A group of European scientists compared the apparent digestibility coefficient of the total tract of nutrients (CTTAD), apparent metabolizable energy (AME) and amino acid (AA) apparent ileal digestibility coefficients (AIDC) of two different insect feeds and a control diet.
“Many authors have pointed out how there is a need for the evaluation of the nutrient digestibility of processed insects as a feed ingredient,” researchers said. “Our study has shown that TM [Tenebrio molitor] TM and Hi [Hermetia illucens] meals are valuable sources of AME and digestible AA. This study has provided updated and never before determined nutritional values of TM meal and HI meal, which could be two potential future ingredients for use in the formulation of broiler feeds.”
Why insect feed?
Food security concerns have highlighted a need to find more sustainable sources of protein for use in animal feeds. Insects are increasingly being recognized as a potential substitute for conventional sources.
The authors note the number of authors that have reported interesting results about the suitability of different types of insect meal as diet ingredients for pigs, poultry or different fish species from Veldkamp et al., 2012, to Van Huis, 2013, to Makkar et al., 2014 and Henry et al., 2015.
“Invertebrates constitute a raw material that is included in the EU Feed Material Register, and although they are currently authorized only for fish and pets, insect-derived feeds could also represent a suitable ingredient for feed manufacturing for pigs and poultry in the near future,” the researchers said. “This aspect could be a first step towards combating the severe challenges of the global capacity to supply sufficient food.”
Additionally, the two insects used for the study, the black soldier fly or Hermetica illucens (HI) and the yellow mealworm or Tenebrio molitor (TM), both have the ability to produce a biomass high in protein and fat, by reclaiming nutrients, including AA and fatty acids, from manure and organic waste, said the researchers.
“All this evidence indicates that the use of insects in feed formulations could be an opportunity to make the broiler chicken supply-chain more sustainable than it currently is,” the scientists said.
For the trial, 90 birds, at 19 days of age and of uniform body weight were chosen and distributed over 30 cages.
Three diets were formulated, researcher said. The control diet was based on corn and soybean meal and the two experimental diets which substituted 250 g/kg of the control diet for insect meals and an acid-insoluble ash digestibility marker.
Total tract digestibility was calculated per cage using collected excreta for four days. Feed eaten was measured per cage. And, the lower half of the ileum was collected at the end of the experiment.
Among the three diets, the HI diet was found to have the largest amount of dry matter and ether extract, researchers said. However, the TM diet had the largest amounts of organic matter, and crude protein. Both insect diets were similar in the amounts of gross energy they offered at about 19 MJ/kg of dry matter compared to 17 MJ/kg in the control diet.
Levels of indispensable AA and dispensable AA were higher in both insect-based diets than they were in the control diet, researcher said. Of the two, the TM diet had larger amounts of the indispensable AAs and almost all the dispensable AAs.
“The AIDC of the AAs in TM ranged from 0.80 to 0.93, while in HI it ranged from 0.42 to 0.89,” they said. “Overall, the AIDC of 17 AA was higher (P < 0.001) in TM (0.86) than in HI (0.68). This reflects the significantly higher (P < 0.05) AIDC levels of isoleucine, lysine, methionine, phenylalanine, valine, alanine, aspartic acid, glycine, glutamic acid and tyrosine in TM than in HI.”
However, there was no statistical difference between the CTTAD of the nutrients for the two insect diets, or for the AME and AMEn values, they reported.
“The compositional data have shown that the two insect larval meals are good sources of protein and fat,” the researchers found. “In particular, the TM meal has shown a higher CP content than soybean meal which is close to that of meat meal, however it has a higher fat content. This result indicates how this insect larval meal could be used as both a protein and an energy ingredient for feeds.”
Additionally, the HI meal compares in CP levels to some plant protein sources, but again offers a higher fat content, they said.
Source: Animal Feed Science and Technology
Title: Nutritional value of two insect larval meals (Tenebrio molitor and Hermetia illucens) for broiler chickens: Apparent nutrient digestibility, apparent ileal amino acid digestibility and apparent metabolizable energy
DIO: available online before print 10.1016/j.anifeedsci.2015.08.006
Authors: M. De Marco, S. Martínez, F. Hernandez, J. Madrid, F. Gai, L. Rotolo, M. Belforti, D. Bergero, H. Katz, S. Dabbou, A. Kovitvadhi, I. Zoccarato, L. Gasco, A. Schiavone