What is “normal”? Morphology and mineralization of tibias from healthy, on farm broilers

SUMMARY: This study aimed to characterize the morphological traits and mineral composition of the tibia of healthy broilers under commercial practices in the UK. Morphological data and mineral composition of tibia of 432 healthy Ross 308 broilers (216 male and 216 female) were collected from 6 farms in Nottinghamshire, The UK. Each farm obtained its birds from 10 hatcheries. The birds in all farms received the same standard broiler growing diet. Morphological traits were measured directly for the right and the left tibia of every bird. Tibia ash and tibia mineral (Ca and P) were determined. Data of the right and left tibia were averaged for each bird.At age of 14 d, the normalized range in tibia length (mm/kg), width (mm/kg) weight (g/kg) and strength (N/kg), ash (%), Ca (%), and P (%) were 81.1 to 239, 5.27 to 16.5, 1.19 to 5.2, 63.8 to 703, 32 to 43.9, 1.62 to 28, and 0.611 to 12, respectively.At age of 28 d, tibia length (mm/kg), width (mm/kg) weight (g/kg) and strength (N/kg), ash (%), Ca (%), and P (%) were 46.8 to 96.8, 3.48 to 7.02, 1.36 to 4.83, 92.3 to 371, 36 to 44.6, 4.62 to 18.3, 1.21 to 6.87 respectively. At slaughter age, these normalized ranges were 35.5 mm/kg to 66.5 mm/kg, 2.46 mm/kg to 4.88 mm/kg, 2.45 g/kg to 3.55 g/kg, 82 N/kg to 211 N/kg, 35 to 44.1%, 2.97 to 18.3%, and 1.23 to 6.44%. The range of tibia morphology and chemical composition decreases considerably by age progression. More care should be taken during lameness diagnosis of older broilers. This study is a benchmark to assess tibia abnormality