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Nutritional factors that influence phosphorus availability and indicators of phosphorus status of ruminants
Abstract
Phosphorus availability in ruminant diets may be influenced by several factors, including vitamin D, P, Ca, and Fe content. Effects of supplementation of cholecalciferol (CC) and P on P retention were evaluated with forty-two sheep assigned to six treatments, consisting of a basal diet supplemented with P and CC: no supplement (basal); 0 g P + CC (basal+); 1 g P and no CC (P1); 1 g P + CC (P1+); 2 g P and no CC (P2); and 2 g P + CC (P2+). Sheep were fed individually for 8 wk, blood serum, and total fecal and urine outputs were collected. Bone samples from carcasses were taken from basal+ and P2+. Phosphorus, Ca, and Mg were determined and P and Ca retention calculated. Calcium and P stores in the body were lower in basal compared with other treatments. Although P retention was similar in all treatments supplemented with P, total P excretion (TPE) was higher in P2 and P2+. No differences were found in DMD, serum alkaline phosphatase, and P, Ca and Mg content of blood and bone samples. Supplementing either 1 or 2 g of P increased P retention, whereas supplementing CC increased P retention only in the P unsupplemented group. Total P excretion was the best indicator of P intake, and this can be predicted from TPE. Effects of diets containing wide Ca:P ratios (5.6 and 9) and high Fe concentrations (350 and 600 ppm) on P utilization were evaluated in two additional experiments. Fifteen lambs were assigned to three treatments in each experiment (Ca:P ratios of 2, 5.6 and 9) and Fe levels (100, 350 and 600 ppm). Diets were fed for 2 wk and P and Ca content and body retention were estimated by total fecal and urine collections. No differences in P retention were observed. Calcium retention increased with increasing Ca intake. Phosphorus and Ca absorption and retention in lambs were not affected by high-Fe diets.
Subject Area
Livestock|Agronomy|Range management
Recommended Citation
Mejia Haro, Ignacio, "Nutritional factors that influence phosphorus availability and indicators of phosphorus status of ruminants" (1999). ETD collection for University of Nebraska-Lincoln. AAI9929215.
https://digitalcommons.unl.edu/dissertations/AAI9929215