Calcium particle size effects on plasma, excreta, and urinary Ca and P changes in broiler breeder hens.

An experiment was conducted using non-colostomized and colostomized broiler breeder hens to determine the effects of feeding limestone of 2 different mean particle sizes (185 microns and 3490 microns) on P excretion, total P and Ca retention, and urinary P and Ca excretion during a 6-week feeding study. Additionally, changes in plasma inorganic P (iP) and ionic Ca (Ca++) and urinary excretion of P and Ca were determined in one egg laying cycle of 24 hours. One-hundred-fifty non-colostomized and 6 colostomized broiler breeder hens, 30 wk of age, were divided into 2 groups and fed broiler breeder diets supplemented with either small particle or large particle limestone. Two % acid insoluble ash (Celite) was added to the feed as a marker. Diets, excreta, and urine samples were analyzed for total P and Ca by ionic coupling plasma (ICP) analysis. The non-colostomized breeders fed large particle limestone compared to small limestone particles produced a significant increase in percent tibia ash (P < 0.0001) and egg specific gravity (P = 0.0382), but P excretion approached a tendency of being reduced (P = 0.1585). The urinary total P and Ca (∼18 and 9%, respectively) of total P and Ca excretion for breeders fed both sizes of limestone was not significantly different in the colostomized breeders. In plasma, both iP and Ca++ reached a peak during 18 to 20 h and 20 to 24 h post oviposition for smaller and larger particle sized limestone fed groups, respectively. The maximal excretion of urinary P was found during 11 to 20 h post oviposition, whereas urinary Ca peaked during 0 to 11 h post oviposition for both smaller and larger particle sized limestone supplemented groups. In summary, the findings indicate that the particle size (smaller and larger) of calcium source did not significantly influence the quantitative total urinary excretion of Ca and P but did influence the timing of Ca and P excretion.

Consequences of a high phosphorus intake on mineral metabolism and bone remodeling in dependence of calcium intake in healthy subjects - a randomized placebo-controlled human intervention study.

BACKGROUND: Epidemiological studies reported an association between plasma phosphate concentrations and a higher risk for death and cardiovascular events in subjects free of chronic kidney diseases. The main aims of the present study were to determine the influence of a high phosphorus intake in combination with different calcium supplies on phosphorus, calcium, magnesium and iron metabolism as well as fibroblast growth factor 23 (FGF23) concentrations within eight weeks of supplementation. METHODS: Sixty-two healthy subjects completed the double-blind, placebo-controlled parallel designed study. Supplements were monosodium phosphate and calcium carbonate. During the first two weeks, all groups consumed a placebo sherbet powder, and afterwards, for eight weeks, a sherbet powder according to the intervention group: P1000/Ca0 (1 g/d phosphorus), P1000/Ca500 (1 g/d phosphorus and 0.5 g/d calcium) and P1000/Ca1000 (1 g/d phosphorus and 1 g/d calcium). Dietary records, fasting blood samplings, urine and fecal collections took place. RESULTS: Fasting plasma phosphate concentrations did not change after any intervention. After all interventions, renal excretions and fecal concentrations of phosphorus increased significantly after eight weeks. Renal calcium and magnesium excretion decreased significantly after eight weeks of P1000/Ca0 intervention compared to placebo. Plasma FGF23 concentrations were significantly higher after four weeks compared to eight weeks of all interventions. CONCLUSIONS: The long-term study showed in healthy adults no influence of high phosphorus intakes on fasting plasma phosphate concentrations. A high phosphorus intake without adequate calcium intake seems to have negative impact on calcium metabolism. Plasma FGF23 concentrations increased four weeks after high phosphorus intake and normalized after eight weeks. TRIAL REGISTRATION: The trial is registered at ClinicalTrials.gov as NCT02095392 .

Effect of dietary mineral sources and oil content on calcium utilization and kidney calcification in female Fischer rats fed low-protein diets.

We studied the effects of dietary mineral source and oil intake on kidney calcification in 4-wk-old female Fischer rats after consuming the AIN-76 purified diet (AIN-76). A modified AIN-76 mineral mixture was used, although the original calcium (Ca)/phosphorus (P) molar ratio remained unchanged. Rats were fed the modified diets for a period of 40 d before their kidneys were removed on the last day. Ca balance tests were performed on days 31 to 36 and biochemical analysis of urine was also studied. Kidney Ca, P, and magnesium (Mg) in the standard diet group (20% protein and 5% oil) were not affected by the mineral source. Kidney Ca, P, and Mg in the low-protein (10% protein) diet group, were found to be influenced by the dietary oil content and mineral source. In particular, the different mineral sources differentially increased kidney mineral accumulation. Pathological examination of the kidney showed that the degree of kidney calcification was proportional to the dietary oil content in the 10% dietary protein group, reflecting the calcium content of the kidney. The information gathered on mineral sources in this study will help future researchers studying the influence of dietary Ca/P molar ratios, and histological changes in the kidney.

Digestive utilization of phosphorus from plant-based diets in the Cassie line of transgenic Yorkshire pigs that secrete phytase in the saliva.

A line of transgenic Yorkshire pigs referred to as the Cassie (CA) line was generated, which possessed a stable, low copy number phytase transgene insertion that enabled phytase secretion in the saliva. This study was conducted to assess growth and efficacy for improving P, Ca, and other macromineral utilization in the CA pigs receiving diets typical of those used for commercial swine production. In Exp. 1, 12 CA boars and 12 CA gilts fed diets without supplemental P gained weight and exhibited feed efficiency similar to conventional age-matched 12 Yorkshire boars and 12 Yorkshire gilts raised on similar diets with supplemental P. Serum concentrations of P and Ca were similar for CA and Yorkshire pigs during the growing and finishing phases, indicating that the CA pigs were not P limited. In Exp. 2, 6 CA (13.1 kg BW) and 6 Yorkshire barrows (8.8 kg BW) were fed 3 diets (control; low in Ca and P; and low in Ca, P, and CP) over 3 phases. The CA barrows fed the diet without supplemental P retained 25 to 40% (P < 0.001), 77 to 91% (P < 0.001), and 27 to 56% (P < 0.001) more P during the weaning, growing, and finishing phases, respectively, than conventional Yorkshire barrows fed similar diets without supplemental P. In Exp. 3, CA and Yorkshire barrows of similar ages weighing 66.2 ± 1.7 kg (n = 10) and 50.0 ± 1.0 kg (n = 10), respectively, were used. The P retention of CA finisher barrows fed a diet without supplemental P was 34% greater (P < 0.001) than conventional Yorkshire barrows fed the same diet with 750 units of exogenous phytase/kg diet. Urinary Ca to P ratio in the CA pigs was 0.27, whereas that for the Yorkshire barrows was 30, thereby, indicating that the Yorkshire barrows suffered a P deficiency. Furthermore, digestive utilization of major electrolyte macrominerals, K and Na, was improved (P < 0.05) by 18 and 16%, respectively, in the CA finisher pigs compared with the conventional Yorkshire finisher pigs fed phytase; however, only K exhibited enhanced retention. In conclusion, the CA line pigs secrete sufficient phytase from the salivary glands to enable efficient digestion of plant P, Ca, and major electrolyte macrominerals.

Influence of high phosphorus intake on salivary and plasma concentrations, and urinary phosphorus excretion in mature ponies.

This study addressed the question whether the concentration of phosphorus (P) in saliva of ponies is influenced by P intake. Six ponies were fed a diet high in P (HP treatment), providing 21 g P/day, and a diet low in P (LP treatment), supplying 7 g P/day. The two diets provided approximately 21 g calcium (Ca) and 6 g magnesium (Mg)/day. The experiment had an A-B-A design with treatment periods of 30 days. The ponies first received the HP diet (HP1), followed by the LP treatment and were then fed again the HP diet (HP2). Urinary P excretion was increased in both HP feeding periods and equalled approximately 7% of P intake vs. 0.5% on the LP diet. Plasma P concentration was higher for the HP treatment. The salivary P concentration ranged from 0 to 1.01 mmol P/l between ponies and there was no effect of P intake. It is suggested that saliva is not an important excretion route of P. The percentage of Ca and Mg in urine (% of intake) was higher for the LP treatment than for the HP treatments. The results of this study suggest that salivary Mg may contribute to Mg homeostasis.

Food mineral composition and acid-base balance in preterm infants.

BACKGROUND: Due to a transient age-related low renal capacity for net acid excretion, preterm infants fed formula are at a considerable risk of spontaneously developing incipient late metabolic acidosis, clinically characterized by e.g., disturbed bone mineralization and impaired growth. AIM OF THE STUDY: From acid-base data in blood and urine under different diets of modified human milk or preterm formulas is attempted to explore the impact of food mineral (and protein) composition on renal regulation and systemic acid-base balance in preterm infants. PATIENTS AND METHODS: Data were collected from 48 infants fed their own mother's milk (28 native human milk, 20 enriched with fortifier) and 34 patients on formula (23 on a standard batch, 11 on a modified batch with reduced acid load). Intake of food was measured and acid-base data were determined in blood and timed-urine (8-12 h) samples. RESULTS: Differences in mineral composition of the diets led to considerable differences of daily "alkali-intake", without significant effects on non-respiratory (base excess, BE) and respiratory (PCO(2)) acid-base data in the blood. In contrast, a highly significant proportionality between individual dietary alkali intake and daily renal base (Na(+) + K(+)-Cl(-)) excretion was observed (y = 0.32x-0.70, n = 80, r = 0.77, P < 0.0001), irrespective of the type of the diet. CONCLUSION: Renal base saving mechanisms are normally effective in preterm infants to compensate for differences in dietary acid-base load. Generally, nutritional acid-base challenges can be judged much earlier and more safely by urinary than by blood acid-base analysis. Taking into account the age specific low capacity for renal NAE, the relatively high nutritional acid load of preterm standard formula should be reduced.

Calcium and phosphorus retention in extremely preterm infants supplemented individually.

UNLABELLED: The aim of this study was to investigate the correlation between the retention of calcium (Ca) and phosphorus (P) and weight gain and intake of Ca and P when using the concept of individualized Ca and P supplementation in extremely low birthweight infants. Three-day Ca and P balances were performed in 20 infants with a mean gestational age of 26.6wk (between 24.1 and 28.7 wk) and a birthweight of 744 g (450-990), when the infant was able to tolerate at least 100 ml/kg/d of milk. The daily supplementation with Ca and P was individually adjusted to achieve a simultaneous excretion of > or = 1.2 mmol/L Ca and > or = 0.4 mmol/L P in the urine. In 16 of the 20 infants, the urinary concentrations of both Ca and P exceeded the lower limits. The retention of Ca (mean 3.8 mmol/kg/d, minimum 0.9; maximum 8.1; 57% of intake, 34-80) and P (2.4,1.1-4.2; 76%, 52-96) was significantly correlated with both the daily weight gain (16 g, 3-28; Ca r2 = 0.22, p = 0.02; P r2 = 0.21, p = 0.03) and the intake of Ca (6.5 mmol/kg/d, 2.4-10.2; r2 = 0.67, p < 0.001) and P (3.1, 1.9-5.3; r2 = 0.85, p < 0.0001). The molar ratio of the Ca and P intake was 2.2 (1.3-4.0). CONCLUSION: It was found that Ca and P retention was a function of growth and intake.

The course of phosphorus excretion in growing pigs fed continuously increasing phosphorus concentrations after a phosphorus depletion.

A balance study was performed in order to quantify the effect of continuously increased phosphorus (P) intake on faecal and urinary P excretion. The aim was to quantify the level of intake where regulatory P excretion becomes relevant for comparative digestibility measurements on P, and when the pig adapts its urinary P excretion to increased P intake. Phosphorus intake of growing pigs was continuously increased on a daily basis starting at a marginal level and P excretion via faeces and urine was continuously followed for 92 days. Two semi-synthetic diets were prepared with different proportions of Na2HPO4 resulting in 2.4 (diet 1) and 6.3 (diet 2) g P/kg DM. Concentration of Ca was adapted to achieve a Ca supply approximately 3.1 fold the digestible P supply. Six castrated male crossbred pigs (31 kg BW) were kept individually in metabolism crates after they had undergone a 14 d P depletion period during which they were fed diet 1 solely. Pigs received 1.04kg of diet 1 per day throughout the experiment, and each day the amount of feed and P supplied to pigs from diet 2 was increased by 12 g and 69 mg, respectively. ME supply was approximately 2.4 fold maintenance and average daily BW gain of pigs during the entire experiment was 690 +/- 30 g. While intake increased linearly, faecal excretion of P and Ca increased non-linearly and could be best described by third order polynomial functions. The proportion of ingested P not excreted via faeces followed a quadratic type of curve with a maximum of 81% at 25 days on experiment and P intake of 4.0 g/d. Thereafter, the proportion decreased continuously. The digestibility of P from diet 2, determined by the slope ratio technique, was constant and not affected by P intake up to a P intake of 5 g/d. Renal P excretion did not exceed inevitable losses until day 60 and increased exponentially thereafter when body P reserves were restored. It is concluded, that an adaptation to surplus P supply occurred earlier on the intestinal than on the renal level. While faecal P excretion appeared regulated depending on the actual requirement for P retention, the regulation via urine depended on the P status of the pig. Once the renal P excretion of growing pigs exceeds a level of 25 mg/d, intake of digestible P cannot be regarded sufficiently low to measure P digestibility as a capacity of the feedstuff.