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PubMed1999

1alpha,25-dihydroxycholecalciferol and cyclosporine suppress induction and promote resolution of psoriasis in human skin grafts transplanted on to SCID mice.

Accumulating evidence has emphasized the importance of immunocompetent cells in determining the psoriatic phenotype. We have investigated the effect of 1alpha,25-dihydroxycholecalciferol, the naturally occurring active form of vitamin D3, cyclosporine A, and interleukin-10 on the phenotype of human psoriatic skin xenotransplants. First, psoriatic skin transplants were injected with either 1alpha,25-dihydroxy- cholecalciferol, cyclosporine A, or interleukin-10. Second, we determined the ability of autologous lymphocytes, activated in vitro using staphylococcal enterotoxin B and interleukin-2 and then exposed to either 1alpha, 25-dihydroxycholecalciferol or cyclosporine A, to induce psoriatic lesions if they were injected into the dermis of uninvolved skin grafts. We found that injections into transplanted psoriatic plaques of either 1alpha,25-dihydroxycholecalciferol or cyclosporine A, but not interleukin-10, resulted in a consistent reduction in the clinical and histologic score of psoriasis with remission towards uninvolved psoriatic skin. Injection of activated immunocytes into symptomless psoriatic skin grafts, changed the grafts towards plaque-type psoriasis with silvery scale, parakeratosis, elongated rete pegs, acanthosis, and dermal angiogenic reaction. In contrast, if activated immunocytes were exposed to 1alpha, 25-dihydroxycholecalciferol or cyclosporine A prior to injection, only minimal changes occurred. It was determined that neither staphylococcal enterotoxin B and interleukin-2 activation by itself, nor the drugs investigated, changed the CD4/CD8 ratio of activated (CD25 + ) cells. Our results are consistent with the hypothesis that psoriasis may be induced by activated T lymphocytes, and indicate that novel immunomodulatory drugs can serve to inhibit the pathogenetic ability of immunocytes in psoriasis.

Animals↗
PubMed2002

Alendronate reduces the risk of multiple symptomatic fractures: results from the fracture intervention trial.

OBJECTIVES: To evaluate the effect of alendronate on the occurrence rate of multiple svmptomatic fractures and on the risk of multiple symptomatic fractures (likelihood of having more than one fracture diagnosed because of the symptoms the fractures caused over the study period) among women with osteoporosis. DESIGN: Primary analysis of data from a randomized, placebo-controlled, double-blind trial. SETTING: Eleven community-based clinical research centers. PARTICIPANTS: Subset of women enrolled in the Fracture Intervention Trial: aged 55 to 81 and having at least one morphometric vertebral fracture at baseline (n=2,027) or having no vertebral fracture but meeting prevailing World Health Organization bone mineral density criteria for osteoporosis (T-score < or =2.5 at the femoral neck)(n = 1,631). INTERVENTION: All participants reporting calcium intake of 1,000 mg/day or less received a supplement of 500 mg calcium and 250 IU cholecalciferol. Participants were randomly assigned to placebo or alendronate sodium (5 mg/day for 2 years and 10 mg/day for the remainder of the study). Average total follow-up was 4.3 years. MEASUREMENTS: Symptomatic fractures were diagnosed by personal physicians and confirmed by review of radiological data by an expert committee blinded to treatment assignments. RESULTS: Eighty-six of 1,817 women receiving placebo experienced multiple symptomatic fractures during the follow-up period, compared with 51 of 1,841 receiving alendronate. Reduction of risk for multiple symptomatic fractures combined was 42% (relative risk (RR) = 0.58, 95% confidence interval (CI) = 0.41, 0.81) and for multiple symptomatic vertebral fractures was 84% (RR = 0.16,95% Cl = 0.05, 0.42). Cumulative incidence curves showed divergence after as little as 3 months of treatment, with a statistically significant (P = .044) reduction at 6 months for multiple symptomatic vertebral fractures. When all fractures over the follow-up period were included, the occurrence rates of all symptomatic fractures and symptomatic vertebral fractures were 34% and 63% lower, respectively, with alendronate than with placebo. These reductions were sustained during the follow-up period. All reductions in risk were consistent across predefined subgroups: age (<75 vs > or =75), morphometric vertebral fracture(present vs absent), prior clinical fracture since age 45 (yes vs no), and whether the subject had fallen in the 12 months before randomization. CONCLUSIONS: These data demonstrate that treatment with alendronate reduces the risk of multiple symptomatic fractures during a treatment period averaging 4.3 years. The reductions were consistent across prespecified sub-groups. This effect is evident early in treatment and is sustained.

Aged↗
PubMed1999

Effects of vitamin D and retinoids on the differentiation and growth in vitro of canine osteosarcoma and its clonal cell lines.

Although canine osteosarcoma is one of the most malignant, aggressive and lethal neoplasms originating from undifferentiated bone cells, it may retain some capacity for normal differentiation. The purpose of this study was to ascertain if the residual capacity for differentiation could be used to suppress its malignant properties. We tested the efficacy of vitamin D and retinoids in inducing differentiation and inhibiting growth of the POS canine osteosarcoma and four of its clonal cell lines, POS 14A (fibroblast type), POS 53B (chondroblast type), POS 53C (undifferentiated type) and POS 53D (osteoblastic type). Treatment with 10(-10)to 10(-8)M concentrations of calcitriol, OCT, cholecalciferol, all-trans retinoic acid (ATRA) and 9-cis retinoic acid for 48-120 hours changed the morphology of POS, POS 53B, POS 53C and POS 53D cells to cells that were elongated and spindle-shaped. Increased number of cytoplasmic organelles and pronounced nuclear activities were induced by concentrations of 10(-8)M and 10(-7)M for 120 hours. All drugs at concentrations of 10(-10)to 10(-8)M for 72 hours inhibited POS growth dose-dependently. OCT significantly reduced the cell number in all cell lines when used at concentrations between 10(-9)and 10(-8)M for 72 hours and exerted significant anti-proliferative effects for eight days culture. This study demonstrated that changed morphology and inhibition of growth was induced by treatment of the cells with these vitamins, that the loss of control of differentiation in the neoplasia was not irreversible and that these drugs may be useful in the clinic.

Animals↗
PubMed1978

Vitamin D and ischaemic heart disease.

Vitamin D has been proposed as a risk factor of ischaemic heart disease. In 12 patients with acute myocardial infarction the major circulating vitamin D metabolite, 25-hydroxy-cholecalciferol (25-HCC), did not show any fluctuations during the first 4 days after onset of symptoms. The serum 25-HCC level was then measured in 128 patients consecutively admitted because of chest pain, 53 of whom had myocardial infarction and 75 had angina pectoris. The values found did not differ from those measured in 409 normal persons. The seasonal variations of serum 25-HCC were less pronounced in heart patients than in normals, probably due to less sun exposure in the summer months. The levels of serum 25-HCC did not correlate with the concentrations of serum cholesterol, glycerides, calcium or magnesium. Low serum calcium and magnesium were observed in all patients. Serum calcium was further reduced in the course of acute myocardial infarctions while serum parathyroid hormone rose significantly. We conclude that patients with ischaemic heart disease are not ingesting or producing in their skin elevated amount of vitamin D.

Alkaline Phosphatase↗
PubMed1978

Effects of calcium intake and renal function on plasma immunoreactive parathyroid hormone levels in rats.

Parathyroid hormone (PTH) was estimated with a radioimmunoassay system which recognised presumably intact rat PTH as the major circulating species. A low calcium diet was found to increase PTH levels in shamoperated and in 5/6-nephrectomized rats. In rats with normal renal function, a low calcium intake resulted in a significant mean increase of PTH levels, while changes in plasma calcium, magnesium, phosphate and protein concentrations were not detectable; at the same time the ability of the duodenum to transport calcium in vitro was accelerated. In 5/6-nephrectomized rats, on the other hand, PTH levels were dramatically increased in hypocalcemic animals kept on a calcium deficient diet, while intestinal calcium transport was impaired. These data support the concept that hypocalcemia is the most important stimulus for increased PTH release. Since increased PTH levels can be seen in situations where increased 1,25-dihydroxy-cholecalciferol synthesis is known to occur, it appears that this metabolite cannot inhibit a rise in plasma PTH levels.

Animals↗
PubMedDate not supplied

[Vitamin D status of children and adolescents of African and Asian diplomats in Germany].

Vitamin D-deficiency has been observed among immigrant children with rickets and osteomalacia in Western Europe. So vitamin D-status in 34 children and juveniles (17 girls, 17 boys) of African and Asian diplomats staying in West Germany only for a certain time is examined. During summer 1989 plasma levels of alkaline phosphatase, calcium, phosphate, 25-hydroxy-cholecalciferol and 1,25-dihydroxycholecalciferol is measured. According to their native country the subjects are divided into three groups: I North Africa (n = 7), II Central Africa (n = 18), III Asia (n = 9). No clinical signs of rickets or osteomalacia are detected. All plasma levels of calcium and phosphate are in the normal range so as most of the values of the alkaline phosphatase. In Group I 85.7% (n = 6), group II 77.8% (n = 14) and group III 44.4% (n = 4) have decreased values of 25-OHD whereas most strikingly elevated amounts of 1,25-OH2D are measured in 57.1% (n = 4) of the subjects in group I, 66.7% (n = 12) in group II and 11.1% (n = 1) in group III. Normal values for both 25-OHD and 1,25-OH2D are rare: one case (11.1%) in group I, no case in group II, four cases (44.4%) in group III. The influence of the time staying in West Germany on vitamin D-status, a possible dietary lack due to inadequate nutrition, the role of skin pigmentation and a potential genetic abnormality of vitamin D-metabolism is discussed to explain the results.

Adolescent↗
PubMed1997

Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older.

BACKGROUND: Inadequate dietary intake of calcium and vitamin D may contribute to the high prevalence of osteoporosis among older persons. METHODS: We studied the effects of three years of dietary supplementation with calcium and vitamin D on bone mineral density, biochemical measures of bone metabolism, and the incidence of nonvertebral fractures in 176 men and 213 women 65 years of age or older who were living at home. They received either 500 mg of calcium plus 700 IU of vitamin D3 (cholecalciferol) per day or placebo. Bone mineral density was measured by dual-energy x-ray absorptiometry, blood and urine were analyzed every six months, and cases of nonvertebral fracture were ascertained by means of interviews and verified with use of hospital records. RESULTS: The mean (+/-SD) changes in bone mineral density in the calcium-vitamin D and placebo groups were as follows: femoral neck, +0.50+/-4.80 and -0.70+/-5.03 percent, respectively (P=0.02); spine,+2.12+/-4.06 and +1.22+/-4.25 percent (P=0.04); and total body, +0.06+/-1.83 and -1.09+/-1.71 percent (P<0.001). The difference between the calcium-vitamin D and placebo groups was significant at all skeletal sites after one year, but it was significant only for total-body bone mineral density in the second and third years. Of 37 subjects who had nonvertebral fractures, 26 were in the placebo group and 11 were in the calcium-vitamin D group (P=0.02). CONCLUSIONS: In men and women 65 years of age or older who are living in the community, dietary supplementation with calcium and vitamin D moderately reduced bone loss measured in the femoral neck, spine, and total body over the three-year study period and reduced the incidence of nonvertebral fractures.

Aged↗
PubMed1985

Regulation by vitamin D metabolites of messenger ribonucleic acid for preproparathyroid hormone in isolated bovine parathyroid cells.

We have recently determined that high calcium concentrations, in parallel with their suppressive effects on parathyroid hormone (PTH) secretion, reversibly and specifically decrease preproPTH mRNA in cultured bovine parathyroid cells. In order to determine whether vitamin D metabolites also regulate the content of preproPTH mRNA, we tested their effects on bovine parathyroid cells in the same culture system. Levels of preproPTH mRNA were determined by dot-blot hybridization or blot hybridization with a labeled cloned cDNA probe. Incubation with 1,25-dihydroxycholecalciferol at doses varying from 10 pM to 0.1 microM caused a direct decrease in mRNA down to 50% of control values at 48 hr. There was no evidence that 1,25-dihydroxycholecalciferol, even at the highest concentrations, had any toxic effects on cell number or viability or on total RNA or RNA synthesis. Levels of alpha-actin mRNA did not change in the same experiments, and the suppression of preproPTH mRNA was reversible. When the relative potency of various vitamin D metabolites in suppressing preproPTH mRNA was evaluated, 1,25-dihydroxycholecalciferol greater than 24,25-dihydroxycholecalciferol greater than 25-hydroxycholecalciferol greater than vitamin D3 (cholecalciferol). These effects were highly specific and suggest that vitamin D metabolites play an important role in regulating the production of PTH.

Animals↗
PubMed1987

Chicken intestinal 28-kilodalton calbindin-D: complete amino acid sequence and structural considerations.

The complete primary structure of the cholecalciferol-induced chicken intestinal 28-kDa calbindin-D is reported. It is a single-chain polypeptide consisting of 261 amino acid residues (computed Mr = 30,042) and is blocked at the amino terminus. Tryptic digestion of the S-pyridylethylated protein followed by HPLC peptide mapping and automated sequence determination provided the bulk of the sequence information. Subsequent chymotryptic and Staphylococcus aureus V8 protease cleavages yielded the sequences of several additional regions as well as extensive overlapping of the tryptic peptides. The primary structure shows six homologous regions of sequence based on the EF-hand concept of calcium binding, four of which are predicted to actually bind calcium. Aside from these regions, there is no overall structural identity or apparent similarity with the mammalian calbindins (9 kDa), calmodulin, or troponin C. It is predicted that the secondary structure of 28-kDa calbindin-D is significantly different from the other proteins of this class, which bind four calcium atoms.

Amino Acid Sequence↗
PubMed1978

The effect of 1-alpha-hydroxycholecalciferol on calcium and phosphorus metabolism in the lactating ewe.

1. The effect of 1-alpha-hydroxycholecalciferol (1 alpha-OH-D3) on calcium and phosphorus metabolism has been studied in ewes at peak lactation by a combination of a mineral balance and a radioisotope technique. 2. The rate of Ca absorption was substantially higher in the treated ewes than in controls. The rates of endogenous loss of Ca into urine, faces and milk, however, were only slightly higher. 3. In consequence, the net retention of Ca was increased and the loss of skeletal reserves of Ca normally associated with peak lactation, prevented. 4. Although the rate of bone accretion increased slightly, the increase in skeletal retention of Ca resulted mainly from a decrease in the rate of bone resorption. 5. This finding conflicts with the generally held belief that bone resorption is increased by cholecalciferol treatment. 6. The rates of apparent absorption and retention of P were increased by the treatment probably as a result of a direct effect of the 1 alpha-OH-D3 on P absorption. 7. These results provide a possible explanationof the beneficial effect of 1 alpha-OH-D3 in preventing parturient paresis (milk fever) in the dairy cow.

Animals↗
PubMed1993

The effect of dietary 1,25-dihydroxycholecalciferol in preventing tibial dyschondroplasia in broilers fed on diets imbalanced in calcium and phosphorus.

Three experiments were carried out to investigate the effects of supplemental dietary 1,25-dihydroxycholecalciferol (1,25(OH)2cholecalciferol) and a low dietary Ca:P ratio on the occurrence of tibial dyschondroplasia (TD) in 3-week-old broilers. Histopathology was used to diagnose TD. In the first experiment, feeding a diet containing 7.5 g Ca and 7.6 g P/kg gave a higher incidence of TD than a control diet containing normal amounts of Ca and P (12 and 6 g/kg respectively). Increasing the dietary supplement of cholecalciferol in the imbalanced diet prevented rickets but did not decrease the incidence of TD. In the second experiment, supplementing the imbalanced diet with 10 micrograms 1,25(OH)2cholecalciferol/kg prevented TD completely but also gave a slight growth depression. In the third experiment the imbalanced diet was supplemented with 0, 2.5, 5 or 10 micrograms 1,25(OH)2 cholecalciferol/kg. The supplement of 2.5 micrograms/kg depressed and the higher supplements prevented the occurrence of TD, this time without a growth depression. Feeding the 10 micrograms/kg supplement for the first week only did not prevent TD. Plasma total Ca, inorganic P and alkaline phosphatase (EC 3.1.3.1) were unaffected by diet but 1,25(OH)2cholecalciferol was higher on the imbalanced than on the control diet. Supplementation of the imbalanced diet with 1,25(OH)2cholecalciferol did not increase plasma levels. It is concluded that 1,25(OH)2cholecalciferol is exerting a powerful biological effect in this model of TD, but the mechanism is unclear.

Animals↗
PubMed1994

Passive uptake in the small intestine and active uptake in the hindgut contribute to the highly efficient mineral metabolism of the common mole-rat, Cryptomys hottentotus.

Cryptomys hottentotus has no access to dietary or endogenous sources of cholecalciferol (D3). Serum concentrations of calcifediol (25(OH)D3) were undetectable (< 5 ng/ml) and calcitriol (1,25(OH)2D3), although detectable in plasma, was at a low concentration (31.40 (SEM 3.06 pg/ml). Despite their naturally impoverished vitamin D status, these animals exhibited highly efficient mineral absorption processes (Ca apparent fractional absorption efficiency, AFA (%) 95.33 (SEM 1.36); inorganic P (P(i)) AFA (%) 93.49 (SEM 0.81)). Furthermore, plasma mineral content was tightly regulated (Ca 2.57 (SEM 0.08) mmol/l; Mg 1.23 (SEM 0.05) mmol/l; P(i) 2.12 (SEM 0.15) mmol/l). Mode of uptake in C. hottentotus was unlike that in other D3-replete mammals. First, passive (rather than active) uptake occurred in the traditional site of active Ca absorption (with serosal:mucosal (S:M) ratios in the duodenum of 1.32 (SEM 0.13)), and the only site of active Ca uptake was the hindgut (caecum S:M 3.35 (SEM 0.46); proximal colon S:M 2.13 (SEM 0.30)). Despite the presence of active uptake in these hindgut regions, their overall contribution to the daily rate of mineral absorption was small (9.53 (SEM 1.27)%). These underground inhabitants rely upon highly efficient, passive mineral uptake. This is adequate to meet their mineral requirements and maintain mineral homeostasis in the absence of vitamin D.

Animals↗
PubMed2003

A western-style diet reduces bone mass and biomechanical bone strength to a greater extent in male compared with female rats during development.

Evidence from epidemiological and animal-feeding trials suggests that a western-style diet that is high in fat, and low in Ca, vitamin D and folic acid may result in low bone mass and poor bone quality: this leads to an increased risk of fragility fracture. The overall objective of the present study was to determine the effect of feeding a western-style diet (low in Ca (0.4 g/kg diet, Ca:P ratio 1:10), cholecalciferol (3 microg/kg diet), folic acid (0.23 mg/kg diet) and fibre (20 g/kg diet), and high in fat (200 g/kg diet)) for 17 weeks on bone mineral content (BMC) and the biomechanical bone strength of rat femurs. A secondary objective was to determine whether femurs from male and female rats (seven to eight rats per group) respond differently to the western-style diet. Male and female rats weighing 150-180 g were fed a western-style diet or a control diet for 17 weeks. At the end of the feeding trial, femur BMC was measured by ashing, and biomechanical properties were determined by three-point bending. Femur BMC and the majority of biomechanical properties measured were lower (P<0.05) among male and female rats fed a western-style diet compared with a control diet, despite similar weight gain and final body weight within genders. However, the western-style diet had a greater negative effect on femur BMC and biomechanical strength properties among male rats compared with females. This may be because male rats experienced greater overall body growth, as assessed by weight gain, than female rats, and suggests that the nutrient composition of the western-style diet did not support the development of strong femurs.

Animals↗
PubMed2002

Positive effects of a chicken eggshell powder-enriched vitamin-mineral supplement on femoral neck bone mineral density in healthy late post-menopausal Dutch women.

Although bone metabolism is largely under genetic control, the role of nutrition is considerable. The present study evaluates the effects of chicken eggshell powder, a new source of dietary Ca, and purified CaCO3 on bone mineral density (BMD) of the lumbar spine and hip. Besides BMD we also looked at biochemical markers of bone and Ca metabolism. Both Ca sources were provided in combination with minerals and vitamins including Mg, cholecalciferol and phylloquinone. We designed a randomised, double-blind, placebo-controlled study to take place over 12 months. Healthy Caucasian women (n 85), selected by age (> or =50 and <70 years), from the databases of general practitioners were recruited by telephone calls. They had to be at least 5 years post-menopausal, with lumbar spine T-score being > - 2.5. At baseline, their mean habitual daily Ca intake was adequate. The women were randomly allocated to: eggshell powder-enriched (group A; n 24), purified CaCO3-enriched (group B; n 22), or a placebo product (group C; n 27). BMD was measured at baseline and then after 6 and 12 months of supplementation as were the biochemical markers bone-specific alkaline phosphatase, amino-terminal propeptide extension of type I collagen, deoxypyridinoline, calcitonin, intact parathyroid hormone, calcidiol, and urinary Ca. After 12 months of supplementation, only mean BMD of the femoral neck in group A was significantly increased (P=0.014) by 1.75% (95% CI 0.18, 3.32) compared with a decrease of -0.60% (95% CI -1.92, 0.72) in group C. This increase coincided with significant decreases in markers of bone resorption and formation. No significant changes were seen in BMD at other sites, including lumbar spine, nor in groups B and C. No differences were found between groups A and B, or B and C. The present study indicates that healthy late post-menopausal women with an adequate Ca intake at baseline may increase BMD of the hip within 12 months following supplementation with the chicken eggshell powder-enriched supplement.

Age Factors↗
PubMed1990

Effect of 1 alpha,25-dihydroxycholecalciferol on egg shell quality and egg production.

1. The effect of replacing dietary cholecalciferol (D3) by 1 alpha,25-dihydroxycholecalciferol (1,25-(OH)2D3) on egg shell quality and egg production was tested on 32-week-old White Leghorn laying hens over 9 weeks. 2. Hens fed on a diet supplemented with 5 micrograms 1,25-(OH)2D3/kg diet, tended to lay more eggs, and the eggs had significantly higher specific gravity and percentage shell than eggs from control hens fed on a diet supplemented with 27.5 micrograms D3/kg diet. 3. The effect became apparent after about 4 weeks of treatment and persisted until the end of the test. 4. Hens fed on a diet without D3 supplement started to lay very thin or soft shelled eggs within 4 weeks, suggesting that the birds' reserves of D3 or its metabolites were depleted within this period. 5. The results suggest that 1,25-(OH)2D3 can be substituted for D3 in layer diets to improve egg shell quality.

Animals↗
PubMed1995

Interaction between dietary 1,25-dihydroxycholecalciferol and calcium and effects of management on the occurrence of tibial dyschondroplasia, leg abnormalities and performance in broiler chickens.

1. Two experiments were performed to compare the relative effectiveness of feeding 1,25-dihydroxycholecalciferol (1,25-DHCC) in minimising leg abnormalities in broilers with other methods and to investigate interactions between dietary 1,25-DHCC and calcium. 2. Adding 5 micrograms 1,25-DHCC/kg to a diet containing 12 g calcium/kg was more effective than early food restriction or meal feeding in preventing leg abnormalities but was found to cause a growth depression. 3. The second experiment, which had a factorial design, with diets containing 7.5, 10.0 and 12.5 g calcium and 0, 2.0, 3.5 and 5.0 micrograms 1,25-DHCC/kg, showed linear and quadratic interactions between these dietary factors. Diets with higher concentrations of both 1,25-DHCC and calcium resulted in growth depression associated with hypercalcaemia. 4. The incidence of tibial dyschondroplasia (TD) at 3 weeks of age was highest with the basal diet containing 7.5 g calcium/kg and was markedly reduced by addition of 1,25-DHCC and/or calcium. The incidence was very low or non-existent when 1,25-DHCC was fed at 3.5 micrograms/kg or greater. 5. Feeding 5 micrograms/kg 1,25-DHCC had no effect on plasma 1,25-DHCC concentrations, although at the higher dietary calcium contents plasma concentrations of 25-hydroxy- and 24,25-dihydroxy-cholecalciferol were lower in those birds fed 1,25-DHCC. 6. It is concluded that 1,25-DHCC is most effective in preventing TD without accompanying growth depression when it is fed in conjunction with diets containing less than 10 g calcium/kg.

Animal Feed↗
PubMed1998

Activity of various hydroxylated vitamin D3 analogs for improving phosphorus utilisation in chicks receiving diets adequate in vitamin D3.

1. Young chicks were used to evaluate the efficacy of 2 new vitamin D3 analogs relative to 1 alpha-hydroxycholecalciferol (1 alpha-OH D3) for their ability to improve the bioavailability of phytate-bound phosphorus (P) when added to P-deficient maize-soyabean meal diets that were superadequate in cholecalciferol. 2. Both 20-epi-19-nor-1,25-(OH)2 D3 and 20-epi-19-nor-1 alpha-OH D3 were observed to have phytate-P releasing activity, as measured by bone ash responses. 3. However, the bioactivity of the 2 new analogs differed when compared with 1 alpha-OH D3. The 20-epi-19-nor-1 alpha-OH D3 analog had a lower (P < 0.05) phytate-P releasing activity (45%) than either 1 alpha-OH D3 of 20-epi-19-nor-1,25-(OH)2 D3, which did not differ. 4. A dietary concentration of 10 to 15 micrograms/kg 1 alpha-OH D3 was found to optimize phytate-P utilisation in 2-week-old chicks.

Analysis of Variance↗
PubMed1999

Composition of vitamin supplements in Spanish poultry diets.

1. The composition of 106 vitamin supplements used in about 85% of the Spanish poultry production diets were studied. Vitamin supplements were grouped by production classes and, for broilers and pullets, also by feeding periods. 2. Four vitamins (niacin, alpha-tocopherol, pantothenic acid, and riboflavin) comprised over 87% of the vitamin supplements by weight (choline excluded), whereas alpha-tocopherol and retinol represented from 51% to 60% of the total vitamin cost. 3. The highest and lowest vitamin supplementation rates were for broilers in the starter and withdrawal periods (106 and 44 mg/kg, respectively) and the mean values for breeders, pullets and layers were 104, 58, and 48 mg/kg, respectively. 4. Supplements with higher vitamin contents showed less variability in their composition. Retinol, cholecalciferol, riboflavin and pantothenic acid showed the lowest variability within supplements (6% to 36% CV), whereas alpha-tocopherol, menadione, thiamin and biotin showed the highest (40% to 224% CV). 5. Vitamin supplementation rates were compared with requirements, taking into account the dietary contribution. In general, vitamin fortification exceeded the NRC recommendations, using a high safety margin for some vitamins such as vitamin A (from 2.6 to 7.8) and for some poultry classes such as breeders (3.2).

Animal Feed↗