Relationship Between Body Weight and Growth Rate of Healthy Gilts with Osteochondrosis Lesions

Growth rate and body weight (BW) of gilts may have an impact on lameness and osteochondrosis. The aim of this study was to evaluate cartilage lesions on gilts (around service BW) and their relationship with previous performance traits. Among 120 gilts (Landrace x Yorkshire) between 210 to 235d of age, 40 were randomly selected and blocked by BW: heavy (HG, 177.7 ± 4.8 kg) and light (LG, 165.3 ± 5.2 kg). Gilts were previously monitored from 35.8 ± 5.9 kg of BW. Gilts were fed ad libitum to meet nutrient requirements for growth (ME: 11.9 MJ/kg, CP: 160 g/kg and Lys: 9.7 g/kg CP). Individual BW and gait observations were performed on trial d 0, 22, 42, 69, 94, 116 and 137 to detect non-infectious lameness. Gilts were slaughtered on d 137 and shoulder, elbow, carpal, femoro-iliac, knee and tarsal joints of the left half carcass were examined. All joints were evaluated by gross examination of abnormalities in cartilage surfaces and osteochondrosis lesions (L): erosions, ulcerations, repair reactions and infolding of the joint cartilage. Since none of the gilts showed more than 3 surfaces with L, the classification was defined as Tibia, Femur and Other. Macroscopic evaluation was performed on each surface: 1) presence or absence of L (0-1); 2) severity: none (0), small (1) (involved less than 5%), moderate (2) (5-10%) and severe (3) (exceeded 10%); and generally, 3) number of surfaces with L (nL); 4) presence or absence of severe L (SevL); and, 5) a total score (Tscore) (sum of severities in all surfaces (0-9)). Prevalence of L was 80%, and 52.5% of all gilts showed a moderate or severe L (SevL 15%). A 5% showed lameness and eventually recovered (BW at detection 161.8 ± 20.1 kg), all showing moderate L. The LG showed increased severity in Tibia, 8 times higher incidence in Tibia and more nL than HG (p<0.10). Similarly, a higher severity in “Other” joints, and in overall, a higher Tscore (2.29) was observed in LG compared to HG (1.19) (p<0.05). Average daily gain (ADG) and age did not influence any parameter of cartilage evaluation, however, classifying gilts by ADG from 100kg to final-BW (high-or-low), low-ADG showed greater Tscore (0.70) than high-ADG (p<0.10). In conclusion, cartilage L is not directly related to clinical lameness. Within a homogeneous herd of grown gilts, a lower BW indicated higher probabilities of osteochondrosis prevalence and severity independently of age differences.