Unlocking Milk's Secrets: Massey Whenua Haumanu Reveals Pasture and Lactation Impacts on Flavour

New research from Massey University's Whenua Haumanu programme has demonstrated that the type of pasture cows graze and the stage of their lactation cycle profoundly shape the flavour, texture, and mouthfeel of milk. In a sensory study conducted by the university's Food Experience and Sensory Testing (Feast) Laboratory, trained panellists reliably distinguished differences between milk samples from cows on standard ryegrass-clover pastures versus diverse multi-species swards. This finding underscores how dietary choices in pastoral systems directly translate to the end product consumers experience. For New Zealand's pasture-based dairy industry, which relies on grass-fed systems for its global competitive edge, these insights open doors to optimising product quality amid growing interest in regenerative agriculture.

The study highlights a critical intersection between farm management and consumer perception. As dairy farmers explore diverse pastures to enhance resilience against climate variability and reduce environmental footprints, understanding sensory outcomes ensures market viability. Early lactation milk emerged as sweeter and creamier, while late-stage samples trended thinner and more sour—variations compounded by pasture composition.

Whenua Haumanu: Massey's Flagship Programme Nurturing Sustainable Pastoral Systems

Whenua Haumanu, meaning 'nurturing the land' in Māori, represents Aotearoa New Zealand's most ambitious investigation into contemporary and regenerative pastoral farming. Launched as a seven-year, $26.12 million initiative funded by the Ministry for Primary Industries (MPI) Sustainable Food and Fibre Futures fund, the programme is led by Professor Danny Donaghy at Massey University. It spans multiple research sites, including Massey's Dairy 1 farm bordering the Manawatū River, the Pasture and Crop Research Unit (PCRU), and Lincoln University's Field Research Centre.

At its core, Whenua Haumanu evaluates how standard ryegrass-dominant pastures compare to diverse mixes—incorporating species like plantain, chicory, clovers, and herbs—under both conventional (high nitrogen fertiliser, set stocking) and regenerative (multi-species rotational grazing, biological amendments, lower inputs) management. Metrics encompass soil health, biodiversity, nutrient leaching, greenhouse gas emissions, animal welfare, and crucially, product quality such as milk composition and sensory attributes. Early results show diverse pastures outperforming standards in resilience to extreme weather, with fortnightly data dashboards tracking progress.

This holistic approach aligns with New Zealand's dairy sector, which milks around 5 million cows across 11,000 farms, producing over 21 billion litres annually, 95% exported. Pasture-based systems define NZ dairy's low-emissions profile, but challenges like variable weather spur diversification.

Unpacking the Sensory Study's Rigorous Methodology

The milk flavour research exemplifies Whenua Haumanu's product quality focus. Milk was sourced from three Dairy 1 farmlets: Herd A on standard ryegrass-clover under contemporary management; Herd B on diverse pastures with regenerative practices; and Herd C on diverse pastures under conventional management. Samples collected across early (November 2023), mid (January 2024), and late (March 2024) lactation were spray-dried into powder for stability, then reconstituted to mimic fresh liquid milk.

Sensory assessment employed the triangle test—a gold standard in food science where panellists sample three milks (two identical, one different) and identify the outlier. Statistical significance above chance (33%) confirmed detectability. Descriptive analysis captured flavour notes like 'rancid' or 'creamy', while accounting for lactation stage variations known from dairy science: early lactation yields high-volume, nutrient-rich milk; late stages concentrate fats and proteins as volume drops.

• Sample Preparation: Bulk tank milk spray-dried and reconstituted to standardise processing effects.
• Testing Protocol: Blind triangle tests followed by open flavour profiling.
• Controls: Lactation stage isolated to spotlight pasture/management influences.

Distinct Flavour Profiles Emerge from Pasture Variations

Panellists pinpointed clear distinctions tied to pasture. Milk from Herd A (standard pasture) was frequently mouth-drying, evoking 'rancid', 'cardboard', 'cow', and 'stale' notes—potentially from higher lipid oxidation in monoculture diets low in antioxidants.

In contrast, Herd B's regenerative diverse pasture produced sweeter, creamier milk with 'oxidised milk' and 'milk powder' aromas, likely from polyphenols and varied fatty acids in multi-species forage. Herd C, on diverse pasture but conventional management, leaned sour, salty, milky, with a dry aftertaste—suggesting management practices modulate dietary impacts.

• Herd A: Rancid, cardboard, cow-like off-flavours.
• Herd B: Sweeter, creamier, oxidised notes.
• Herd C: Sour-salty, dry persistence.

These align with global reviews where pasture diversity boosts beneficial volatiles and reduces off-notes.

Lactation Dynamics: From Creamy Peaks to Challenging Late Stages

Lactation stage amplified differences. Early lactation (November) milk was robust: stronger flavours, elevated sweetness, creaminess, and chalky/earthy aftertastes—reflecting peak metabolism and colostrum-like richness. Mid-lactation (January) felt thicker, balancing sweetness and saltiness.

Late lactation (March) shifted dramatically: thinner viscosity, diminished sweetness, heightened sourness/saltiness, unpleasant aftertastes, even tallowy notes. Across herds, March samples diverged most sharply, consistent with metabolic reviews showing late-stage metabolite shifts (e.g., higher free fatty acids influencing rancidity). In NZ's 270-day lactation cycle, this informs seasonal blending strategies for consistent quality.

Voices from the Lab: Researchers on Game-Changing Insights

Lead researcher Simone Poggesi noted, "Consumers could reliably tell the difference between milks from different pastures. This demonstrates that what cows eat can have a noticeable impact on the sensory properties of milk." Feast Director Professor Joanne Hort added, "While consumers could notice differences... future research looking at consumer acceptance will help us better understand how pasture feeding and lactation stages interact to shape consumer acceptance."

Programme head Professor Danny Donaghy emphasised practicality: "If farmers are going to adopt more diverse pastures, or regenerative practices, the products still need to meet consumer expectations. Understanding how milk flavour may change is critical." These perspectives position Massey as a bridge between lab and land.

Ripples for NZ Dairy: Balancing Innovation, Quality, and Sustainability

New Zealand's dairy sector, valued at $18 billion in exports, thrives on grass-fed credentials. Yet, with climate pressures, ~20-30% of farmers experiment with diverse pastures for drought resilience and lower nitrogen use. Whenua Haumanu data shows diverse swards yield consistently higher, even in extremes.

Flavour shifts could enable premium 'regenerative' labelling, akin to grass-fed premiums fetching 20-50% uplifts overseas. Processors might blend seasonally to mitigate late-lactation off-notes. For more on industry trends, see Farmers Weekly's coverage.

Complementing sensory work, related NZ studies link regenerative systems to healthier milk: 10.7% higher omega-3 fatty acids, elevated CLA and polyphenols for anti-inflammatory benefits. This dual sensory-nutritional edge bolsters adoption.

Massey's Feast Lab: Vanguard of Dairy Sensory Innovation

The Feast Laboratory, directed by Professor Hort, specialises in sensory and consumer science, hosting state-of-the-art booths for immersive testing. Recent expansions include TasteBench for innovators and VR tasting simulations. Beyond milk, it probes emotional food responses and plant-based alternatives. As a consultancy hub, Feast equips NZ's $50B food sector with data-driven insights.

Charting the Future: Next Steps in Dairy Research and Careers

Upcoming Whenua Haumanu phases will probe preferences, purchasing intent, and meat/wool quality. Broader trials at Pāmu farms scale findings. For aspiring researchers, Massey's research jobs in agronomy and sensory science abound, alongside university jobs in NZ dairy hubs.

Professionals can leverage academic CV tips for roles blending farm systems and consumer science. Explore professor ratings via Rate My Professor.

Elevating Aotearoa Dairy: Massey's Role in a Tasty, Sustainable Future

Massey Whenua Haumanu research illuminates how pasture diversity and lactation timing craft milk's sensory identity, guiding regenerative transitions without sacrificing appeal. As NZ dairy navigates sustainability demands, these evidence-based steps promise resilient farms and superior products. Stay tuned for preference studies—and consider higher ed jobs shaping tomorrow's dairy. For career advice, visit higher ed career advice; share insights in comments below.

Photo by David Clode on Unsplash