Can Population Control Shrink the Yield Gap? Developing Solutions for Developing Regions

A recent article by Andrew Jack in the Financial Times (the iconic pink-colored newspaper carried by all self-respecting business men on London tube trains each morning) reports that developing countries in Africa will be responsible for the greatest increases in population growth over the next 90 years, with the global population predicted to hit 10 billion by 2100. Given the number of dire predictions currently being bandied around regarding population increases, food demand and climate change it’s easy to become blasé and dismiss it as just another issue that will be solved by the next generation. After all, what difference can we possibly make to rural communities in developing countries?

Rises in per capita are predicted for developing countries over the next century and as Andrew Jack notes, increasing affluence results in improved healthcare, urbanisation and a decline in birth rates. Nonetheless, this pattern is not being currently being exhibited by regions in Africa and S. Asia, which are unable to improve per capita income as population increases overcome economic growth.

So how do we curtail the rise in population growth? Even in a developed country such as the USA, mentioning the politically-charged phrase “population control” often leads to an uncomfortable silence, images of an Orwellian constraint on family size (1 child good, 2 children bad?) or debate over the rights and wrongs of abortion. Yet simply providing access to contraception, considered to be an inherent human right by many women in the developed world, could conceivably (pardon the pun) improve future sustainability.

Reducing the number of children born in developing countries would improve female health and lessen the burden on economic and environmental resources placed by increasing population size. This would be a crucial step forwards in mitigating future food shortages, yet it does not solve the underlying problem. One of the major drivers behind population growth is parental reliance on support from the younger generation. As discussed in Jared Diamond’s excellent book “Guns, Germs and Steel“, higher birth rates potentially allow for a greater number of children to work on the land and improve societal stability. However, the promise of  future affluence is a major stimulant that causes young people to migrate from rural areas to urban regions that are already suffering from significant overcrowding.

A considerable yield gap exists between developing and developed countries, both in terms of animal and crop production. If productivity could be improved and the yield gap reduced, food security would improve in rural areas with positive effects on per capita income and infrastructure, and potential reductions in the number of inner-city migrants. Nonetheless, the major question remains unanswered – how to improve productivity?

If we use dairy farming as an example, a recent report from the Food and Agriculture Organisation noted a negative relationship between productivity and carbon footprint – as we move across the globe from developed to developing regions, productivity decreases and the carbon footprint per kg of milk increases (see graph). Carbon can also be considered a proxy for land, water and energy use, thus reduced productivity increases both resource use and environmental impact. The logical conclusion would therefore be to implement systems and management practices currently seen in N. America, Europe and Australasia in an attempt to educate farmers in S. Asia and Africa. However, sustainability cannot be improved by implementing a one-size-fits-all solution, but calls for a region-specific approach.

Identifying traits within indigenous and imported animal breeds and plant varieties that will make the best use of available resources allows development of production systems that match environmental, social and economic demands. Further implementation of continuous improvement and best management practices in developing countries is crucial in order to improve affluence, reduce population growth and mitigate environmental impact both now and in future. However, this is not a situation that can simply be solved by improving yield per acre, but requires a multifactorial approach coordinating population control, education, food security and human health and welfare. Providing contraception without a concurrent effort to improve agricultural productivity will fail in its prophylactic intent to control either population growth or world hunger.

Feed = Food? Do livestock really compete with humans for food?

Can we feed up to 10 billion people in 2100 by improving crop yields, reducing deforestation, and reducing meat and dairy consumption? These solutions are among those suggested by Jonathan Foley at the University of Minnesota’s Institute of the Environment to enable the increase in food production required by the future global population. These are logical suggestions, yet the proposal that meat and dairy consumption should be reduced is likely to be the most-debated, particularly as livestock industry stakeholders may regard this as yet another attack on animal agriculture.

The futility of the “Meatless Mondays” campaign has been discussed ad infinitum, yet in contrast to the EWG’s recent report, Foley does not attempt to promote a vegetarian or vegan ideology or to suggest that climate change could be reversed if only we all ate humanely-certified or organic meat. Instead, the report concludes that resources could be saved if we shifted to meat consumption towards pork and poultry production as:

…it takes 30 kilos [66 lb] of grain to produce one kilo [2.2lb] of boneless beef… We’re better off producing grass-fed beef or more chicken and pork, which requires far less grain feed

Based on those data, Foley’s conclusion is entirely logical. However, as Carl Sagan said, “Extraordinary claims require extraordinary evidence” – and here the evidence is lacking. A recent review of feed efficiency by Wilkinson reports that monogastric animals require 4.0 kg (swine) or 2.3 kg (poultry) of feed per kg of gain. Monogastrics are indeed considerably more efficient than their ruminant counterparts as beef animals require 8.8 kg feed per kg gain – considerably more than swine or poultry, but far less than Foley’s estimate.

It would be convenient to argue that the errors in Foley’s feed efficiency data (not to mention religious limitations on pork consumption) negate the report’s conclusions. But isn’t it logical to argue that we should eat meat produced in systems that use fewer resources to produce animal protein? Personally, I spend more than half my time traveling to present precisely that message to the animal industry and to encourage livestock producers to improve efficiency. I absolutely believe that we need to improve productivity and efficiency in order to feed the growing population. However, traditional feed efficiency data have a major flaw – it’s assumed that all animal feed could otherwise be used to feed humans.

Wilkinson suggests that the traditional concept of feed efficiency be re-examined to reflect the quantity of human-edible crop inputs that are used to produce a unit of energy or protein from animal products. For example, humans cannot digest pasture, only 20% of the nutritional value of oilseed meals can be utilized for human food and yet 80% of nutrients within cereals, pulses and soybean meal are human-edible. By partitioning out the human-edible component of animal feed, Wilkinson demonstrates that the human-edible energy feed efficiency ratios for pork and cereal beef are similar (Figure 1*) and that dairy production actually produces twice the amount of human-edible energy than it uses (input:output ratio of 0.5). On a protein basis, cereal beef has a higher human-edible protein feed efficiency ratio (3.0) than pork (2.6), but suckler beef systems where cattle are grazed on pasture again produce more human-edible protein than they consume (input:output ratio of 0.9, Figure 2*). Not only are these revised feed efficiency estimates considerably lower than those quoted by Foley, but they underline the importance of herbivorous grazing animals in utilizing human-inedible forage to produce animal protein.


Numbers have power – it’s always tempting to base a suggestion around a single data point that “proves” the argument. Feed efficiency is a useful metric, but as we face an ever-increasing challenge in balancing food demand, resource availability and consumer expectations, it’s critical that we examine the bigger picture. The ruminant animal has a major evolutionary advantage in its ability to digest forages – we may be better acquainted with the human dietary advantages of probiotic bacteria than our ancestors, but until we are equipped with human rumens (humens?) we cannot hope to effectively make use of all crop resources.

*The importance of acknowledging the human-edible component of feed efficiency was part of my presentation at the Alltech Ruminant Solutions Seminar in Ireland this week – to go to a PDF copy of my presentation please click here.