UV-light and dietary vitamin D and their effects on ionized calcium and 25-OH-D plasma concentrations in captive gentoo penguins (Pygoscelis papua)

Application of Ultraviolet Light for Poultry Production: A Review of Impacts on Behavior, Physiology, and Production

The application of ultraviolet (UV) light in poultry production is garnering increased interest with the drive toward improved poultry welfare and optimized production. Poultry can see in the UV spectrum (UVA wavelengths: 320–400 nm) thus inclusion of these shorter wavelengths may be viewed as more natural but are typically excluded in conventional artificial lights. Furthermore, UVB wavelengths (280–315) have physiological impact through stimulation of vitamin D pathways that can then improve skeletal health. However, better understanding of the effects of UV supplementation must occur before implementation practically. This non-systematic literature review aimed to summarize the impacts of UV supplementation on the behavior, welfare, and production of laying hens, meat chickens (breeders and growers), and other domestic poultry species including directions for future research. The literature demonstrated that UVA light has positive impacts on reducing fear and stress responses but in some research, it significantly increases feather pecking over age during the production phase. UVB light will significantly improve skeletal health, but an optimum duration of exposure is necessary to get this benefit. Supplementation with UVB light may have more distinct impacts on egg production and eggshell quality when hens are experiencing a dietary vitamin D3 deficiency, or if they are at the terminal end of production. The relative benefits of UVB supplementation across different ages needs to be further verified along with commercial trials to confirm beneficial or detrimental impacts of adding UVA wavelengths. Further research is warranted to determine whether adding natural light wavelengths to indoor poultry production is indeed a positive step toward optimizing commercial housing systems.

CLINICAL AND PATHOLOGIC FINDINGS OF AN OUTBREAK OF VITAMIN D3-RESPONSIVE METABOLIC BONE DISEASE IN HERON AND EGRET (FAMILY ARDEIDAE) CHICKS FED CAPELIN (MALLOTUS VILLOSUS)

An increase in cases of metabolic bone disease (MBD) in chicks of six species of heron and egret (family Ardeidae) was identified at a wildlife rehabilitation center in the spring and summer of 2018. The outbreak affected 34.3% of birds in care for four or more days during the first 3 mo of the study and was the most common reason for euthanasia during that time. Cases were characterized by lameness, increased flexibility of multiple long bones, angular deformities, and bone fractures. Gross postmortem examinations were conducted on 145 nestlings and fledglings that died or were euthanatized either because of MBD or for unrelated conditions. Histology was performed in four cases and three controls. Histologic findings were characterized by multiple lesions in the appendicular long bones, including variable elongation of the physis, retention of cartilage cores in the metaphyseal primary spongiosa, poorly mineralized osteoid seams within the primary spongiosa, thinning or lack of diaphyseal cortical bone compaction, and folding fractures typically propagating through the physis-metaphyseal interface. Folding fractures were often associated with focal metaphyseal fibroplasia. The parathyroid gland diameter of birds diagnosed postmortem with MBD in care was significantly larger than that of unaffected birds. The authors hypothesized that a dietary deficiency of vitamin D₃ because of low levels in the bird's captive diet of capelin (Mallotus villosus) was the cause of the MBD. Starting in mid-July every chick's diet was supplemented with 714 IU oral vitamin D₃/kg body weight per day, after which the number of birds developing MBD declined to a rate of 4.3%. This study characterizes the clinical, gross, radiographic, and histologic features of vitamin D₃-responsive MBD in young herons and egrets and provides evidence to support the recommendation that captive birds on a diet of capelin be supplemented with vitamin D₃, especially during growth.