Livestock and its positive impact on the environment or how recycling started

10,000 years ago the most impactful change ever took place: domestication of plants and animals.

Hunting was a dangerous activity: animals could attack the hunters, it was very tiring: hunters had to walk or run long miles pursuing the preys, it may yield poor results as many times hunters came back empty handed and too many times it was low productive as any leftover would rot very quickly.

Figure 1: Hunting scene in a pre-historic painting

That’s why, when humankind managed to domesticate animals, many problems were solved in one shot. Suddenly, people started to have a more reliable source of protein, it was no longer dangerous because only animals who put up with people’s proximity would become domestic and, finally, animals were slaughtered only when their use could be maximized and not left overs were going to be lost.

Figure 2. Goats manage to feed on poor, barren lands where only a few dry grasses grow.

They transform these plants into rich, wholesome, high quality protein in the form of milk and meat.  

Animal protein became available whenever it was needed. Meat was a really coveted asset as it contains all the essential amino-acids, B group vitamins, iron, selenium, calcium and, more generally a very digestible and bio available protein. Milk, eggs and meat could be eaten at any time, without risks and what was even better: they were almost free.

Figure 4: Hogs festing on discarded leaves and potatoes

Domestic animals lived on grass or on any inedible by products that the tribe produced: fruit peels, pulps, rotten tubers, intestines, skins and even excrements of other animals, egg shells, any wormed veggie and so on. In a few months, that piglet or calf would become a fatty animal on which the tribe would fest. Hunting was no longer necessary and that allowed for a lot of free time that permitted individuals to devote it to writing, reading, painting and developing all the arts and science. Without coprophage pigs, we wouldn’t have today the Sistine chapel or Notre Dame in Paris. Neither Galileo or Newton would have been able to make their scientific discoveries.

Today, livestock continues to be the recycling factor in our food chain. According to FAO estimates, 86% of what livestock eats is not edible by humans. Think of a corn field, if a farmer harvests 200 bushels/acre of grain, that same farmer will harvest 5 times that amount in stalks, the inedible (for humans) stems of the plants. All that would be lost, but thanks to livestock –in this particular case mostly dairy cows- it will be processed as silage, fed to the cows and transformed into rich, complete food such as milk or meat. The meal that results from extracting oil from soybeans (85% of soybeans are milled for oil as their oil is the most used in the world for cooking) will be added to chicken and pig feed. Beet and sugar cane pulp will have the same destination once sugar is extracted from these plants. Also, the by-products from beer and alcohol industry will be used as feed for animals.

Figure 4: On the left corn plants. Without cows the stalks would have to be destroyed.

On the right, by products of beer production, also used as feed for animals.

Without livestock 6,000 millions of tons of vegetal by-products would have to be destroyed with the consequent impact on the environment. However, livestock transform those –for us- useless plant parts and transform them into rich, bio-available, complete proteins, vitamins, minerals and certain key fatty acids such as araquidónique  and eicosapentanoic.

Again today, as it happened in pre-history, from useless materials, animals deliver excellent top quality food in the form of meat, eggs, milk and other valuable products such as leather, wool or other valuable assets very coveted by many industries. Everything is used from animals, nothing is left, here a few examples illustrate this point:

Intestinal mucus from pigs is used to synthesize heparin an anti-clogging medicine, animal bones will be used as fertilizers or will be processed to obtain collagen that will be used to produce glue. Here a short TED talk that explains the myriad of uses that a pig carcass can deliver:

On top of that, many animal parts that we don’t eat are also used as pet food. Also important to consider the manure that livestock produce will be key to fertilize the fields (4 x 109 Kg of nitrogenous fertilizers only in the US). Moreover, livestock has other functions in other regions. For example, it is used as traction force to plough the fields. it has also an important role to avoid the growth of too much bush that puts the fields at risks of fire.



Figure 5: From left to right: parmigiano cheese, parma ham and curdled cheese with whey at the bottom

I would like to put an end to this article with an example that illustrates the recycling power of pigs:

Parma region is renowned for two excellent, lovely foods: Parmigiano cheese and Parma ham. What probably most don’t know is that both products are intimately related and that this ham wouldn’t exist without the influence of cows.

In order to produce 2lb of this great cheese, manufacturers need 4 gallons of milk. Once the cheese solidifies, there is some liquid that remains. This liquid, called whey, still has some proteins and fats that make it pretty interesting from a nutritional perspective. Food was very scarce in the Middle Ages and nobody wanted to through away this rich liquid. That’s why some cheese producers started to feed pigs with it. This is, still today, a key component of pigs feed in that region. Nothing is lost, everything can be recycled and livestock recycle really a lot.

No, livestock is not a threat to the environment, quite the opposite: they use millions of tons of waste into rich, digestible, nutritious, affordable food that thanks to this virtuous circle arrives to our tables.


Jessica R Baber, Jason E Sawyer, Tryon A Wickersham; Estimation of human-edible protein conversion efficiency, net protein contribution, and enteric methane production from beef production in the United States, Translational Animal Science, 2018. Oxford University Press

Livestock: On our plates or eating at our table? A new analysis of the feed/food debate Global Food Security 14 (2017) 1–8

Anne Mottet. Nutritional and greenhouse gas impacts of removing animals from US agriculture Robin R. Whitea. Proceedings of the National Academy of Sciences. 2017

Peter Golbitz, Using Soy in Food Products:challenges and Opportunities, 2007

Christien meindertsma. Pig 05049. 2007

Osoro, Koldo, et al. Los pastos permanents: importancia, dinámica y necesidades de actuación para su sostenibilidad. 2016. Boletín informativo del SERIDA, nº 17, pp 34-40

PROSCIUTTO DI PARMA DENOMINAZIONE DI ORIGINE PROTETTA (Disciplinare Generale e Dossier di cui all’articolo 4 del Regolamento CEE n° 2081/92 del Consiglio del 14 luglio 1992)

Smil, V. Feeding the world. Massachusetts Institute of Technology. 2002


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