A comparative meta-analysis on the relationship of faecal calcium and phosphorus excretion in mammals

Böswald, L. F. and Dobenecker, B. and Clauss, M. and Kienzle, E.

J Anim Physiol Anim Nutr (Berl) (2018) 102: 370–379

DOI: 10.1111/jpn.12844

Abstract

To investigate the relationship between faecal calcium (Ca) and phosphorus (P) excretion in different mammalian species, a meta-analysis on digestibility data derived from the literature was conducted. Seventy-three studies on carnivores, omnivores, large and small hindgut fermenters, ruminants and hippos (a total of 21 mammalian species, precondition for inclusion dietary Ca/P ratio 1.5/1 - 3.0/1) were analysed for Ca and P digestibility. Dietary Ca/P ratios were lower than faecal Ca/P ratios in carnivores, omnivores, ruminants and hippos. In hindgut fermenters, dietary Ca/P ratios were higher than faecal Ca/P ratios, indicating higher intestinal Ca absorption in these species. In all species investigated, there was a significant positive relationship between Ca intake and faecal Ca excretion and between P intake and faecal P excretion. In the biologically relevant range, these equations predicted lower faecal Ca losses in hindgut fermenters than ruminants, for faecal P vice versa. In all species, faecal Ca and P excretion correlated significantly. In carnivores, this highly linear correlation was exceptionally strong (R² = .92). Yet, the linearity of the correlation was questionable in omnivores and ruminants. Possibly, the strong linear correlation of faecal Ca and P excretion in carnivores is due to the formation of insoluble Ca/P complexes in their relatively short and simple gastrointestinal tract. Another hypothesis is that in carnivores, Ca homeostasis relies on modifying bone turnover to a higher degree than on changes in intestinal Ca absorption. For the formation of bone matrix, a constant ratio of Ca and P absorption is of advantage.

Citation

Böswald, L. F., Dobenecker, B., Clauss, M., & Kienzle, E. (2018). A comparative meta-analysis on the relationship of faecal calcium and phosphorus excretion in mammals. J Anim Physiol Anim Nutr (Berl), 102(2), 370–379. https://doi.org/10.1111/jpn.12844 Animals, Digestion/physiology, digestibility, phosphorus, calcium, bone turnover, Calcium/chemistry/*metabolism, comparative, Feces/*chemistry, Mammals/classification/*physiology, Phosphorus/chemistry/*metabolism

Keywords

• Animals
• Digestion/physiology
• digestibility
• phosphorus
• calcium
• bone turnover
• Calcium/chemistry/*metabolism
• comparative
• Feces/*chemistry
• Mammals/classification/*physiology
• Phosphorus/chemistry/*metabolism