All hay varietals do not have the same amino acid profiles. Amino acid composition, which determines protein quality, varies significantly based on the plant species (legume vs. grass), stage of maturity at harvest, and growing conditions. [1, 2, 3, 4, 5] 

 

Key Differences in Amino Acid Profiles: 

  • Legumes (e.g., Alfalfa, Clover): Generally have a higher crude protein content (15-22%+) and a more favorable amino acid profile (higher in lysine) compared to grass hays. 
  • Cool-Season Grasses (e.g., Timothy, Orchardgrass): Typically contain moderate protein (10-16% CP) and provide a different, often less concentrated, amino acid balance than legumes. 
  • Warm-Season Grasses (e.g., Teff, Bermudagrass): Usually have lower crude protein (8-12%) and, in the case of teff, have been shown to have lower levels of essential amino acids, such as threonine, compared to cool-season grasses. 
  • Harvest Maturity: Early-cut hay (leafier) has a higher protein content and a better amino acid profile than late-cut (stemmier) hay. [6, 7, 8, 9, 10, 11, 12] 

While the total amino acid levels in a horse's blood may not differ dramatically regardless of the forage type, specific limiting amino acids—particularly threonine—can be lower in animals consuming warm-season grasses like teff compared to those eating cool-season grass mixtures. [6, 13] 

 

AI responses may include mistakes.

[1] https://madbarn.com/how-to-choose-hay-for-your-horse/

[2] https://www.youtube.com/watch?v=Ad24I9d-j38

[3] https://extension.umn.edu/horse-nutrition/understanding-your-hay-analysis

[4] https://link.springer.com/chapter/10.1007/10_2014_269

[5] https://www.mdpi.com/2410-3888/7/5/225

[6] https://extension.umn.edu/horse-nutrition/amino-acids-forages-and-horses

[7] https://www.platinumperformance.com/articles/hay-analysis.html

[8] https://extadmin.ifas.ufl.edu/media/extadminifasufledu/cflag/image/docs/fl-equine-institute/2006/SelectingHay.pdf

[9] https://extension.umn.edu/horse-nutrition/amino-acids-forages-and-horses

[10] https://equine.caes.uga.edu/2025/10/the-hay-equation-understanding-hay-selection/

[11] https://tributeequinenutrition.com/blogs/news/whats-the-difference-between-grass-and-legume-forages

[12] https://www.localag.com.au/blog/protein-hays-and-how-they-compare

[13] https://hayandforage.com/article-2224-Forage-amino-acids-and-horse-health.html