**3. Nutritional aspects of insect meals**

The proper way to go for the use of alternative ingredients in animal feed is to understand their nutritional characteristics (physical, chemical, and biological). Knowledge of these traits will be of paramount importance in assessing the potential for their use in animal feed, either as a substitute or complimentary. It is necessary to evaluate these ingredients in the diet of the animals, considering digestibility, performance, nutrient balance, carcass characteristics, economic results, and sustainability in the production chain.

The potential of insect use in animal and human food is mainly because there are more than 1 million known species. This generates innumerable possibilities and alternatives for its use; however, many studies are necessary since after identifying a species with potential, strategies should be created for production, reproduction, genetic evolution, and processing. The nutritional composition of several insect meals was compiled and divided into amino acid, bromatological composition, and fatty acid profile (**Table 1**).

Insect meal may have a high content of ethereal extract, and its variation influences the crude energy (kcal kg<sup>−</sup><sup>1</sup> ) of the diets, the energy:protein ratio, as well as the ethereal extract of the carcasses. Other authors have also reported high values of ethereal extract in insect meal that prevented the high inclusion of these in the diets [18]. High values of ethereal extract are premises for the occurrence of oxidation (rancidity) of fats, reducing the shelf life of this product. The inclusion of antioxidant additives in insect meals is suggested. A short-term solution would be to further develop preprocessing and manufacturing procedures to extract the excess lipid in the meals and then utilize it as a lipid source in feeds or in any other industry, approach already adopted to manufacture terrestrial animal by-product meals.

Some studies show large crude protein variation and ethereal extract between the same species, found 40% of crude protein and 25% of ethereal extract for tenebrio, lower value than other studies [24, 25] that reported crude protein values higher than 50%, but lower ethereal extract levels than in the present study. In this context, insects can be used as a source of protein and energy. The larval stage of insects usually has higher ethereal extract values, as these accumulate energy for metamorphosis. Its fatty acid profile is very variable, suggesting that as feed occurs modulation of the fatty acid profile of the insects, which may be a prelude to the inclusion of EPA (eicosapentaenoic acid, 20:5n-3) and DHA (docosahexaenoic acid, 22:6n-3) of lower quality ingredients. Roasted meal is an excellent source of protein (~66.84%), being superior to

**123**

**Species** *Phyllognathus excavates*

*Rhynchophorus ferrugineus*

*Tenebrio molitor*

*Zophoba morio* *Calliphora vicina*

*Chrysomya megacephala*

*Chrysomya megacephala*

*Eristalis tenax* *Hermetia illucens*

*Hermetia illucens*

*Lucilia sericata* *Lucilia sericata* *Musca domestica*

*Musca domestica*

*Protophormia terraenovae*

*Protophormia terraenovae*

*Acheta domestica*

*Anacridium aegyptium*

*Gryllus assimilis*

*Heteracris littoralis*

*Locusta migratoria*

Pupae Adult Adult Adult Adult Adult

4.0 ± 0.0

29.9 ± 0.5

58.5 ± 0.5

7.6 ± 0.1

6.33

0.54

4.28

36.4 ± 0.1

15.9 ± 0.4

5.1 ± 0.1

8.8 ± 0.0

74.4 ± 1.0

11.7 ± 1.0

6.01

1.02

3.9

27.7 ± 0.6

42.1 ± 0.1

4.8 ± 0.1

23.2 ± 0.6

64.9 ± 0.5

7.0 ± 0.3

6.46

1.1

4.11

34.0 ± 0.6

37.5 ± 0.3

3.7 ± 0.1

17.6 ± 0.2

66.0 ± 5.0

12.7 ± 4.8

5.73

2.36

4.49

30.3 ± 1.7

30.0 ± 0.7

5.6 ± 0.0

15.9 ± 0.2

73.1 ± 3.3

5.4 ± 0.3

6.16

1.49

4.1

34.2 ± 0.1

43.2 ± 0.1

8.8 ± 0.1

23.6 ± 0.3

56.0 ± 2.0

11.6 ± 2.2

7.89

2.55

4.83

26.6 ± 1.6

21.7 ± 0.2

Larvae (L3)

3.9 ± 0.1

28.3 ± 0.6

46.3 ± 0.6

21.5 ± 0.1

8.23

2.3

4.78

27.1 ± 0.2

21.9 ± 0.2

Pupae Larvae (L3) Larvae (L5)

Pupae Larvae (L3)

Pupae Larvae (L3)

Pupae

8.4 ± 2.9

33.7 ± 0.7

40.1 ± 0.4

17.8 ± 0.3

7.57

3.44

5.28

30.0 ± 1.1

7.5 ± 0.4

6.5 ± 1.5

31.3 ± 1.6

46.9 ± 4.1

15.3 ± 4.0

8.36

3

4.87

32.6 ± 0.1

7.6 ± 0.1

4.9 ± 0.2

26.6 ± 1.0

59.0 ± 1.5

9.5 ± 0.1

7.91

3.08

4.6

28.8 ± 0.4

11.0 ± 0.1

4.9 ± 0.9

28.4 ± 1.5

53.5 ± 4.4

13.2 ± 4.6

7.66

3.36

5.38

27.8 ± 0.1

9.5 ± 0.4

19.7 ± 0.1

15.6 ± 0.1

40.7 ± 0.4

24.0 ± 0.7

7.31

3.26

4.95

65.8 ± 0.1

1.1 ± 0.0

9.3 ± 0.3

18.0 ± 1.6

36.2 ± 0.3

36.5 ± 1.0

7.6

1.5

5.39

67.1 ± 0.6

15.9 ± 0.6

13.9 ± 0.4

5.8 ± 0.6

40.9 ± 0.9

39.4 ± 1.1

8.45

2.37

5.02

41.7 ± 1.4

1.6 ± 0.0

6.1 ± 0.1

16.5 ± 0.0

46.8 ± 1.1

30.6 ± 1.1

7.87

2.76

5.02

35.4 ± 0.6

26.2 ± 0.1

Larvae (L3)

7.2 ± 0.1

27.0 ± 3.2

61.8 ± 0.3

4.0 ± 3.4

8.53

2.22

4.51

35.9 ± 1.2

31.3 ± 0.7

Larvae Larvae Larvae Larvae

8.0 ± 0.1

20.1 ± 0.7

48.3 ± 0.9

23.6 ± 0.1

7.99

2.16

4.86

28.5 ± 0.2

28.0 ± 0.1

2.5 ± 0.3

38.0 ± 0.3

53.5 ± 0.4

6.0 ± 1.1

5.82

0.76

4.33

38.8 ± 0.2

24.0 ± 0.0

3.5 ± 0.2

30.1 ± 0.7

58.4 ± 0.4

8.0 ± 0.2

6.03

0.64

4.49

22.2 ± 0.1

31.5 ± 0.1

6.6 ± 0.6

11.8 ± 1.5

34.6 ± 0.3

47.0 ± 1.3

6.18

0.45

4

42.5 ± 0.4

13.0 ± 0.4

Adult

7.8 ± 0.2

15.9 ± 1.4

65.7 ± 1.3

10.6 ± 0.1

6.34

1.42

4.1

28.7 ± 3.0

11.8 ± 0.4

**Stage** **ASH %**

**EE %**

**CP %**

**NFE %**

**LYS**

**MET**

**THR**

**Satura.**

**Proximate analysis (% dry matter)**

**Amino acid (% total)**

**Fatty acid (% total)**

**Polyuns.**

*Insects in Aquaculture Nutrition: An Emerging Eco-Friendly Approach or Commercial Reality?*

*DOI: http://dx.doi.org/10.5772/intechopen.90489*


#### *Insects in Aquaculture Nutrition: An Emerging Eco-Friendly Approach or Commercial Reality? DOI: http://dx.doi.org/10.5772/intechopen.90489*

*Emerging Technologies, Environment and Research for Sustainable Aquaculture*

The proper way to go for the use of alternative ingredients in animal feed is to understand their nutritional characteristics (physical, chemical, and biological). Knowledge of these traits will be of paramount importance in assessing the potential for their use in animal feed, either as a substitute or complimentary. It is necessary to evaluate these ingredients in the diet of the animals, considering digestibility, performance, nutrient balance, carcass characteristics, economic

*Adult and larvae of* Tenebrio molitor *(A) and feeding with plastic (B). Source: A, available at* 

The potential of insect use in animal and human food is mainly because there are more than 1 million known species. This generates innumerable possibilities and alternatives for its use; however, many studies are necessary since after identifying a species with potential, strategies should be created for production, reproduction, genetic evolution, and processing. The nutritional composition of several insect meals was compiled and divided into amino acid, bromatological composition, and

Insect meal may have a high content of ethereal extract, and its variation

well as the ethereal extract of the carcasses. Other authors have also reported high values of ethereal extract in insect meal that prevented the high inclusion of these in the diets [18]. High values of ethereal extract are premises for the occurrence of oxidation (rancidity) of fats, reducing the shelf life of this product. The inclusion of antioxidant additives in insect meals is suggested. A short-term solution would be to further develop preprocessing and manufacturing procedures to extract the excess lipid in the meals and then utilize it as a lipid source in feeds or in any other industry, approach already adopted to manufacture terrestrial animal by-product meals. Some studies show large crude protein variation and ethereal extract between the same species, found 40% of crude protein and 25% of ethereal extract for tenebrio, lower value than other studies [24, 25] that reported crude protein values higher than 50%, but lower ethereal extract levels than in the present study. In this context, insects can be used as a source of protein and energy. The larval stage of insects usually has higher ethereal extract values, as these accumulate energy for metamorphosis. Its fatty acid profile is very variable, suggesting that as feed occurs modulation of the fatty acid profile of the insects, which may be a prelude to the inclusion of EPA (eicosapentaenoic acid, 20:5n-3) and DHA (docosahexaenoic acid, 22:6n-3) of lower quality ingredients. Roasted meal is an excellent source of protein (~66.84%), being superior to

) of the diets, the energy:protein ratio, as

**3. Nutritional aspects of insect meals**

*<plantascarnivoras.com.br> access 09/20/2016; B - [4].*

**Figure 1.**

results, and sustainability in the production chain.

fatty acid profile (**Table 1**).

influences the crude energy (kcal kg<sup>−</sup><sup>1</sup>

**122**


#### **Table 1.**

**125**

*Insects in Aquaculture Nutrition: An Emerging Eco-Friendly Approach or Commercial Reality?*

the main protein ingredients used in the formulation of diets for fish such as soybean meal, fishmeal, meat and bone meal, meal of viscera [32], and lower feather meal and

should be further investigated, especially when using foods with high levels of mycotoxins (residues). The mycotoxins, when is consumed by insects, besides being able to cause problems in the production, have the property of being bioaccumulative and being able to compromise the quality of insect meal and influence animal

**4. Practical developments: some examples on aquaculture nutrition**

Many studies have been carried out to evaluate the use of insects in animal feed, including aquaculture. A study was performed with house fly larvae (*Musca domestica*) as a complimentary source of protein in Nile tilapia (*Oreochromis niloticus*) feeds. The authors observed superior growth rates (~3.76%/day) and reduced feed conversion ratio (1.05) possibly due to a better amino acid profile in this protein blend containing (28% fish meal, 25% house fly larvae, and 12% soy meal) [18]. In addition, the authors reported a high content of lipid (19.8%) in fly larvae, which should be considered when formulating diets. In a similar work, the replacement of 50–60% of fish meal by fly larvae meal (*Musca domestica*) in the feeding of tilapia fingerlings provided adequate growth and performance for the animals [20].

For feeding of African catfish (*Clarias gariepinus*), the larvae of flies have shown to be viable for their use [19]. However, the same positive response was not achieved by using butterfly larvae (*Bematistes macaria*) for feeding of African catfish, under experimental conditions [21]. The partial replacement of 40% fish meal with tenebrio meal for African catfish displayed no differences [22]. The animals have grown as well or better than those fed on the commercial diet. By partially replacing 25% of the fish meal with the tenebrio meal in gilthead seabream (*Sparus aurata*), no differences in weight gain and final weight were noticed [23]. However, for the 50% replacement level reduction in growth and specific growth rate, an increase in feed conversion was observed. One study tested levels of 25 and 50% of fish meal replacement by teneral flour for rainbow trout (*Oncorhynchus mykiss*) [34]. The results showed that there was no difference in performance and growth until the

For European juvenile sea bass (*Dicentrarchus labrax*), the inclusion of tenebrio meal at 25% had no adverse effects, but at 50% inclusion rate, the specific growth rate was reduced [35]. The use of tenebrio meal for Nile tilapia in partial replacement of fish meal at 25 and 50% levels reduced fish growth by around 29% [10]. According to the authors, the use of tenebrio meal for tilapia cannot be used in high proportions, because it is necessary to understand better the role of chitin in digestion and a better detection of possible toxins that can affect the growth of the fish. Another hypothesis may be related to the digestibility of tenebrio (FLT) meal, which in the form of the larvae's composition can influence its digestibility [36]. Studies evaluating the replacement of fish meal with giant tenebrio (*Zophobas morio*) for Nile tilapia obtained better feed conversion ratio and weight gain than the control, with ideal replacement value of 25%, which corresponded to 7.5% of

Low survival rates were reported by other authors who worked with insect meal,

for example, house fly larvae [38, 39] and tenebrio meals. The level of inclusion above 45% reduced survival to 70% [18]. The 50% fish meal replacement with FLT fish for common catfish (*Ameiurus melas* Raf.) resulted in inferior performance and

inclusion of 50% (isoprotein diets with 45% crude protein) [34].

inclusion of giant tenebrio meal in the feed [37].

In terms of nutritional profile, the use of organic residues for insect production

blood meal, which rely on processing to improve their digestibility [32].

*DOI: http://dx.doi.org/10.5772/intechopen.90489*

performance.

*Proximate analysis, amino acids (lysine, methionine, and threonine), and fatty acid (saturated and monounsaturated fatty acids) of selected insects, fish meal, and soybean meal. Values were based on [33].* *Insects in Aquaculture Nutrition: An Emerging Eco-Friendly Approach or Commercial Reality? DOI: http://dx.doi.org/10.5772/intechopen.90489*

the main protein ingredients used in the formulation of diets for fish such as soybean meal, fishmeal, meat and bone meal, meal of viscera [32], and lower feather meal and blood meal, which rely on processing to improve their digestibility [32].

In terms of nutritional profile, the use of organic residues for insect production should be further investigated, especially when using foods with high levels of mycotoxins (residues). The mycotoxins, when is consumed by insects, besides being able to cause problems in the production, have the property of being bioaccumulative and being able to compromise the quality of insect meal and influence animal performance.

#### **4. Practical developments: some examples on aquaculture nutrition**

Many studies have been carried out to evaluate the use of insects in animal feed, including aquaculture. A study was performed with house fly larvae (*Musca domestica*) as a complimentary source of protein in Nile tilapia (*Oreochromis niloticus*) feeds. The authors observed superior growth rates (~3.76%/day) and reduced feed conversion ratio (1.05) possibly due to a better amino acid profile in this protein blend containing (28% fish meal, 25% house fly larvae, and 12% soy meal) [18]. In addition, the authors reported a high content of lipid (19.8%) in fly larvae, which should be considered when formulating diets. In a similar work, the replacement of 50–60% of fish meal by fly larvae meal (*Musca domestica*) in the feeding of tilapia fingerlings provided adequate growth and performance for the animals [20].

For feeding of African catfish (*Clarias gariepinus*), the larvae of flies have shown to be viable for their use [19]. However, the same positive response was not achieved by using butterfly larvae (*Bematistes macaria*) for feeding of African catfish, under experimental conditions [21]. The partial replacement of 40% fish meal with tenebrio meal for African catfish displayed no differences [22]. The animals have grown as well or better than those fed on the commercial diet. By partially replacing 25% of the fish meal with the tenebrio meal in gilthead seabream (*Sparus aurata*), no differences in weight gain and final weight were noticed [23]. However, for the 50% replacement level reduction in growth and specific growth rate, an increase in feed conversion was observed. One study tested levels of 25 and 50% of fish meal replacement by teneral flour for rainbow trout (*Oncorhynchus mykiss*) [34]. The results showed that there was no difference in performance and growth until the inclusion of 50% (isoprotein diets with 45% crude protein) [34].

For European juvenile sea bass (*Dicentrarchus labrax*), the inclusion of tenebrio meal at 25% had no adverse effects, but at 50% inclusion rate, the specific growth rate was reduced [35]. The use of tenebrio meal for Nile tilapia in partial replacement of fish meal at 25 and 50% levels reduced fish growth by around 29% [10]. According to the authors, the use of tenebrio meal for tilapia cannot be used in high proportions, because it is necessary to understand better the role of chitin in digestion and a better detection of possible toxins that can affect the growth of the fish. Another hypothesis may be related to the digestibility of tenebrio (FLT) meal, which in the form of the larvae's composition can influence its digestibility [36]. Studies evaluating the replacement of fish meal with giant tenebrio (*Zophobas morio*) for Nile tilapia obtained better feed conversion ratio and weight gain than the control, with ideal replacement value of 25%, which corresponded to 7.5% of inclusion of giant tenebrio meal in the feed [37].

Low survival rates were reported by other authors who worked with insect meal, for example, house fly larvae [38, 39] and tenebrio meals. The level of inclusion above 45% reduced survival to 70% [18]. The 50% fish meal replacement with FLT fish for common catfish (*Ameiurus melas* Raf.) resulted in inferior performance and

*Emerging Technologies, Environment and Research for Sustainable Aquaculture*

**124**

**Species** Fish meal

Soybean meal

—

—

*Polyuns., polyunsaturated fatty acids, all fatty acids ≥2 double bonds.*

**Table 1.** *based on [33].*

7.8 ± 0.0

3.0 ± 0.0

50.4 ± 0.2 *EE, ethereal extract; CP, crude protein; NFE, nitrogen-free extract, includes fiber; LYS, lysine; MET, methionine; THR, threonine; Satura., saturated fatty acids, all fatty acids without double bonds;* 

*Proximate analysis, amino acids (lysine, methionine, and threonine), and fatty acid (saturated and monounsaturated fatty acids) of selected insects, fish meal, and soybean meal. Values were* 

38.8 ± 0.3

6.34

1.01

4.17

24.0 ± 1.9

55.4 ± 0.8

18.0 ± 0.2

8.2 ± 0.0

73.0 ± 0.8

0.8 ± 0.7

8.78

2.93

6.26

36.1 ± 1.1

37.3 ± 0.0

**Stage** **ASH %**

**EE %**

**CP %**

**NFE %**

**LYS**

**MET**

**THR**

**Satura.**

**Polyuns.**

**Proximate analysis (% dry matter)**

**Amino acid (% total)**

**Fatty acid (% total)**

survival, dropping of approximately 9% compared to the control (0% FLT) [40]. In contrast in rainbow trout, there was an increased survival with the inclusion of FLT but lower performance, digestibility, and alteration in the fillet fatty acid profile [24]. Jointly, these data suggest that in the early stages, FLT influences survival that is not pronounced in the final stages. In European juvenile sea bass (*Dicentrarchus labrax*), the inclusion of 25% FLT did not affect growth performance, while a higher inclusion level (50%) compromised the weight gain [25]; similar results were obtained in gilthead seabream juveniles, which included inclusions of 25–50%, compromising weight gain, specific growth rate, feed conversion efficiency, and protein efficiency ratio [23].

For tilapia [27], used the white larvae dry meal to formulate isonitrogenous and isoenergetic diets with maggot meal inclusions at 0, 30, 50, and 80 g/kg substituting gradually three conventional expensive feedstuffs: fish meal, fish oil, and soybean meal. The results showed no significant difference in growth parameters (final weight, weight gain, and SGR) and feed utilization efficiency (FCR and PER and feed intake) between treatments. Similarly fish whole body composition (dry matter, crude protein, lipid, ash, and fiber) was unaffected by the treatments except the fatty acid compositions which mirrored that of the diets. The cockroach (*Nauphoeta cinerea*) meal has also been tested for Nile tilapia with very promising results including superior zootechnical performance as compared to control diets [26].

Insect meals have also been evaluated in biofloc technology system [41–45]. As this system exhibits a series of particularities that separate it from the traditional clear and green water production systems such as recirculating aquaculture system, flow-throw, cages, and ponds, the following findings should be considered within the biofloc context and carefully extrapolated to other production systems. Levels higher than 10% of cockroach meal inclusion decrease the performance of the Nile tilapia juvenile in biofloc technology system, which may be related to the composition of the exoskeleton of the cockroach, especially chitin combined with sclerotin, which confers resistance and flexibility [41].

The use of tenebrio meal at 10% inclusion rate in the nursery stage of Nile tilapia in biofloc technology system did not affect the performance, somatic, hematological, and carcass composition indexes [42, 44]. Inclusion levels higher than 10% decreased productivity and survival and increased hepatosomatic index and lipid content, and in the carcass, consequence of the high lipid content and antinutritional factors is present in the tenebrio meal. Differently from the previous findings, a trial investigating gradual inclusion levels (0, 5, 10, 15, and 20%) of cockroach and tenebrio meal, individually, with *Litopenaeus vannamei* in biofloc technology system, concluded that juvenile shrimp accepted up to 15% of cockroach meal and up to 5% tenebrio meal [43, 45]. There is also a growing interest on the use of insects in shrimp feeds, as seen by several papers lately [46–50]. For additional and more scientific information, there are several papers on this topic [16, 51–54].

#### **4.1 Constraints and future perspectives**

Besides the cost and reliable commercial scale production, the diversity in terms of nutritional profile is considered one of the major issues of insect meal inclusion in aqua feeds. Some constraints were already discussed such as (i) excess lipid, (ii) amino acid imbalance, (iii) the presence of mycotoxins and possible antinutritional factors such as chitin [10], and the endogenous production of 1,4-benzoquinone toxin [55]. These isolated or combined factors may compromise the animal's immune system [10] and survival rates [56].

**127**

diets.

acceptance.

followed.

**5. Conclusion**

*Insects in Aquaculture Nutrition: An Emerging Eco-Friendly Approach or Commercial Reality?*

Chitin is an acetylated aminopolysaccharide similar to cellulose, but with a greater number of hydrogen bonds established with adjacent polymer chains, this confers extra resistance [56], which suggests greater difficulty in digestion. Tilapia fed diets with chitin and purified chitosan had impaired weight gain and feed conversion, and the chitin level of 2% was already harmful [57]. In addition, insects

and when included in a ratio of 10%, inclusion will represent ~0.74% of dietary chitin, and for 20% inclusion will represent 1.50% of dietary chitin reaching critical levels. Some authors related high chitin levels with the reduction of feed consumption, availability of nutrients, and negative effects on performance [10, 22, 42, 44]. In this sense, it is fundamental to better understand the factors that limit the inclusion of insect meal into diets, either antinutritional or nutritional limit factors. Costeffective formulations that met all animal requirements and selection of the other ingredients are crucial for good results. The diets isonitrogenous and isoenergetic with similar amino acids and fatty acids profile that met the nutritional requirement of the target species are fundamental points when comparing insect meal-based

But one question remains unanswered: does insect in aquaculture nutrition a future eco-friendly approach or a commercial reality? The answer depends on the industry. For salmon, one of the biggest and high-value chain aquaculture sectors, the insect meal already offers an alternative to fish meal and soya in early stages of salmon production [46, 49, 50]. An example such as Skretting in Norway observed that fish showed the same zootechnical performance with feeds using insect meal as with traditional protein sources. The diets were normally made from the larvae of the black soldier fly. This feedstuff is an EU-approved commodity, and recent surveys show that Norwegian consumers are positive to eating salmon that has had insect meal in the feed formulation. In the future, an educational approach (e.g., focused on the blue economy) will play a major role to increase consumers'

In order for such eco-friendly approach to reach another level, the industrial

The use of insect meal in animal feed has been the subject of research, but the results are varied and divergent. Much is explained by the nutritional variability of insect meal production. In addition to knowing the nutritional values of insects, we must consider the study of insect nutrition, since depending on the species we can modulate the fatty acid profile with EPA and DHA and amino acid profile, mainly in the lysine, methionine, threonine, and tryptophan ratios. Understanding better

production of insect meal must be increased to meet the actual aquaculture demand. For example, in the European market, there is now little available insect meal for use on a large scale. To supply the feed mill demand, companies need to work together with manufacturers who wish to come up at a commercial level [46, 49, 50]. According to [46, 49, 50], by 2022 there will be at least five different European suppliers, each producing 20,000 tonnes of insect meal per year, that is, two thirds of the amount of soybean concentrate Skretting Norway uses today. In regard to other industries, although tests were successfully performed with tilapia [18, 27, 36, 37] and *L. vannamei* [46–50], the use of insects in a short-term due to massive volumes of feed demand for these industries is unlikely. The salmon example applying insects in early stages of production is one alternative that will be

of body chitin [57]. The estimation done by

of chitin in *Nauphoeta cinerea* meal,

*DOI: http://dx.doi.org/10.5772/intechopen.90489*

have between 11.6 and 137.2 mg kg <sup>−</sup><sup>1</sup>

[56] indicated an average value of 74.4 mg kg<sup>−</sup><sup>1</sup>

#### *Insects in Aquaculture Nutrition: An Emerging Eco-Friendly Approach or Commercial Reality? DOI: http://dx.doi.org/10.5772/intechopen.90489*

Chitin is an acetylated aminopolysaccharide similar to cellulose, but with a greater number of hydrogen bonds established with adjacent polymer chains, this confers extra resistance [56], which suggests greater difficulty in digestion. Tilapia fed diets with chitin and purified chitosan had impaired weight gain and feed conversion, and the chitin level of 2% was already harmful [57]. In addition, insects have between 11.6 and 137.2 mg kg <sup>−</sup><sup>1</sup> of body chitin [57]. The estimation done by [56] indicated an average value of 74.4 mg kg<sup>−</sup><sup>1</sup> of chitin in *Nauphoeta cinerea* meal, and when included in a ratio of 10%, inclusion will represent ~0.74% of dietary chitin, and for 20% inclusion will represent 1.50% of dietary chitin reaching critical levels. Some authors related high chitin levels with the reduction of feed consumption, availability of nutrients, and negative effects on performance [10, 22, 42, 44]. In this sense, it is fundamental to better understand the factors that limit the inclusion of insect meal into diets, either antinutritional or nutritional limit factors. Costeffective formulations that met all animal requirements and selection of the other ingredients are crucial for good results. The diets isonitrogenous and isoenergetic with similar amino acids and fatty acids profile that met the nutritional requirement of the target species are fundamental points when comparing insect meal-based diets.

But one question remains unanswered: does insect in aquaculture nutrition a future eco-friendly approach or a commercial reality? The answer depends on the industry. For salmon, one of the biggest and high-value chain aquaculture sectors, the insect meal already offers an alternative to fish meal and soya in early stages of salmon production [46, 49, 50]. An example such as Skretting in Norway observed that fish showed the same zootechnical performance with feeds using insect meal as with traditional protein sources. The diets were normally made from the larvae of the black soldier fly. This feedstuff is an EU-approved commodity, and recent surveys show that Norwegian consumers are positive to eating salmon that has had insect meal in the feed formulation. In the future, an educational approach (e.g., focused on the blue economy) will play a major role to increase consumers' acceptance.

In order for such eco-friendly approach to reach another level, the industrial production of insect meal must be increased to meet the actual aquaculture demand. For example, in the European market, there is now little available insect meal for use on a large scale. To supply the feed mill demand, companies need to work together with manufacturers who wish to come up at a commercial level [46, 49, 50]. According to [46, 49, 50], by 2022 there will be at least five different European suppliers, each producing 20,000 tonnes of insect meal per year, that is, two thirds of the amount of soybean concentrate Skretting Norway uses today. In regard to other industries, although tests were successfully performed with tilapia [18, 27, 36, 37] and *L. vannamei* [46–50], the use of insects in a short-term due to massive volumes of feed demand for these industries is unlikely. The salmon example applying insects in early stages of production is one alternative that will be followed.
