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Ann. Anim. Sci., Vol. 18, No. 3 (2018) 795–800 DOI: 10.2478/aoas-2018-0012
DO INSECTS SMELL ATTRACTIVE TO DOGS? A COMPARISON
OF DOG REACTIONS TO INSECTS AND COMMERCIAL
FEED AROMAS – A PRELIMINARY STUDY* *
Bartosz Kierończyk1♦, Mateusz Rawski1,2, Pola Pawełczyk1, Joanna Różyńska1,
Julia Golusik1, Zuzanna Mikołajczak1, Damian Józeak1
1Department of Animal Nutrition, Poznań University of Life Sciences, Wołyńska 33,
60-637 Poznań, Poland
2Division of Inland Fisheries and Aquaculture, Poznań University of Life Sciences,
Wojska Polskiego 71c, 60-625 Poznań, Poland
♦Corresponding author: bkieron@up.poznan.pl
Abstract
The goal of the present study was to investigate the olfactory attractiveness of air-dried insects
used as aromas to dogs. The trial consisted of 35 adult dogs (20 males, 15 females) aged between 12
months and 7 years (mean = 3.6), varied in terms of breed, kept as companion animals. The dogs
had free olfactory access to selected unprocessed dried insects, i.e., mealworm (Tenebrio molitor),
Turkestan cockroach (Shelfordella lateralis), black soldier y (Hermetia illucens), and tropical
house cricket (Gryllodes sigillatus), as well as commercial dried and pelleted dog feed, which was
used as a control treatment. Samples (100 g) were located separately in non transparent closed
boxes with 5 perforations in the cover (7 mm each) to improve the intensity of the aromas without
direct contact with the tested samples. The box was recorded as chosen when the dog showed in-
terest in it for more than 15 seconds continuously per each attempt (3 attempts per dog). The pre-
sented study shows that the selected insect species were chosen as frequently as the control group
(P=0.03). However, in terms of preferences by dog gender, Tenebrio molitor was favored more often
by males than by females, which preferred Shelfordella lateralis. The current preliminary data
suggest that the olfactory features of the selected insect species may be attractive to dogs.
Key words: dogs, feed additives, insects, aroma, nutrition
Edible insects are considered novel, environmentally friendly, and nutritious
compounds used in animal nutrition (Józeak et al., 2016). Moreover, even in the
case of Europeans, who do not traditionally eat insects, the acceptance for insect use
in animal nutrition is increasing. This acceptance is mainly caused by the need for
alternative protein sources to soybean and sh meal (Verbeke et al., 2015). The Eu-
*This work was supported by several sources i.e., the funds of Poznań University of Life Sciences;
TEAM TECH/2016-2/11-0026 project entitled: Insects as novel protein sourcs for sh and poultry, -
nanced by Fundation of Polish Science (POIR4.4); as well as founds of the National Centre for Research
and development, no POIR.01.01.01-00-0828/15, entitled: InnSecta: innovative technology of feedstuffs
production based on insect biomass.
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ropean Union has dened insect meal as a processed animal protein and has imposed
legislative barriers (Regulation (EC) No. 1069/2009) to its inclusion into livestock
diets. However, insect meal may be used in companion animal nutrition, such as in
hypoallergenic diets. Currently, live insects are frequently used as nutrition for exotic
animals such as amphibians, reptiles, birds and rodents, and in some cases, insects in
dried or lyophilized form are included in commercial diets to increase the attractive-
ness of the meals. The application of insects as an innovative feedstuff component is
becoming one of the most interesting issues in the case of companion animal nutri-
tion and is used in the case of hypoallergenic feeds in which soybean or chicken are
eliminated. Moreover, insects are considered a functional feed due to their chitin and
antimicrobial peptide contents (Józeak et al., 2016; Józeak and Engberg, 2017).
In addition, it is well known that in animal, nutritional aromas and avors are sup-
plemented in feeds as attractants (Chen et al., 2017). These substances stimulate feed
intake as well as the consumption of poorly palatable feedstuffs. However, the use
of supplemental aromas and avors in pet foods generates additional costs without
direct feed quality improvement. Insect use may be an alternative that improves both
palatability and quality of the feed. It is particularly important in the case of pet
food production, which reached 19 billion US dollars in the United States in 2012
alone (Koppel, 2014). In the available literature, there are no data about the effect of
various insect species as an aroma source on dogs’ preferences. Due to the above-
mentioned facts, the goal of the present study was to investigate the attractiveness of
selected insect aromas to dogs.
Material and methods
The present study was carried out using 35 dogs kept as companion animals.
The dogs’ age varied between 12 months and 7 years (mean = 3.6), 20 males and
15 females differing in terms of breed (Yorkshire Terrier, Beagle, Labrador Retriev-
er, and mongrels) participated in the study. The dogs which were used in the present
study met the following criteria: no human-directed aggression history; no illness or
injury; no oestrus or lactating period. The dogs were not fed with insect-containing
feeds earlier, and each dog was subjected to the test separately. Due to neophobia
limitations, only adult animals were used in the study (Bradshaw, 1986). Further-
more, before the experiment, each dog was fed diversely (commercial and home
prepared feeds) to eliminate the “monotony effect”. Moreover, the dogs were not
fasted before trial. The design of the current trial was performed in accordance with
commonly used palatability measurements, i.e., the bowl test (Koppel, 2014). In the
experiment, the dogs had free olfactory access to 4 selected dried (50°C for 48 h)
insect species, i.e., Tenebrio molitor, Shelfordella lateralis, Hermetia illucens, and
Gryllodes sigillatus, as well as a commercial dry pelleted feed for dogs (based on
maize, wheat, chicken and turkey meal, animal fat, as well as soybean meal, digest),
which was used as a control. The nutritive value of each component was shown in Ta-
ble 1. The experiment was conducted in each dog’s household environment condi-
tions by the owner (without experimenter presence) to eliminate stress factor, impact
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Do insects smell attractive to dogs? 797
of new places and habituation on the experimental room, which could affect the
results. Insects were offered as whole dried, unprocessed larvae (Tenebrio molitor,
Hermetia illucens) or imagoes (Shelfordella lateralis, Gryllodes sigillatus). The se-
lection of life stages of the insects was determined by their practical use in animal
nutrition. The components were presented in separate tightly closed boxes with per-
forations (5 holes in the cover, each hole in each corner and one in the center; 7 mm
in diameter), to improve the intensity of the smell without the possibility of direct
contact with the components. The dogs were not able to see the experimental com-
ponents in boxes and choose visually preferred component due to the usage of white
covers, as well as the identical non transparent boxes. A total of 5 experimental feeds
including control were offered repeatedly (3 times) to dogs using a randomized block
design. The olfactory test was conducted at the opposite site of the room to where
the sampling had taken placed. The dog was held on a leash at a starting point, which
was located 2.0 m in front of the experimental boxes. The distance from the start-
ing point to each box was equal. The boxes were located on the oor, 50 cm apart.
When the owner led the dogs to the experimental area, they were walked around the
experimental boxes and allowed to choose the most preferred component. The box
was recorded as chosen when the dog showed interest in it for more than 15 seconds
continuously per each attempt. After the rst choice, the owner came back to the
starting point and was waiting two minutes for the next attempt, as well as provided
the dog with no form of attention at this time. After that, the experimenter was chang-
ing the order of the boxes for the next attempt. There were 105 replications, with 3
attempts per dog.
Table 1. Nutritive value of selected insect species and control feed used in the study
Item Control diet
Gryllodes
sigillatus
Hermetia
illucens
Tenebrio
molitor
Shelfordella
lateralis
Imago Larva Larva Nymph
Per kg of DM1
crude protein (g) 236.1 564 404 588 734
crude fat (g) 161 177 335 273 192
crude ber (g) 21 60 97 85 86
crude ash (g) ND266 71 45 46
1DM – dry matter; 2ND – data not available.
All obtained data were tested for a normal distribution using the Kolmogorov-
Smirnov test. Analysis of variance was conducted using Bartlett’s test. The signi-
cance of differences among groups was determined by Duncan’s multiple range test
at a signicance level of P≤0.05. The following general model was used:
Yi = µ + αi + δij
where:
Yi is the observed dependent variable,
μ is the overall mean,
αi is the effect of offered aroma,
δij is the random error.
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Ethics statement
According to the Polish law and the EU directive (No. 2010/63/EU), the experi-
ments conducted within the study did not require approval of the Local Ethical Com-
mittee for Experiments on Animals in Poznań.
Results
No acceptability disturbances were recorded during the experiment. The present-
ed study showed no signicant differences between the control treatment and the
experimental treatments. However, the aromas of Tenebrio molitor, as well as Shel-
fordella lateralis, were chosen as frequently as the control treatment. Despite those
results, different choices were noticed between males and females. Males showed
strict preferences towards Tenebrio molitor (Figure 1) in comparison to females,
which preferred Shelfordella lateralis (Figure 2) more than the other components
(P=0.03).
Figure 1. The frequency of aroma rst choice in male dogs
Figure 2. The frequency of aroma rst choice in female dogs
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Do insects smell attractive to dogs? 799
Discussion
Olfaction in canines is one of the most important senses. It determines sexual
behavior and ingestion, as well as assessment and localization of feed. Moreover, it
was proven that smell also plays a crucial role in indicating nutritional preferences
(Houpt et al., 1978). The olfactory attractiveness analysis of pet foods or their com-
pounds have been limited in the current literature. Simultaneously, this kind of ex-
amination is crucial to understand canine behavior and expand knowledge about diet
formulation for dogs. However, Di Donfrancesco et al. (2012) described a few attrib-
utes (aromas) in dog food samples, i.e., sh, meaty, liver, oil, burned, dusty, and soy,
as well as spice complexes. It is well known that various dog breeds are character-
ized by the different preferences of feed, e.g., Basset hounds and German Shepherds
prefer sh meal in comparison to Salukis, which mainly choose corn akes (McCay
et al., 1949). However, from a practical point of view, the design of the present trial
examined the preferences of a wide population of various dog breeds with the aim
of verifying the usefulness of insect attractants, in general. Moreover, in the avail-
able literature, there is no information about the inclusion of insect species in com-
panion animal diets as an aroma additive. However, there is abundant evidence that
insects are part of wild Canidae diets, such as those of Atelocynus microtis, Otocyon
megalotis, Vulpes rueppellii, Vulpes zerda, Canis lupus, and Lycaon pictus (Sawosz-
-Chwalibóg and Kosieradzka, 2012). The current study demonstrated a positive ef-
fect of Tenebrio molitor as well as Shelfordella lateralis on improving attractiveness.
In the literature, there are very few studies that consider the effect of aroma on pal-
atability in dog genders separately. Houpt et al. (1978) observed more inclinations
to take in sugar by females compared to males. In contrast to this, Guerra (2015)
noticed that dog gender did not inuence preference for diet type. From this point of
view, it is difcult to explain why males and females preferred the abovementioned
insect species. In addition, there is a lack of information about what characterizes the
volatile substance proles in insects. These data could be very helpful to understand-
ing the attractiveness of the selected insects in comparison to the commercial diets.
The increased interest of dogs may be caused not only by odorant substances but also
by additional nutrient sources. Józeak et al. (2016) presented the nutritional value
of insect species predominantly used in animal nutrition. In comparison to other
components used in the study, Tenebrio molitor and Shelfordella lateralis contained
the highest crude protein levels, up to 59% and 73%, respectively. Moreover, the fat
content of selected insects was higher than that of the control feed. The possibility of
insect application to dog diets provides the double benet of an encouraging aroma
as well as an additional, high-quality nutrient source. It is important from a practi-
cal point of view, where producers of companion animal feed use expensive aroma
and avor supplements that do not provide any nutrients. As shown in the present
study, insects may effectively affect dogs to the same extent as the commercial feed
containing aroma, simultaneously provide an additional source of high-quality crude
protein and fat.
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Conclusions
The obtained preliminary data suggest that insects may play important roles as
alternatives for commercial aroma additives in dog nutrition. However, more data
are needed to explore insect attractants of other insect species, especially in terms of
their volatile substances.
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Received: 9 XI 2017
Accepted: 6 II 2018
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