Litter size has been estimated to be 25-30% smaller in bitches receiving frozen semen compared to fresh and chilled (6,8,10,11,12). Litter size using intra-uterine AI of frozen-thawed semen is also significantly larger than by vaginal AI. Whelping rates by intrauterine AI in the dog are significantly better than those obtained by vaginal AI not only for frozen-thawed semen (by 51%) but also for chilled (by 44%) as well as for fresh semen (by 30%). The keys to obtaining good results by canine artificial insemination are proper timing of the insemination, the use of an adequate number of spermatozoa of good quality, good semen handling and preparation methods, and to apply an intrauterine inseminaton technique. Breeders now use stud dogs from all over the world, and save semen from valuable dogs to be used in later generations. Email: interest from dog breeders to use artificial insemination (AI) is rapidly increasing world wide both because the results are improving due to advances in our understanding of canine reproduction, and improvement of the techniques, but also because of an increasing awareness that by AI spread of diseases can be prevented. Transcervical insemination has the advantage of allowing two inseminations when there are enough straws available to do so.Catharina Linde Forsberg, Division of Reproduction, Department of Clinical Sciences¸ Box 7054, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden. Many factors influence this figure, especially the quality of the individual semen sample and the number of inseminations.
Surgical or transcervical insemination yields a success rate as high as 85%. Vaginal deposition generally leads to a success rate <25% because the thawed sperm only live for about 12 hours. Success with frozen semen depends on consistent attention to detail, good breeding management (ovulation timing), and intrauterine deposition of semen by surgical or transcervical insemination.
CANINE MINITUBE FULL
A tester straw (the last, partially full one) is always thawed and checked in order to make the needed calculations. Most collections yield between one and five breedings. Some dogs’ semen may not perform as well, meaning more straws per breeding.
CANINE MINITUBE PLUS
In other words, some dogs freeze very well and give 70% return on motility plus minimal defects post-thaw. The number of breedings possible when using a frozen sample depends on the semen evaluation and the dog’s individual sensitivity to the freezing process. We need 100 million normal, motile sperm per breeding. The number of straws needed for breeding depends on the quality of the semen (motility and morphology). The number of straws produced depends on the total number of sperm per ejaculate. We collect the male, do a semen evaluation, and process the semen to allow about 50 million sperm per straw. For example, if a sample has 80% motility pre-freezing, then we can get 56% progressive motility post-thaw.
Using Minitube’s methodology and equipment, we can approach a 70% return of sperm motility on thawing of frozen semen.
This progressive company has been processing 95% of the world’s porcine (pig) semen for years, and they are now applying their expertise to canine reproductive techniques. We work with Minitube products and technology. When frozen semen is thawed, the optimal rate is fast enough to prevent ice crystal formation, but slow enough to prevent cells from rupturing as fluid re-enters. The rate of freezing should be fast enough to prevent excessive shrinkage of sperm cells as fluid leaves them (changing osmotic gradient), but slow enough to prevent ice from forming inside the cells. Antibiotics are added to prevent bacterial growth, sugars are included to provide energy, and fresh egg yolk is used to protect cell membranes from cold shock. Buffering compounds maintain an optimum pH of 6.9-7.1 despite hydrogen ion production by sperm metabolic activity (tends to increase the pH). Glycerol, a cryoprotective agent, is allowed to penetrate the cells after chilling. Special extenders are designed to protect the sperm cells during freezing. Once frozen, semen can be stored indefinitely. We must be meticulous, but we do not require ‘100% clean rooms’ or other high-priced technological aids. Luckily, canine semen is less sensitive than many other species.
When we freeze semen in liquid nitrogen, we are asking the sperm cells to survive a drop in temperature from 37 C to 4 C during the chilling process, followed by a plunge to –196 C during the freezing process.
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