Time of occurrence and prevalence of severe lameness in fattening Charolais bulls: Impact of type of floor and space allowance within type of floor

摘要

This study aimed at assessing the prevalence of lameness in a large number of batches of Charolais bulls housed in deep litter (DL) or fully slatted concrete (FSC) pens with different space allowance. Data from eight intensive beef farms located in Italy were recorded during 18 months. Five farms housed bulls in DL pens, with space allowance of 5.0 m(2)/head (two farms) and of 5.5 m(2)/head (three farms) respectively. Three farms housed bulls in FSC pens, with space allowance of 3.5 m(2)/head (two farms) and of 4.0 m(2)/head (one farm) respectively. Lameness events were categorized as: mild, when they did not impair the regular conclusion of the fattening cycle of the affected bull, or severe, when they imposed the early culling of the animal. Date and average body weight of each batch of bulls at arrival to farm and at slaughter were collected as well as those of severely lame bulls at the time of culling. The study analysed data of 314 batches for a total of 7201 bulls. Prevalence of bulls showing mild lameness was 1.23% and was similar between floor types. Severe lameness had a higher prevalence in bulls housed on FSC than on DL (1.86 vs. 0.56%; P 0.001), and the relative risk of early culling in FSC pens was more than three times higher than in DL. An increased space allowance from 3.5 to 4.0 m(2)/head in FSC pens acted as a preventive measure against both mild and severe lameness. A wider space allowance from 5.0 to 5.5 m(2)/head in DL pens did not reduce the prevalence of severe lameness, which was always below 1%, however. Regardless of type of floor, severe lameness events were always recorded in the final part of the cycle (178 +/- 28 (SEM) days of fattening) and their occurrence was unaffected by the space allowance within type of floor.