Reducing greenhouse gas emissions is a growing priority in dairy farming, and many believe that feeding cows home-grown feed is a simple way to reduce emissions. After all, feed grown on one's own farm avoids emissions from transportation, storage and processing. But is it really that simple?
To answer this question, we used Farmdesk Climate to simulate different feeding strategies on a high-yielding dairy farm. The results provide a more nuanced picture and highlight the critical importance of efficiency in sustainable milk production.
The business situation
The reference farm has 100 cows, producing an average of 30 kg of milk per day, with a fat content of 42.7 g/ltr (4.14%) and a protein content of 34.1 g/ltr (3.31%). Each cow consumes 20.7 kg of dry matter (DS) feed daily, consisting mainly of forage (13.4 kg DS), including corn silage (7.74 kg DS) and grass-clover silage (5.68 kg DS).
The remaining ration consists of homegrown barley (2.51 kg DS), beet pulp (2.00 kg DS), brewer's grains (1.00 kg DS), turnip meal (0.91 kg DS, RE = 39%) and soybean meal (0.87 kg DS, RE = 49%).
Crops are grown on 57.25 acres:
Barley: 16.55 ha (29%) with a yield of 7.5 tons PROD/ha
Corn silage: 18.5 ha (32%) with a yield of 18 tons DS/ha
Grass-clover: 22.2 ha (39%) with a yield of 11 tons DS/ha, grown without fertilizer
Comparison of four feeding strategies
We tested four feeding strategies, each changing only the source of one main component:
Reference: barley, corn silage and grass-clover silage are homegrown
Barley is purchased
Corn silage is purchased
Grass-clover silage is purchased
| Scenario | Emissions (g CO₂-eq/kg FPCM). | Feed cost (/100 kg FPCM) | Feed profit (/year) |
|---|---|---|---|
|
1. Reference (homegrown) |
963 |
€ 14,79 |
€ 352.661 |
|
2. Barley purchased |
971 |
€ 13,56 |
€364.704 |
|
3. Corn silage purchased |
988 |
€ 17,92 |
€322.080 |
|
4. Grass-clover pit purchased |
975 |
€14,57 |
€361.805
|
The results show that not all purchased feed is equally problematic. While purchased corn silage resulted in the highest emissions (+2.6% vs. reference) and the lowest profit (-8.7%), purchasing barley resulted in a higher profit (+3.4%), despite a slight increase in emissions (+0.8%). This was largely due to favorable market prices at the time of the study.
Efficiency: the real gamechanger
When thinking about reducing emissions and increasing feed profits on a dairy farm, the focus should not just be on purchased or homegrown feed. What really matters is how efficiently that feed is produced and used.
We looked at what happens when yields of the three main crops increase:
Barley increased to 10 tons PROD/ha (+2.5 tons)
Corn silage to 21 tons DS/ha (+3 tons)
Grass-clover to 15 tons DS/ha (+4 tons)
These yield increases produced clear benefits:
Lower greenhouse gas emissions per kg of milk (up to 2.1% reduction)
Lower feed costs (more than €2/100 kg FPCM lower at increased yields)
Higher annual feed profits (up to 7.7% or more than €27,000 extra per year)
Important detail: if barley yields fall below 5.5 tons per acre, purchased barley would result in lower emissions in our model. But most farms are already above this level, so there is a realistic opportunity to maintain or improve efficiency.
Conclusion: bet on efficiency first
The results show that homegrown feed results in lower emissions only when it is produced efficiently. Purchased feed, such as barley, corn or grass, can sometimes be cheaper or appear to produce fewer emissions, depending on market conditions.
Important is how efficiently feed, especially homegrown, is produced and utilized on the farm. This means:
More yield per acre,
Smart handling of inputs, and
Getting more milk from each kilogram of feed.
As proprietary yields increase, you may need less land for the same amount of feed. That can free up space for alternative crops or to replace purchased, low-emission feeds (such as imported soy), allowing for further reductions in carbon footprint.
For a more comprehensive look at larger greenhouse gas reduction opportunities (up to 30% on an average Flemish dairy farm), check out our full in a previous article.
"So ultimately it's not about whether the feed is purchased or homegrown, but how efficiently it's used in your system."
