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Insect protein: myths and facts – we’ll take a look at a study.
Since the European Commission has officially approved insects as food, countless pro and con opinions have been going around the web.
Attempts are being made to banish the valuable use of insect meal/protein of various insect species from the diet with contra opinions, but is the same true in pet food?
Basically, it is worth mentioning that the black soldier fly (Hermetia illucens) is only included in the Feed Act and is currently not allowed in food. Insects are considered livestock under Regulation (EU) 2017/893 if they are used for the production of processed animal protein. It follows that the feed bans of Regulation (EC) 999/2001 and Regulation (EC) 1069/2009 also apply to insects and no food waste or ruminant proteins may be fed to beneficial insects. This is not prohibited outside the EU. And this is where the whole story hits a snag. Where does the insect protein come from? What has been fed? How are the insects processed until they are used in food or feed.
The production of entoVITAL Hermetia larvae?
Our Austrian larvae are sourced sustainably and washed and inactivated during growth under strict regulatory requirements, ensuring that there is no contamination. The inactivation is at the same time the hygienization or sterilization. Furthermore, our larvae contain only 2% chitin before the pupal stage. Through countless tests and trials with technical colleges, we were able to determine the best larval pupal stage for further processing into animal feed.
Again, we can separate our larvae from the chitin, because the valuable chitin is readily seen as a sustainable alternative in the cosmetics or packaging industry. Thus, not all insect protein is the same.
Insects have been in our diet for a long time - did you know this fact?
Scarlet scale insects and paint scale insects have been used in the food industry for much longer.
For example, a red dye called „red carmine“, „E120“ is obtained from the scarlet scale lice, pregnant lice are dried and boiled, mainly this substance is popularly used in sweets. In cosmetics, this extracted substance is listed as „Carmine“, CI 75470“ or „Conchenille“.
The so-called shellac, in turn, is obtained from the excretions of the lacquer scale insects. Shellac forms a glossy coating – its use ranges from paints and varnishes to nail polish, hairspray or even as a coating agent for sweets under the number „E904“.
Do Hermetia larvae sense like we humans do?
Hermetia larvae do not have a brain or central nervous system as we know it, thus these little animals do not feel like other animals or humans.
Myth: Do hermetia illucens have "antinutrients" against predators?
This is not the case with the larvae of Hermetia illucens, because they are also eaten by their colleagues and also by chickens and co. Everything harmful is excreted by their natural metabolism. Not all insects are the same.
Myth: Insects are not healthy? Is insect protein really this much of a minus maker?
As described in the inaugural dissertation of Dr. Heide 2017 at the Free University of Berlin under the guidance of Univ.- Prof. Dr. Zentek: Larval Meal of Hermetia illucens as a Protein Carrier in Dog Food, we now turn to the topic.
What was the topic of this dissertation?
The chitin content and its digestibility were determined, as well as whether the chitin content in the feed has an effect on enzymatic processes, specifically on chitinase activity in the dog’s digestive tract.
Total fecal volume per day was used to determine apparent total nutrient digestibility and chtin utilization.
Chitinase content in feces was determined using color reaction. When chitinase converts colloidal chitin azure, the dye azure is released and can be measured photometrically at 560nm.
Chitin is a polysaccharide composed of N-acetyl-D-glucosamine units. Blood parameters as well as feces were used for analysis to evaluate digestive parameters, bacterial metabolites, chitin content determination and chitinase activity measurement.
None of the dogs exhibited any health problems during the test nor did they have to be removed from the series of tests, which in itself is a positive sign.
However, the dry matter content of the feces between the two feeding groups was not different. The hematological parameters did not differ between the two feeding groups, and the differential blood count did not show any differences either; all parameters were within the normal range. There were also no statistically significant differences in lymphocyte populations during the experiment between the two feeding groups.
There were no differences in lymphocyte stimulability (stimulation index) between the two feeding groups by the dietary antigen-induced lymphocyte proliferation assay.
A difference in the evaluation revealed. Apparent dry matter digestibility of potassium, zinc, phosphorus, and sodium were higher in dogs fed the experimental diet. The apparent digestibility of calcium, magnesium and iron showed higher values in the control group.
The concentrations of acetic acid as well as total fatty acids in the feces were higher in the dogs fed the control diet.
distribution of short-chain fatty acids in the feces between the feeding groups, no differences could be demonstrated.
Neither fecal D- nor L-lactate concentrations differed significantly between the two feeding groups.
A difference was demonstrated between the two feeding groups in terms of fecal ammonium concentration. The control group had higher fecal ammonium levels.
Activity of chitinase in the fecal sample
No difference was found when comparing the activity of chitinase in the feces of both feeding groups.
Chitin content in feed and fecal samples
The chitin concentration (in g/kg DM) in the feces of the dogs differed between the two feeding groups. The chitin concentration in the feces of the experimental group was significantly higher than in the control group.
Blood count and differential blood count
To record the health status of the dogs during the experiment, a blood count including differential blood count was obtained. Looking at the results, no feeding-related differences were found between the two diets and all values were within the reference range. Swanson et al. (2004) fed a diet based on plant components and a diet based on animal components over a 12-month period and compared them.
No feeding-related difference was observed between erythrocytes, hematocrit, and hemoglobin in this study either.
Total digestibility
The higher the crude fiber content of the ration, the lower the apparent digestibility of the organic matter. The nature of the plant cell wall components is also crucial. Compared with the control diet with lamb as protein source, the experimental diet had higher apparent digestibility of organic matter, dry matter and crude ash. In contrast, the apparent digestibilities of crude fiber, crude fat, and crude protein were higher when the control diet was administered.
There were other protein sources in both diets, so the apparent digestibilities cannot be related only to the main protein sources. In addition, the crude fiber and crude ash values of the two feeds are different, so that the apparent digestibility of these crude nutrients is comparable only to a very limited extent.
Bacterial metabolites in the fecal samples
There were some differences in fecal concentrations of short-chain fatty acids and ammonium levels between feeding groups. Looking at the lactate levels measured in the feces of the test animals in the present study, there was no feeding-related influence.
Short-chain fatty acids
Despite the higher crude fiber content of the experimental diet containing Hermetia illucens in the present work, higher levels of short-chain fatty acids were not observed in the feces of the dogs fed this diet. In general, it can be seen from the results of the short-chain fatty acids that there was more fermentation in the large intestine of the dogs after feeding the control diet. However, the distribution of short-chain fatty acids as a percentage of total fatty acids is comparable to other studies (Middelbos et al., 2007; Sunvold et al., 1995).
Ammonium and feces
If more proteins enter the colon, microbial fermentation processes produce end products such as ammonia or ammonium (Meyer and Zentek, 2013). Also, Beloshapka et al. (2016) observed decreasing ammonium concentration in the feces of dogs with increasing soybean extraction meal levels in the diet.
The highest fecal ammonium levels were obtained in the dogs that received poultry by-products as the main protein source in their rations. The ammonium concentration or ammonia absorption depends on the pH value in the intestine. Moreover, the speed of production of ammonium and hence the concentration in the feces also depends on the microbiota of the colon and the available energy (Hesta et al., 2003).
Chitinase activity in the fecal samples
There have been studies in which chitin content in insects have been measured using gravimetric methods (Lovell et al., 1968). Since the chitin content in feces and feed is very low in contrast to the chitin content in insects, a new method using ion chromatography was evaluated for the present study. Chitin is a polysaccharide composed of N-acetyl-D-glucosamine units.
The glucosamine produced from hydrolysis is thus related to the chitin content in the samples. The more chitin in the ration, the lower was the digestibility of chitin. In this study, it remains questionable why glucosamine was measured in the control diet and in the feces of the dogs that were fed the control diet. It is likely that the control diet contained N-acetyl-D-glucosamine in the form of other polysaccharides rather than chitin. N-acetyl-D-glucosamine is a component of some glycosaminoglycans such as hyaluronic acid, heparan sulfate and keratan sulfate.
These glycosaminoglycans are found in synovial fluid, blood vessels, cartilage, cornea, or the nucleus pulposus, among others (Thonar et al., 1985). The detection of glucosamine after control feeding can probably be explained by the fact that it was then not chitin but other polysaccharides containing N-acetyl-D-glucosamine.
Chitin content in feed and fecal samples
The question of whether dogs express the enzyme chitinase and whether activity is increased by chitin supplementation should be addressed by examining chitinase activity. Schon Lundblad et al. (1974) demonstrated chitinase activity in the serum of goat, cow, chicken, sheep and pig. No chitinase could be detected in the serum of human, monkey, horse, cat, dog, rabbit, hamster or guinea pig. This chitinase plays a role in the defense against chitin-containing bacteria, among other things (Suzuki et al., 2002). Chitinolytic enzymes in the digestive tract may be produced by the animal itself, derived from the feed, or synthesized by the microbiota (Simunek et al., 2001). In a study by Koh and Iwamae (2013), the activity of chitinase and N-acetyl-β-D-glucosaminidase enzymes present in the mucosa of the glandular stomach and in the different sections of the small intestine was tested after feeding a chitin-containing diet and a control diet. Enzyme levels did not increase with the chitin-rich diet.
The aim of this study was to find out whether dogs produce the enzyme chitinase in the gastrointestinal tract and whether the enzyme is increased by chitin-containing feed. Chitinase activities of 0.12 units were measured in the feces of the control group. The results thus provide evidence that chitinase activity occurs in the digestive tract of dogs, but that this activity is not increased by chitin-containing food, since similar activity was also measured in the experimental group. Thus, there was no promotion of bacterial chitinase activity by the chitin-containing experimental diet.
Further studies might clarify whether a chitinase is constitutively present in the gastrointestinal tract in dogs. In addition, because chitinase was determined in the feces of the dogs, it is also possible that the actual amount of chitinase was no longer detectable in the feces if possible chitinase production occurred in the stomach or small intestine and the enzyme would possibly be degraded during colonic passage.
Conclusion
The results demonstrated similar apparent digestibility of crude nutrients compared to a commercial complete feed with lamb as the main protein source.
The results available show no evidence of incompatibility, so that the use of the larval meal studied as a protein component in the diet of dogs is possible.
Neither immunological nor hematological differences between the two feeding groups could be detected. Examination of the concentrations of microbial metabolites in the fecal samples revealed higher concentrations of short-chain fatty acids and ammonium in the feces of the dogs after ingestion of the control diet. As expected, more chitin was detected in the experimental diet than in the control diet. This did not affect the chitinase activity in the feces.
Within the scope of this study, no negative effects could be determined in the feeding trial by the experimental feed with Hermetia illucens larvae meal in dogs, so that a good tolerance can be assumed within the investigated dosage range.