A meat free diet can ensure future food security

Astrid Jankielsohn – Senior researcher at Agricultural Research Council

The greatest challenge in agriculture today is to ensure food security for a growing human population. It is estimated that with the current growth rate of 2% a year the human population in South Africa will reach 82 million by 2035 (Agriculture: Facts and Trends South Africa. 2013. WWF-SA). The production of food will have to more than double to feed this population adequately. Drastic changes are needed, firstly in our eating habits and secondly in the type and production of food, to be able to manage these challenges successfully. We will have to determine which farming practices will deliver the greatest production with the least impact on natural resources and move to integrated systems where biological cycles are combined with the effective use of external inputs to increase yield through improved crop cultivars.

If we look at basic ecological principles we can already get a good idea of which systems will be most efficient and sustainable. Primary producers (plants) comprise the first trophic level, followed by primary consumers (herbivores) and secondary consumers (carnivores) on the highest trophic level. Energy is lost from one trophic level to the next and only 10% of the energy used in one level is available for the next level. For any system to remain ecologically viable the biomass of organisms will have to decrease from one level to the next since less energy is available when moving up to higher trophic levels and there are therefore fewer herbivores than plants and fewer carnivores than herbivores in a system. If we consider the numbers of the total human population it makes no ecological sense for humans to occupy the highest trophic level.

The use of animal products (milk, cheese and eggs) and meat (chickens, pigs and cattle) as food source is a less effective use of South Africa’s grain compared to direct human consumption. 4.5 Million tons, approximately half of South Africa’s maize is used for animal feed (The Maize Trust. 2013. Prospectus on the South African Maize industry). We can only look at the cattle industry to see how unsustainable meat production really is. Currently 75% of cattle in South Africa spend a third of their lives in feedlots where they are fed grains produced on scarce arable land. Many litres of water and other limited natural resources are lost in this process. To produce 1kg of meat 2.7kg maize is needed. The water efficiency of maize is 1.6 kg/m, 0.63kg/mwater is used to produce 1kg of maize and to produce 2.7kg maize 1.69 kg/m(1 690l) water is therefore needed. The total drinking water for a kg feedlot meat is 26.75l. A total of 1 716.75l water is therefore used to produce 1kg of grain fed beef (SA feedlots and Crop Water Productivity for maize data reported by FAO). Feedlots also put a lot of pressure on South Africa’s maize production. Maize is the staple diet of the majority of the South African population and an affordable source of energy and protein. According to the World Health Organization an intake of 56g protein is sufficient for a 75kg man. The recommendation is that our daily energy intake should contain 10% protein for our daily requirement. Legumes (beans, peas and lentils) contain 27% protein, nuts 13% and grain 12%. The protein in alternative plant food sources is therefore sufficient for a human’s daily requirements. A great deal of energy and water is lost in the process of converting plant protein to animal protein while the direct use of plant protein is sufficient for humans. To be able to produce sustainable food for a growing population in future we will have to take these facts into account and adapt to alternative farming systems to ensure food security in future.


Dear Astrid

The greatest challenge today is to ensure that we dedicate enough resources (education) to drastically reduce the growth in the human population. Human population growth is the pivotal problem.

If this can’t be done, nothing that we do will be sustainable even if all of us eat just plants.

But let me correct the central assumption in your statement: “Currently 75% of cattle in South Africa spend a third of their lives in feedlots where they are fed grains produced on scarce arable land”.

This assumption is totally incorrectwhich then question the value of any other “facts” provided in the rest of the statement.

The feedlot industry feed on average 1 400 000 calves (7 months and older) per year for an average of 100 days. That is just over 10% of the cattle population and not 75% as stated by you.

The other 90% of the cattle are grazing on the natural grass fields which grow due to natural rainfall – these ruminants consume grass (high fiber) that can only be digested through the microbial action in the large stomach (rumen) of these ruminants. Humans can’t eat or digest these plants (grass).

Most of these grasslands (majority of the surface area of South Africa) can’t be used for any other crop production. Ruminant animals are needed to utilize and maintain the growth and vitality of these vast carbon fixing grasslands. Our role as scientist is to support livestock producers to do it as effectively as possible.

Secondly the calves in South African feedlots are not fed with maize meal that can be used for humans – they are fed with the byproducts of the milling industry(mainly hominy chop – the maize husk). These byproducts can’t be used by humans because again it is high fiber material that can only be digested through the microbial action in the large stomach of ruminant animals.

So if you consider the role of the ruminant livestock industry (cattle, sheep, goats and game), it serves the South African population well by producing nutritional products with a high biological value by utilizing plant material that can’t be used for human food and in the process maintaining the vitality of vast carbon fixing grasslands in South Africa.


The bottom line is: We must not be compelled to over extend the resources of the earth to meet the demand of a growing population, we need to decrease the human population growth to match the resources that can be provided by the earth in a sustainable way.