Feeding the future: A sustainable approach to dairy farming
What does the science say? What is the data telling us? These questions driving conversations around human health and the novel coronavirus are also informing how stakeholders in the feed-to-food chain think about livestock production and sustainability.
Analysis of ruminant animals’ biological processes, production practices in various regions of the globe and environmental issues such as greenhouse gas emissions all suggest opportunities to mitigate livestock production’s impact on the environment.
Concerns about climate change have given rise to media reports about how dairy production affects methane and greenhouse gas levels. But what does the science say about animal agriculture and its impact on the environment? What data confirms or refutes media headlines?
Among species categories, ruminants play a key role in global food production systems. Dairy cows and beef cattle are uniquely suited to utilise Earth’s grasslands and plant byproducts while providing a highly nutritious source of dietary protein for human consumption. Science can help address critical questions such as: What demands does dairy farming place on the planet? How much does dairy production contribute to greenhouse gas emissions? How can we conserve earth’s finite resources while also producing sufficient protein to meet demand?
Responsible food production and sustainability
Environmental sustainability is just one component of ‘responsible food production’ along with food safety, food security, animal welfare and socially sustainable production practices. Environmentally sustainable food production requires utilising renewable resources such as sunlight, water and soil to yield food without depleting resources. From a practical application perspective, food production should have a neutral impact on biodiversity without expanding land use. A balanced approach to environmental sustainability as part of a circular approach to responsible food production requires the utilisation and recycling of elements such as carbon, nitrogen, phosphorous and trace minerals.
Renewed attention is being placed not only on food production systems but also on the changing mindset of farmers and what motivates their practices. As fewer but larger farms feed the world, today’s dairy farmers are balancing economic objectives with environmental stewardship and animal welfare. A recent report from the Intergovernmental Panel on Climate Change (IPCC) illustrates how today’s farms have tremendously increased productivity without requiring much additional natural resources. Since the early 1960s, cropland has increased just 15% globally and pastures have grown by 8%, while cropland production has increased 3.5 times, and animal production has increased 2.5 times. More food is available for a global population that has doubled in the same time. The IPCC experts also indicate that greenhouse gas emissions per unit of food produced are about 60% lower than in 1960, showing that although the total footprint of food production has increased, this has not happened proportionally to food production or human population growth. These productivity and efficiency achievements are the result of agricultural technologies mainly implemented in advanced economies. Implementation of these technologies in Iow-and mid-income countries can and will further reduce the global footprint of food. Low-and-mid-income geographies account for 70% of ruminant emissions today, but the transformation of these societies and their food production systems is on its way.
Starting point for efficient protein production
Cattle have evolved to support their efficient survival using natural resources. As domesticated species, they present some inherent challenges as well as opportunities. As cattle take at least two years to reach reproductive adulthood and nearly a year is required for calf gestation, bovine animals have significant reproductive and developmental limitations as compared to pigs and poultry. On the other hand, dairy cows are versatile animals. They are geographically and seasonally adaptable and are able to digest a broad range of substrates that humans or other animals cannot consume.
The efficiency and productivity of dairy production is highly variable across the world and highly dependent on efficient feed and farm practices. As 42M professionally reared cows produce 40% of the world’s milk, it would only take 100M such animals to meet global milk production. This contrasts with today’s total global herd of dairy animals between 200 and 300M.
Intensive dairy and extensive tropical grazing beef cattle are two of the most successful ruminant production systems. Dairy and beef cattle provide distinct opportunities to improve production efficiencies. In both production environments, about one third of animals go to slaughter every year. In a dairy system, this is far too many animals and in a beef system, this is far too few.
In modern intensive dairy farms, it is common to replace 1/3 of the lactating herd every lactation. Consequently, about half of the animals on a dairy farm are not lactating and the feed resource dedicated to rearing new animals is a burden to farm efficiency. The efficiency news is better once a cow begins lactating, as a high producing dairy cow uses about 60% of her feed for producing milk and only 40% for maintenance. Resource efficiency in modern dairy operations can be further improved by increasing animal productivity, and by reducing culling rates. Examples from commercial farms point to the feasibility of combining high productivities and longevities. This combination approach results in economic efficiency, minimizes the environmental footprint of milk production and positively relates to animal welfare. It is not common, but examples of cows yielding more than 100,000 kg of milk in their lifetime expose the opportunity for a next level of efficiency in dairy farming.
Ruminant efficiency should be viewed through a broader lens, considering the complete cycle associated to production, and interactions between dairy and beef production systems such as the trend toward more dairy cows being inseminated with beef breed semen. Finally, the nutrient output in terms of finished food and the opportunity to reduce food waste should be considered when thinking about animal efficiency. Crop residues derived from cereals, oilseeds, vegetables and many other crops represent 60% of the world’s crop yield and provide an available food source for ruminants, allowing for additional protein yields without mobilising any additional resources.
Edible protein produced by an animal as well as the animal’s ability to utilise crop products not suitable for human consumption factor into the efficiency equation. Compared to the six-week production cycle of poultry and broilers’ impressive feed efficiency, ruminants require a much longer time investment to reproduce, develop and do not convert kg of feed into kg of food. At first glance, this might make dairy seem less efficient. However, if we consider the edible value of the inputs and the outputs, feed efficiencies level out with other farm animal species.
Even when viewed in terms of the protein fed to a dairy cow or broiler chicken vs. the food protein they produce, performance is comparable. Chickens retain dietary protein very efficiently as they grow, but they yield food protein in meat fractions (breast, thigh, drumstick, wing). In contrast, 100% of the protein the cow yields in milk is food protein. This is another example illustrating that standard approaches to measure efficiency are imperfect to describe the complexity of food production efficiency.
Efficient nutrition also applies to feeding practices for animals across their various life stages. For example, in the dairy sector today, just half of live born calves receive a milk replacer. This scenario suggests many litres of milk are being used to rear calves at the expense of sourcing this milk for human consumption. Now that calf nutrition is gaining the attention it deserves, milk volumes required for rearing are increasing. Feeding calves with high quality milk replacer programs aims to support adequate nutrition for both humans and animals.
Viewed through the lens of resource allocation, dairy cattle are remarkably efficient production animals and complement crop and non-ruminant livestock production. From an environmental perspective, cattle are innately suited to utilise grasslands and play an ecological role in marginal lands. Physiologically, cattle can digest the fibrous byproducts intrinsic to crop production and can even utilise non-protein nitrogen to spare protein in their diets.
In summary, dairy cattle present a tremendous opportunity to exploit food production efficiency. Considering the bovine species’ capacity for production in context with modern production systems and advances in animal nutrition, producers can make dairy production even more efficient. Along with beef cattle, dairy animals can meet the world’s growing demand for protein while responsibly utilising production resources.
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