Understanding Forage Quality and Winter Feeding for Horses


Objectives of a Balanced Ration

A well‑formulated ration for pregnant mares should:

  • Maintain mares in healthy, sound condition throughout gestation and production.
  • Ensure delivery of a healthy, vigorous foal.
 

Key Components of a Ration

All equine diets must supply five essential components in appropriate balance:

  • Energy
  • Protein
  • Minerals
  • Vitamins
  • Water

Feed testing is recommended as an inexpensive and effective tool for designing rations that meet nutritional requirements and avoid unexpected issues.

 

Energy

  • Rations for pregnant mares typically rely on medium‑quality forages to maintain appropriate protein levels.
  • Early‑cut forages are high in protein and energy but low in fibre. As grasses mature, fibre increases while protein and energy decrease.
  • Mature, low‑protein forages require grain supplementation (oats or barley) to maintain body condition.
  • General guideline: feed 1 lb of grain per 100 lb of body weight, adjusted for forage quality and mare condition.
  • Mares in good condition: ribs not visible but easily felt.
  • High‑fibre forages provide essential bulk and maintain gut function.
Feeding mature low-protein forages requires supplementation with oats or barley grain as an energy source to keep the mares in

 

 

Protein

  • Meeting minimum protein requirements is critical for health of the mare and fetus.
  • Protein requirements (100% dry matter):
    • Early gestation: 9–10%
    • Last 90 days: 10–11%
  • Approximately 70% of fetal growth occurs in the final 90 days.
  • Excess protein should be avoided.
    • Digestion produces ammonia → converted to urea in the liver.
    • Excess intake raises blood urea levels, leading to increased urinary excretion.

 

Digestion of Protein and its breakdown of digestible Ammonia 

 

 Grass Growth Stages

  • Vegetative stage: leaf production; high nutrient quality; no stem development.
  • Boot stage: seed head enclosed but not visible.
  • Reproductive stage (heading/flowering): seed head emerges; pollen shed is visible as powder.
 

Harvest Timing

  • Protein content is strongly influenced by cutting date:
    • Just after flowering: ~16% protein
    • 2–3 weeks later: 8–10% protein
 

Climatic Effects on Protein

  • Cool, wet conditions: slower decline in protein as grasses mature.
  • Hot, dry conditions: rapid drop in protein.
 

Grass Categories in Manitoba

Basal Type (Pasture Grasses)

  • Growth point remains near ground level.
  • High leaf production; suitable for grazing.
  • Tend to maintain higher protein at maturity.
  • Difficult to cure as hay due to regrowth through the swath.

Examples:

  • Meadow Brome
  • Meadow Fescue
  • Orchardgrass
  • Russian Wild Rye
  • Tall Fescue

Joint Stem Type (Hay Grasses)

  • Growth point is near the tip and moves upward.
  • More stem than leaf as plants mature.
  • If grazed too early, regrowth is slow.
  • Protein declines more quickly with maturity.

Examples:

  • Crested Wheatgrass
  • Smooth Brome
  • Tall Wheatgrass
  • Reed Canarygrass
  • Timothy
  • Intermediate Wheatgrass
  • Slender Wheatgrass
  • Pubescent Wheatgrass