Tracking forced moult by computer tomography and serum biochemical parameters in laying hens

For a complex investigation of forced moulting 27 Hy-Line Brown laying hens were exposed to total feed withdrawal with ad libitum water supply, for a trial period of 12 days. Computer tomography for the determination of the total body composition and its changes was performed on days 0, 6, 12 and after 3 wks of refeeding. Blood samples were collected every 3 days for the monitoring of the metabolic status of the hens. Compared to the initial values at the 6th and 12th days of moulting the volume of fat depots, abdominal organs and muscle tissue were reduced to 52.5, 59.7, 85.0, %, and 29.5, 43.5 and 77.9%, respectively. Following the regeneration period of 3 weeks respective values were 89.6, 100.1 and 86.1%, indicating a nearly fully reversible process. Body composition data were exactly quantified using a 3D smoothing method. Blood metabolic parameters indicated changes referring to total feed deprivation (triacylglycerol, total and HDL cholesterol) and low activity (creatinine) as well as the consequent cessation of egg yolk and shell production (total protein, Ca). The enzymatic adaptation was much less pronounced. It was stated that the in vivo CT scanning may be an effective tool for the comparison of alternative moulting methods.