19 Overview of the National Pork Board replacement gilt feet and leg evaluation trial

Abstract

Abstract Replacement gilt feet and leg conformation traits are subjectively evaluated at early ages (150 d) in order to select acceptable replacements. The objectives of this study were to: 1) evaluate replacement gilt feet and leg conformation (FLC) using subjective and objective measurement methods, 2) estimate objective joint angle changes over two parities, and 3) evaluate the effect of three diets differing in standardized ileal digestible (SID) lysine concentrations on FLC traits using the objective evaluation method. Crossbred Large White × Landrace gilts (n = 641) were used. Gilts were moved to GDU at 77 days-of-age and randomly allotted to three ad libitum fed dietary treatments providing similar ME but differing in SID lysine concentrations (low, medium, and high) during the grow-finisher period. All animals received common gestation and lactation diets. Feet and leg conformation traits were evaluated at 100 d, 200 d, 1st litter (392 ± 25 d) and 2nd litter (548 ± 49 d) weaning events. Subjective evaluation was done on a scale from 1 to 5. Data were analyzed using mixed linear model methods. The majority of gilts received the intermediate score (i.e. 3) when joint angles were subjectively evaluated. No differences (P ≥ 0.05) were observed for knee, front pastern and hock objective joint angles between subjective scores assigned. Differences in subjectively evaluated rear pastern (P < 0.05) were observed, where objective joint angles associated with scores of ≤ 2 and 3 were lower than score of ≥ 4. There was no interaction between dietary treatment and objective evaluation time-period for any FLC traits studied (P > 0.05). Females with greater knee, hock, front and rear pastern objective joint angles at 100 d of age, continued to have greater joint angles (0.2 ± 0.04 degrees; P < 0.001) later in life. Front and rear pastern joint angles decreased (P < 0.001) and hock joint angles increased from 100 d to end of study (P < 0.001).