title: Porcine field fertility with two different insemination doses and the effect of sperm morphology.
abstract: In swine artificial insemination, several dose regimens are applied, ranging from 1.5 x 10(9) to 6.0 x 10(9) spermatozoa per intra-cervical insemination dose. A lower sperm dose is more profitable for artificial insemination centres and offers a more effective use of superior boars. To evaluate fertility, 50 boars were used for a total of 10 773 homospermic first inseminations at a dose of 2 billion spermatozoa. In addition, 96 boars were used at a dose of 3 billion spermatozoa for 34 789 homospermic first inseminations. Fertility was determined by a 60-day non-return rate (NR%) of first inseminations. Litter size was registered by total number of piglets born separately in primiparous and multiparous farrowings. On average, a sow was inseminated 1.5 times. A significant decrease was observed in all three fertility parameters (NR%, litter size of both primiparous and multiparous farrowings) with a dose of 2 billion spermatozoa compared with a dose of 3 billion spermatozoa. The NR% was 75.8% and 84.0% (p < 0.001), the mean litter size of primiparous farrowings 10.1 and 10.7 (p < 0.001) and the mean litter size of multiparous farrowings 11.7 and 12.1 (p < 0.001) for 2 and 3 billion spermatozoa/dose, respectively. The proportion of normal spermatozoa in the sperm morphology analysis correlated significantly with NR% in both insemination regimens: p < 0.001, r = 0.604 and p < 0.05, r = 0.223 for 2 and 3 billion spermatozoa/dose, respectively. These results confirm that quantity can at least partly compensate for poor sperm quality. When the boars with <70% normal spermatozoa in the morphology evaluation were excluded from the data there were no correlation between the sperm morphology and NR%. However, the difference between the NR% and litter size remained statistically significant (p < 0.001) in favour for the bigger insemination dose. In conclusion, a decrease in sperm dose from 3 to 2 billion spermatozoa on commercial farms will severely decrease prolificacy at least under field conditions, where a sow is inseminated an average of 1.5 times/heat, and the semen is typically used within 3 days after collection. We recommend that under commercial circumstances the homospermic semen doses contain no <3 billion spermatozoa/dose.
authors.affiliation: Department of Clinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, Saarentaus, Finland. karolina.alm@helsinki.fi
authors.forename: K
authors.initials: K
authors.lastname: Alm
authors.forename: O A T
authors.initials: OA
authors.lastname: Peltoniemi
authors.forename: E
authors.initials: E
authors.lastname: Koskinen
authors.forename: M
authors.initials: M
authors.lastname: Andersson
mesh_terms: D000818:Animals; D005260:Female; D005298:Fertility / Q000502:physiology*; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D008098:Litter Size; D008297:Male; D010298:Parity; D011247:Pregnancy; D018873:Pregnancy Rate; D012661:Semen / Q000166:cytology / Q000502:physiology; D013076:Sperm Count / Q000662:veterinary*; D013094:Spermatozoa / Q000502:physiology*; D013552:Swine / Q000502:physiology*