title: Litter size and vagina-cervix catheter penetration length in gilts.
abstract: As in other species, the reproductive tract in pigs increases in size with age and body weight, and the development of the reproductive tract depends on a balance between development of the pituitary-ovarian axis and the influence of metabolic hormones. Two experiments were conducted in prepubertal Duroc gilts, 150-180 days of age, to determine whether litter size is related to vaginal-cervix catheter penetration length during insemination. In experiment 1, oestrus was induced in 452 gilts with a combined dose of 400 IU Pregnant Mare Serum Gonadotrophine (PMSG) + 200 IU human chorionic gonadotropin (hCG). The gilts were classified into three catheter penetration length groups: Ih, < or = 21 cm; IIh, > 21 and < 28 cm, IIIh, > 28 cm. The litter size was lowest in group Ih (7.35 +/- 0.15) compared with groups IIh (7.81 +/- 0.12; p < 0.05) and IIIh (10.0 +/- 0.36; p < 0.001). In experiment 2, first oestrus was induced in 162 gilts by boar exposure. The gilts were classified into three catheter penetration length groups at insemination during their second oestrus: In, < or = 24 cm; IIn, > 24 and < 26 cm; IIIn, > 26 cm. As in experiment 1, the litter size was lowest in the group with the shortest catheter penetration length (8.32 +/- 0.19). The litter size was not different among gilts of groups IIn and IIIn (8.84 +/- 0.35 and 9.56 +/- 0.46, respectively), but litter size was lower (p < 0.05) in group In than in group IIn. Based on the combined data from both experiments, the correlation between the catheter penetration length and total number of piglets born was expressed as: y =5.346 +/- 0.104x; r = 0.361 (p < 0.05). Fertility rate was not different among the groups of gilts induced into oestrus by hormone treatment or inseminated in the second oestrus; however, the total fertility rate of boar-exposed gilts was higher (p < 0.0001) than PMSG/hCG treated animals. Thus, it is possible to conclude that litter size at first farrowing is associated with vaginal-cervix catheter penetration length during insemination of the gilt.
authors.affiliation: Veterinary Faculty of Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Martin Rillo
authors.forename: C
authors.initials: C
authors.lastname: de Alba Romero
authors.forename: A
authors.initials: A
authors.lastname: Romero Rodriguez
authors.forename: R
authors.initials: R
authors.lastname: Cidoncha
authors.forename: A J
authors.initials: AJ
authors.lastname: Ziecik
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D002404:Catheterization / Q000662:veterinary; D002584:Cervix Uteri / Q000033:anatomy & histology*; D005260:Female; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D008098:Litter Size; D010298:Parity / Q000502:physiology; D011247:Pregnancy; D013552:Swine / Q000033:anatomy & histology / Q000502:physiology*; D014621:Vagina / Q000033:anatomy & histology*