The use of live insect larvae to improve sustainability and animal welfare in organic chicken production

Summary

It is known that worldwide meat consumption has drastically increased over the last decades, especially in developed countries. Indeed, recent studies show that animal-based proteins consumption increased on average from 61 g per capita per day in 1961 to 80 g per capita per day in 2011 (Sans et al.; 2015). This phenomenon is related to the rapid growth of global population, economic development of countries and urbanization (Godfray et al.; 2018). In
fact, not only are countries getting richer (therefore increasing GDP and gaining access to
foods that were once considered exclusive to the middle and upper class), but also meat is
getting cheaper and quicker to produce (Sans et al.; 2015).
Meat is now easier to produce mainly due to:
1) genetic selection of the animals: these animals are able to produce more in less time due
to higher adaptability, quicker development and better feed conversion ratio (FCR)
2) selection of feed: due to the high requirements of farmed animals, nowadays feeds pre-
sent high nutritional values and are especially high in proteins
3) innovative farming systems: thanks to the constant research, we can now increase the
welfare of farmed animals, therefore increasing productivity (Brameld et al.; 2016).
As stated before, meat consumption increased worldwide but some countries underwent
strong economic transitions and are now consuming more meat than other countries. Among
these, we can find Argentina, Australia, Brazil, Chile, China, New Zealand and U.S.A. The
only exception to this trend is India, where most of the population prevalently consumes a
vegetarian diet. This country doesn’t show any important change in meat consumption over
the last decades(www.ourworldindata.org). The type of meat consumed changes across each
country. On average, poultry and pork are the most consumed worldwide (www.fao.org).
In 2018 FAO estimated that roughly 69 billion chickens were slaughtered for meat produc-
tion. The countries with the highest poultry density are Brazil, China and U.S.A
(www.fao.org). With this data overview, it is interesting to understand why poultry meat is
largely consumed and why it is convenient to raise chickens for meat.
It is well known that chickens underwent an important selection within the past decades. The
same genetic stock can grow globally, under any type of husbandry conditions. Through the
genetic selection, the chickens’ weight has dramatically increased, yet the FCR has de-
creased (Brameld et al.; 2016).
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Chickens specifically reared for meat are called broilers. These animals underwent a strong
selection in order to reach market weight at a very young age as, broilers are slaughtered at
43 days of age, on average (Bianchi et al.; 2007). In 1985, broilers at 35 days of age required
3.22 kg of feed to reach a weight of 1.4 kg and had a FCR of 2.3. In 2010, broilers only required 3.66 kg of feed in order to reach a body weight of 2.44 kg at 35 days, with a FCR equal to 1.5 (Siegel et al.; 2014). In other words, modern broilers are able to produce more meat while consuming less feed.
This development obviously comes with health implications since artificial selection led to several health and welfare problems.
Broiler diseases may depend on their genetics and physiology. Moreover, also the farming
condition can affect diseases development. Among the several diseases that affect broilers
we can find:
1) Cardiovascular dysfunctions: broilers are selected to abnormally develop their breasts
and thighs. The organs, on the other hand, do not grow proportionally to the targeted
muscles. This incongruous ratio between energy-supplying and energy-consuming or-
gans leads to various metabolic disorders, such as ascites and “sudden death syndrome”
(Baghbanzadeh et al.; 2008).
a) Ascites (picture 2) is characterized by myocardial hypertrophy and dilatation, abnor-
mal liver function, pulmonary insufficiency, and hypoxemia (Luger et al.; 2003)
b) SDS (“sudden death syndrome”) mainly affects fast-growing chickens. Suddenly the
broiler, even though it appears to be healthy, flaps its wings, fallsto the side and dies.
This all happens under a minute (Newberry et al.; 1987). In Europe this syndrome
usually affects 3% of birds (Turner et al.; 2014).
2) Skeletal dysfunctions(picture 3): varus and valgus deformities, osteodystrophy, dyschon-
droplasia and femoral head necrosis are common in broilers. These dysfunctions lead to a
severe lameness in the chickens, inducing them to spend more time lying on the ground and
sleeping. If the broilers spend too much time lying down, under the abnormal weight of their
bodies, not only can they suffocate, but also, they will develop integument lesions (Juliani;
1998).
3) Integument lesions: these birds are often subjected to dermatitis (e.g.: hock burn, footpad
lesions), hyperkeratosis and necrosis of the epidermis (picture 4). This is not only due to the
poor blood circulation, but also due to the prolonged contact with the ammonia in the litter
(Greene et al.; 1985).
Another issue related to the production of poultry meat is its important environmental im-
pact. Feeding poultry requires a huge quantity of feed and these animals annually excrete
important amounts of nitrogen and phosphorus to the environment, which conditions the
production sustainability of this chain (Andretta et al., 2021). Nevertheless, poultry produc-
tion has been found to be relatively environmentally friendly compared to other livestock
productions, such as that of cattle. (Leinonen et al., 2016). The environmental impact of
poultry production can roughly be divided into feed production and transportation, housing
emissions and manure emissions.
One of the main critical aspects related to poultry production is the amount of feed necessary
to grow these animals. These feeds are particularly high in proteins, in order to satisfy the
high requirements of chickens. Poultry feeds are made of cereals and their by-products (e.g.:
corn, wheat, corn gluten meal), vegetable protein meals (such as soybean meal), oils, vita-
mins and minerals. The most important protein source in poultry feed is soybean, usually
given as a meal. This ingredient is high in proteins, low in fibers and high in lysine and
tryptophan (even if deficient in methionine). Soybean meal is relatively inexpensive com-
pared to other protein sources, such as corn gluten meal. The main issue related to soybean
isthat it has a strong impact on the environment, mainly due to the fact that in the past couple
of decades some areas around the world (like South America and South Asia) have been
converted from natural foreststo soya crops (Kastens et al.; 2017). Then this ingredient must
be transported to the feed mills around the world (mainly Europe, America and Asia). The
loss of ecosystem carbon storage as a consequence of such conversion was added to the
carbon dioxide emissions, therefore to the global warming potential arising from this system
(Leinonen et al; 2016).
For what concerns the housing emissions, recent studies show an important difference in
terms of emissions based on the type of housing system. Three systems were taken into
consideration: standard (indoor), free range and organic. Studies show that less intensive
poultry systems had higher environmental impacts compared to the more intensive ones
(Leinonen et al; 2016) in such way: organic systems have higher contributions in terms of
eutrophication potential and acidification potentials (due to the emissions of NH3 and N2O),
but extensive poultry production can reduce the use of fossil fuels, fertilizers and has lower
housing emissions (Leinonen et al.; 2016). Although organic systems show less manure in
the litter, it still has an environmental impact. On average, a single broiler excretes 0,6kg of
N and 0,1kg of P each year. The amount of N found in the uric acid, expresses as kg/year, is
equal to 0,5 (Rotz; 2004). Usually, poultry manure is used as a fertilizer, although it must be
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used with caution due to the high concentration of N, P and K. If used incorrectly, it could
severely damage the crops and it could lead to the excessive eutrophication and acidification
of the soil (Leinonen et al.; 2016).
Despite what preceded, how could we possibly reduce the environmental impact of poultry
meat production? Scientists all over the world are trying to find new farming strategies in
order to produce high quality meat with a lower environmental impact. Genetic selections,
as stated before, has improved the FCR of animals (chickens can now produce more while
eating less feed, at a faster rate), but the main ingredients in feed cannot be totally substituted
now. The main challenge nowadays is to find an appropriate substitute for soybean meal,
which is known to be the least environmental-friendly ingredient.
The purpose of the project POULTRYNSECT is to test the effects of live insect larvae on
slow and medium-growing organic chickens to allow sustainable meat production and to
improve animal welfare. Insect larvae are reared on organic food by-products and are used
as feed ingredient and environmental enrichment for chickens.

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