Browsing by Subject "Calcium"

Now showing 1 - 5 of 5

Nutritional and climatic effects on berry shrivel of grapevines in Southern Germany
(2012) Bachteler, Kristina; Wünsche, Jens Norbert
Berry shrivel (BS) is one of the economically most important physiological disorders in grapevine, but it is also one of the least studied ones. At the beginning of the ripening process, berries stop accumulating sugars and lose their turgescence. The must weight remains low, the berries taste sour and bitter. During the last ten years, several studies were conducted to narrow eliciting factors. As a result, an unbalanced ratio of K and Mg in the soil was considered likely to induce BS. To verify this hypothesis, two fertilization trials with two different varieties each, one via the soil and one foliar fertilization trial, were initiated. Within two years, no effect on the incidence of BS was evident. In the foliar fertilization trials, Mg, K and Ca fertilizers were tested with their effect on BS. For the first year, no significant differences could be observed. In the second year, more berries were affected by BS in the plots treated with Ca fertilizer. The plots with Mg fertilizer showed significantly less berries affected by BS than the untreated control in one variety. Extensive analysis of concentrations of Ca, Mg and K in berries illustrate that berries affected by BS show significantly higher concentrations of Ca compared to healthy berries. The loss of quality of wines made of berries affected by BS was demonstrated by must and wine analysis as well as by a consumer preference analysis. Phenolic compounds (in particular resveratrol) that are often used as indicators of abiotic stress were analysed as well. It was supposed that BS is caused or increased by abiotic stress so that the concentration of resveratrol in berries affected by BS is increased as well. However, in all varieties analysed, the concentration of resveratrol was higher in healthy berries than in affected ones. A direct connection between weather condition at bloom and especially at ripening was examined. Observations at monitoring sites and reports from other countries seem to show that cool and wet weather at these phenological stages might increase the risk of BS. It was only possible to statistically prove a connection between the precipitation at bloom and the incidence of BS.
Studies of phytate degradation and associated mineral utilization in growing pigs
(2024) Klein, Nicolas; Rodehutscord, Markus
Phosphorus (P) is primarily stored in plant seeds as phytate, which is any salt of phytic acid (myo-inositol hexakisphosphate; InsP6). The enzymatic capacity of pigs and the microorganisms present in their digestive tract allows for only partial and incomplete prececal degradation of InsP6. To address this limitation, the addition of exogenous phytases to feed has been state-of-the-art for more than three decades. Phytases, found in various organisms like bacteria, fungi, plants, and animals, initiate the breakdown of InsP6 and inorganic phosphate, thereby making the liberated phosphate available for digestion. Substantial scientific research and practical field applications have shown that adding exogenous phytases to the diet of non-ruminants leads to an improvement in P digestibility and a reduction in P excretion. Over time, phytases with enhanced thermal profiles and higher activity at physiological pH milieus have been engineered. Additionally, advancements in plant breeding have increased intrinsic phytase activity in feed ingredients relevant to animal nutrition. Thus, this thesis aimed to deepen the understanding of inositol phosphate (InsP) degradation in ileal-cannulated pigs, focusing on how dietary variables can influence this process along the digestive tract. In the first study (Manuscript 1), diets based on wheat with variable intrinsic phytase activity and the addition of an exogenous phytase on InsP degradation in pigs were investigated. Although wheat intrinsic phytase contributed to increased InsP degradation and P digestibility in pigs, variation in intrinsic phytase activity by crossbreeding wheat, as achieved in this study, was not reflected in InsP degradation and P digestibility data. This discrepancy may be attributed to an inadequate proteolytic resistance of wheat phytase in the gastric compartment of the pig. A marked increase in prececal InsP degradation and P digestibility was achieved by adding a microbial phytase to the wheat-based feed. While exogenous phytase increases the digestibility of InsP-P, other dietary components may impair its hydrolytic activity. In the second study (Manuscript 2), the single and interactive effects of dietary Ca concentration and exogenous phytase in pigs were investigated. The study assessed the effects of dietary Ca and exogenous phytase on InsP degradation and nutrient digestibility in growing pigs. Additional dietary Ca decreased prececal InsP6 disappearance, but only with exogenous phytase. Concentrations of lower InsP isomers and myo-inositol in the ileal digesta and prececal P digestibility were greater with exogenous phytase, but not affected by dietary Ca concentration. In contrast, fecal InsP6 disappearance was lower and the concentration of InsP4-5 isomers in feces was greater with additional dietary Ca. The study revealed that dietary Ca concentration is relevant for InsP disappearance in the hindgut, but not in the ileum. However, when exogenous phytase is used, the dietary Ca concentration is important because prececal InsP degradation is affected by the Ca level in the diet. The third study (Manuscript 3) aimed to investigate the effects of dietary Ca sources, exogenous phytase, and formic acid on InsP degradation and nutrient digestibility in growing pigs. Replacing limestone with Ca formate reduced prececal InsP6 disappearance and prececal P digestibility. However, adding formic acid to a diet containing limestone and phytase enhanced prececal InsP6 disappearance and increased InsP2 and myo-inositol concentrations in the distal ileal digesta. Accordingly, prececal P digestibility was increased when formic acid was added to the diet containing limestone and exogenous phytase. This suggested that Ca formate is not a suitable alternative Ca source to limestone for optimizing prececal P release from InsP in growing pigs. The release of P from InsP by exogenous phytase in limestone diets can still be further increased by adding formic acid. In conclusion, the degradation of InsP in growing pigs is a complex process affected by dietary Ca concentration, dietary Ca source, and the presence of phytase. However, investigated dietary traits mainly affected InsP6, with lesser effects on lower InsP isomers, highlighting the importance of prececal hydrolytic breakdown of InsP6 to InsP5. This directly affected P digestibility of growing pigs. Intrinsic phytase activity in feed ingredients, such as wheat, can contribute to prececal InsP degradation but may be neglected when exogenous phytase is present in the feed. Exogenous phytase addition notably increased prececal InsP degradation and P digestibility in plant-based diets, and complete dephosphorylation of InsP in the prececal tract was implied by the increase of the final degradation product myo-inositol in the ileum content, urine, and blood. However, some P remained bound to InsP at the end of the ileum of growing pigs and was therefore not available for digestion. Nevertheless, some diets with exogenous phytase tested in this thesis met the recommended digestible P concentration. This suggests that diets formulated with adequate InsP-containing ingredients and exogenous phytase may obviate the need for mineral P addition, reducing the reliance on finite P sources in growing pig nutrition.
Tachysterol2 increases the synthesis of fibroblast growth factor 23 in bone cells
(2022) Ewendt, Franz; Kotwan, Julia; Ploch, Stefan; Feger, Martina; Hirche, Frank; Föller, Michael; Stangl, Gabriele I.
Tachysterol2 (T2) is a photoisomer of the previtamin D2 found in UV-B-irradiated foods such as mushrooms or baker’s yeast. Due to its structural similarity to vitamin D, we hypothesized that T2 can affect vitamin D metabolism and in turn, fibroblast growth factor 23 (FGF23), a bone-derived phosphaturic hormone that is transcriptionally regulated by the vitamin D receptor (VDR). Initially, a mouse study was conducted to investigate the bioavailability of T2 and its impact on vitamin D metabolism and Fgf23 expression. UMR106 and IDG-SW3 bone cell lines were used to elucidate the effect of T2 on FGF23 synthesis and the corresponding mechanisms. LC-MS/MS analysis found high concentrations of T2 in tissues and plasma of mice fed 4 vs. 0 mg/kg T2 for 2 weeks, accompanied by a significant decrease in plasma 1,25(OH)2D and increased renal Cyp24a1 mRNA abundance. The Fgf23 mRNA abundance in bones of mice fed T2 was moderately higher than that in control mice. The expression of Fgf23 strongly increased in UMR106 cells treated with T2. After Vdr silencing, the T2 effect on Fgf23 diminished. This effect is presumably mediated by single-hydroxylated T2-derivatives, since siRNA-mediated silencing of Cyp27a1, but not Cyp27b1, resulted in a marked reduction in T2-induced Fgf23 gene expression. To conclude, T2 is a potent regulator of Fgf23 synthesis in bone and activates Vdr. This effect depends, at least in part, on the action of Cyp27a1. The potential of oral T2 to modulate vitamin D metabolism and FGF23 synthesis raises questions about the safety of UV-B-treated foods.
Vergleich der Wirksamkeit von 25-Hydroxycholecalciferol und konventionellem Cholecalciferol in der Fütterung von Zuchtsauen anhand von Blutmetaboliten, Leistungs- und Knochendaten
(2017) Schnor, Stella; Rodehutscord, Markus
In addition to the reproductive performance, the longevity of the sow plays an essen-tial role in the efficiency of piglet production (Pluym et al. 2013). According to Freitag and Wittmann (2009), lameness, in addition to fertility problems, is one of the most common reasons for the culling of sows. Fundament problems are about the occur-rence of multifactorial disease which can be influenced by management, genetic pre-disposition environmental conditions as well as by feed (Schalk and Schafzahl 2010). In this context, vitamin D plays an essential role in regulating the metabolism of calci-um and phosphate as well as the associated bone metabolism (v. Engelhard and Breves 2010). The aim of the present study was to investigate the use of 25-hydroxycholecalciferol as compared to conventional cholecalciferol in the nutrition of sows, and to evaluate the potential effects of the use of 25-hydroxycholecalciferol on performance, health and bone metabolism and the fundamental strength of sows. For this purpose, 145 sows were fed with a concentration of the conventional vitamin D3 of 2000 I.U. / kg and 137 sows were fed with an equivalent concentration of 50 μg HyD (25-Hydroxycholecalciferol) / kg in the first reproductive cycle (pregnancy and lactation). In the second cycle, 99 sows of each group were fed in the same way as in the first production cycle. Performance parameter, body condition and the movement of the sows were captured throughout the observation period. In addition, the plasma concentration of calcium, phosphate and the two bone markers were measured. The bone density was also determined by a computer tomography. There were no signifi-cant differences between the content of conventional vitamin D and 25-hydroxycholecalciferol in terms of performance parameters (whether born alive, still-born, mummified or weaned piglets). The birth and weaning weights of piglets from sows, which were fed with the metabolite 25-hydroxycholecalciferol, tend to be higher but the differences were only significant with sows in the second and third to fifth litter as well as in the sixth to tenth litter. The results of the measurement of the body con-dition and thickness of the fat on the back as well as of the scoring of locomotion, confirmed the excellent status of the flock, in terms of body condition and locomotion. The blood parameters have shown that by feeding the sows with 25-hydroxycholecalciferol, this could result in a significantly higher level of 25-OHD3 plasma concentration. These results confirm the studies of Lauridsen et al. (2010)and Weber et al. (2014) who used the same product. There was no influence on the calcium and phosphate concentration by feeding the sows with 25-hydroxycholecalciferol in this trial. Both groups showed nearly the same concentra-tions of the minerals. The development of the bone markers also displayed the same progress. The CrossLaps of the animals fed with HyD tend to be higher whereas the osteocalcin concentrations were lower compared to the control flock. However, these differences were not significant at any particular time. Even the results of the bone density showed no influence as a result of the feeding of the metabolite 25-hydroxycholecalciferol and both groups had almost the same values in this parame-ter.
Zum Einfluß von mikrobieller Phytase und Calcium auf die Blei-, Cadmium und Zinkretention beim wachsenden Schwein
(1997) Zacharias, Bernhard; Drochner, Winfried
In the present study the influence of microbial phytase and/or calcium supplementation in rations of growing pigs (15 to 30 kg resp. 50 kg) on the retention of lead, cadmium and zinc in kidneys, liver, muscles and bones was investigated. The rations consisted of a barley-soy mixture supplemented with lead, cadmium and zinc either in the form of Pb-, Cd- and Zn-polluted barley or of CdCl2, Pb(CH3COO)2, and ZnSO4. The rations contained an average of 1,45 mg Pb, 0,78 mg Cd, and 55,7 mg Zn per kg dry matter and were given either with or without an addition of 800 U microbial phytase per kg. Compared to the reference group the addition of microbial phytase resulted in diets with a nomal calcium supply (6 g/kg) to a significant increase in the concentration of lead in the phalanx 1 and cadmium in kidneys and liver. The zinc concentration, however, only was increased in tendency in bones and liver. By augmenting the calcium concentration to 12 g/kg it was possible to avoid phytase-induced increase in the retention of lead in phalanx 1 and in the deposition of cadmium in kidneys and liver. For zinc, however, this effect of calcium could not be detected. The higher lead concentration in liver, kidneys and bones after addition of Pb(CH3COO)2 may be due to the 51 higher dietary Pb level as compared to the normally polluted barley rations. The reduced Cd-accumulation in livers and kidneys after feeding CdCl2 supplemented diets with a high calcium level may be explained by an increased formation of insoluble cadmium-calcium-phytate that cannot be hydrolysed by phytase. For the heavy metals lead, cadmium, and zinc the addition of phytase might probably result in an increased metal availability due to phytase-induced hydrolysis of the phytate complex. The effect of a calcium supply exceeding the recommended level may be explained by a reduction in the solubility of phytate which results in a decreased ability of phytate to be splitted by phytase and therefore leads to a reduced