Conventional methods of assessing bone integrity of layers have involved destructive testing on dissected samples. Bone ash, calcium and phosphorus levels give an indication of mineral content while breaking strength is at best a relative measure subject to numerous potential errors in methodology. More recently non-destructive methodologies have been accepted in human medicine, the most promising being quantitative ultrasonography (QUS) and axial x-ray micro-computed tomography (Micro CT). QUS relies on capturing sound waves that have travelled through the bone, where density will influence time between emitting and capture of the signal. In our preliminary studies, the humerus is the most appropriate bone for such studies since there is a minimum of overlying tissue. Micro CT relies on 720 images, taken at 0.5° angles around a sample, and then software allows rebuilding of a 3-D image. Micro CT also provides quantitation of density in selected areas on the image. Most Micro CT scanners currently necessitate isolated bone samples, although second generation machines will have the capacity to scan sedated animals such as chickens and small mammals.

The present study aimed to investigate the prevalence and seasonal variation of hypovitaminosis D (defined as serum 25-hydroxyvitamin D level below 30 nmol/l) among healthy subjects and hospitalized patients living in central Italy. We studied 297 subjects, 131 in February 1997 and 166 in July 1997, subdivided into four groups: (a) young healthy blood donors; (b) healthy postmenopausal women; (c) inpatients with various medical diseases and (d) inpatients engaged in long-term rehabilitation programmes because of various neurological disorders. In all subjects and patients serum levels of 25-hydroxyvitamin D were measured by radioimmunoassay. We found a significant seasonal variation (P < 0·0001) of serum 25-hydroxyvitamin D levels, mean values being higher in summer in all groups, except in patients with a longer hospitalization time (group (d)). In each group, a significantly higher prevalence of hypovitaminosis D was found in winter compared with summer time (P < 0·001), being unexpectedly high in postmenopausal women (winter 32 % and summer 4·5 %); furthermore, in both seasons, inpatients were characterized by the highest incidences of hypovitaminosis, particularly those in group (d) (winter 82·3 % and summer 57·8 %). The results of the present study emphasize the importance of 25-hydroxyvitamin D measurement, and the need to increase vitamin D intake in Italy; foodstuff fortification and supplement use must be considered in order to prevent negative effects of vitamin D deficiency on skeletal integrity.

Skeletal integrity of end-of-lay birds is becoming a major concern for both egg producers and meat processors. Osteoporosis induced by continual demands for shell calcification causes loss in skeletal integrity as the layer gets older. This loss in bone structure, coupled with minimal exercise, leads to very fragile bones in older birds. Bone breakage as high as 20% has been reported in birds entering the processing plant, while some degree of bone breakage is found in a much higher proportion of eviscerated carcasses. Bone breakage on the farm, during transport and subsequent handling is obviously a welfare concern, while processors are also concerned about bone contamination of meat products. Factors affecting the development of osteoporosis are discussed and include genetics, level of egg production, environment and nutrition. There is no simple solution to the problem in terms of long-term or short-term nutritional modification. In the case of caged birds, bone strength characteristics can be improved by removing them to other systems for a period of time prior to transport, although this is rarely a commercial solution. However, so-called alternative housing systems are themselves responsible for skeletal defects in some birds.