The effect of age at the first mating and herd size on the lifetime productivity of sows

The effect of age at the first mating and herd size were evaluated in the reference Spanish Databank (BDporc) of 37 698 sows born between 1991 and 1995 and with individual lifetime records. The data included dates of births at entrance and culling, first mating, repetitive mating and conception, first farrowing and weaning records. Individual records were validated before the analysis by screening them through a tolerance “filter” in order to eliminate the extreme values from the analysis. The total database of the sows was classified in 7 classes according to age at the first mating (< 210, 210–220, 221–230, 231–240, 241–250, 251–270, and > 270 days) and in 6 classes of herd size (< 200, 200–300, 301–400, 401–600, 601–800, and > 800 sows). The total number of litters and number of weaned piglets obtained from each sow during the lifetime production were significantly (P < 0.05) greater for gilts between 221 and 240 d of age at the first mating. There was a significant (P < 0.001) effect of the herd size on the reproductive performance of the sow, and the best performance was obtained with herds with 401 to 600 sows compared to < 200 or > 800 sow-herds. Furthermore, a significant (P < 0.001) interaction between age at the first mating and herd size was detected and can be associated with a particular pattern for the herd size class 401–600 sows with the best performances obtained for the sows first mated at less than 200 days. For the other herd sizes, the results indicated that sows mated for the first time at the right age, 221–240 days, are more productive, both in the number and size of the parities throughout lifetime production. age at first mating / sow / productivity / performance / longevity / litter size / pigs Résumé — Incidence de l’âge à la mise à la reproduction et de la taille du troupeau sur la productivité des truies. L’effet de l’âge à la mise à la reproduction (première insémination) et de la taille du troupeau a été évalué à partir de la banque de données espagnole, BDporc. Dans cette étude, ont été considérés les données individuelles de 37 698 truies nées entre 1991 et 1995 et portant sur l’ensemble de la carrière de l’animal. Les données ont inclu les dates de naissance, d’entrée dans l’élevage 49 * Correspondence and reprints Tel.: 34-973-702568; fax: 34-973-702874; e-mail: [email protected] ** Current address: Department of Animal Science, McGill University, Canada. Anim. Res. 52 (2003) 49–64  INRA, EDP Sciences, 2003 DOI: 10.1051/animres:2003001