A comparison of fecal output determined by total fecal collection or titanium dioxide in horses.
Abstract: Total fecal collection studies to determine digestibility of nutrients are costly and laborious. The use of externally dosed indigestible markers, such as titanium dioxide (TiO2), to estimate digestibility using spot samples could be advantageous, but studies validating their use in horses are inadequate. Two experiments were conducted to determine if TiO2 in fecal spot samples effectively estimated fecal output in horses. In Exp. 1, four mature horses were fed a forage-based diet (85:15 forage: concentrate) split into two equal meals with 1.75 ± 0.03 g TiO2/kg DM (10 g TiO2) per day top-dressed on their daily ration. Horses were fed the marker for 10 d before a 4-d total fecal collection period. Fecal samples were collected every 4 h to examine TiO2 excretion and calculate fecal output (cFO), which was compared to actual total fecal output (aFO). In Exp. 2, 15 horses were split into three dietary treatments: low forage (LO, 45% forage), medium forage (MED, 73% forage), and high forage (HI, 95% forage) diets. Daily rations were divided into three equal meals with 2 g TiO2/kg dry matter per day thoroughly mixed in their feed. The marker was fed for at least 12 d before a 5-d total fecal collection period, with spot samples obtained similarly to Exp. 1. In Exp. 1, cFO overestimated aFO by 10% (P < 0.05) across all horses and days. The aFO and cFO determined by fecal spot samples were poorly correlated (P > 0.10; R2 = 0.148). In Exp. 2, cFO was not different from aFO when averaged across all horses and days (P > 0.10), but there were differences (P < 0.05) between cFO and aFO for 10 out of 15 individual horses. In addition, compared to the MED and LO diets, mean fecal output calculated from TiO2 underestimated aFO (P < 0.05) for horses fed the HI diet. Due to a large amount of variation within horses, the use of TiO2 in fecal spot samples to estimate fecal output needs to be better optimized before its use can be recommended as an alternative to total fecal collections. Using fecal spot samples and an indigestible marker to calculate fecal output (FO) is an attractive alternative to conducting total fecal collections, but the method needs to be validated in horses. In two experiments, horses were fed titanium dioxide (TiO2), then fecal spot samples were collected every 4 h to calculate FO, which was compared to actual total FO. In Exp. 1, when four horses were fed twice daily with TiO2 top-dressed on each meal, actual FO was overestimated by 10% when calculated from fecal TiO2 concentrations. In Exp. 2, we used 15 horses, mixed the TiO2 thoroughly into all feed, and divided the ration into three, evenly spaced daily meals. Actual FO was accurately calculated from spot samples when all samples were averaged. However, TiO2 failed to accurately calculate FO for 10 out of 15 horses. Also, FO calculated from TiO2 underestimated actual FO for horses fed a high-forage diet (93% forage) compared to horses fed lower-forage diets (45 and 73% forage). Due to the large variation in fecal TiO2 concentrations within horses and across diets, the method to calculate FO using TiO2 needs optimization before it can be recommended as a replacement for total fecal collections.
© The Author(s) 2025. Published by Oxford University Press on behalf of the American Society of Animal Science.
Publication Date: 2025-10-28 PubMed ID: 41148061PubMed Central: PMC12619977DOI: 10.1093/jas/skaf375Google Scholar: Lookup
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- Journal Article
- Comparative Study
Cite This Article
APA
Fowler AL, Pyles MB, Hayes SH, Crum AD, Lawrence LM.
(2025).
A comparison of fecal output determined by total fecal collection or titanium dioxide in horses.
J Anim Sci, 103, skaf375.
https://doi.org/10.1093/jas/skaf375 Publication
Researcher Affiliations
- Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506.
- Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506.
- Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506.
- Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506.
- Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506.
MeSH Terms
- Animals
- Horses / physiology
- Titanium / chemistry
- Titanium / metabolism
- Feces / chemistry
- Animal Feed / analysis
- Diet / veterinary
- Male
- Female
- Animal Nutritional Physiological Phenomena
- Digestion
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