Drought response strategies alter dairy performance and cheese characteristics
INRAE researchers have documented how different dairy farming adaptations to drought affect cheese production from pasture to plate. Their comprehensive study reveals that while corn-based systems produce more milk, completely removing fresh grass severely compromises cheese quality. Conversely, supplementing hay in grass-based systems maintains product characteristics while improving environmental performance.
Climate change is causing more frequent and severe droughts, profoundly affecting dairy production systems that rely on grasslands. New research conducted by France’s National Research Institute for Agriculture, Food and Environment (INRAE) reveals that adaptation strategies to manage summer forage shortages significantly impact not only cow performance but also the nutritional and sensory qualities of cheese.
How climate change threatens grass-based dairy systems
In semi-mountainous areas like France’s Massif Central, dairy farming systems are increasingly confronted with summer droughts, affecting both grass quantity and quality. Dr. M. Bouchon and colleagues at INRAE explain: “In the short term, farms in these areas often rely on greater levels of indoor feeding of conserved forages and concentrates as a tactical adaptive strategy. In parallel, the cultivation of complementary forage crops such as corn silage is increasingly adopted as a medium-term strategy to reduce vulnerability of farming systems to recurrent forage losses.”
As climate change progresses, farms that have traditionally relied on hay stocks for winter are finding their regions becoming suitable for growing fodder crops like maize (corn), which can then be introduced into animal rations. These practices – previously marginal in cheese production areas – raise significant questions about product quality.
To investigate these effects systematically, researchers conducted a 4-month trial on an INRAE experimental farm in the Massif Central. They compared two distinct dairy systems: a traditional grass-based system and a more intensive corn-based system, each subjected to simulated forage shortages that might occur during drought periods.
Four groups of ten dairy cows were established: two groups received rations based primarily on grazed grass, while the other two received corn silage-based diets. To simulate drought conditions, researchers reduced grass availability for one group in each system – decreasing grazed grass from 75% to 50% in the grass-based diet, and completely eliminating grazed grass from one of the corn-based diet groups.
Different adaptation responses in grass versus corn systems
The research showed distinct performance differences between the systems when faced with forage shortages. While milk production was generally 28% higher in corn-based systems compared to grass-based systems, the adaptation strategies had different impacts within each system.
In grass-based systems, reducing grass and increasing hay and concentrates actually improved feed efficiency by 17.8% (from 0.76 to 0.90 kg fat-and-protein-corrected milk per kg of dry matter intake) and reduced methane emission intensity. “Grass reduction in the grass-based diet better maintained milk yield, enhanced feed efficiency, and reduced methane emission intensity,” the researchers noted in their study published in the Journal of Dairy Science.
For corn-based systems, completely removing grazed grass had no significant effect on milk production but impaired feed efficiency. This finding suggests that different adaptive strategies may be necessary depending on the baseline feeding system.
The study’s detailed measurements – recording individual feed intake, milk yield, milk composition, and estimating methane emissions – allowed researchers to develop a comprehensive understanding of how dietary adaptations affected overall system performance. Notably, cows in the corn-based system were heavier than those in the grass-based system by approximately 62 kg at the experiment’s conclusion, indicating different body condition responses to the dietary changes.
Cheese quality: nutritional and sensory impacts
Perhaps the most striking findings concerned the effects on cheese quality. Milk from each experimental group was processed into Cantal-type cheeses, which were then subjected to extensive chemical, microbiological and sensory analyses.
The results revealed that cheese from cows fed with more grazed grass showed distinctive qualities. According to the researchers: “Cheese softness increased with proportion of grass in the diet, and it was positively correlated with primary proteolysis (αS1-casein and β-casein breakdown) but negatively correlated with the C16:0/C18:1 ratio and the calculated fat melting point.” Sensory analysis conducted by a panel of ten trained evaluators assessed 28 different attributes of the cheeses. Grass-fed cow cheese scored higher for global, animal, and plant aromas compared to corn-fed cow cheese. The more grass in the cows’ diet, the yellower and more aromatic the cheese, with distinct textural properties as well.
“Cows fed on grazed grass produced smoother, yellower, more aromatic cheeses, while cows fed little to no grass produce whiter, firmer cheeses with milder flavours,” the researchers noted in their paper.
Crucially, the adaptation strategy had different impacts on cheese quality depending on the baseline feeding system. In corn-based systems, completely removing grazed grass from the diet had a dramatic impact on cheese quality, producing cheese that was less yellow and had less flavour. In contrast, when grass-based systems were supplemented with hay to manage drought conditions, the impact on cheese quality was less severe. This difference appears related to both biochemical and microbiological factors. The fatty acid profile showed that milk from grass-fed cows was lower in saturated fatty acids (-7.9%) and higher in monounsaturated fatty acids (+15.2%) compared to corn-fed cows. Polyunsaturated fatty acids were significantly higher (+28.7%) in grass-fed cow milk, which also contained twice the amount of omega-3 fatty acids but lower levels of omega-6 fatty acids (-31.6%).
Microbial analysis revealed that the cheeses from grass-fed cows contained higher levels of beneficial bacteria, including heterofermentative lactobacilli, which contribute to flavour development during ripening. When grazed grass was completely removed from corn-based diets, these microbial populations were significantly altered, corresponding to the reduced flavour development in the resulting cheese.
Practical implications for dairy systems management
This research has significant implications for dairy farmers adapting to climate change while maintaining product quality. The findings suggest that different approaches may be needed depending on the baseline feeding system.
For corn-based systems, the research indicates that maintaining at least some fresh grass in the diet is crucial for preserving cheese quality. “In corn-based systems – a crop which is becoming increasingly popular in semi-mountainous areas – the quality of the cheese is severely compromised by the loss of grazed grass, which is likely to occur as a result of drought,” the researchers conclude. “Maintaining fresh grass in corn-based diets, even in small quantities, proved to be crucial in order to preserve the nutritional and sensory quality of the cheese.”
For grass-based systems, introducing hay during periods of reduced grass availability appears to be an effective adaptation strategy. “In grass-based systems, the traditional practice of supplementing cows with hay allows farmers to cope with an episode of drought, and the impact on cheese quality is not as severe,” the researchers state. This approach not only maintains reasonable cheese quality but also improves feed efficiency and reduces methane emission intensity.
The findings help explain the traditional emphasis on grass feeding in many cheese-producing regions. Beyond the direct impact on flavour compounds, grass feeding affects the microbiota throughout the production chain, influencing both the biochemical processes during cheese ripening and potentially the microbiota of consumers. The INRAE team notes that additional research is forthcoming on “the microbial transfers that occur along the agri-food chain depending on the cows’ diet, and to study how changes in common practices are likely to impact the microbiota of consumers.”
As climate change continues to affect agricultural systems, particularly in marginal areas like semi-mountainous regions, maintaining cheese quality while adapting farming practices will require careful attention to feeding regimes. This research provides evidence-based guidance for producers seeking to balance adaptation with product quality.
For cheese producers and dairy industry stakeholders, these findings emphasise the importance of working closely with farmers to ensure that adaptation strategies consider product quality outcomes, not just production efficiency. The research suggests that complete replacement of grazed grass with corn silage may improve certain production metrics but could significantly compromise the distinctive qualities that consumers value in traditional cheeses.
In conclusion, this comprehensive study demonstrates that climate adaptation strategies in dairy systems have complex, interconnected effects on animal performance, environmental impact, and product quality. Finding the optimal balance between these factors will be crucial as the dairy sector navigates the challenges of climate change in the coming decades.
Reference
Bouchon, M., Martin, B., Bord, C., et. al. (2025). Adaptation strategies to manage summer forage shortages improve animal performance and better maintain milk and cheese quality in grass- versus corn-based dairy systems. Journal of Dairy Science, 108(5), 4796-4817. https://doi.org/10.3168/jds.2024-25730
