Beef Basics: (i)

This is the first of 3 articles dedicated to examining the complexities of carbon footprints and beef production written by VetSalus Director and former Chair, Lewis Griffiths.

The production of animal protein from plant material involves some complex biochemistry which many species, especially ruminants, have steadily developed and adapted over millions of years. The basic process is very simple: the combination of sunlight, carbon dioxide and water, with a few additional elements thrown in, uses photosynthesis to eventually produce a range of plant proteins and carbohydrates, which vary in their digestibility and nutritional value. These plants are then consumed, in the case of beef, by bovine species, and further complex rumen biochemistry results in the production of volatile fatty acids, bacterial proteins and other nutritional material, which is digested further along the animal’s digestive tract and metabolically integrated to fuel both maintenance and growth; both of which involves the synthesis and storage of animal proteins. This process has several by products including, large volumes of faecal material which is returned to the soil, nitrogen rich urine and of course, a little methane and carbon dioxide.

It is both a beautifully simple and highly complex process, one which has attracted considerable attention as the carbon footprint and sustainability of agricultural systems are increasingly analysed. On this planet, for millions of years before the development of agriculture, large grazing ruminants would have been consumed by carnivores, including homo sapiens, or have died naturally; the carbon cycle involved is a closed, biogenic one. The role of large ruminants, particularly cattle, as important components of grassland ecology is becoming more widely understood; the ability of these species to selectively graze, suppress weed species and enhance biodiversity has been widely reported (1).

It is with the arrival of intensive agriculture, following the green revolution, that the simple system described above has become fundamental when sustainability and climate change are considered. Intensive animal production systems have been led by pigs and poultry, but there are also a wide range of beef production systems (2). Beef can be sourced from extensive ranching type operations, many of which can be classed as organic and regenerative, and also from intensive feedlots where many thousands of cattle are crowded into pens. The food sources available to the animals will range from selectively grazed pasture in rough hill country, where few other agricultural systems would thrive, through monocultures of nitrogen dependent pasture species, to carefully calculated diets with many ingredients, some of which may be grown many thousands of miles away from their eventual consumption location. Beef production systems can vary from a few cattle owned by a peasant farmer on the Savannah to the major feedlots outlined above. The variation in carbon footprints of these systems will be vast and also extremely complicated to calculate.

Human farming systems have modified the simple animal protein production system summarised above, by limiting grazing and substituting consumed species, while also modifying the genetics of the animals themselves and adding an array of additional chemicals, such as nitrogenous fertilisers, into the mix. A rapidly growing world population required feeding and the green revolution of the fifties and sixties was accompanied by a similar explosion in animal production systems.

As science communicators, (all veterinarians are to some extent involved in science communication) we face a fundamental conundrum when presenting issues like these, especially when our audience has a limited appetite for the complexity of scientific articles. Good communication simplifies and brings focus to a few key points; the major casualty of this focus is often accuracy. For example, methane production by ruminants has attracted recent attention from many journalists and yet when the entire digestive process is considered, much more than methane is produced. This is not to suggest that methane from generic fermentation is not a very important greenhouse gas: it is. But when presenting the science to an eager public, it is very easy to fall into the trap of quoting a few simple facts and thus ignore the complexity of the entire picture. What value has bovine faeces in the prevention of soil erosion and carbon sequestration? How do we best measure the impact of methane produced, which will have a relatively short lived but very intense global warming impact?

At VetSalus, we are in the business of science communication and one of our recent publications, our sustainable farming factsheet, shows average beef production with a carbon footprint, per 100 grams of protein, which is six times that of poultry. (See Fig 5. VetSalus Sustainable Farming Factsheet NZ 2024) The graphic provides a convenient discussion point; it may well initiate valuable conversations. But behind that simple fact lies much variation in beef production systems, the value of byproducts and impacts upon carbon sequestration and soil health.

Future articles in this series will look at this variation in more detail and also review future trends such as rumen modification and cell cultured beef. Keep an eye out for the second article, released next week.

References

1. For example see: https://pure.aber.ac.uk/ws/portalfiles/portal/65657933/1_s2.0_S1751731122002282_main.pdf
2. See: https://www.researchgate.net/publication/287686202_A_short_history_of_livestock_production for a brief overview

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