title: Time of ovulation and reproductive performance over three parities after treatment of primiparous sows with PG600.
abstract: Primiparous sows from a commercial pig farm in central Brazil were utilized to investigate the effect of post-weaning gonadotrophins (given during summer) on estrus, time of ovulation and reproductive performance over three parities. One group of sows (PG600) was treated with a combination of 400 IU equine chorionic gonadotrophin (eCG)+200 IU human chorionic gonadotrophin (hCG) (PG600) 24h after weaning (n=420), whereas the control group received saline (n=408). In a subset of sows (n=150), estrus was detected and time of ovulation was determined by transcutaneous ultrasound. Treatment with PG600 increased the percentage of primiparous sows in estrus within 10 days after weaning (94.8% versus 79.7%) and reduced the first weaning-to-estrus interval (5.3 days versus 8.0 days) relative to control sows (P<0.05). Although the duration of estrus was longer (P<0.05) in sows given PG600 (65.7 h versus 61.0 h), the interval from estrus to ovulation was not different (P>0.05) between PG600 and control sows (46.6 h versus 43.3 h). Treatment with PG600 did not affect (P>0.05) rates of return-to-estrus and farrowing over three parities, but it increased the number of total piglets born (P<0.05) in the second parity (11.2 versus 10.4), thereby minimizing the magnitude of second-litter syndrome. Culling rates from the first to the fourth parity were 26.7 and 24.5% (P>0.05) for PG600 and control sows, respectively. In conclusion, PG600 given 24 h after the first weaning reduced the weaning-to-estrus interval and increased the size of the second litter.
authors.affiliation: Setor de Suínos, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, CEP 90540 000 Porto Alegre, RS, Brazil.
authors.forename: Anamaria J
authors.initials: AJ
authors.lastname: Vargas
authors.forename: Mari L
authors.initials: ML
authors.lastname: Bernardi
authors.forename: Ivo
authors.initials: I
authors.lastname: Wentz
authors.forename: Guilherme Borchardt
authors.initials: GB
authors.lastname: Neto
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Bortolozzo
mesh_terms: D000818:Animals; D001947:Breeding; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004338:Drug Combinations; D004971:Estrus / Q000187:drug effects* / Q000502:physiology; D004972:Estrus Detection; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D008098:Litter Size / Q000187:drug effects*; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology; D010298:Parity; D011247:Pregnancy; D012098:Reproduction / Q000187:drug effects / Q000502:physiology; D013552:Swine / Q000502:physiology*; D013997:Time Factors; D014886:Weaning
chemical_list: D006063:Chorionic Gonadotropin; D004338:Drug Combinations; D006064:Gonadotropins, Equine; C006116:chorionic gonadotropin, pregnant mare serum gonadotropin drug combination