Dietary calcium to phosphorus ratio affects postprandial phosphorus concentrations in feline plasma

Abstract

The impact of dietary phosphorus on chronic renal disease in cats, humans and other species is receiving increasing attention. As calcium (Ca) and phosphorus (P) metabolism are linked, the ratio of Ca:P is an important factor for consideration when formulating diets for cats and other animals. Here, we describe a fully randomized crossover study including 24 healthy, neutered adult cats, investigating post-prandial responses in plasma P, ionised Ca (iCa) and parathyroid hormone (PTH) following one meal (50% of individual metabolic energy requirement) of each of six experimental diets. Diets were formulated to provide P at either 0.75 or 1.5 g/1000kcal (4184kJ) from the soluble phosphorus salt sodium tripolyphosphate (STPP, Na5P3O10), variable levels of organic Ca and P sources, and an intended total Ca:P of ∼1.0, 1.5 or 2.0. For each experimental diet, baseline fasted blood samples were collected prior to the meal, and serial blood samples collected hourly for 6 hours thereafter. For all diets, a significant increase from baseline was observed at 120mins in plasma PTH (p<0.001). The diet containing the highest STPP inclusion level and lowest Ca:P induced the highest peaks in post-prandial plasma P and PTH levels (1.8mmol/l and 27.2pg/ml, respectively) and the longest duration of concentrations raised above baseline were observed at 3 hours for P and 6 hours for PTH. Data indicate that Ca:P modulates postprandial plasma P and PTH. Therefore, when formulating diets containing soluble P salts for cats, increasing the Ca:P ratio should be considered.

Short-term postprandial changes in select serum biochemistry analytes in healthy adult cats

“…These findings were expected, attributable to recent feeding and diurnal variation, and previously documented in healthy cats. 1,3,4,10 A postprandial rise in BUN, phosphorus and bicarbonate could be of importance in both healthy cats and those with disease, particularly in the monitoring and management of kidney disease.…”

“…In cats, inorganic dietary phosphorus increases postprandial concentrations in a dose-dependent manner, while the consumption of diets containing solely organic phosphorus results in either decreased concentrations or unchanged concentrations postprandially. 3,4,10 In an experimental diet trial in cats, the diet with the highest amount of inorganic phosphorus provided as sodium tripolyphosphate (1.5 g/1000 kcal) and the lowest Ca:P ratio (1.0) had the highest peak postprandial plasma phosphorus concentration and the longest duration of concentrations raised above baseline. 4 The effect of a meal on serum phosphorus in cats is repeatedly short lived, with peaks observed between 2 and 3 h postprandially and returning to baseline by or before 6 h, depending on diet composition.…”

“…1,2 As the nutrient composition of the diet could impact the findings for some analytes, it is important to confirm repeatability and validate these findings. 3 –7…”

“…1,2 As the nutrient composition of the diet could impact the findings for some analytes, it is important to confirm repeatability and validate these findings. [3][4][5][6][7] The objective of the study was to assess the short-term postprandial changes in select serum biochemistry analytes (creatinine, blood urea nitrogen [BUN], phosphorus, bicarbonate, glucose, magnesium, chloride, total calcium, cholesterol, sodium, potassium) in healthy adult cats fed a stable controlled commercial diet. We hypothesized that some analytes, particularly BUN and phosphorus, vary over a 12 h period after feeding, compared with a fasted state.…”

Effect of Different Dietary Zinc Sources on Growth, Element Deposition, Antioxidation, Lipid Metabolism, and Related Gene Expression in Hybrid Grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus)

“…Furthermore, changes in the level of one mineral element will impact the content of other mineral elements, such as the antagonism of copper and Zn, as well, as iron overload affecting manganese homeostasis, etc. [82][83][84]. In addition, the affinity of different zinc sources to target organs was different, and the affinity of ZnO to all organs was higher than ZnSO 4 and protein zinc.…”