.8 and 1.0, respectively, for the production tier. The profits per ewe per year from VNE, VSE1 and VSE2 were Birr 12.2, 21.7 and 24.5, but the profit from VNE for the production tier was zero. CAI generated more genetic gains in the breeding objective (Birr 4.8) than CNM1 (Birr 2.5) and CNM2 (Birr 0.0) in the production tier. However, CAI was less profitable than CNM1 and CNM2. In conclusion, hormonal oestrus synchronization was found to be a feasible technological aide to accelerate genetic progress in village-based programmes. CNM1 and CNM2 could not be recommended as CNM1 requires large nucleus of 10 325 ewes and CNM2 results in zero genetic gain in the production tier. CAI could overcome the challenge in central nucleus programmes, namely unaffordable large nucleus, but the scheme needs to be subsidized by the public sector to be economically feasible for farmers.     

The artificial insemination of bumblebee queens

Summary: Artificial insemination (AI) is a technique to transfer instrumentally sperm from the male into the female's reproductive system. AI is widespread in vertebrates for economical animal breeding and for conservation biology. However, in invertebrates only a few cases of successful AI have been reported. In this paper we describe a new technique to artificially inseminate bumblebee queens (Bombus spp.). Males were dissected and the accessory testes were removed and washed in insect ringer. They were then opened and the outflowing sperm was picked up with a glass capillary mounted on a syringe. For the sperm transfer into the queen we adapted a standard apparatus used for honeybee inseminations. The queen was anaesthetized with CO₂, held in place by a queen holder and the sting chamber was opened using two hooks. The sperm containing glass capillary was introduced into the queen's sexual tract. The sperm was released into the bursa copulatrix very near the opening of the spermathecal duct of the queen. Inseminated queens were hibernated for 2 weeks and produced a normal colony under field conditions. Multiple inseminations proved to be successful since different patrilines could be detected in the worker offspring. Successful inseminations were performed for B. terrestris, B. lucorum and B. hypnorum.     

The levels of artificial insemination and missing sire information make genomic selection not always beneficial in meat sheep

Numerous meat sheep breeding programs in developed and developing countries are characterized by incomplete sire information and a predominant use of natural matings. These two parameters potentially affect the benefit of genomic selection (GS), especially for the selection of a late-in-life trait. Using stochastic simulations, the genetic gains obtained using genomic and conventional strategies for a maternal trait were evaluated in meat sheep population. Natural mating and artificial insemination (AI)-based designs, inspired by the current diversity of designs used for French meat sheep breeds, were modeled and three genomic strategies were tested and compared with a conventional selection strategy: parentage assignment, GS based on a male or a male and female reference population. Genomic selection based on a male reference population did not always outperform conventional selection. Its benefit depended on the design, the level of missing information on dam sires, and the level of AI. Genomic selection based on a male and female reference population always outperformed the conventional selection strategy, even if only 25 % of the females in the nucleus were genotyped.     

Successful artificial insemination in Lemur fulvus mayottensis

A method is reported for collection of sperm by electrostimulation or prostatic massage in order to carry out artificial in utero insemination in Lemur fulvus mayottensis. Using fresh sperm, one success out of 7 attempts was obtained, although it was achieved with a vesiculectomized male.