Grains aren't natural to a cow's biological system for several key reasons:

Digestive System Structure:

- Cows are ruminants with a complex 4-chambered stomach designed specifically for grass and fibrous plants

- Their rumen (first stomach) contains specific bacteria that break down grass cellulose

- The rumen maintains a neutral pH when processing grass, but becomes acidic with grains

Health Issues from Grain:

1. Acidosis:

- Grains ferment quickly, creating excess acid in the rumen

- This acid can damage the rumen wall

- Can lead to liver abscesses and ulcers

2. Digestive Problems:

- Reduced cud chewing, which is essential for proper digestion

- Less saliva production, which normally helps buffer stomach acid

- Can cause bloat and other digestive disturbances

3. Bacterial Changes:

- Grain feeding alters the natural gut microbiome

- Promotes growth of harmful bacteria like E. coli

- Reduces beneficial bacteria that aid in digestion

4. Nutritional Stress:

- Forces their bodies to process nutrients they didn't evolve to handle

- Can lead to vitamin and mineral deficiencies

- Places stress on their liver and other organs

Natural Behavior:

- Cows naturally spend 8-12 hours daily grazing grass

- Grain feeding disrupts this natural behavior

- Can lead to stress and behavioral issues

This is why many farmers who grain-feed must also give their cattle antibiotics and other medications to manage these health issues, while grass-fed cattle typically require far fewer interventions.