Feeding Dairy Cow with Grass Hay
This page analyzes the use of grass hay as a feed source for dairy cow. At 8% crude protein and 52% TDN, grass hay is does not meet protein or energy requirements as a sole feed for dairy cow at maintenance level (requires 16% CP and 70% TDN). Below you will find daily feeding rates, costs across herd sizes, and a life-stage breakdown showing how requirements change through the production cycle.
Grass Hay for Dairy Cow by Life Stage
Feed requirements change significantly across life stages. The table below shows the daily as-fed quantity of grass hay needed for each dairy cow life stage, along with whether the feed meets the adjusted protein and TDN requirements for that stage. Life stages with higher demands (lactation, growth) may require supplementation even if grass hay is adequate at maintenance.
| Life Stage | Daily DMI | As-Fed/Day | Protein Need | Protein OK? | Monthly Cost |
|---|---|---|---|---|---|
| Fresh Cow (0-21 days) | 41.7 lbs | 47.3 lbs | 17.6% | No | $106.49 |
| Mid Lactation | 53.9 lbs | 61.3 lbs | 16% | No | $137.81 |
| Late Lactation | 46.6 lbs | 52.9 lbs | 14.4% | No | $119.02 |
| Dry Period | 29.4 lbs | 33.4 lbs | 12% | No | $75.17 |
| Replacement Heifer | 49.0 lbs | 55.7 lbs | 18.4% | No | $125.28 |
Herd Feed Budget: Dairy Cow on Grass Hay
For operations feeding grass hay to multiple dairy cow animals, the table below projects total feed requirements and costs. These estimates use the maintenance-level feeding rate of 55.7 lbs as-fed per head per day at $150/ton.
| Head Count | Daily As-Fed Total | Monthly Tons | Annual Tons | Monthly Cost | Annual Cost |
|---|---|---|---|---|---|
| 1 | 55.7 lbs | 0.74 tons | 8.94 tons | $125.28 | $1,524.29 |
| 5 | 278.4 lbs | 3.68 tons | 44.71 tons | $626.42 | $7,621.45 |
| 10 | 556.8 lbs | 7.35 tons | 89.43 tons | $1,252.84 | $15,242.90 |
| 25 | 1,392.0 lbs | 18.38 tons | 223.56 tons | $3,132.10 | $38,107.24 |
| 50 | 2,784.0 lbs | 36.75 tons | 447.13 tons | $6,264.20 | $76,214.49 |
| 100 | 5,568.0 lbs | 73.50 tons | 894.25 tons | $12,528.41 | $152,428.98 |
Feeding Rates by Body Weight
The daily amount of grass hay varies with the individual animal's body weight. The table below shows as-fed feeding rates and monthly costs across a range of weights for dairy cow.
| Body Weight | Daily DMI | As-Fed/Day | Monthly Feed | Monthly Cost |
|---|---|---|---|---|
| 980 lbs | 34.3 lbs | 39.0 lbs | 1,029 lbs | $87.70 |
| 1,190 lbs | 41.7 lbs | 47.3 lbs | 1,250 lbs | $106.49 |
| 1,400 lbs | 49.0 lbs | 55.7 lbs | 1,470 lbs | $125.28 |
| 1,610 lbs | 56.4 lbs | 64.0 lbs | 1,691 lbs | $144.08 |
| 1,820 lbs | 63.7 lbs | 72.4 lbs | 1,911 lbs | $162.87 |
Nutritional Analysis: Grass Hay for Dairy Cow
Grass Hay provides 8% crude protein on a dry matter basis, while dairy cow at maintenance require a minimum of 16% crude protein. This means grass hay falls short of the minimum protein requirement by 8 percentage points. A protein supplement such as soybean meal, cottonseed meal, or a commercial protein block would be needed to balance the ration.
For energy, grass hay provides 52% TDN compared to the dairy cow requirement of 70% TDN. Energy supplementation is needed. Adding corn (88% TDN), barley (84% TDN), or a fat supplement (180% TDN) to the ration would address the energy deficit. The amount of supplementation required depends on the magnitude of the shortfall and the animal's production level.
The dry matter content of grass hay is 88%, meaning that for every 100 lbs of as-fed feed, the animal receives 88 lbs of actual dry matter nutrition and 12 lbs of water. At $150 per ton as-fed, the effective cost per ton of dry matter is $170. When comparing feeds, always use the dry matter cost rather than the as-fed cost to make fair comparisons between feeds with different moisture levels.
For a comprehensive feeding program, consider combining grass hay with complementary feeds that address any nutritional gaps. Browse the complete feed comparison to identify the most cost-effective supplements, or use the calculator to model different feed combinations. Always provide free-choice mineral supplementation and clean water regardless of the forage and grain program.
More Feeding Combinations
Explore other feed options for dairy cow or see how grass hay works for other species.
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