Species Matter

When exploring interventions and the direction of travel for feed sustainability, the discussion is complicated because of the vast differences across species and production systems.

Monogastric species – such as poultry, pigs and fish – are more reliant on grains and pulses that compete for land that could grow human food. Ruminant species – such as sheep, cattle and goats – rely more on grasses and forages that are inedible by humans. This is a simplistic but important differentiation.

The feed conversion ratio (FCR) is helpful to understand how efficiently animal feed is converted into food. While I’ve noted that feed for monogastrics can directly compete for land for food, Figure 9 shows that how these species are much more efficiency converters of feed.

However while useful, FCR is also imperfect when comparing between species. It is highly variable across farming systems and doesn’t take into account the nutritional quality of the end product, therefore misleading conclusions can be derived.

Figure 9. Comparing feed conversion ratios, which vary significantly by farming system. Aquaculture species are excluded from this dataset, but typically have a high feed efficiency, typically above poultry.

Monogastric Systems

The feeds fueling the rapid growth of monogastric livestock systems has been the expansion of intensively grown commodity crops such as corn and soy. This period of cropland expansion is beginning to slow and the feed industry faces increasing price volatility, complex trade dynamics and significant risks to future yields due to climate breakdown.

Figure 10. Large, monocultural farming systems dominate many farming landscapes today

Much of the feed innovation today focuses on efficiency gains. For example, feed supplements such as amino acids can help optimise diets and reduce soy dependency. Integrating food-waste into feedstocks or scaling novel, less land-intensive ingredients such as insects, algae and single-cell proteins. Many opportunities exist, although it is not clear which (if any) are capable of providing a wholesale replacement for the mainstream feed crops used today.

Integrating more regenerative or agroecological practices into the cropland for monogastric feedstocks is another opportunity. These farming systems tend to be more diversified, so this shift will be more compatible with a future where humans have greater crop diversity in their diets, and “less and better” animal protein.

 Figure 9. Contrasting two modern poultry systems: on the left, battery-cage layers. On the right, Kipster Farm (Netherlands), who aim to be most animal-friendly and environmentally-friendly poultry farm in the world.

Ruminant systems

Ruminants like beef get a bad stick. They have a poor feed conversion ratio, high water and land area requirements and have played a major role in driving deforestation (most newly-deforested land tends to be first put into beef production).

They also emit high rates of methane, a much more potent greenhouse gas than carbon dioxide but one that has a much shorter life in the atmosphere. This means their contribution to climate change over time is different to monogastric animals.

Ruminants have the advantage of being able to process protein inaccessible to humans. The impact of ruminant systems is highly variable depending on the practices adopted. Figure 11 contrasts two modern cattle systems. One is highly intensive, entirely reliant on external compound feeds that will include grains and pulses. The other is a low-intensity, grazing system, where feed is foraged from a managed landscape and the grazing is part of a system helping to restore degraded soil and increase biological diversity. Most farming systems sit somewhere in between, with varying feed management strategies.

In the more intensive ruminant systems, more reliant on compound feedstocks, there is some innovation on novel feed sources. Microbial proteins made from algae and yeast are showing promise in reducing cattle emissions. However as with the novel feedstocks for monogastrics, these innovations do not appear to be wholesale feed replacements.

Figure 11. Contrasting cattle production systems: a) Calves live in hutches at Bengbu Farm in Anhui Province, China. With at least 36,000 cows, it’s the largest dairy operation in the country, helping meet the rapidly increasing dairy consumption. Image credit: National Geographic. b) grazing cattle at Knepp Estate, a free-range, low-intensity system that has radically increased soil carbon and biodiversity.

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