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Nutrition, Feeding & WaterSupplementing Grazing Dairy Cows
Pasture rarely supplies everything a producing cow needs. A good supplement program fills the gaps without wasting feed or upsetting the rumen.
Key points
- Supplements fill the gaps pasture leaves, and the gaps change with the season.
- Test pasture before choosing a supplement.
- Spread grain into smaller feedings and keep fiber in the diet.
- Feed groups differently when possible.
- Track body condition, milk and feed cost together.
Why grazing cows need supplements
A high-producing cow has large energy and nutrient needs. Pasture can supply a great deal, but it may fall short on energy, on certain minerals, or on fiber depending on the stage of the grass. Intake on pasture is also limited by how much the cow can bite and chew in a day.
Supplements make up the difference. The right amount and type depends on the cow, her stage of lactation, the pasture and the season.
Start with what the pasture provides
You cannot choose a supplement without knowing the pasture. Have it sampled and analyzed through the season, and estimate how much pasture the cows actually eat. Your nutritionist uses that information to find the shortages.
Early lush growth, midsummer slump and fall regrowth all differ. A supplement plan that never changes will be wrong for part of the year.
Common types of supplement
Most grazing herds use some combination of grain-based feed at milking, stored forage such as hay or silage, and a mineral program. Some also use byproduct feeds when the price and quality fit. Each does a different job.
Stored forage adds fiber when pasture is lush and fills in when growth slows. Grain adds energy. Minerals cover needs that grass alone may not meet. Ask your nutritionist which mix suits your farm.
- Energy feeds to support milk yield and body condition.
- Stored forage to add fiber and fill gaps in growth.
- Mineral and vitamin supplements balanced to local forage.
- Protein sources when pasture protein is lacking.
Protect the rumen
Feeding a large amount of grain at one time, especially to cows on lush low-fiber pasture, raises the risk of rumen upset. Splitting grain into smaller feedings and keeping fiber in the diet help protect rumen health.
Introduce changes gradually. Cows need days to adjust to a new feed, and quick swaps cause drops in intake and milk.
Think about cow groups
Fresh cows, high producers, late lactation cows and first-calf heifers do not need the same supplement. Where you can, feed according to production and condition. Even a simple split into two groups can reduce waste.
Watch body condition on the 1-to-5 scale. Thin cows may need more energy. Cows gaining too much late in lactation may be getting more than they need.
Watch cost and waste
Supplement is often the largest purchased feed cost on a grazing dairy. Feed what the cows will turn into milk or needed condition, and skip what they will not use. Ask your nutritionist how milk response compares with extra feed on your farm.
Do not look only at price per ton. Compare price with what the feed delivers, and ask about the quality, consistency and delivery of any new ingredient before you commit.
Records and common mistakes
Keep feeding records, milk records and pasture notes in one place. Review them with your nutritionist several times a year.
Frequent mistakes on grazing farms include these.
- Feeding the same amount of grain all season.
- Ignoring minerals because cows are on grass.
- Large grain meals with no fiber support.
- Not tracking body condition.
- Letting supplement quality vary without checking.
Sources and further reading
Organization homepages are linked so you can search them for current guidance on this topic.