Effects of maternal and offspring treatment with two dietary sources of vitamin D on the mineral homeostasis, bone metabolism and locomotion of offspring fed protein- and phosphorus-reduced diets.

The present study aims to compare the effects of maternal and offspring treatment with 25-hydroxycholecalciferol (25-OHD3) and vitamin D3 on vitamin D status, mineral homoeostasis, bone metabolism and locomotion in the offspring. Either vitamin D3 (50 µg/kg diet) or 25-OHD3 (50 µg/kg diet) was supplemented to the gestation and lactation diets of 49 multiparous sows and/or to the diets of their growing offspring. Treatment of the sows did not affect plasma concentrations of 25-OHD3 of the offspring. Pigs fed 25-OHD3 had higher plasma concentrations of 25-OHD3 than pigs that received vitamin D3 during rearing and fattening. However, neither plasma concentrations of calcium, phosphate and bone markers during the observation period nor bone ash and bone mineral density at slaughter were clearly affected by the treatment. Maternal and offspring treatment with 25-OHD3 instead of vitamin D3 resulted in a slight reduction in the prevalence of leg swelling. In addition, more pigs walked with even steps and normal stride length. Further studies are needed to test whether the slight effects observed in the present experiment are reproducible and of relevance for animal health and welfare. In that case, the underlying mechanisms should be revealed in order to take advantage of potentially beneficial influences especially under certain feeding regimes.

Dietary supplementation of 25-hydroxycholecalciferol as an alternative to cholecalciferol in swine diets: A review.

25-hydroxycholecalciferol (25-OHD3 ) formed via hepatic hydroxylation from vitamin D, cholecalciferol, represents the precursor of the biologically active vitamin D hormone, 1,25-dihydroxyvitamin D. Due to a higher absorption rate and the omission of one hydroxylation, dietary supplementation of 25-OHD3 instead of vitamin D3 is considered to be more efficient as plasma concentrations of 25-OHD3 are increased more pronounced. The present review summarises studies investigating potential beneficial effects on mineral homeostasis, bone metabolism, health status and performance in sows, piglets and fattening pigs. Results are inconsistent. While most studies could not demonstrate any or only a slight impact of partial or total replacement of vitamin D3 by 25-OHD3 , some experiments indicated that 25-OHD3 might alter physiological processes when animals are challenged, for example, by a restricted mineral supply.

Low potassium diets with different levels of calcium in comparison with different anionic diets fed to prepartum dairy cows: Effects on sorting behaviour, total tract digestibility, energy metabolism, oxidative status and hormonal response.

This study investigated the effects of low potassium diets with different levels of Ca compared to two diets low in dietary cation-anion difference (DCAD) fed prepartum as a strategy to prevent hypocalcemia on sorting behaviour, total tract digestibility, oxidative status and energy and protein metabolism of transition cows. Forty-eight pregnant dairy cows were assigned to 4 treatment groups: Low Ca, low K (LCLK), High Ca, low K (HCLK), Supplementation with anionic mineral mixture (AMS) supplementation with SoyChlor (CAS). After parturition, all animals were fed a standard postpartum diet. Data were collected until 21 DIM. Prepartum urinary pH was significantly reduced by the low DCAD diets, while postpartum Ca homeostasis was affected by the HCLK ration. Feeding AMS induced sorting against particles <1.18 mm in favour of particles >19 mm prepartum. In contrast, cows fed CAS showed an increase in selective consumption of fine particles and sorted against longer particles similar to the HCLK and LCLK groups. Postpartum sorting activity was not affected by the dietary treatments. After calving, apparent digestibility of NDF was significantly reduced in the HCLK group. Prepartum, we observed effects on serum concentrations of non-esterified fatty acids were higher and insulin sensitivity was lower in the AMS group. Blood urea nitrogen (BUN) was decreased in cows fed the CAS ration. Postpartum, we found serum protein to be decreased with the low DCAD diets while BUN was decreased in the CAS group. The low DCAD rations increased prepartum serum malondialdehyde concentrations, while postpartum total antioxidant capacity was lower in the HCLK and the AMS group. From these data, we conclude that AMS decreased prepartum intake due to compromised palatability. Intermediate protein metabolism was affected by the low DCAD diets, while parameters of oxidative stress were probably affected by acid-base balance and Ca homeostasis.

Dietary phosphorus restriction affects bone metabolism, vitamin D metabolism and rumen fermentation traits in sheep.

Homeostasis of calcium (Ca) and phosphate (Pi ) is maintained by a concerted interplay of absorption and reabsorption via the gastrointestinal tract and the kidney and by storage and mobilization from the bone regulated mainly by parathyroid hormone (PTH), 1,25-dihydroxycholecalciferol and calcitonin. The present study aimed at characterizing the effects of dietary P restriction on bone, vitamin D metabolism and rumen fermentation traits reflecting the endogenous P cycle maintaining the ruminal P supply for microbial metabolism. The experiments were done in eleven female, non-pregnant, non-lactating four- to nine-year-old Black Headed Mutton sheep allotted to two feeding groups: "P-restricted" (0.11% P/kg DM and 0.88% Ca/kg DM) and "Control" (0.38% P/kg DM and 0.88% Ca/kg DM). Dietary P restriction did not lead to hypophosphataemia, probably due to a compensation by bone mobilization, demonstrated by increased serum concentrations of a resorption marker and altered gene expression in bone tissue. In addition, the RNA expression of fibroblast growth factor 23, a bone-derived factor involved in the regulation of vitamin D metabolism, was significantly reduced with dietary P restriction. Furthermore, several genes related to vitamin D metabolism and plasma concentrations of 1,25-(OH)2 D were associated with serum concentrations of phosphate (Pi ). In the parotid gland, the expression of the Pi transporter NaPi2b was negatively associated with serum Pi and positively with parathyroid PTH expression. Although Pi concentrations in saliva and the gastrointestinal tract were significantly reduced, we found no adverse effects of the P-restricted ration on the production of short chain fatty acids, but slight differences in the production of butyrate as well as its relationship to rumen Pi and ammonia concentrations that might indicate an impact on ruminal fermentation.

Calcinosis in a roe deer fawn (Capreolus capreolus) in northern Germany.

BACKGROUND: Calcinosis has been reported for a broad range of different animals. Causes for calcinosis include metabolic disorders due to kidney failure, intoxication with calcinogenic plants, or iatrogenic overdose of vitamin D. Especially young animals seem to be very susceptible to developing calcinosis. Currently, however, there is a lack of information on calcinosis in wildlife. CASE PRESENTATION: The following case report describes a roe deer fawn admitted to a clinic due to general weakness and myiasis. Plasma levels for creatinine, urea and phosphate were highly elevated, whereas the total calcium level was decreased. Necropsy revealed calcinosis due to calcification in many organs. The reason for calcinosis in this particular case might be kidney failure. Plasma samples from other hunted roe deer fawns also showed high phosphate levels. CONCLUSIONS: Roe deer fawns might be susceptible to calcinosis due to high plasma phosphate, which could be a result of kidney failure or different feed. Further research into calcium and phosphate homeostasis in roe deer is necessary.

Blood leukocyte composition and function in periparturient ewes kept on different dietary magnesium supply.

BACKGROUND: Transition period (TP) is characterised by physiological and metabolic changes contributing to immunodysregulation. Since knowledge about this period in sheep is scarce, we analysed changes in selected immune variables during the TP in ewes and whether dietary magnesium (Mg) supplementation could modulate these immune variables. Pregnant ewes (2nd and 3rd lactation) were divided into a control group (CONT, n = 9) and a Mg group (MAG, n = 10) supplemented with Mg oxide resulting in a daily Mg intake of approximately 0.30 and 0.38% (MAG) of dry matter during ante- (a.p.) and post-partum (p.p.) periods, respectively. Blood samples were collected between days (d) 30 a.p. and d 30 p.p.. Whole blood neutrophil phagocytic activity, monocyte subset (classical cM, intermediate intM, non-classical ncM) composition and the proliferative capacity of lymphocytes were determined flow cytometrically. At d 14 a.p., all ewes were vaccinated against Mycobacterium avium subsp. paratuberculosis (MAP). RESULTS: Both groups showed a sharp increase in the total leukocyte counts (TLC) and neutrophil counts (P < 0.0001), at d 1 p.p., while, monocytes and their subpopulations displayed the highest values at d 30 p.p. (P ≤ 0.05). At d 1 p.p. the neutrophil phagocytic activity was higher (P < 0.05) in MAG ewes. Throughout the TP, the proliferative response of CD4+ cells was significantly higher in the MAG group (P < 0.05). Ewes in both groups responded with an increase in the TLC, neutrophil numbers (P ≤ 0.05) and ncM (P < 0.001) 24 h post vaccination, whereas monocytes and cM dropped in numbers (P ≤ 0.05). Numbers of intM only increased in MAG ewes (P < 0.05), whereas lymphocyte numbers decreased (P < 0.01). Mg supplementation did not affect the significant increase in MAP-specific antibodies at d 7 and 21 post vaccination. Total Mg and Ca serum levels did not show any differences between the two groups. CONCLUSION: Whereas TP-associated fluctuations in blood leukocyte numbers are not influenced by Mg supplementation, neutrophil phagocytic activity, the proliferative capacity of CD4+ cells and the cellular response within 24 h after a vaccination are subject to modulation.

Symposium review: Transition cow calcium homeostasis-Health effects of hypocalcemia and strategies for prevention.

The effects of subclinical hypocalcemia have been explored in numerous observational and mechanistic studies in recent years. Besides obvious, well-known effects on muscle contractility, the role of Ca with respect to immune function and intermediary metabolism explains the contribution of subclinical hypocalcemia to the development of several diseases observed in early lactation and underlines its importance in high-performing dairy cows. The present review aims at integrating recent scientific progress, such as discoveries about the role of the mammary gland in regulating bone mobilization, into generally accepted aspects of the endocrine control of Ca homeostasis. We will discuss Ca transport mechanisms through absorption, resorption, secretion, and mobilization, as well as the physiological regulation of Ca through parathyroid hormone, 1,25-dihydroxyvitamin D, fibroblast growth factor 23, and serotonin, in addition to dietary mineral requirements. To improve hypocalcemia prevention strategies, our knowledge of the physiological mechanisms necessary to maintain normocalcemia and their endogenous regulation should be combined with data derived from herd-level studies. Using such studies, we will discuss prepartum nutritional strategies aimed at reducing the incidence of subclinical hypocalcemia, as well as options for postpartum Ca supplementation and their effects on early-lactation health and production. Especially in respect to approaches that might interfere with endogenous adaptation processes, such as supplementation with vitamin D metabolites or large doses of Ca, a thorough understanding of the underlying mechanisms that might induce unwanted hypocalcemia rebound effects will be crucial to ameliorate our future management of transition cows. Continued efforts by researchers to understand the interaction of Ca homeostasis with prevention strategies is necessary to optimize cow health and support copious milk production.

In vivo measurement of strontium absorption from the rumen of dairy cows as an index of calcium absorption capacity.

Absorption of dietary calcium from the rumen is a quantitatively important process in calcium homeostasis of ruminants. In 3 separate experiments in dairy cows, we applied a technique developed in sheep to measure the rate of strontium (Sr) absorption from the rumen as an indicator of calcium absorption capacity. Absorption from the rumen after an oral dose of SrCl2 resulted in a maximum plasma concentration of Sr after 1 h, whereas absorption from the small intestine after injection of SrCl2 into the abomasum through a cannula occurred more slowly. The second experiment demonstrated that the calcium absorption capacity index of the rumen was significantly greater in 21 lactating Friesian cows (230 ± 66, mean ± SEM) than in 6 mature, nonlactating, nonpregnant heifers (101 ± 21, mean ± SEM). In a third experiment, we compared clinically normal cows at the onset of lactation with those that developed parturient paresis. In cows that developed severe hypocalcemia, plasma concentrations of 1,25(OH)2D were significantly elevated (144 ± 60 pg/mL vs. 90 ± 54 pg/mL; means ± SEM) and their rumen calcium absorption index was significantly decreased compared with that of clinically normal cows. Evidence suggested that mobilization of calcium from bone as lactation commenced was significantly depressed in paretic cows compared with those that did not show clinical signs of hypocalcemia. Moreover, ruminal stasis suppressed the absorption of calcium from the rumen. We conclude that measurement of Sr concentration in blood plasma after an oral dose of SrCl2 into the rumen can be used as an index of rumen calcium absorption capacity under different states of calcium homeostasis.

Contrary seasonal changes of rates of nutrient uptake, organ mass, and voluntary food intake in red deer (Cervus elaphus).

Northern ungulates acclimatize to winter conditions with restricted food supply and unfavorable weather conditions by reducing energy expenditure and voluntary food intake. We investigated in a study on red deer whether rates of peptide and glucose transport in the small intestines are also reduced during winter as part of the thrifty phenotype of winter-acclimatized animals, or whether transport rates are increased during winter in order to exploit poor forage more efficiently. Our results support the latter hypothesis. We found in a feeding experiment that total energy intake was considerably lower during winter despite ad libitum feeding. Together with reduced food intake, mass of visceral organs was significantly lower and body fat reserves were used as metabolic fuel in addition to food. However, efficacy of nutrient absorption seemed to be increased simultaneously. Extraction of crude protein from forage was higher in winter animals, at any level of crude protein intake, as indicated by the lower concentration of crude protein in feces. In line with these in vivo results, Ussing chamber experiments revealed greater electrogenic responses to both peptides and glucose in the small intestines of winter-acclimatized animals, and peptide uptake into jejunal brush-border membrane vesicles was increased. We conclude that reduced appetite of red deer during winter avoids energy expenditure for unproductive search of scarcely available food and further renders the energetically costly maintenance of a large gut and visceral organs unnecessary. Nevertheless, extraction of nutrients from forage is more efficient in the winter to attenuate an inevitably negative energy balance.

Modulation of intestinal calcium and phosphate transport in young goats fed a nitrogen- and/or calcium-reduced diet.

Feeding ruminants a reduced N diet is a common approach to reduce N output based on rumino-hepatic circulation. However, a reduction in N intake caused massive changes in Ca and inorganic phosphate (Pi) homoeostasis in goats. Although a single dietary Ca reduction stimulated intestinal Ca absorption in a calcitriol-dependent manner, a concomitant reduction of Ca and N supply led to a decrease in calcitriol, and therefore a modulation of intestinal Ca and Pi absorption. The aim of this study was to examine the potential effects of dietary N or Ca reduction separately on intestinal Ca and Pi transport in young goats. Animals were allocated to a control, N-reduced, Ca-reduced or combined N- and Ca-reduced diet for about 6-8 weeks, whereby N content was reduced by 25 % compared with recommendations. In Ussing chamber experiments, intestinal Ca flux rates significantly decreased in goats fed a reduced N diet, whereas Pi flux rates were unaffected. In contrast, a dietary Ca reduction stimulated Ca flux rates and decreased Pi flux rates. The combined dietary N and Ca reduction withdrew the stimulating effect of dietary Ca reduction on Ca flux rates. The expression of Ca-transporting proteins decreased with a reduced N diet too, whereas Pi-transporting proteins were unaffected. In conclusion, a dietary N reduction decreased intestinal Ca transport by diminishing Ca-transporting proteins, which became clear during simultaneous N and Ca reduction. Therefore, N supply in young ruminant nutrition is of special concern for intestinal Ca transport.

Differences in peripartal plasma parameters related to calcium homeostasis of dairy sheep and goats in comparison with cows.

Recently it has been demonstrated that there are differences between sheep and goats in respect to adaptation to a calcium-restricted diet. It was the aim of the present study to evaluate whether species-specific peculiarities also occur when calcium homoeostasis is challenged by lactation. Therefore, we investigated the time courses of plasma parameters related to calcium homoeostasis (calcium, phosphate, calcitriol, the bone resorption marker CrossLaps and the bone formation marker osteocalcin) during the transition period in multiparous animals of both species and compared the results to data from a former study carried out with dairy cows. As in cows, plasma calcium and the ratio of bone formation to bone resorption decreased at parturition in goats while plasma calcitriol increased. On day 10 post partum the bone parameters of goats reached prepartum values again, which was not the case in cows. Sheep were found to experience a challenge of calcium homoeostasis already 10 d before parturition, reflected by a very low ratio of bone formation to bone resorption, which was not accompanied by an increase in plasma calcitriol. Additionally, sheep and goats which had been in milk for 3 months were sampled, dried-off and sampled again 6 weeks later. In dried-off animals there were no detectable differences in parameters of bone metabolism. In conclusion we could show that the contribution of bone mobilisation to the compensation for the enhanced calcium demand due to lactation differs between the three ruminant species.

Ex vivo intestinal studies on calcium and phosphate transport in growing goats fed a reduced nitrogen diet.

In ruminant feeding, the reduction of dietary protein is an effective approach for decreasing the excretion of N. In non-ruminant species, the intestinal absorption of Ca was affected when dietary protein was reduced. Therefore, it was the aim of the present study to characterise the intestinal absorption of Ca and inorganic phosphate (P(i)) in goats fed different N and Ca diets. Intestinal flux rates of Ca and P(i) were determined in goats fed a reduced N and Ca diet by Ussing chamber experiments. For a more mechanistic approach, the uptake of Ca and P(i) in intestinal brush-border membrane vesicles (BBMV), the expression levels of the epithelial Ca channel transient receptor potential vanilloid channel type 6 (TRPV6), the sodium-dependent P(i) transporter (NaPi) IIb and the vitamin D receptor (VDR) were measured. In goats fed a reduced N and Ca diet, the intestinal flux rates of Ca and P(i) were elevated. However, the reduced N and Ca diet had no effect on the uptake of Ca and P(i) in intestinal BBMV, while the expression of TRPV6 and NaPi IIb protein in the corresponding intestinal segments was even decreased. The mRNA expression of NaPi IIb and VDR was not affected. Therefore, a post-transcriptional regulation of TRPV6 and NaPi IIb protein was suggested in goats fed a reduced N and Ca diet. From these data, it can be concluded that the intestinal absorption of Ca and P(i) in growing goats was affected by changes in dietary N and Ca intake like those in single-stomached animals but differently modulated.

In contrast to sheep, goats adapt to dietary calcium restriction by increasing intestinal absorption of calcium.

Many studies aimed at understanding calcium homeostasis in the cow use sheep or goats as ruminant models. However, the comparability of relevant homeostatic processes between ruminant species has not been assessed. Therefore, we investigated whether the mechanisms of maintaining calcium homeostasis are similar in different ruminant species. Dietary calcium of goats was restricted along with treatment with calcitriol in a similar protocol to that in a recent study with sheep. Plasma calcium and phosphate and parameters of bone metabolism were analysed. Gastrointestinal calcium transport was characterised in vitro in Ussing chambers. The expression of apical epithelial calcium channels, calbindin-D(9K), and the basolateral plasma membrane Ca(2+)-ATPase was determined by quantitative RT-PCR and Western blot analysis. In contrast to sheep, the goats were able to compensate for low dietary calcium supply by increasing active calcium absorption in the small intestine, especially in the jejunum. As in sheep, the observed ruminal calcium transport of goats was affected neither by the calcium restricted diet nor by the calcitriol treatment, thus indicating the presence of an alternative, vitamin D-independent mechanism of calcium transport in the forestomachs. These results demonstrate that mechanisms for maintaining calcium homeostasis differ significantly between ruminant species.

In vitro studies on intestinal calcium and phosphate transport in horses.

Transepithelial transport mechanisms play a key role in regulating the absorption and secretion of calcium (Ca(2+)) and inorganic phosphate (P(i)) in the gastrointestinal tract. Although intestinal disorders with imbalances in macromineral homeostasis are frequently observed in horses, available data on intestinal Ca(2+) and P(i) transport are limited. The aim of the present study was to characterize the intestinal Ca(2+) and P(i) transport functionally by using the in vitro radioisotope tracer technique with Ussing chambers and to identify components involved in Ca(2+) transport at both mRNA and protein level. Among the different intestinal segments, the duodenum showed significant and highest active Ca(2+) absorption. The findings from RT-PCR and Western blot analysis suggest that the epithelial Ca(2+) channel TRPV6, the cytosolic calcium binding protein calbindin-D(9K) and the plasma membrane calcium ATPase PMCA may be involved in active transcellular Ca(2+) transport. Regarding the P(i) transport, the results indicate significant active P(i) secretion in the jejunum, but the contributing mechanisms remain unclear. A significant inhibiting effect of ouabain as an antagonist of the basolateral Na(+)/K(+)-ATPase on the serosal-to-mucosal P(i) transport suggests a pivotal role of Na(+) in jejunal P(i) transport in the horse.

Egg yolk colour in organic production as affected by feeding - Consequences for farmers and consumers.

In organic table egg production, saponified extracts of carotenoids are not allowed to intensify egg yolk colour. Therefore, we investigated the suitability of organically produced marigold flower meal (Tagetes erectus, TE) and spinach (Spinacia oleracea, SO) as carotenoid sources (mixture of 25% TE and 75% SO) to reach values of 9-10 'Roche Yolk Colour Fan' units (RYCF units). Feeding a completely unsupplemented control diet resulted in a yolk colour of 4.7 RYCF units, a total supply of 11.1 g/kg, 14.6 g/kg and 17.5 g/kg of TE and SO as stand-alone carotenoid sources induced a significant increase to 8.0, 8.2 and 8.9 RYCF units. Under 'winter-feeding conditions', i.e. minimal carotenoid supply in the diet, 17.5 g/kg TE and SO resulted in 9.3 ± 0.7 RYCF units. It can be concluded that supplementing TE and SO is suitable to improve the yolk colour in organically produced table eggs.

Comparative Study of the Effects of Two Dietary Sources of Vitamin D on the Bone Metabolism, Welfare and Birth Progress of Sows Fed Protein- and Phosphorus-Reduced Diets.

To investigate the influence of two dietary sources of vitamin D on the vitamin D status, bone metabolism, welfare and birth progress of gestating and lactating sows, forty-nine multiparous sows were randomly assigned to one of two diets: "CON" (n = 25; 50 µg vitamin D3/kg feed) and "HYD" (n = 24; 50 µg 25-hydroxycholecalciferol/kg feed). The basal diets were protein- and phosphorus-reduced. The trial started on day 3 ante insemination of the sows and ended with weaning of the piglets on day 28 postpartum. Dietary supplementation of 25-hydroxycholecalciferol resulted in improved maternal vitamin D status (p < 0.001), fewer gait changes (p < 0.01) and longer standing time after feeding (day 5 ante partum; p < 0.05) compared to vitamin D3. However, the bone markers CrossLaps and osteocalcin were not affected. Overall, the present results suggest that sows fed 25-hydroxycholecalciferol instead of vitamin D3 showed improved locomotion and stance strength. However, this outcome is probably not related to altered bone metabolism. The underlying mechanisms must be investigated in further studies.

Serum parameters related to mineral homeostasis and energy metabolism in ewes kept on different dietary magnesium supply during the transition period.

The present study investigated the effects of dietary magnesium supplementation on mineral status and intermediary metabolism of ewes during the transition period (TP). For this purpose, 19 pregnant ewes (2nd and 3rd lactation) were divided into a control group (Con, n = 9) kept on a daily magnesium intake of approximately 3.0 g ante-partum (a.p.) and 5.0 g post-partum (p.p.), and a magnesium group (Mg, n = 10, 4.2 g a.p., 7.7 g p.p.). Blood was collected at day (d) 30 a.p., d 14 a.p., d 1 p.p., d 14 p.p. and d 30 p.p., respectively. Serum levels of total magnesium were not affected by the treatment. In Con animals, serum levels of total calcium and phosphate were lower at d 1 p.p. in comparison to d 30 a.p. (P ≤ 0.05). Only in Con ewes, serum glucose levels showed significant fluctuations throughout the entire observation period (P ˂ 0.05) and were correlated negatively with those of beta-hydroxybutyrate (r2: 0.70; P < 0.01, r2: 0.76; P < 0.01) and positively with insulin (r2: 0.46; P < 0.05, r2: 0.59; P < 0.05) on d 30 and 14 a.p., respectively. At d 30 p.p., serum insulin levels were lower in the Mg group compared to the Con group (P < 0.05). As serum concentrations of calcium, phosphate and glucose seemed more stable throughout the TP, magnesium supplementation might be an approach to promote metabolic health in ewes.

An investigation on the relevance of prolactin, insulin-like growth factor-1 and 25-hydroxyvitamin D3 (25-OHD3 ) in canine benign prostatic hyperplasia in a predisposed breed model.

Serum concentrations of prolactin (PRL), insulin-like growth factor-1 (IGF-1) and 25 hydroxyvitamin D3 (25-OHD3 ) were analysed to investigate their possible involvement in the pathogenesis of benign prostatic hyperplasia (BPH). For this, dogs of the Rhodesian Ridgeback (RR) breed were used because of a verified breed disposition for the development of BPH. Labrador Retrievers (LR) served as controls. The prostate gland status was characterised by the prostate gland volume, clinical signs of BPH (haemospermia and sonographic findings) and the plasma concentration of canine prostate-specific arginine esterase (CPSE). Breed specificity in the RR was expressed by a correlation of PRL with breed (p < 0.05). Similar relationships existed in the dogs with normal CPSE (CPSEn) with respect to the IGF-1 concentrations (LR: p < 0.05). The latter were negatively correlated with prostatic volume and age (both p < 0.05). Concentrations of 25-OHD3 were tendentially (p = 0.18) lower in the RR with increased CPSE (CPSEi) compared with the CPSEn LR and RR showing clinical signs of BPH. A negative correlation between serum 25-OHD3 and age (p < 0.05) existed in the CPSEi RR. Proof of 25-OHD3 in prostatic secretion proved to be a breed specific feature in the RR (p < 0.0001). For all RR dogs showing clinical signs of BPH, a close to significant (p = 0.06) positive correlation with prostate gland volume was found. The results of the present study reveal no clear hints towards the significance of PRL and IGF-1 in the pathogenesis of canine BPH. In the RR breed there were indications of a causal relationship with age-dependent changes in the vitamin D metabolism. The data suggest the possibility of preventing or treating canine BPH by administering vitamin D or substances involved in the intraprostatic vitamin D metabolism.

Calcinosis in Alpaca Crias (Vicugna pacos) Due to Vitamin D Intoxication-Clinical, Laboratory and Pathological Findings with a Focus on Kidney Function.

Alpacas kept in Central Europe are often deficient in vitamin D3, which is supplemented orally or by injection by the owners or veterinarians. Vitamin D3 can be specified in two different units (IU and µg), which differ by a factor of 40. By mixing up these units, an overdosage can be induced. In this study, three alpaca crias were examined after vitamin D3 intoxication, with particular reference to kidney function. All three animals developed non-specific clinical alterations 1-2 weeks after a vitamin D3 overdose of approximately 40 times. Plasma of the animals revealed several alterations. The main findings were severe azotemia, hypercalcemia and hyperphosphatemia, 15 days after treatment. Kidney function analysis (endogenous creatinine clearance) in two of the crias revealed severe glomerular damage. All crias died despite intensive treatment within 23 days after vitamin D3 treatment. Necropsy revealed calcification in different organs, mainly the kidneys, lungs and liver. Since nine other crias in the same group were treated with comparable doses of vitamin D3 and no clinical signs were observed in these animals, it is concluded that individual animals show different levels of sensitivity to vitamin D3.

Dietary protein and calcium modulate parathyroid vitamin D receptor expression in young ruminants.

For economic reasons and in order to minimize nitrogen excretion and thus pollution, the crude protein content in the diet of livestock animals should be as low as possible without negatively affecting the animals´ health and performance. As ruminants can efficiently use dietary protein because of the ruminohepatic circulation of urea, they are considered to cope more easily with such a feeding regime than monogastric animals. However, despite unaltered daily weight gain, massive changes in mineral homeostasis and vitamin D metabolism were observed with dietary protein reduction (N-) in young, growing goats. Serum concentrations of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) were decreased with a low N intake, even if calcium (Ca) was also restricted (Ca-). Interestingly, concentrations of cyclic adenosine monophosphate (cAMP) measured as an indirect assessment for the parathyroid hormone (PTH) activity were not affected by low protein. Therefore, it was hypothesized that the sensitivity of the parathyroid gland is modulated during these dietary interventions. Four groups of male German colored goats received a control (N+/Ca+), a reduced protein (N-/Ca+), a reduced Ca (N+/Ca-) or a reduced protein and Ca (N-/Ca-) diet. After six weeks we determined the expression of PTH, PTH receptor, Ca sensing receptor (CASR), vitamin D receptor (VDR), retinoid X receptor (RXRα), Klotho, fibroblast growth factor receptor 1c-splicing form, and the sodium-dependent Pi transporter (PiT1) in the parathyroid glands. Concentrations of cAMP were not affected, while those of Ca and 1,25-(OH)2D3were diminished and that of 25-hydroxyvitamin D3 was increased with N- feeding. The expression patterns of the described target genes were not altered. In contrast, animals fed the Ca- rations showed enhanced serum 1,25-(OH)2D3 and cAMP levels with no changes in blood Ca concentrations demonstrating an efficient adaptation. The mRNA expression of expression of VDR and CASR in the parathyroid gland was significantly diminished and RXRα, PTHR and PiT1 expression was elevated. Instead of the assumed desensitization of the parathyroid gland with N-, our results indicate elevated responsiveness to decreased blood Ca with feeding Ca-.