AUTHOR=Zillinger Luisa S. , Hustedt Karin , Schnepel Nadine , Hirche Frank , Schmicke Marion , Stangl Gabriele I. , Muscher-Banse Alexandra S. 

TITLE=Effects of dietary nitrogen and/or phosphorus reduction on mineral homeostasis and regulatory mechanisms in young goats

JOURNAL=Frontiers in Veterinary Science

VOLUME=11

YEAR=2024

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2024.1375329

DOI=10.3389/fvets.2024.1375329

ISSN=2297-1769

ABSTRACT=<sec id="sec1001"><title>Introduction</title><p>The reduction of nitrogen (N) and phosphorus (P) in ruminant feed is desirable due to costs and negative environmental impact. Ruminants are able to utilize N and P through endogenous recycling, particularly in times of scarcity. When N and/or P were reduced, changes in mineral homeostasis associated with modulation of renal calcitriol metabolism occurred. The aim of this study was to investigate the potential effects of dietary N- and/or P-reduction on the regulatory mechanisms of mineral transport in the kidney and its hormonal regulation in young goats.</p></sec><sec id="sec3001"><title>Results</title><p>During N-reduction, calcium (Ca) and magnesium (Mg) concentrations in blood decreased, accompanied by a lower protein expression of cytochrome P450 family 27 subfamily B member 1 (CYP27B1) (<italic>p</italic> = 0.016). The P-reduced fed goats had low blood phosphate concentrations with simultaneously high Ca and Mg levels. The insulin-like growth factor 1 concentrations decreased significantly with P-reduction. Furthermore, gene expression of <italic>CYP27B1</italic> (<italic>p</italic> &lt; 0.001) and both gene (<italic>p</italic> = 0.025) and protein (<italic>p</italic> = 0.016) expression of the fibroblast growth factor receptor 1c isoform in the kidney were also significantly reduced during a P-reduced diet. ERK1/2 activation exhibited a trend toward reduction in P-reduced animals. Interestingly, calcitriol concentrations remained unaffected by either restriction individually, but interacted significantly with N and P (<italic>p</italic> = 0.014). Additionally, fibroblast growth factor 23 mRNA expression in bone decreased significantly with P-restriction (<italic>p</italic> &lt; 0.001).</p></sec><sec id="sec4001"><title>Discussion</title><p>These results shed light on the complex metabolic and regulatory responses of mineral transport of young goats to dietary N and P restriction.</p></sec>