Molt Performance and Bone Density of Cortical, Medullary, and Cancellous Bone in Laying Hens During Feed Restriction or Alfalfa-Based Feed Molt

ABSTRACT A study was conducted to evaluate the effects of alfalfa-basedmolt diets onmolting performance and bone qualities. A total of 36 Single Comb White Leg-horn hens were used for the study. There were 6 treat-ments: pretrial control (PC), fully fed (FF), feed with-drawal (FW), 90 % alfalfa:10 % layer ration (A90), 80 % al-falfa:20 % layer ration (A80), and 70 % alfalfa:30 % layer ration (A70). For the PC treatment, hens were euthanized by CO2 gas, and bones were collected before molt was initiated. At the end of the 9-d molt period, hens were euthanized, and femurs and tibiaswere collected to evalu-ate bone qualities by peripheral quantitative computed tomography, mechanical testing, and conventional ash weights. The hens fed alfalfa-based molt diets and FW stopped laying eggs within 5 d after molt started, and all hens in these groups had reduced ovary weights com-pared with those of the FF hens. In the FW and A90 groups, total femur volumetric bone mineral densities (vBMD) at the midshaft were significantly lower, but those of the A80 and A70 groups were not significantl