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Journal of animal physiology and animal nutrition2019; 104(6); 1912-1918; doi: 10.1111/jpn.13251

Phosphorus excretion by mares post-lactation.

Abstract: Across the equine literature, estimates of true P digestibility range from -23% to 79%. This large range cannot be explained by differences in P intake or phytate-P intake alone. However, differences in endogenous P secretion into the GI tract may explain the variation. In horses, excess absorbed P is not excreted in the urine but is re-secreted into the GI tract, increasing faecal P and leading to estimates of low P digestibility. Thus, accurate estimates of P digestibility can only be obtained if absorbed P is retained in the horse. The objective of this study was to examine P digestibility in post-lactational mares and control mares that were fed similar amounts of P. It was hypothesized that post-lactational mares would have greater P retention and higher apparent P digestibility than control mares. Prior to the study, four lactating and four non-lactating mares were fed a diet that provided 100% of the control mares' P requirement, but only 55% of the lactating mares' P requirement. During the study, both groups were fed P at the rate recommended for non-lactating mares. Post-lactational mares did not retain more P than control mares but tended to excrete more P than control mares (p = .082), presumably due to differences in endogenous P secretion into the GI tract. Metabolic changes occurring during mammary gland involution may have contributed to the increase in P excretion. However, faecal P excretion exceeded P intake in both groups (p = .08) and both groups lost weight during the study. Tissue mobilization during weight loss may have influenced P secretion into the GI tract.
© 2019 Blackwell Verlag GmbH.
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Publication Date: 2019-11-13 PubMed ID: 31721308DOI: 10.1111/jpn.13251Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study explored the digestion and excretion of phosphorus (P) in post-lactational and non-lactating mares. The findings suggest that phosphorus digestibility varies widely among horses due to factors such as excess absorbed P re-entering the gastrointestinal tract, rather than being excreted in urine, and changes in metabolism during mammary gland involution.

Research Objective and Hypothesis

  • The objective of this study was to investigate phosphorus digestion in post-lactational mares (the ones that have stopped lactating recently) and control mares (the non-lactating ones).
  • The researchers hypothesized that post-lactational mares would retain more phosphorus and would show higher apparent phosphorus digestibility than control mares, owing to their recently ceased lactation.

Study Design and Methodology

  • Prior to the study, both lactating and non-lactating mares were fed a diet that fully met the phosphorus requirement of the control mares, but only satisfied 55% of the requirement for lactating mares.
  • During the research, both groups were given phosphorus at the rate recommended for non-lactating mares to examine the variations in phosphor digestion.

Results and Findings

  • Contrary to the hypothesis, post-lactational mares did not retain more phosphorus than the control mares.
  • Instead, post-lactational mares tended to excrete more phosphorus than the control group, likely because of variations in endogenous phosphorus secretion into the gastrointestinal tract.
  • Mammary gland involution (a reduction in size after lactation) might have caused metabolic changes that increased phosphorus excretion in the post-lactational mares.
  • Both post-lactational mares and control mares excreted more phosphorus in feces than they consumed, suggesting that they released phosphorus stored in their bodies in addition to their phosphor intake.
  • Both groups lost weight during the study period, indicating that tissue mobilization (the process of moving nutrients) during weight loss could affect phosphorus secretion into the gastrointestinal tract.

Cite This Article

APA
Fowler AL, Pyles MB, Hayes SH, Crum AD, Lawrence LM. (2019). Phosphorus excretion by mares post-lactation. J Anim Physiol Anim Nutr (Berl), 104(6), 1912-1918. https://doi.org/10.1111/jpn.13251

Publication

Journal of animal physiology and animal nutrition
ISSN: 1439-0396
NlmUniqueID: 101126979
Country: Germany
Language: English
Volume: 104
Issue: 6
Pages: 1912-1918

Researcher Affiliations

Fowler, Ashley L
  • Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky.
Pyles, Morgan B
  • Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky.
Hayes, Susan H
  • Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky.
Crum, Andrea D
  • Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky.
Lawrence, Laurie M
  • Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky.

MeSH Terms

  • Animal Feed / analysis
  • Animals
  • Diet / veterinary
  • Digestion
  • Feces
  • Female
  • Horses
  • Lactation
  • Phosphorus
  • Phytic Acid

References

This article includes 21 references
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