With global warming and environment destruction by the expansion of industry, the land area intended for food production is successively shrinking (11, 43). This situation urges the search for alternative food sources, with the most attention being paid to insects, which are perceived as food of the future (32). This claim is justified because insects have high contents of protein, fat, carbohydrates, fibre, minerals, amino acids and fatty acids, and offer an excellent production efficiency compared to other conventional food groups (21, 51). It is also worth emphasising that edible insects represent a source of many bioactive substances (29). These include chitin, which – as a polysaccharide – accounts for 5–20% of the dry weight of insects and may play an important role as dietary fibre (30). In addition, insects provide multiple peptides exhibiting antibacterial, antifungal and antiprotozoal activity (7, 39); therefore, they can mitigate the growing problem of drug resistance of microorganisms (6, 34). Furthermore, they contain peptides that inhibit the angiotensin-converting enzyme, thereby reducing blood pressure (46, 48), as well as antioxidant enzymes (4) and endopeptidases effective in the treatment of coeliac disease (12). Nevertheless, as van Huis and Oonincx (43) claimed, the nutritional value of insects varies depending on their diet, stage of development, sex, species or the environment they inhabit.
While edible insects are included in the multifaceted strategy of ensuring global food security and environmental sustainability of food production (where their merits are low greenhouse gas emissions, high feed conversion efficiency, low land use, and their ability to transform low-value organic side streams into high-value protein products) (42), their high nutritional value, minimal space requirements, and low environmental impact also make them an attractive option as an animal feedstuff (5, 45). In addition, insect-based animal feeds are particularly attractive in terms of price, especially because the cost of standard feeds accounts for around 70% of livestock production costs today (44). This motivates more and more researchers to address the use of insects as a protein-rich component of feed mixtures for poultry, pigs, and fish (3, 17–19, 27, 33, 35, 37, 45, 47, 49).
Although approximately 2,000 insect species are consumed in at least 113 countries (50), the most thoroughly analysed species that are potentially suitable for mass production for feedstuff purposes are only two,
The literature data indicate that further research is necessary to more fully evaluate the possibility of deploying insects in animal nutrition and to assess the impact of such a diet on animal health. Therefore, this study was undertaken feeding broiler chickens a diet containing different proportions of full-fat HI larvae meal as substitutes for the protein of genetically modified soybean meal to assess its impact on their health and selected elements of their humoral and cellular immunity.
Ingredient composition and nutrient content of complete diets (g/kg, as-fed basis) with or without full-fat
Item | Diet | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Starter (1–14 dol) | Grower (15–35 dol) | Finisher (36–42 dol) | |||||||||||
HI-0 | HI-50 | HI-75 | HI-100 | HI-0 | HI-50 | HI-75 | HI-100 | HI-0 | HI-50 | HI-75 | HI-100 | ||
Substitution1 (%) | 0 | 50 | 75 | 100 | 0 | 50 | 75 | 100 | 0 | 50 | 75 | 100 | |
Ingredients | |||||||||||||
Corn | 300.0 | 300.0 | 300.0 | 300.0 | 300.0 | 300.0 | 300.0 | 300.0 | 200.0 | 200.0 | 200.0 | 200.0 | |
Wheat | 288.0 | 303.6 | 288.1 | 274.6 | 315.6 | 330.3 | 319.0 | 311.2 | 467.6 | 494.6 | 489.6 | 484.1 | |
Soybean meal | 340.0 | 170.0 | 85.0 | 0.0 | 300.0 | 150.0 | 75.0 | 0.0 | 240.0 | 120.0 | 60.0 | 0.0 | |
Soybean oil | 30.0 | 0.0 | 0.0 | 0.0 | 45.0 | 25.0 | 30.0 | 25.0 | 55.0 | 35.0 | 30.0 | 25.0 | |
HI larvae meal | 0.0 | 200.0 | 300.0 | 400.0 | 0.0 | 170.0 | 250.0 | 340.0 | 0.0 | 130.0 | 200.0 | 270.0 | |
Monocalcium phosphate | 15.0 | 4.0 | 4.0 | 3.0 | 13.0 | 4.0 | 4.0 | 3.0 | 12.0 | 3.0 | 3.0 | 3.0 | |
Fodder chalk | 12.5 | 6.0 | 6.0 | 4.0 | 12.5 | 6.0 | 6.0 | 4.0 | 12.5 | 4.0 | 4.0 | 4.0 | |
Sodium bicarbonate | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | |
Fodder salt | 2.0 | 0.5 | 0.5 | 0.5 | 2.0 | 1.0 | 0.0 | 0.0 | 2.0 | 0.5 | 0.0 | 0.0 | |
L-Lysine HCl | 2.5 | 4.2 | 4.5 | 6.0 | 2.5 | 3.5 | 5.7 | 6.5 | 1.8 | 3.0 | 3.5 | 4.0 | |
DL-Methionine | 2.4 | 2.8 | 3.0 | 3.0 | 1.6 | 1.7 | 1.9 | 1.9 | 1.2 | 1.5 | 1.5 | 1.5 | |
L-Threonine | 0.2 | 1.5 | 1.5 | 1.5 | 0.4 | 1.0 | 1.0 | 1.0 | 0.5 | 1.0 | 1.0 | 1.0 | |
Choline chloride | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | |
Mineral-vitamin premix2 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | |
Calculated nutrient content | |||||||||||||
AMEN, kcal/kg | 3,000 | 3,000 | 3,000 | 3,000 | 3,120 | 3,120 | 3,120 | 3,120 | 3,180 | 3,180 | 3,180 | 3,180 | |
Total protein4 | 233.6 | 238.1 | 237.8 | 237.2 | 213.8 | 218.2 | 214.9 | 216.3 | 196.1 | 192.5 | 194.5 | 195.0 | |
Lysine3 | 13.5 | 13.5 | 13.5 | 13.5 | 11.7 | 11.8 | 11.8 | 11.8 | 10.0 | 10.0 | 10.0 | 10.0 | |
Methionine3 | 6.3 | 6.4 | 6.7 | 6.7 | 5.9 | 6.0 | 6.0 | 6.0 | 4.7 | 4.9 | 5.0 | 5.0 | |
Met+ Cys3 | 10.1 | 10.2 | 10.2 | 10.3 | 9.5 | 9.6 | 9.6 | 9.6 | 7.5 | 7.7 | 7.7 | 7.7 | |
Threonine3 | 8.2 | 8.2 | 8.4 | 8.4 | 8.2 | 8.4 | 8.4 | 8.4 | 6.8 | 7.0 | 7.0 | 7.1 | |
Tryptophan3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.2 | 2.1 | 2.2 | 2.1 | 2.1 | 2.0 | 2.0 | 2.0 | |
Crude fibre4 | 28.8 | 32.4 | 31.3 | 34.2 | 27.8 | 35.3 | 35.6 | 35.8 | 27.8 | 30.5 | 31.7 | 31.2 | |
Crude fat4 | 50.3 | 74.0 | 93.5 | 131.5 | 64.9 | 75.6 | 105.7 | 125.7 | 75.8 | 82.2 | 104.3 | 119.1 | |
Total calcium3 | 10.0 | 10.0 | 9.9 | 9.9 | 9.4 | 9.4 | 9.3 | 9.3 | 8.8 | 8.8 | 8.6 | 8.6 | |
Available phosphate3 | 4.8 | 4.9 | 4.9 | 4.9 | 4.5 | 4.6 | 4.6 | 4.6 | 4.0 | 4.1 | 4.1 | 4.1 | |
Na3 | 1.7 | 1.7 | 1.8 | 1.8 | 1.7 | 1.6 | 1.6 | 1.6 | 1.7 | 1.6 | 1.6 | 1.6 |
1 – Substitution of proteins from genetically modified soybean meal with processed insect protein derived from farmed
2 – Premix composition on days 1–35: 2,400,000 IU of vitamin A; 600,000 IU of vitamin D3; 10,000 IU of vitamin E; 600 mg of vitamin K3; 400 mg of vitamin B1 1,400 mg of vitamin B2; 6,000 mg of niacin (B3); 2,800 mg of pantothenic acid; 800 mg of vitamin B6; 5,000 μg of vitamin B12; 30,000 μg of biotin; 80,000 mg of choline chloride; 300 mg of folic acid; 14,000 mg of iron; 20,000 mg of manganese; 2,400 mg of copper; 12,000 mg of zinc; 200 mg of iodine; 80 mg of cobalt; 50 mg of selenium; 5,000 mg of antioxidant; 240 g of calcium; 14,000 mg of salinomycin coccidiostat. Premix composition on days 36–42: 1,800,000 IU of vitamin A; 600,000 IU of vitamin D3; 7,500 IU of vitamin E; 300 mg of vitamin K3; 300 mg of vitamin B1; 1,000 mg of vitamin B2; 4,000 mg of niacin (B3); 2,800 mg of pantothenic acid; 600 mg of vitamin B6; 4,000 μg B12; 24.000 μg of biotin; 80,000 mg of choline chloride; 300 mg of folic acid; 14,000 mg of iron; 20,000 mg of manganese; 2,400 mg of copper; 12,000 mg of zinc; 200 mg of iodine; 80 mg of cobalt; 50 mg of selenium; 5,000 mg of antioxidant; 340 g of calcium
3 – Calculated according to Polish feedstuff analysis tables (40)
4 – Values analytically evaluated according to standard methods (1)
DL – dextro- and levorotatory; L – levorotatory; AMEN – Apparent metabolisable energy corrected to zero nitrogen balance; Met – methionine; Cys – cysteine
The dietary formulae in Table 1 were used to produce experimental feed mixture pellets at the Gorzyń Experimental Department of Animal Feeding, Poznań University of Life Sciences (Poznań, Poland). The full-fat HI larvae meal was obtained from a commercial producer (HiProMine S.A., Robakowo, Poland). The composition and energy value of full-fat HI larvae meal are shown in Table 2.
Ingredient composition and energy value of full-fat
Ingredients | % |
---|---|
Dry matter | 93.20 |
Crude protein | 40.76 |
Crude fat | 29.38 |
Crude fibre | 6.65 |
Crude ash | 6.94 |
Ca | 1.38 |
Na | 0.23 |
Total P | 0.78 |
Energy value | MJ/kg |
Gross energy | 24.81 |
AMEN | 18.16 |
AMEN – Apparent metabolisable energy corrected to zero nitrogen balance
Production parameters of broiler chickens fed diets with different levels of full-fat
Parameter | Age (days) | Group | SEM | P-value | |||
---|---|---|---|---|---|---|---|
HI-0 | HI-50 | HI-75 | HI-100 | ||||
BW (g) | 42 | 3046.0a | 2727.0b | 2504.5b | 2378.0c | 39.80 | <0.001 |
FCR (kg/kg) | 1–42 | 1.63a | 1.59a | 1.59a | 1.77b | 0.068 | 0.009 |
CM (%) | 1 – 42 | 3.15a | 5.20b | 7.20c | 28.20d | 0.62 | <0.001 |
BW – body weight; FCR – feed conversion ratio; CM–culling and mortality
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
SEM – standard error of the mean
a–d – mean values within a row (dietary treatment) not followed by a common superscript are significantly different by Tukey’s test (P < 0.05)
On the 42 dol, the birds differed significantly by treatment group in terms of body weights, especially in the group fed the diet with the highest content of insect larvae meal. As observed at this time point (experiment end), the average group body weights of broiler chickens were significantly lower in correlation with the increasing content of full-fat HI larvae meal in the diet group by group, and only reached 2,375 g in group HI-100 compared to 3,046 g in group HI-0. The body weights of birds from groups HI-50 and HI-75 were significantly lower than those from group HI-0 and significantly higher than those from group HI-100. Also the FCR evaluated for birds from group HI-100 was significantly higher than the FCR of birds from the other groups and was 1.77
Mean values (± standard deviation) of haematological parameters in blood samples of 21-day-old broiler chickens (n = 5)
Group | Parameter | Leukogram (%) | |||||||
---|---|---|---|---|---|---|---|---|---|
RBC |
WBC |
Hb |
PCV |
Lymphocytes | Granulocytes | Monocytes | |||
Heterophils | Eosinophils | Basophils | |||||||
HI-0 | 1.92 |
29.60 |
9.34 |
25.40 |
53.60 |
39.60 |
0.60 |
1.20 |
5.20 |
HI-50 | 1.56 |
26.70 |
9.1 |
25.60 |
57.40 |
37.00 |
0.80 |
2.20 |
3.00 |
HI-75 | 1.22 |
18.2 |
9.38 |
26.60 |
60.20 |
34.00 |
0.80 |
1.80 |
3.20 |
HI-100 | 1.58 |
20.90 |
8.82 |
24.20 |
55.80 |
37.80 |
0.90 |
1.60 |
4.80 |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25:75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
RBC – red blood cells; WBC – white blood cells; Hb – haemoglobin; PCV – packed cell volume
Mean values (± standard deviation) of haematological parameters in blood samples of 42-day-old broiler chickens (n = 5)
Group | Parameter | Leukogram (%) | |||||||
---|---|---|---|---|---|---|---|---|---|
RBC |
WBC |
Hb |
PCV |
Lymphocytes | Granulocytes | Monocytes | |||
Heterophils | Eosinophils | Basophils | |||||||
HI-0 | 2.02 |
10.40 |
11.26 |
30.80 |
26.30 |
77.40 |
0.40 |
0.20 |
4.20 |
HI-50 | 1.40 |
17.60 |
9.84 |
26.40 |
34.00 |
62.20 |
0.30 |
0.10 |
3.8 |
HI-75 | 1.48 |
11.70 |
9.48 |
25.60 |
29.60 |
73.40 |
0.30 |
0.20 |
4.6 |
HI-100 | 1.34 |
17.50 |
10.28 |
27.80 |
25.30 |
42.80 |
0.50 |
0.30 |
3.8 |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
RBC – red blood cells; WBC – white blood cells; Hb – haemoglobin; PCV – packed cell volume
The substitution of soybean meal with the full-fat HI larvae meal had no effect on the values of the haematological markers evaluated in either 21-day-old or 42-day-old chickens, regardless of the dietary inclusion level of larvae meal.
Mean values (± standard deviation) of biochemical parameters in blood serum samples of 21-day-old broiler chickens (n = 10)
Group | Parameter | ||||||||
---|---|---|---|---|---|---|---|---|---|
ALT |
AST |
ALP |
TP |
CK |
LDH |
CALC |
PHOS |
UA |
|
HI-0 | 9.80 |
239.00 |
29,881.00 |
2.60 |
4,966.00a |
1,780.00 |
11.43a |
7.81a |
6.75a |
HI-50 | 9.21 |
177.00 |
39,223.00 |
2.69 |
2,058.00b |
1,502.00 |
12.27ab |
4.45b |
8.80ab |
HI-75 | 8.69 |
163.00 |
33,367.00 |
2.71 |
2,104.00b |
1,419.00 |
12.33ab |
6.06b |
8.41ab |
HI-100 | 8.93 |
169.00 |
19,175.00 |
2.64 |
2,021.00b |
1,588.00 |
12.58b |
6.13b |
10.10b |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
ALT – alanine aminotransferase; AST – aspartate aminotransferase; ALP – alkaline phosphatase; TP – total protein; CK – creatine kinase; LDH – lactate dehydrogenase; CALC – calcium; PHOS – phosphorus; UA – uric acid
a–b – mean values in a column not followed by a common superscript are significantly different at P ≤ 0.05
Mean values (± standard deviation) of biochemical parameters in blood serum samples of 42-day-old broiler chickens (n = 10)
Group | Parameter | ||||||||
---|---|---|---|---|---|---|---|---|---|
ALT |
AST |
ALP |
TP |
CK |
LDH |
CALC |
PHOS |
UA |
|
HI-0 | 14.50 |
428.00a |
9,020.00 |
3.01 |
28,086.00a |
4,679.00a |
11.14a |
7.09a |
4.60a |
HI-50 | 11.70 |
338.00b |
5,668.00 |
3.16 |
15,321.00b |
2,843.00b |
11.35ab |
6.49ab |
6.66b |
HI-75 | 12.30 |
265.00c |
6,662.00 |
3.27 |
13,469.00b |
2,206.00c |
12.61b |
5.73b |
6.70b |
HI-100 | 10.70 |
278.00bc |
5,575.00 |
3.21 |
14,805.00b |
2,280.00c |
11.95b |
5.80b |
6.78b |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
ALT – alanine aminotransferase; AST – aspartate aminotransferase; ALP – alkaline phosphatase; TP – total protein; CK – creatine kinase; LDH – lactate dehydrogenase; CALC – calcium; PHOS – phosphorus; UA – uric acid
a–c – mean values in a column not followed by a common superscript are significantly different at P ≤ 0.05
The levels of soybean meal substitution with full-fat HI larvae meal had no significant effect on the majority of the analysed parameters in 21-day-old chickens. In all groups that received full-fat HI larvae meal, there was a significant decrease in CK activity and PHOS levels compared to the control group. In addition, the HI-100 group chickens showed a statistically significant increase in serum CALC and UA levels compared to the control group (HI-0).
A statistically significant increase in AST, CK and LDH activity and UA level was found in 42-day-old chicks that had received full-fat HI larvae meal compared to control birds. In addition, there was a statistically significant increase in CALC and decrease in PHOS levels in the HI-75 and HI-100 groups compared to the control chickens from group HI-0.
Mean values of post-vaccination antibody titres in serum samples of broiler chickens on the 21st and 42nd days of life (n = 23)
Group | Titre age of birds (days) | |||||
---|---|---|---|---|---|---|
aMPV | NDV | IBV | ||||
21 | 42 | 21 | 42 | 21 | 42 | |
HI-0 | 9 | 5 | 213 | 197 | 172 | 2,147a |
HI-50 | 5 | 1 | 287 | 108 | 140 | 877b |
HI-75 | 26 | 27 | 209 | 88 | 169 | 866b |
HI-100 | 5 | 25 | 368 | 117 | 133 | 918b |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal aMPV – avian metapneumovirus; NDV – Newcastle disease virus; IBV – infectious bronchitis virus;
a–b – mean values in a column not followed by a common superscript are significantly different at P ≤ 0.05
On the 42nd of life, the broiler chickens fed a diet with the addition of full-fat HI larvae meal had highly significantly lower titres of anti-infectious bronchitis virus (IBV) antibodies compared to the control birds (HI-0).
Results of cytometric analysis of blood samples of broiler chickens on the 21st and 42nd days of life (n = 8)
Group | Mean size of particular T and B cell subpopulations as percentages of gated lymphocytes (± standard deviation) age of birds (days) | |||||||
---|---|---|---|---|---|---|---|---|
CD3+CD4+ | CD3+CD8a+ | CD4+CD8a+ | CD3−Bu-1+ | |||||
21 | 42 | 21 | 42 | 21 | 42 | 21 | 42 | |
HI-0 | 4.81a |
9.59 |
3.70ab |
2.12 |
0.55 |
0.27 |
5.2 |
5.19 |
HI-50 | 5.09a |
7.22 |
3.95a |
2.20 |
0.39 |
0.22 |
5.49 |
5.08 |
HI-75 | 6.60b |
7.58 |
3.68ab |
2.99 |
0.45 |
0.21 |
5.19 |
5.24 |
HI-100 | 5.67ab |
6.59 |
2.34b |
3.27 |
0.46 |
0.24 |
5.09 |
5.58 |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
a–b – mean values in a column not followed by a common superscript are significantly different at P ≤ 0.05
Results of cytometric analysis of spleen samples of broiler chickens on the 42nd day of life (n = 8)
Group | Mean size of particular T and B cell subpopulations as percentages of gated lymphocytes (± standard deviation) | |||
---|---|---|---|---|
CD3+CD4+ | CD3+CD8a+ | CD4+CD8a+ | CD3−Bu-1+ | |
HI-0 | 30.91a |
49.14 |
2.16 |
13.92 |
HI-50 | 25.18a |
51.14 |
2.17 |
14.86 |
HI-75 | 23.06ab |
55.48 |
1.81 |
13.03 |
HI-100 | 22.70b |
55.98 |
1.95 |
14.51 |
HI-0 – group that received fodder without the addition of full-fat HI larvae meal; HI-50 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 50 : 50 ratio; HI-75 – group that received fodder with proteins from soybean meal and full-fat HI larvae meal in a 25 : 75 ratio; HI-100 – group that received fodder exclusively with proteins from full-fat HI larvae meal
a–b – mean values in a column not followed by a common superscript are significantly different at P ≤ 0.05
On the 21st dol, the percentage of T cells which were CD3+CD4+ was significantly higher in the blood samples of group HI-75 than in those of HI-0 and HI-50. The size of the CD3+CD8a+ T cell subpopulations was significantly lower in group HI-100 in comparison with HI-50. The full-fat HI larvae meal had no significant effect on the size of the T and B cell subpopulations in blood samples collected from birds on day 42 of life.
No significant differences between treatment groups were found in the percentages of immune cells which were CD4+CD8a+ T cells and CD3−Bu-1+ B cells in blood and spleen samples. On the 42nd dol, the percentage of T cells which were CD3+CD4+ was significantly lower in the spleen samples of group HI-100 than in those of HI-0 and HI-50. In general, the increasing proportion of full-fat HI larvae meal in the diet increased the percentage of CD3+CD8a+ T cells and decreased that of CD3+CD4+ T cells in both blood and spleen samples in 42-day-old chickens.
Insects are receiving much attention these days as a proposition for a food of the future (32). Interest in edible insects increased sharply when the Food and Agriculture Organization (FAO) began promoting them as a viable dietary option for humans (44). They have also drawn growing interest as an attractive source of animal feedstuff (5, 45), especially in response to Commission Regulation (EU) 2017/893 of 24 May 2017 on the possibility of using insect protein in feeding strategies for aquaculture and to EU Regulation No. 2021/1372 allowing the use of processed animal proteins derived from farmed insects in fodders for poultry and pigs (13).
In response to the greater awareness of the exploitability of insect protein, numerous studies have been conducted for many years on the economic effects of feeding poultry with diets with different inclusion levels of this protein as fishmeal or soybean meal replacement (3, 27, 33, 49). Józefiak
The analysis of the production results from the present study indicates a progressive negative impact of the increasing content of insect protein in the feed mixtures on the body weight gains, FCR values, and bird mortality. This seems to be in contradiction to the results of previous insect meal feed studies conducted on various species of birds including broiler chickens, in which the meal yielded a beneficial effect on the production performance of birds (9, 20). Earlier studies with laying hens demonstrated better body weight gains and better FCR in the groups receiving feed mixtures with the addition of partly de-fatted HI larvae meal (28, 31). In the study by Marono
The results of haematological analyses show that the diet with insect protein addition had no significant influence on evaluated parameters, which is consistent with the findings reported by Schiavone
Based on the selected biochemical parameters, it is possible to determine the impact of the diet on liver, kidney, bone and muscle functions in birds (15). Although there were statistically significant differences between the groups in the levels of CALC, PHOS, and UA and the activities of AST, CK, and LDH, the values of these parameters were still within the reference ranges for this poultry species (23). The presented results correspond to the observations of other authors. Marono
When assessing the post-vaccination response, it should be noted that out of the three vaccinations given to the broiler chickens as part of the experiment, the one against infectious bronchitis should elicit the strongest immune response, because IBV antigens are characterised by the highest immunogenicity. This is reflected in the results of serological tests: the six-week-old birds showed more clearly marked IBV seroconversion than the three-week-old birds. As our observations show, feeding birds a diet in which the standard protein component was replaced by HI larvae protein significantly impaired the effectiveness and efficacy of vaccination against IBV, as manifested by the statistically significantly lower titres of post-vaccination antibodies in six-week-old birds from these groups. This situation is most likely due to lower daily feed intake, which resulted in poorer body weight gains and deterioration of the general condition of birds in these groups, which translated into low production results and debilitated immune systems. Unfortunately, so far there has been no similar research on the development of post-vaccination immunity in birds fed with insect protein supplemented diets. The only available reports on the protein obtained from HI larvae and the efficacy of vaccination concern fish and indicate a complete lack of its influence on the level of anti-infectious pancreatic necrosis virus specific antibodies (26). On the other hand, the results of the present study correspond with findings of other authors concerning the impact of deficient feeds on post-vaccination immunity in poultry,
The cytometric analysis of blood and spleen samples conducted in the present study showed no effect of the protein component on the size of the B cell subpopulation, but indicated an increase in the percentage of T cells which were CD3+CD8a+ and a decrease in the percentage of them which were CD3+CD4+. These results contradict the research of Lee
One conclusion of the present study results is that full-fat HI larvae meal used as a protein and substitute for genetically-modified soybean meal has a negative effect on the health of broiler chickens. The low production results and high mortality in experimental birds may indicate the need to use feeds with a lower insect component than those tested in this study or to use only purified insect proteins.