In contrast to corn, wheat and triticale exhibit high phytase activities. This enzyme enhances phytic phosphorus availability, as demonstrated in pigs given wheat diets. To study the utilization of triticale phosphorus in pigs, the importance of dietary phytase content and the mineral and bone disorders related to high phytate feeding, a nutritional experiment was carried out in 12 growing pigs fed either a corn- or a triticale-based diet for 6 wk. The diets were almost identical except for the cereal component; their phosphorus contents were low (0.4%) and mainly phytic. The following parameters were measured: calcium and phosphorus balances, bone and plasma contents of calcium and phosphorus, plasma vitamin D metabolites and parathyroid hormone (PTH), bone bending moments and intestinal phosphatase activities. Both diets provoked a phosphorus deficiency, but hypophosphatemia occurred less rapidly, hypercalciuria and hypophosphaturia were less marked and phosphorus availability was greater when the triticale diet was fed. This was attributed to the high phytase content of triticale because intestinal phytase and alkaline phosphatase activities were similar in pigs fed either diet. Calcium absorption was not modified by calcium retention was greater for pigs fed triticale and led to higher bone scores. In conclusion, the higher the phytase activity of the diet, the greater the phytate P availability and the lower the bone-mineral disorders.
A colorimetric method was used on water-soluble much extracted from m u d scraping!? and contents of the caecum and the colon of five germ-free (GF) rats and five heteroxenic (HE) rats harbouring a hnmao flora (GF rats d a t e d with a human flora). These rats were fed on a diet containing either 100 g sucrose/kg or 100 g inulin/kg. Histological stains, periodic aciMChiff, alcian blue pH 2.5 and alcian blue pH0-5 were used to discriminate between neutral, acidic and acidic sulphated mucins respectively. Spectrocolorimetric assays led to a calculated absorbance value for 1 mg of the initial much extract. Each much type was compared between treatments. The caecal contents of GF rats contained more acidic mucin than sulphomucin, which was present in the same proportion as neutral mucin. Their colonic contents contained more acidic mucins than sulphomucin, which in turn was more abundant than neutral mucin. Their caecal mucosa mucin distribution differed from that of the contents: very little acidic much was present and neutral and dphomucin proportions were of the same order of magnitude. Inulin increased the amount of neutral much in the caecal contents and of sulphated mucios in the colonic contents and increased the amounts of neutral and acidic mucins in the caecal mucwa. Mucin distribution in the HE rats was very different from that in the GF rats: the caecal contents contained a high proportion of acidic m u c h and very little sulphomucin. The same distribution of mucins was observed in the colonic contents. The caecal mucaw contained less acidic much and more sulphomucin than the caecal contents. Inulin decreased acidic mucins and increased sulphated m u c h in the caecal contents and increased neutral and sulphated mucins in the colonic contents. Inulin increased sulphomucin in the caecal m u m and decreased acidic much in the caecal and colonic mucosas. The very low amount of mucin that was recovered in the colonic mucosa suggests that, in the presence of the bacterial flora and associated with inulin in the diet, much was extensively released from the mucosa to the colonic lumen. This might be related to the bacterial metabolites produced.
1. Vitamin-D-deficient pigs were fed on a phytate-phosphorus diet and treated with vitamin D, (+D) to examine the time-course of adaptative changes in plasma minerals, vitamin D metabolites, parathyroid hormone (PTH) and calcium balance and intestinal Ca-binding protein (CaBP).2. The 5-week vitamin D repletion (25 pg cholecalciferol/kg diet) regimen restored plasma Ca, P and alkaline phosphatase (EC 3.1.3.1) to normal, decreased PTH and markedly and rapidly increased plasma 25-hydroxycholecalciferol (25-OHD, sevenfold after 4 d) and 1,25-dihydroxycholecalciferol (I, 25(OH),D,, 1.8-fold after 4 d).3. CaBP concentrations were markedly elevated all along the digestive tract, especially in the distal regions. 4. Ca absorption and retention were enhanced (fourfold and sixfold respectively) by the + D diet. 5. The improved Ca absorption, coupled with increased CaBP and 1,25(OH),D, levels, suggest that vitamin D metabolism in phytate-P-fed pigs is sensitive to the depressed Ca availability due to phytate feeding. It also indicates that CaBP may play an important role in the adaptation of Ca absorption.6. Persistent hypercalciuria indicates that mineral metabolism was still affected by the phytate nature of the dietary P in spite of the vitamin D treatment.Phosphorus depletion induces increases in circulating 1,25-dihydroxycholecalciferol (1,25(OH),D,), intestinal calcium-binding protein (CaBP) and Ca absorption (for review, see Sommerville et al. 1985b). Phytate-P, which is the predominant P source in pig feeds, leads to P deficiency if no additional inorganic P is provided (Pointillart et al. , 1985, and phytate-P absorption is improved by vitamin D supplementation (Fontaine et al. 1985) demonstrating the importance of this form of P for pig husbandry. Diets in which the bulk of the phosphate is in the form of phytate also give rise to major disturbances of Ca metabolism (hypocalcaemia, hypercalciuria) and cause significant reductions in the utilization of Ca by the formation of poorly absorbed insoluble Ca phytate (Pointillart et al. 1985). These disturbances are aggravated by vitamin D deficiency (Pointillart et al. 1985). In the present study, we have used vitamin-D-deficient pigs to examine the capacity of vitamin D repletion to overcome the disturbances of Ca metabolism caused by consumption of a diet whose phosphate content, while normal, is largely (80%) in the form of phytate.We have also examined the changes in the principal plasma variables linked to plasma phosphate and Ca regulation, 25-hydroxycholecalciferol~25-OHD), 1,25(OH),D,, alkaline phosphatase (EC 3 . 1 . 3 . 1 ; AP) and parathyroid hormone (PTH) levels, throughout the experimental period. They were measured before and during the period of vitamin D supplementation and compared with those of non-supplemented vitamin-D-deficient pigs, At the end of the experimental period the pigs were killed and the CaBP contents of a number of areas of the small intestine were measured to determine what, if any, correlation existed between the values and the Ca ab...
At least 2/3 of the phosphorus consumed by the pig are phytates. To analyse the interrelationships between phytate phosphorus digestibility and intestinal alkaline phosphatase and phytase activities, three balance experiments were carried out in pigs fed low mainly phytic phosphorus diets. In the first experiment, we observed a better P-digestibility with wheat than with maize diets and this was imputed to the higher phytase content of wheat. Results from the 2nd experiment showed that the two intestinal enzymes did not adapt themselves to variable phytic-P intakes. They also confirmed the negative effects of dietary phytates on calcium-phosphorus metabolism in the pig. In the last experiment, one group received a vitamin-D supplement (1000 IU ! kg diet) whereas the other did not. The vitamine-D addition led to a greater P-absorption ( X 2) while the intestinal phosphatase activities were unchanged. In conclusion, organic-P digestibility was usualiy poor (mean value : 30 p. 100 intake), varying in a wide range (from 5 to 50 p. 100) and the animals did not adapt themselves to mainly phytic-P diets. Thus, they all showed signs of P-deficiency (bone disorders and hypophosphaturia).
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