Use of computed tomography to determine body composition of heavy strain turkey hens (Meleagris gallopavo) from rearing to early laying. (31st July 2018) - Dewez, Marine F
ABSTRACT: Genetic selection has improved the growth performance of poultry, but also influenced other metabolic parameters and physiological functions such as reproduction. To counter the negative effects of this enhanced development, modifications of the environment or diet are frequently used. As all animals are not equally sensitive and do not respond in the same way, the evolution of the body composition has got to be better characterized with non-invasive tools to reach a higher flock homogeneity and improve production yield. Thus, we have analyzed turkey breeder hens' body composition using computed tomography scan and measurements of biochemical markers from 16 to 34 wk old. During rearing, body weight was strongly correlated to muscle, fat, and bone volumes (r > 0.75), and increased with hen age until sexual maturity (31 wk). These correlations did not maintain after photostimulation was initiated (29 wk). Muscle volume linear regression with hen age resulted in a R² value of 0.626 over the whole trial study. Bone volume was better fitted by a quadratic regression (R² = 0.7) and was proportional to calcium plasma level evolution, both increasing after 28 wk of age. Conversely, fat volume quadratic regression (R² = 0.5) was symmetrical to triglyceride levels, the first decreasing notably at sexual maturity, the other increasing massively after 28 wk. Egg, yolk, and albumen weights increased with hen age, as did yolk triglyceride levels. In conclusion, computed tomography allows to investigate turkey breeders' body composition and bring new data in the genetic selection strategy. In addition, the evolution of the fat deposition and bone changes have been monitored over time and could help to optimize breeders' diet strategy.