Effect of fast vs. moderate growth rate related to nutrient intake on developmental orthopaedic disease in the horse

Abstract

Osteochondrosis and other developmental orthopaedic diseases (DOD) constitute major problems in the horse industry. High food allowances and fast growth might be contributory factors. The aim of this experiment was to test the effect of high balanced nutrient allowances and associated fast growth, on the prevalence of several DOD. This study was carried out from birth to one year of age. Foals of a high feeding group (HL, n = 20) were fed 130% (0 to 2 months) and 150% (2 to 12 months) of the moderate level group (ML, n = 19, 100% of INRA recommendations). All foals were radiographed at 5.5 and 11 months, and 8 foals from each group were necropsied at 12 months of age for gross inspection of joints. Body weight, height at withers and cannon width were higher at 12 months in the HL group (+88.4 kg, +4.6 cm, and +2.1 mm respectively). The gains in body weight were 1254 and 873 g per day in the HL and ML respectively during the 0-6 month period, and 668 and 528 g per day in the HL and ML respectively during the 7-12 months period. The occurrence and severity of limb DOD were not statistically different in the HL and ML groups. Fast growth was positively correlated to the occurrence of some DOD lesions, but the body weight was more weakly correlated to the prevalence of DOD than cannon width or height at withers. The power of correlation varied for different types or localisations of lesion. In conclusion, high balanced feeding level was not a sufficient factor in our study, but fast development was a factor of risk for DOD. The lower correlations obtained with body weight do not support the theory that biomechanical limb loading due to increased bodyweight alone increases risk for osteochondrosis. High endomembranous or endochondral ossification rate would be more critical in causing DOD. © INRA, EDP Sciences, 2006.