title: Lifetime reproductive performance and survival of English Berkshire female pigs raised in commercial herds in subtropical Japan.
abstract: The objective of the present study was to compare lifetime reproductive performance and survival probability of English Berkshire female pigs and crossbred females in a subtropical region of Japan. We analyzed records of 20,417 females entered into the 12 herds in Southern Japan from 2003 to 2007. Generalized linear mixed-effects models were conducted to compare the lifetime reproductive performance of the Berkshire and crossbred females. Multilevel mixed-effects models were conducted to compare the lifetime reproductive performance of the Berkshire and crossbred females. Also, a multilevel proportional hazard model was used to examine the survival probabilities for the two breeds. Berkshire gilts were 39.8 days older at first-mating than crossbred gilts (P = 0.05). The pigs born alive (PBA) in Berkshire and crossbred gilts increased from 5.8 to 6.9 pigs and from 10.7 to 11.1 pigs, respectively, as age at first-mating increased from 220 to 310 days old (P < 0.05). More Berkshire gilts were culled for reproductive failure than crossbred gilts (7.5 vs. 3.8 %; P < 0.05). Also, Berkshire females had 2.7 lower parity at removal, 224.4 days lower reproductive herd-life, and 4.2 pigs fewer average lifetime PBA than crossbred females (P < 0.05) and tended to have a lower survival probability (P = 0.05). In summary, Berkshire females had later puberty, were more sensitive to age at first-mating for increasing PBA, and had lower fertility and a lower survival probability than crossbred females in commercial herds.
authors.affiliation: School of Agriculture, Meiji University, Higashi-mita 1-1-1, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan, cf30202@meiji.ac.jp.
authors.forename: Shiho
authors.initials: S
authors.lastname: Usui
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Koketsu
mesh_terms: D000818:Animals; D001947:Breeding; D005260:Female; D007564:Japan; D008460:Meat; D011247:Pregnancy; D012098:Reproduction / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D014329:Tropical Climate