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

In this study, the effect of ultraviolet (UV) light and dietary vitamin D on calcium metabolism in permanently indoor‐housed gentoo penguins (Pygoscelis papua ) was investigated. The study consisted of three periods, each completed with blood samples to analyse plasma concentrations of 25‐OH‐D, 1,25‐(OH)₂‐D, ionized (iCa) and total calcium (tCa). During the first study period (D), animals were housed under routine conditions without UV‐light and fed a diet of different fish species, supplemented with 1,000 IU vitamin D per animal and day. The following study period (Baseline) of 28‐day duration consisted of the same diet without any vitamin D supplementation and without UV‐light. During the study period (UVB) artificial UV‐light was added for 3 weeks. The vitamin D content of fish was measured by high‐performance liquid chromatography. It varied between fish species and between facilities, ranging from no measurable content in capelin (Mallotus villosus ) to 7,340 IU vitamin D/kg original matter (OM) in herring (Clupea spp). The average dietary vitamin D content was 311 IU/kg OM at facility 1 and 6,325 IU/kg OM at facility 2, resulting in a vitamin D intake per animal and day without supplementation of 130 IU (25.5 IU/kg body weight BW) and 2,454 IU (438.2 IU/kg BW) respectively. The supplementation of vitamin D elevated significantly the plasma concentrations of 25‐OH‐D by an intraindividual difference of 15 (range ?2 to 59) nmol/L and tCa by 0.1 (0.0–0.3) mmol/L only at facility 2. The exposure to UV‐light raised the blood concentrations of tCa at facility 2 by 0.15 (0.1–0.2) mmol/L, and of iCa and tCa for females at facility 1 by 0.23 (0.13–0.41) mmol/L and 1.8 (1.1–2.5) mmol/L respectively. No significant influence of the study periods (D) and (UVB) was found for the concentrations of 1,25‐(OH)₂‐D at both facilities.     

Dry matter and calcium digestibility in captive veiled chameleons (Chamaeleo calyptratus)

Although metabolic bone disease (MBD) is a very common disease in reptiles kept as pets, empirical data on the calcium (Ca) metabolism of reptiles are still scarce. We used the opportunity of a large-scale experimental study on growth and clinical manifestations of MBD in captive veiled chameleons (Chamaeleo calyptratus) to measure the apparent dry matter (DM) and Ca digestibility in 19 animals (6-49 g), receiving locust nymphs (Locusta migratoria) of two size classes (0.05 and 0.5 g) with or without supplementation of Ca, vitamin A and cholecalciferol (Group A: Ca 0.04-0.09%DM; Group B: Ca 0.47-0.84%DM). Dry matter digestibility was significantly lower for animals receiving smaller-sized prey. A regression analysis of dietary Ca vs. digestible Ca content revealed a complete 'true' digestibility of Ca for the range of investigated diets, which might indicate that requirements for this mineral were not yet exceeded by the diets used (so that a reduction in Ca absorption would be induced). Options of higher dietary Ca provision, and reactions of chameleons to such diets, should be further investigated.     

Effects of bisphenol A administration to pregnant mice on serum Ca and intestinal Ca absorption

Bisphenol A (BPA) is a xenoestrogen commonly used in food storage plastics. The present study was conducted to clarify the effects of BPA administration to pregnant mice on serum calcium (Ca) and Ca metabolism of the gut and kidney. From 6.5 to 16.5 days post coitus (dpc), pregnant mice were administered at 2 mg or 20 mg/kg body weight/day of BPA. Serum Ca was decreased in mice treated with 20 mg BPA at 17.5 dpc, but no remarkable differences were detected in the alkaline phosphatase activity and vitamin D receptor protein expression in the duodenum and jejunum. The messenger RNA (mRNA) expressions of calcium binding protein (CaBP‐9k) and active vitamin D synthesis enzyme (CYP27B1) in the kidney were increased in mice treated with 20 mg BPA. The mRNA expressions of occludin and junction adherence molecular A (JAM‐A) in the duodenum and ileum, which regulate paracellular transport, were increased in mice treated with 20 mg BPA. However, the administration of 2 mg BPA had no effect on serum Ca and mRNA expressions of relative genes in Ca metabolism. These results imply that BPA administration at 20 mg/kg body weight/day during pregnancy decreases serum Ca in pre‐delivery mice, which may be partly due to decreased paracellular Ca absorption.     

Vitamin D receptor amounts across different segments of the gastrointestinal tract in Brown Swiss and Holstein Frisean cows of different age

During different stages of lactation, different requirements of calcium have to be met depending on the milk amount. Vitamin D receptors (VDR) regulate calcium homeostasis by increasing the entry of Ca into blood from bone stores and dietary sources. The purpose of this study was to investigate if age and breed of cows influence VDR amounts across different segments of the gastrointestinal tract. Thirty-six cows were used (18 Brown Swiss, 18 Holstein Friesan, both > 5.5 years or < 4.5 years). Tissue specimens of the intestines were collected from the cows. Formaldehyde-fixed and microwave-treated paraffin sections were used for VDR immunohistochemistry employing a biotinylated monoclonal rat antibody and streptavidin peroxidase technique. The results showed that nuclei and cytoplasm of enterocytes stained positively for VDRs. Strongest immunoreactions were observed in intermediate and basal glandular cells. No significant differences were observed between the different groups. Vitamin D receptors immunoreactivities were prominent in duodenal mucosa, lower in jejunum and in colon, decreased further in ileum and were lowest in caecum. Decreases in number of positively marked cells and staining intensities resulted in reduced immunoreactions. The results of this study indicate that VDR are highly expressed at the site of maximal intestinal calcium absorption. No significant influence of age and breed was observed. The animals used were not in a negative Ca balance. The cows were all in the stage of late or mid lactation. During these periods, the Ca requirements are low and the diets are high in Ca concentration; and the animals are adapted to these circumstances. Passive absorption in adult animals seems to dominate when Ca intake is adequate or high. The active absorption may play a considerably more significant role during the peripartal period, when Ca homeostatic mechanisms are challenged because of tremendous Ca demand at the initiation of lactation.     

Impacts of UVB provision and dietary calcium content on serum vitamin D3, growth rates,skeletal structure and coloration in captive oriental fire‐bellied toads (Bombina orientalis)

Many amphibian species are dependent on ex situ conservation interventions for their long‐term persistence. However, projects have been jeopardised by husbandry issues involving poor calcium metabolism and nutritional metabolic bone disease (NMBD). Healthy calcium metabolism requires appropriate dietary calcium content and access to vitamin D₃. In many animals, vitamin D₃ can be photobiosynthesised in skin exposed to UVB radiation, as well as extracted from the diet, but the extent of vitamin D₃ photobiosynthesis in amphibians is poorly known. Additionally, prey insects for captive amphibians are deficient in calcium and calcium content must be artificially increased, but the effects of different levels of augmentation and their interaction with UVB exposure are also little understood. We fed captive fire‐bellied toads (Bombina orientalis) with crickets augmented to contain 5% and 10% calcium and housed them with and without UVB exposure. Despite additional dietary vitamin D₃ supplementation, we found that toads exposed to UVB radiation exhibited significantly higher serum vitamin D₃ levels, indicating that this species may partly rely on photobiosynthesis sources of vitamin D₃. These data are the first to show a direct link between UVB exposure and serum vitamin D₃ in an amphibian. We found significant positive effects of UVB exposure and 10% dietary calcium content on skeletal structure, as well as complex interactions between treatments. We also found UVB radiation exposure resulted in more rapid natural coloration acquisition. Together, this indicates that standard calcium plus vitamin D₃ supplementation methods may not fully substitute for UVB exposure and for increased feeder insect calcium content. This may have implications for the success of ex situ amphibian conservation, as well as for the welfare of captive amphibians in general. Our data lend support for the provision of UVB radiation for captive, basking amphibians.     

Effects of coumestrol administration to maternal mice during pregnancy and lactation on renal Ca metabolism in neonatal mice

The present study was conducted to clarify the effects of coumestrol administration to maternal mice during pregnancy and lactation on serum Ca and Ca metabolism in their neonatal mice. From 6.5 to 16.5 days post coitus and from 3 to 10 days after parturition, maternal mice were administered at 200 µg/kg body weight/day of coumestrol. Coumestrol administration did not affect weight gains, serum Ca and the expression of vitamin D receptor (VDR) protein in the kidney of neonatal mice, but weight gains of maternal mice were decreased by coumestrol administration. Coumestrol administration increased the messenger RNA (mRNA) expressions of epithelial Ca channels 1 (ECaC1) and VDR in the kidney of neonatal mice, and also increased the mRNA expressions of ECaC2 in the kidney and small intestine of male neonatal mice. The mRNA expressions of ECaC1, ECaC2, calbindin‐D_9k (CaBP‐9k) and estrogen receptor (ER)α in the kidney and VDR in the small intestine of male neonatal mice were higher than those of female mice. Thus, coumestrol administration to maternal mice during pregnancy and lactation may affect renal Ca metabolism in neonatal mice, especially male neonatal mice via maternal milk.     

EFFECTS OF NATURAL ULTRAVIOLET RADIATION ON 25-HYDROXYVITAMIN D3 CONCENTRATIONS IN FEMALE GUINEA PIGS (CAVIA PORCELLUS)

Vertebrates have 2 methods of acquiring vitamin D: through the diet and/or secondary to exposure to ultraviolet B (UVB) radiation. Although some species (e.g., dogs) can only acquire vitamin D through their diet, many others also utilize UVB radiation to generate vitamin D. Prior to their extirpation, guinea pigs were naturally exposed to varying levels of sunlight (UVB) in their native habitat; however, in captivity we do not routinely recommend UVB radiation for these animals. Recently, it has been shown that captive guinea pigs can synthesize 25-hydroxyvitamin D (25-OHD₃) after exposure to UVB lightbulbs. However, it is not known how natural sunlight impacts 25-OHD₃ concentrations in this species. The purpose of this study was to determine whether 25-OHD₃ concentrations in female guinea pigs exposed to natural sunlight would increase as a result of UVB exposure. Eight adult female guinea pigs were used for this study. The animals were held indoors during winter months and then placed outside in the spring when temperatures were appropriate. Blood samples were collected before the animals were placed outdoors (baseline) and 30 days after being exposed to natural sunlight. There was a significant difference in 25-OHD₃ concentrations over time (P = 0.006) and values collected after the guinea pigs were housed outdoors were 1.8 times higher than baseline. This study confirmed that female guinea pigs can increase 25-OHD₃ concentrations after exposure to natural sunlight. This suggests that these animals have conserved this pathway despite domestication, and supplementation should be considered to optimize captive guinea pig habitats.     

Effects of gestation and lactation on vitamin D receptor amounts in goats and sheep

During gestation and lactation, an increased demand for calcium (Ca) due to the development of fetal skeleton and excretion via milk is observed. The higher need for Ca is met by an augmented mobilisation of Ca from bones and by an increased absorption from the intestines. The main influence on this physiological process of active absorption has Vitamin D, acting through Vitamin D receptors (VDR) located in the mucosal wall of the intestines, thus increasing Ca absorption. As a consequence of inadequate Ca absorption, metabolic diseases like milk fever can develop. In this study immunohistochemical procedures were applied to colon mucosa biopsies of pregnant and lactating goats and sheep, to study the effect of late gestation, parturition and lactation on VDR amount. Colon mucosa biopsies were collected 2 weeks before parturition, 1 and 4 weeks post partum (pp), 2, 3, 4, and 5 months pp from 11 dairy goats and 11 sheep. Immunohistochemistry was performed employing a biotinylated monoclonal rat anti-VDR antibody and streptavidin peroxidase techniques. Nuclei and cytoplasm of enterocytes stained positively for VDRs. Strongest immunoreactions were observed in intermediate and superficial glandular cells. The biopsy samples taken during early lactation revealed a lower immunoreaction for VDR compared with samples taken during later stages of lactation. In conclusion, immunochemistry and biopsy technology are useful tools to assess changes in VDR expression in relation to varying demands for Ca in the process of a reproductive cycle. These results show that in dairy goats and sheep, an influence of gestation and lactation on VDR is obvious.     

饲粮维生素D添加形式对公猪繁殖性能的影响

本试验旨在研究饲粮维生素D添加形式对种用公猪繁殖性能的影响。选取16头18月龄的约克公猪,随机分成2组,2组饲粮中分别含有50μg/kg维生素D3(VD3)和25-羟基维生素D3(25-OHD_3),每组8个重复,每个重复1头猪。试验期16周。结果表明,与VD3组相比:1~16周,25-OHD_3组公猪精子活力和每次射精的有效精子数显著提高(P0.05),而精子畸形率显著降低(P0.05);第112天,25-OHD_3组血浆钙离子(Ca2+)和雌二醇含量及芳香化酶活性显著提高(P0.05),精清25-OHD_3、Ca2+、果糖含量和酸性磷酸酶的活性显著提高(P0.05);25-OHD_3组芳香化酶、维生素D 25-羟化酶、维生素D 24-羟化酶和维生素D受体基因的表达量显著升高(P0.05)。综上所述,与同等水平VD3相比,种公猪饲粮中添加25-OHD_3能更有效增加血浆维生素D含量,从而改善精子的形态和运动能力,提高公猪的繁殖性能。     

The effect of soy isoflavones on egg quality and bone mineralisation during the late laying period of quail

1. Soy isoflavones play a role in calcium and bone metabolism. Poor egg quality, skeletal abnormalities and architectural deterioration of bone tissue are common problems under hot climate conditions and with increased age in poultry. 2. In this study, we investigated the effects of soy isoflavone supplementation on egg production, egg quality, bone mineral density (BMD), levels of osteocalcin (OC), vitamin D, calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) activity in quail (Coturnix coturnix japonica) during the late laying period. 3. The birds (n = 180; 28 weeks old) were randomly assigned to 6 treatment groups consisting of 6 replicates of 5 birds each in a 2 x 3 factorial arrangement of treatments (temperatures, soy isoflavone concentration). Birds were kept in wire cages in a temperature-controlled room at either 22 degrees C (thermo-neutral, TN) or 34 degrees C (heat stress, HS) for 8 h/d (09:00 to 17:00 h; until the end of the study) and fed either on a basal (control) diet or on the basal diet supplemented with either 400 or 800 mg of soy isoflavones/kg of diet. 4. Heat exposure reduced feed intake, egg production, egg quality, BMD, OC, vitamin D, Ca, P and ALP when the basal diet was given. Feed intake, egg production and egg weight were not affected, while eggshell thickness and eggshell weight increased in soy isoflavone-supplemented quails reared under TN conditions. However, feed intake, egg production, egg weight, eggshell thickness, eggshell weight and Haugh units were positively influenced by soy isoflavone supplementation in HS groups for quail during the late laying period. Bone mineral density, serum OC, vitamin D, Ca, P levels and ALP activity were significantly improved by soy isoflavone supplementation in both the TN and HS groups in quail during the late laying period. 5. Soy isoflavone supplementation of basal diet significantly improved egg quality and bone mineralisation in quail during the late laying period.     

Expression and localisation of calbindin D28k in all intestinal segments of the laying hen

1. The aim of the present study was to investigate expression and localisation of a 28-kDa calcium-binding protein (CaBP-D28k) related to active calcium (Ca) absorption, in the entire intestine of egg-laying hens. 2. Western blotting analysis showed that the entire intestine expressed CaBP-D28k to the following degree: duodenum > jejunum > caecum > ileum > colon. Immunohistochemistry showed strong CaBP-D28k localisation in enterocytes along the villus tip-crypt axis in the duodenum and in villus tips in the caecum and colon. The jejunum and ileum had moderate localisation with respect to the number of immunoreactive cells and staining intensity. 3. These results suggest that laying hens actively absorb Ca in both the large and small intestines.     

Effects of Ultraviolet Radiation on Serum 25-Hydroxyvitamin D Concentrations in Captive Chinchillas (Chinchilla laniger)

Vitamin D is an important hormone in vertebrates, and most animals acquire this hormone through their diet and/or exposure to ultraviolet B (UVB) radiation. To date, no study has determined how chinchillas (Chinchilla laniger) acquire vitamin D. The objective of this study was to determine whether exposure to UVB radiation had an effect on serum 25-hydroxyvitamin D levels in captive chinchillas. Overall, 10 juvenile chinchillas were used for this scientific investigation. Baseline blood samples were collected from the animals while under isoflurane anesthesia to determine their serum 25-hydroxyvitamin D concentrations. The chinchillas were then randomly assigned to 2 treatment groups: Group A, 12 hours of UVB exposure per day and Group B, no UVB exposure. At the end of the study (Day 16), a second blood sample was collected from each animal while again under isoflurane anesthesia to measure serum 25-hydroxyvitamin D concentrations. Mean ± standard deviation serum 25-hydroxyvitamin D concentrations differed significantly (P = 0.048) between juvenile chinchillas provided supplemental UVB radiation (189.0 ± 102.7 nmol/L) and those not provided supplemental UVB radiation (87.8 ± 34.4 nmol/L). This study found that exposing juvenile chinchillas to UVB radiation significantly increased their circulating serum 25-hydroxyvitamin D levels. Because vitamin D is an essential hormone in vertebrates, these findings suggest that the provision of UVB radiation to captive chinchillas may be important. Further research to elucidate the importance of 25-hydroxyvitamin D and UVB radiation in captive chinchillas is required.     

Vitamin D and Ultraviolet B Radiation Considerations for Exotic Pets

Vitamin D is an essential hormone that regulates many different functions in vertebrates and can have a protective effect against various disease conditions. Providing exotic pets appropriate access to vitamin D, through the diet, ultraviolet B (UVB) exposure, or a combination of both, is important for veterinarians and exotic pet owners to consider. Although it is commonly thought that most animals derive the vitamin D they need through their diet, there are a number of species that appear to benefit more from UVB exposure. In addition, there has been minimal study to investigate appropriate dietary levels of vitamin D for many of our exotic pets. Although the recommendation of providing UVB lighting has been primarily limited to captive reptiles, research with other species (e.g., birds and small mammals) suggests that these animals may also benefit from this type of lighting. However, the provision of UVB is not without its potential side effects. The purpose of this article is to review the important roles of vitamin D in animals, the different methods animals use to acquire this hormone, the potential clinical signs associated with hypovitaminosis or hypervitaminosis D, the role of artificial UVB lighting in the synthesis of vitamin D, and the potential side effects associated with UVB radiation.     

Ultrasonographic appearance of the coelomic cavity organs in healthy veiled chameleons (Chamaeleo calyptratus) and panther chameleons (Furcifer pardalis)

Veiled chameleons (Chamaeleo calyptratus) and panther chameleons (Furcifer pardalis) are the most popular chameleons over the world, and consequently, two of the most frequent species presenting to veterinary practices. However, published studies on normal ultrasonographic anatomy for these lizards are currently lacking. The objectives of this prospective anatomic study were to develop an ultrasound protocol for evaluation of the coelomic cavity in these species and describe the normal ultrasonographic anatomy of the coelomic organs. Seventeen healthy veiled chameleons and 15 healthy panther chameleons were included. A linear 18 MHz transducer was used. Chameleons were sedated and restrained in right lateral recumbency by an assistant. Longitudinal and transverse images were acquired, and authors recorded qualitative and quantitative ultrasonographic characteristics of the coelomic structures. The kidneys, liver, caudal vena cava, hepatic veins, portal vein, gallbladder, wall of the stomach and intestine, gonads and, when distended, urinary bladder could be visualized during ultrasonography of the coelomic cavity in both species. The spleen, pancreas, and adrenal glands could not be identified. Findings from the current study supported the use of ultrasonography for veiled chameleons (Chamaeleo calyptratus) and panther chameleons (Furcifer pardalis) with suspected intracoelomic diseases and provided normal reference information for future studies of these chameleon species.     

Undetectable vitamin D3 in equine skin irradiated with ultraviolet light

Vitamin D requirements for most animals are expected to be fulfilled through daily exposure of the skin to solar ultraviolet B radiation. The synthesis of vitamin D₃ in skin depends on different factors including melanin pigmentation, the amount of UVB radiation reaching the skin, type of clothing/hair coat, latitude and altitude, season, and time of day. Alternatively vitamin D₂ may be obtained from UVB irradiated pasture species. Recent studies have shown that in unsupplemented grazing horses 25-hydroxyvitamin D₂ is the predominant form of vitamin D in plasma, and that 25OHD₃ is undetectable suggesting horses may rely on diet to obtain vitamin D. In order to mimic the natural environment of skin to sunlight exposure, five equine and two ovine devitalized skin samples were irradiated with 5 J/cm² of UVB light followed by measurement of 7-dehydrocholesterol (7-DHC) and vitamin D₃ concentrations using reverse-phase high pressure liquid chromatography (HPLC). HPLC revealed the presence of 7-DHC in the skin of both horses and sheep. Vitamin D₃ was undetectable in both ovine and equine skin prior to irradiation, but after irradiation with UVB light, ovine skin showed an increase in vitamin D₃ concentration (mean 0.16 ± 0.07 µg/g), whereas vitamin D₃ was undetectable in equine skin. These results provide additional evidence that horses make negligible quantities of vitamin D₃ in their skin after exposure to UVB light and may therefore rely on their diet as a primary source of vitamin D.     

Effects of boron supplementation of adequate and inadequate vitamin D3-containing diet on performance and serum biochemical characters of broiler chickens.

In this study, supplementation of two levels (5 and 25 parts per million; ppm) of boron into broiler diets including 125 IU kg(-1) (inadequate) and 2000 IU kg(-1) (adequate) vitamin D3 was investigated. The effects of supplementation on performance and biochemical characters (Ca, P, Mg, glucose and AP) of broilers from 1 to 45 days of age were evaluated. Boron provided significant increases in performances of chicks fed both adequate and inadequate vitamin D3-containing diets. The improvements in the inadequate vitamin D3-containing group were higher than that of adequate vitamin D3-containing group. The boron addition had a positive effect on Ca, P and alkaline phosphatase levels of chicks. Boron might be regarded as beneficial in inadequate vitamin D3-containing broiler feed.