Lysine requirement for growing-finishing immunocastrated male pigs.

Abstract

Eighty boars (19.3 ± 2.49kg) were vaccinated twice (100 and 128days of age) against gonadotropin releasing hormone (Vivax™ vaccine), for a randomised block design study aiming to evaluate five digestible lysine (DLys) level treatments, with three phase-feeding per treatments (9-8-7; 10-9-8; 11-10-9; 12-11-10 and 13-12-11g/kg) during the growing-finishing phases (54-100, 100-128 and 128-155days of age, respectively). Pigs were fed their respective diets ad libitum from 54 to 155days and weighed at 100, 128 and 155days. Pig loin (Longissimus dorsi) area, loin depth and backfat thickness were measured by ultrasound at 100 and 155days. Hot carcass weight, meat quantity and meat yield were measured at slaughter. From 54 to 100days (pre-immunocastration), DLys levels linearly improved pig feed conversion and loin area, the level of DLys for minimum feed conversion and maximum loin area was 13g/kg. However, DLys levels had no effect on the performance of boars from 54 to 128days (pre-immunocastration), nor on the performance and carcass parameters of immunocastrated male pigs between 54 and 155days. A sequence of diets containing 9, 8 and 7g/kg of DLys fed from 54 to 100, 100 to 128 and 128 to 155days, respectively, meet the requirement of growing-finishing immunocastrated male pigs.