J. Anim. Sci. 2005. 83:1543-1548
© 2005 American Society of Animal Science
ANIMAL GROWTH, PHYSIOLOGY, AND REPRODUCTION |
Technical Note: Transcervical deep cornual insemination of goats
B. Sohnrey and
W. Holtz1
Institute of Animal Husbandry and Genetics, University of Goettingen, D-37075 Goettingen, Germany
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Abstract
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A newly developed technique for trans-cervical deep uterine insemination of goats is described. An experiment was conducted to compare this transcervical method with the laparoscopic intrauterine insemination using frozen-thawed semen. Of the 46 primiparous and 21 multiparous estrus-synchronized Boer goat does inseminated transcervically, 71% (22/31) kidded compared with 53% (19/36) of does inseminated laparoscopically (P < 0.025). The corresponding litter sizes were 2.27 and 1.89 (P < 0.01). In another 34 parous does inseminated transcervically without preceding hormone treatment, kidding rate and litter size were 71% and 1.76, respectively. We conclude that transcervically conducted bilateral deep cornual insemination may be considered a viable alternative to laparoscopic insemination.
Key Words: Artificial Insemination • Goat • Laparoscopy
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Introduction
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A reliable means of inseminating goats with frozen-thawed semen would be most advantageous, not only for commercial breeders interested in genetic improvement of their stock, but also for smaller producers who can not afford a breeding buck of their own, and for persons (or their neighbors) who have a problem with the smell of a billy goat in their yard. In France, where systematic genetic improvement of dairy goats is pursued, AI is part of the management routine. When competently conducted, AI with fresh semen produces conception rates comparable to those obtained with natural breeding. With frozen-thawed semen, lower conception rates generally are encountered. For the French situation, conception rates of 60 to 65% have been reported (Leboeuf, 1992
, 1998). In other circumstances, less favorable results frequently are experienced, although rarely reported. Superior and more consistent pregnancy rates may be accomplished when inseminating laparoscopically (Ritar et al., 1990; Vallet et al., 1992). The advantage of laparoscopic insemination is that the semen is deposited closer to the site of fertilization. Deep uterine insemination has been shown to be advantageous in several domestic species, such as sheep (Salamon and Maxwell, 1995; Wulster-Radcliffe et al., 2004), goats (Ritar and Salamon, 1983; Moore et al., 1988), cattle (Dalton et al., 1999; López-Gatius, 2000; Verberckmoes et al., 2004), horses (Morris and Allen, 2002), and pigs (Martinez et al., 2002; Rath, 2002; Watson and Behan, 2003), especially when sperm numbers are limited or sperm quality is suboptimal. Laparoscopy has the disadvantage of requiring elaborate equipment and special skill. Therefore, we attempted to develop a transcervical method based on experience acquired in the process of establishing a transcervical embryo collection technique for goats (Pereira et al., 1998; Holtz et al., 2000; Suyadi et al., 2000). The present article presents a comparison of the newly developed technique of transcervical deep intrauterine insemination with the well-established technique of laparoscopic insemination.
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Materials and Methods
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A group of 67 Boer goat does (46 primiparous and 21 multiparous) from our own breeding flock, ranging in BW from 38 to 64 kg, was synchronized with half a progestagen-containing s.c. implant for cows (1.75 mg of Norgestomet; Crestar, Intervet, Boxmeer, The Netherlands) for 12 d (Holtz and Sohnrey, 1992). Two days before the end of the progestagen treatment, the does received 1-mL i.m. injections of a luteolytic dose of PGF2
(6.71 mg; Dinoprost-Trometamol Dinolytic, Pharmacia, Erlangen, Germany) and 200 IU of equine chorionic gonadotropin (Intergonan; Intervet, Unterschleissheim, Germany). A single insemination with 200 x 106 frozen-thawed spermatozoa was conducted 46 h after implant removal. In 36 of the does, insemination was conducted laparoscopically, whereas in the remaining 31 animals, a newly established transcervical insemination technique was employed. The semen had been pellet-frozen in a Tris-glucose-egg yolk diluent, with glycerol as the cryoprotectant. It originated from five bucks, with semen from these bucks being distributed randomly to treatment groups.
Before laparoscopic insemination, does were deprived of feed for 2 d, and of water for 1 d. During this 2-d period, they consumed small amounts of the straw that covered the pen floor. Emptiness of the digestive tract and bladder facilitates fast and easy operation and decreases the pressure exerted by the abdominal organs on the diaphragm while the animals are in a head-down position. Laparoscopic insemination involves restraint of the animals in dorsal recumbency on a laparoscopy cradle, and it was conducted much as described by Vallet et al. (1992). In brief, the animals were tilted into a head-down position at an angle of at least 45°. Approximately 8 cm cranial to the udder and 8 cm to the left and right of the midline, the skin was nicked with the tip of a scalpel blade and, with the aid of a trocar, two 5-mm cannulas were punched through the abdominal wall. A laparoscopic telescope (Panaview Plus; 5.3 mm; 25° viewing angle; Wolf, Knittlingen, Germany) and an insemination instrument (UA 111; IMV, l’Aigle Cedex, France) were introduced through the cannulas. The abdomen was slightly insufflated with a moderate amount of air to aid visibility. The uterine horns were punctured with the fine tip of the insemination pipette near the middle of the great curvature to deposit the semen in the uterine lumen. The sperm was distributed to both uterine horns.
To conduct the transcervical deep cornual insemination, the rear quarters of the animal were lifted, with the front legs remaining on the ground. With the aid of a duckbill speculum (UA045; IMV) and a penlight (Figure 1), the lip of the external cervical os was grasped by introducing sharp-pointed uterine tenaculum forceps, 255 mm long ("Possi," Aesculap, Tuttlingen, Germany), from the side between the slightly opened jaws of the speculum. The speculum was then removed and the rear of animal was placed back on the ground. The cervix was gently drawn toward the vulva, and a 3.2-mm o.d. catheter (Charrière (Ch) 10, catalog No. 221100; Ruesch, Kernen, Germany), with a 1.2 mm diameter stainless steel stylet inserted, was introduced. The stylet was removed once the tip of the catheter had passed through the cervix. The catheter was advanced another 10 to 12 cm, while being guided toward one of the uterine horns by a finger located in the vaginal fornix (Figure 2). A 40-cm-long 1.52 mm o.d. polyethylene (PE) tube (Portex, Hythe, Kent, U.K.) containing half the insemination dose was passed all the way through the catheter. The catheter was retracted by about 2 cm while holding the PE tube in position, exposing the tip of the PE tube to ensure the semen is expelled into the uterine lumen. Once the semen was discharged, the PE tube was removed from the catheter and loaded with the other half of the insemination dose. The catheter was then partially withdrawn and redirected toward the other uterine horn, and the insemination procedure was repeated. The time required to conduct each insemination, including positioning of the doe and thawing of the semen, rarely exceeded 5 min.
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Figure 1. Equipment required for transcervical deep cornual insemination of goats: duckbill speculum and penlight, uterine tenaculum forceps, catheter and stylet, and thin polyethylene tube with a 1-mL syringe attached.
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Figure 2. Reproductive tract of a goat showing fixation of the cervix with a uterine tenaculum forceps and the depth of introduction of the catheter into a uterine horn (arrow).
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Subsequent to the comparative trial described above, another 34 does of similar breed, age, and BW of, on average, 52 kg were inseminated by the transcervical technique without estrus synchronization. The does were checked for estrus with an aproned buck twice daily at 0800 and 1600. The time of estrus onset was assumed to be half the interval between the last rejection and the first toleration of the buck mounting. Twelve to 27 h after the estimated onset of standing estrus, a single insemination was conducted.
Four weeks after insemination, the does were subjected to pregnancy detection by real-time ultrasonography with a rectal 7.5-MHz linear-array transducer, as described elsewhere (Padilla-Rivas et al., 2005). At parturition, kidding rate and litter size were recorded.
Differences between the proportion of does pregnant and litter size were tested for significance by 
2 test (Steel and Torrie, 1960).
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Results
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Ultrasonographic pregnancy examination conducted four weeks after insemination revealed that, of the synchronized does that had been inseminated laparoscopically, 56% (20/36) were pregnant. Of the synchronized does inseminated transcervically, 74% (23/31) were pregnant. In each group, one doe aborted. Thus, of the does inseminated laparoscopically, 53% (19/36) kidded, compared with 71% (22/31) of does inseminated by the modified transcervical technique (P < 0.025). The corresponding litter sizes were 1.89 ± 0.17 (range = 1 to 3) and 2.27 ± 1.90 (range = 1 to 4), respectively, and the difference was significant (P < 0.01). Of the does inseminated without synchronization treatment, 79% (27/34) became pregnant and 71% (24/34) kidded, averaging a litter size of 1.76 ± 0.16 (range = 1 to 3). All kids born were normal and viable, and the overall female-to-male ratio was 47:53.
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Discussion
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Unsatisfactory pregnancy rates are a common complaint when inseminating goats with cryopreserved semen. In our own flock of Boer goats, approximately 600 inseminations conducted by the traditional transcervical method (Evans and Maxwell, 1987) over 6 yr led to kidding rates between 20 and 30%. The technique involves introduction of a rigid insemination pipette into the cervix under visual control while the hind quarters of the animal are elevated. In 60% of cases, it was possible to deposit the semen (200 x 106 spermatozoa) in the uterine body. In the remaining cases, the semen was deposited intracervically (30%) or deep in the vagina (10%). Once we turned to laparoscopic intrauterine insemination, pregnancy rates nearly doubled, agreeing with observations by Moore et al. (1988), Ritar et al. (1990), and Vallet et al. (1992). Consequently, in recent years, all inseminations in our flock with cryopreserved semen have been conducted laparoscopically. For that reason, in the present comparative trial, the conventional transcervical insemination technique was not taken into account.
The reason for the superiority of the transcervical over the laparoscopic technique is open to conjecture. Conceivably, the lower pregnancy rate observed after laparoscopic insemination may be attributed to the temporary withholding of feed and water or the emotional strain accompanying restraint in a supine head-down position. The transcervical technique requires some skill and experience, but is, by all accounts, simpler to conduct than the laparoscopic approach. For fixation of the cervix, sharp-pointed uterine tenaculum forceps are required. Grasping timidly or using forceps that are not sufficiently sharp to effectively pierce the lip of the external cervical os will lead to excessive bruising or tearing. Tearing brings about profuse bleeding that obscures the vision and bears the risk of introducing blood into the uterus. Initially, it was thought that the manipulation of the cervix must be painful; therefore, a local anesthetic (i.e., xylocain spray) was applied. This practice was discontinued, however, after it was observed that the greatest stress exhibited by the goats was caused by having their hindquarters lifted up, the duckbill speculum introduced, and the vagina dilated. Once the speculum had been removed and the animals were back on their feet, they were docile and fairly oblivious to further manipulations. One person, seated on a chair, held the does by their head. It was, in all instances, possible to passage the cervix. The catheter must be sufficiently pliable to follow the curvature of the uterus, yet rigid enough not to kink or coil. The tip must be rounded, so as to negotiate through the folds of the uterine mucosa without causing significant epithelial damage. Occasionally, after withdrawal, a trace of blood would be observed on the outside of the catheter. The PE tube containing the sperm must be firm enough not to kink when being passed through the catheter. Its 0.86 mm diameter lumen provides sufficient luminal space to accommodate half the 0.25 mL of diluted semen contained in a French mini-straw or a frozen-thawed semen pellet. We are confident that we can control which uterine horn the catheter is directed to from the experience gained in the process of devising the nonsurgical embryo collection technique. The drainage of the first flushing from each uterine horn was always characterized by the presence of cellular debris, which was not observed in subsequent flushings. The operation would be even simpler if it were sufficient to deposit the semen in only one uterine horn. There are opinions to the contrary (Killeen and Caffery, 1982; Maxwell, 1986), but evidence in sheep indicates that deposition of semen in a single uterine horn leads to fertilization of ova in both horns (Evans and Armstrong, 1984; Reinhold et al., 1990; Eppleston, 1993). The question of whether unilateral insemination will suffice is being addressed in an ongoing study.
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Implications
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Deep cornual insemination of goats with frozen-thawed semen may be conducted by transcervical route without the need for elaborate equipment or special skills. Based on our results, pregnancy rates compare favorably with laparoscopic inseminations.
1 Correspondence: Albrecht-Thaer-Weg 3 (phone: +49-551-395605; fax: +49-551-395587; e-mail:wholtz{at}gwdg.de).
Received for publication December 7, 2004.
Accepted for publication April 6, 2005.
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Abstract
Introduction
