Effects of replacing soybean oil with selected insect fats on broilers
Introduction
Insects are a potential protein source in poultry (Bovera et al., 2016; Józefiak et al., 2016a,b; Maurer et al., 2016), swine (Jin et al., 2016), fish (Henry et al., 2015) and companion animal nutrition (Bosch et al., 2014). The crude protein (CP) content of insects is species-dependent and varies from 40% to 60% (Makkar et al., 2014). It should be emphasized that the CP quality also depends on the production technology and feed composition for larval rearing (Tschirner and Simon, 2015). However so far, in the European Union, the usage of insect meal in livestock nutrition is banned (Regulation (EC) No. 1069/2009) because these compounds are considered to be processed animal protein (PAP, Regulation (EC) No. 999/2001). Currently, the EU Standing Committee on Plants, Animal, Food and Feed (SCoPaFF) only allows the use of insects as a protein source in the case of fish, mink and pet-food nutrition. In addition to protein, edible invertebrates at all life stages are rich sources of other valuable nutrients, including crude fat. This raw material may be an alternative to replace resource-intensive and more expensive soybean oil, palm kernel oil, coconut oil, and fish oil. Additionally, from a legislative point of view, insect fat can be used in poultry diets in the EU. The authors estimate that in Poland alone, 240,000 tonnes of dietary fat is used for broiler chicken nutrition annually, at a total cost of more than 170 M USD. Therefore, there is a large market for novel sources of dietary fats, including insect-derived ones, and an emphasis should be placed on the yield and quality of the insect fat. Up to date, there is limited data about the usage of insects as an alternative energy source for poultry, including broiler chickens. Only few insect species were taken into consideration in animal nutrition, however, the emphasis is put on Hermeria illucens larvae, in this case (Schiavone et al., 2016). Whereas, there is a wide spectrum of edible insect species available on the market. In the present study, Tenebrio molitor, as well as Zophobas morio, were chosen as an alternative energy source in view of the fact that are commonly available, their production is seamless and well understood, as well as their fat content is relatively high. For instance, in most Tenebrionidae larvae, fat can constitute more than 30% of the dry matter content. In the case of T. molitor, it can reach up to 43% crude fat (Józefiak et al., 2016a,b). Furthermore, the quality of insects’ fat is comparable to already used energy sources in animal production. As DeFoliart (1991) reported, the degree of unsaturated insect fatty acids is similar to fish oil; however, insect fatty acids are richer in polyunsaturated fatty acids (PUFA). In general, the dominant fatty acids of insects are oleic, linoleic (LA) and palmitic acids (Jones et al., 1972; Martin et al., 1976; Finke, 2002; 2013). However, Bukkens (1997) suggested that the fatty acid profiles are species-dependent and reflect insects’ feed composition.
Currently, the soybean oil is one of the most commonly used energy source ingredient in the poultry diets, due to its high metabolizable energy content, as well as digestibility. Whereas, the price of this compound increase annually, and the supply of non-genetically modified soybeans is limited. From the above-mentioned reasons, it is crucial to expand knowledge about replacing soybean oil by alternative sources such as insects’ origin fat. Hitherto, the experiments carried out on H. illucens fat suggests no adverse effects on the growth performance, carcass traits, as well as overall meat quality (Schiavone et al., 2018). However, in the available literature, there is a lack of data on T. molitor and Z. morio as novel fat sources for poultry. Therefore, the aim of this study was to examine how fats obtained from Tenebrio molitor and Zophobas morio using super-critical CO2 extraction affect the broiler chicken growth performance, nutrient digestibility, lipid fatty acid composition of liver and breast muscle tissue, and expression of selected genes in the liver.
Section snippets
Diets
The composition of the basal diet is shown in Table 1. In both experiments, birds had ad libitum access to water and feed for 28 days. The composition of basal diets was designed according to Tancharoenrat et al. (2013) and was formulated on the basis of maize and soybean meal. The basal diet were developed by substituting soybean oil (SO), T. molitor oil (TM; Exp. 1) or SO, TM, and Z. morio (ZM; Exp.2) dietary fats for 50 g/kg of the basal diet. The crumbled form of the diets was produced in
Experiment 1 and 2
The fatty acid profiles of the selected fat sources are summarized in Table 2. In each fat source, the unsaturated fatty acids (UFA) were dominant. The highest amount of UFA, mainly oleic and linoleic acid, was present in SO (84.0%), followed by TM oil (78.6%), and the lowest value was observed in ZM oil (57.8%). Furthermore, insect oils had a higher concentration of MUFA in comparison to SO, and SO had more PUFA (both linoleic and linolenic) than the other oils used in this study. The fat
Discussion
Hitherto, edible insects were not considered to be an energy source for livestock nutrition, including broiler chickens. This is perplexing because the most frequent invertebrate species used as feed contain high fat concentrations, often more than 30% of the dry matter concentration. Sosa and Fogliano (2017) compared animal fats (butter, lard, beef tallow) with insect oils (superworm, yellow mealworm, lesser mealworm, cricket, cockroach) and vegetable oils (coiza, linseed, rapeseed, sesame
Conclusions
The results of the current study suggest that inclusion of TM, as well as ZM, obtained using super-critical CO2 extraction can be used to completely replace soybean oil in broiler chicken diets without any adverse impact on the growth performance and digestibility of nutrients. Furthermore, only TM added to the basal diet positively affected the breast meat fatty acid content, which is a component of consumer quality requirements. However, some undesirable changes in the fatty acid profile
Conflict of interest
The authors declare that there are no conflicts of interests.
Acknowledgements
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 sources for fish and poultry, financed by Foundation of Polish Science (POIR 4.4); as well as funds 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. The authors would like to thank the HiProMine S.A. company
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