Occurrence of Non-Infectious Lameness during Rearing of Gilts and Its Relationship with Body Weight and Growth Rate

Within a herd, higher growth rate could be related with increased probabilities of showing leg problems. The aim of this study was to evaluate the current growth of rearing gilts and their relationship with occurrence of non-infectious lameness. A total of 600 gilts (Landrace x Yorkshire) between 57-106d of age and 25.6 ± 8.6 kg of body weight (BW) were monitored for a 137d-study. Gilts were blocked by BW (four categories) and randomly distributed into 15 pens (10/pen) within the blocks of BW. Feed was offered ad libitum and based in three phases (ME: 12.5, 11.9, 11.5 MJ/kg; CP: 180, 167, 142 g/kg; and Lys: 12.5, 10.2, 8.0 g/kg CP, respectively of phases 0-14, 15-90, 90-137) of corn, wheat, barley and soya meal diet. Individual BW and observations of gait were performed on d0, 22, 42, 69, 94, 116 and 137 by free walk on a 10 m corridor. Lameness was defined as any degree of gait difficulty without visual infection and swelling. Variables BW, average daily gain (ADG) between measurements and ADG calculated from BW intervals before lame detection (29-111, 50-111 kg), were analyzed through ANOVA. Lameness and BW were analyzed through repeated measures over time including sow as random effect. Logistic regression was used to analyze BW at lame detection with age or time. Occurrence of lameness was 8.34%, which eventually showed recovery a 46.15%. The first lame detection was at BW [114.6, 130.5] kg as confidence interval (CI) and age of [170.9, 187.8] d CI. From 115d onwards, lame gilts showed lower BW and ADG than those non-lame (p<0.029). Besides, differentiation of lame gilts through BW or ADG was not possible three weeks before lame detection (last observation). In fact, for ADG29-111 and 50-111 kg, no differences were observed. Nevertheless when broaden the BW interval of ADG as 29-130 kg, the lame gilts showed lower growth rate than those non-lame [0.942, 0.963] vs. [0.882, 0.949] kg/d ADG CI (P<0.039). Therefore, it was observed that lameness was increasing with BW and time (P<0.001). In conclusion, non-infectious lameness is directly related with BW and independent of previous growth rate. Lameness generally appeared in gilts above 115 kg. Performance was compromised since lame detection. Apparently, pre-diagnosis of lameness in replacement gilts cannot be related with higher growth rate or BW when regime is ad libitum and the diet formulated for gilts.