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Animal science journal = Nihon chikusan Gakkaiho2026; 97(1); e70168; doi: 10.1111/asj.70168

Pasture Intake of Whole-Day Stocked Thoroughbred Foals With Growth.

Abstract: We investigated the changes in the forage and nutrient intake of thoroughbred foals on pastures with whole-day stocking with age. Twelve thoroughbred foals were used and were allowed to graze on a pasture for 21 h/day from June to September. All foals were weaned just before 5 months of age. The pasture intake of the foals was measured using the double-indicator method. During the suckling period, the total voluntary dry matter intake (VDMI) of the pasture for foals was higher at 4 months (2.1 kgDM/day) than at 2 months (1.3 kgDM/day). However, VDMI of pastures per body weight (%BW) for foals was not significantly different (approximately 1%BW). After weaning, the VDMI of the pasture for foals at 5 months (4.8 kgDM/day) increased more than that at 4 months old. Thoroughbred foals under whole-day stocking during the nursing period were dependent on dam's milk for approximately 60% of digestible energy (DE) requirements even at 4 months of age just before weaning. After weaning, crude protein was able to meet the requirement only with grass, whereas DE was able to reach 89% of the DE requirement from pasture and can meet this requirement with approximately 1 kg of the concentrate.
© 2026 Japanese Society of Animal Science.
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Publication Date: 2026-04-28 PubMed ID: 42044950DOI: 10.1111/asj.70168Google 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.

Overview

  • This study examined how forage and nutrient intake of thoroughbred foals grazing on pasture all day changes as they grow from 2 to 5 months old.
  • It focused on measuring pasture intake before and after weaning, and assessing whether pasture alone meets their energy and protein needs during growth.

Study Design and Methodology

  • Subjects: Twelve thoroughbred foals grazing on pasture for approximately 21 hours per day from June to September.
  • Weaning occurred just before the foals reached 5 months of age.
  • Pasture intake was measured using the double-indicator method, a technique that estimates forage intake through markers.
  • Measurements focused on voluntary dry matter intake (VDMI) at the ages of 2, 4, and 5 months to track changes as foals matured.

Findings on Pasture Intake

  • During the suckling period:
    • VDMI increased from 1.3 kg of dry matter per day at 2 months old to 2.1 kg at 4 months old.
    • However, when pasture intake was expressed relative to body weight (% BW), it remained roughly constant at about 1%, indicating intake scaled with growth.
  • After weaning at 5 months:
    • VDMI increased substantially to 4.8 kg dry matter per day.
    • This suggests that once foals stop nursing, they compensate by consuming more pasture.

Nutritional Dependency and Requirements

  • Before weaning:
    • Foals obtained approximately 60% of their digestible energy (DE) requirements from their dam’s milk, showing heavy reliance on nursing for energy.
  • After weaning:
    • Crude protein requirements could be met by pasture alone, indicating pasture quality and intake were sufficient for protein needs.
    • Digestible energy from pasture met 89% of energy requirements, slightly short of full requirements.
    • Supplementing about 1 kg of concentrate feed could fulfill the remaining energy needs.

Implications and Conclusions

  • Thoroughbred foals increase their pasture intake both in absolute terms and relative to their energy needs as they mature and especially after weaning.
  • Milk remains a critical energy source during the nursing period, but transition to pasture feeding post-weaning is marked by increased forage consumption.
  • Pasture provides adequate protein but may require minor supplementation for energy post-weaning to fully meet nutritional demands.
  • This information is valuable for managing feeding regimes in young thoroughbred foals to support healthy growth and development.

Cite This Article

APA
Tanabe T, Matsui A, Tominari M, Ueda K, Mitani T, Kawai M. (2026). Pasture Intake of Whole-Day Stocked Thoroughbred Foals With Growth. Anim Sci J, 97(1), e70168. https://doi.org/10.1111/asj.70168

Publication

Animal science journal = Nihon chikusan Gakkaiho
ISSN: 1740-0929
NlmUniqueID: 100956805
Country: Australia
Language: English
Volume: 97
Issue: 1
Pages: e70168

Researcher Affiliations

Tanabe, Tomoki
  • Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.
Matsui, Akira
  • Hidaka Training and Research Center, Japan Racing Association, Urakawa, Hokkaido, Japan.
Tominari, Masataka
  • Hidaka Training and Research Center, Japan Racing Association, Urakawa, Hokkaido, Japan.
Ueda, Koichiro
  • Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
Mitani, Tomohiro
  • Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
Kawai, Masahito
  • Shizunai Livestock Farm, Field Science Center for Northern Biosphere, Hokkaido University, Shin-Hidaka, Hokkaido, Japan.

MeSH Terms

  • Animals
  • Horses / growth & development
  • Horses / physiology
  • Animal Nutritional Physiological Phenomena / physiology
  • Weaning
  • Animal Feed
  • Eating / physiology
  • Diet / veterinary
  • Energy Intake / physiology
  • Nutritional Requirements
  • Animals, Suckling
  • Male
  • Poaceae
  • Time Factors
  • Dietary Proteins
  • Female
  • Milk

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