title: Risk factors associated with the occurrence of the second-litter syndrome in sows in southeastern Mexico.
abstract: The objective was to estimate the incidence of and to determine the effect of some risk factors on the decrease of litter size at parity 2 of sows in three commercial farms in Yucatan, Mexico. Data on 8,592 farrowing records of 4,296 sows were analyzed using a binomial logistic regression procedure. The model included the fixed effect of farm (1, 2, and 3), year of farrowing (2003-2011), season of farrowing (dry, rainy, and windy), number of pigs born alive at first parity (<9, 9-10, 11-12, and >12 piglets), lactation length (<18, 18-24, and >24 days), and weaning to conception intervals (<4, 4-11, and >11 days). Fifty-five point eight percent of all sows presented a reduced or similar litter size at parity 2. The odds of decrease in the second litter size were 1.56 and 2.01 for farms 2 and 3, respectively. Higher odds were found for sows farrowing during the rainy and dry seasons (1.20 and 1.24, resp.) and for sows with large litters at parity 1 (>12 piglets, odds = 33.2). Sows with weaning to conception intervals <4 days and between 4 and 11 days had higher odds of a decrease in the second litter (1.78 and 2.74 pigs, resp.).
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Yucatán, Km 15.5 Carretera Mérida-Xmatkuil, Apdo. Postal 4-116, Mérida, YUC, Mexico.
authors.forename: José C
authors.initials: JC
authors.lastname: Segura Correa
authors.forename: Alejandro
authors.initials: A
authors.lastname: Alzina-López
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Santos-Ricalde
mesh_terms: D000818:Animals; D005260:Female; D007774:Lactation / Q000502:physiology; D008098:Litter Size / Q000502:physiology*; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors; D012621:Seasons; D013552:Swine / Q000502:physiology*; D013997:Time Factors; D014886:Weaning