Full-fat insect meals in ruminant nutrition: in vitro rumen fermentation characteristics and lipid biohydrogenation

Abstract

Background The most used protein sources in ruminant nutrition are considered as having negative impacts in terms of environmental sustainability and competition with human nutrition. Therefore, the investigation of alternative and sustainable feedstuffs is becoming a priority in ruminant production systems. Results This trial was designed to evaluate eight full-fat insect meals (Acheta domesticus – ACD; Alphitobius diaperinus – ALD; Blatta lateralis – BL; Gryllus bimaculatus – GB; Grylloides sygillatus – GS; Hermetia illucens – HI; Musca domestica – MD; and Tenebrio molitor – TM) as potential protein and lipid sources in ruminant nutrition. Fermentation parameters and fatty acids (FA) of rumen digesta after 24-h in vitro ruminal incubation of the tested insect meals were measured and compared with those of three plant-based meals (soybean meal, rapeseed meal and sunflower meal) and fishmeal (FM). Similarly to FM, the insect meals led to a significantly lower total gas production (on average, 1.75 vs. 4.64 mmol/g dry matter—DM), methane production (on average, 0.33 vs. 0.91 mmol/g DM), volatile FA production (on average, 4.12 vs. 7.53 mmol/g DM), and in vitro organic matter disappearance (on average, 0.32 vs. 0.59 g/g) than those observed for the plant meals. The insect meals also led to lower ammonia of rumen fluid, when expressed as a proportion of total N (on average, 0.74 vs. 0.52 for the plant and insect meals, respectively), which could be an advantage provided that intestinal digestibility is high. Differences in ruminal fermentation parameters between the insect meals could be partially explained by their chitin, crude protein and ether extract contents, as well as by their FA profile. In particular, high content of polyunsaturated FA, or C12:0 (in HI), seems to partially inhibit the ruminal fermentations. Conclusions The tested full-fat insect meals appear to be potentially an interesting protein and lipid source for ruminants, alternative to the less sustainable and commonly used ones of plant origin. The FA profile of the rumen digesta of ACD, ALD, GB, GS and TM, being rich in n-6 polyunsaturated FA, could be interesting to improve the quality of ruminant-derived food products.

Are insects a solution for feeding ruminants? Legislation, scientific evidence, and future challenges

“…Ruminal degradation of SBM proteins has been well characterized, whereas information on protein fractions and protein degradation rate of insect meals is still very scant. Renna et al (2022b) observed lower ruminal ammonia content when comparing the use of various full-fat insect meals and plant meals, consistent with a previous comparison between H. illucens larvae meal and SBM ( Jayanegara et al, 2017a ). Such result would be advantageous in ruminant nutrition provided that intestinal digestibility of nondegraded protein in the rumen is high.…”

“…However, a subsequent study by the same research team showed that lowering the chitin content in Gryllus assimilis did not improve its overall digestibility characteristics ( Jayanegara et al, 2017b ), suggesting a minor role of chitin on overall digestibility. Renna et al (2022b) also found that B. lateralis had the highest chitin content among the tested full-fat insect meals, but it displayed the most promising results in terms of fermentation. These results would support that chitin is degradable to certain extent in the rumen ( Fadel El-Seed et al, 2003 ).…”

“…The high crude protein (CP) and ether extract (EE) contents of H. illucens larvae meal suggested a suitable use to substitute SBM but decreases in in vitro organic and dry matter digestibility (IVOMD and IVDMD, respectively) were found compared to SBM. Using cannulated sheep as inoculum donors, Renna et al (2022b) investigated the in vitro effects of eight insect meals (for species of origin, see Table 1 ) on rumen fermentation characteristics. Consistent with Jayanegara et al (2017a) , Renna et al (2022b) observed poor IVOMD for the insect meals, except for Blatta lateralis , compared to reference plant meals (i.e., soybean, sunflower, and rapeseed meals).…”

“…Using cannulated sheep as inoculum donors, Renna et al (2022b) investigated the in vitro effects of eight insect meals (for species of origin, see Table 1 ) on rumen fermentation characteristics. Consistent with Jayanegara et al (2017a) , Renna et al (2022b) observed poor IVOMD for the insect meals, except for Blatta lateralis , compared to reference plant meals (i.e., soybean, sunflower, and rapeseed meals). Nevertheless, low inclusion levels of insects may help avoiding the depression of digestibility parameters, as suggested by Ahmed et al (2021) after replacing 25% of SBM (≈10% of total diet) with insect meals obtained from A. domesticus , Brachytrupes portentosus , and Gryllus bimaculatus adults, and from B. mori pupae.…”

Comparative Analysis of In Vitro Fermentation Parameters in Total Mixed Rations of Dairy Cows with Varied Levels of Defatted Black Soldier Fly Larvae (Hermetia illucens) as a Substitute for Soybean Meal

“…A relatively lower ammonia concentration was observed in an in vitro study where Gryllus bimaculatus was used at 25% inclusion instead of SBM [18]. However, different insect species can exhibit variable fermentation patterns in the rumen, as highlighted in a study with Blatta lateralis beetles, which produced more NH 3 -N [40]. This variation is attributed to differences in protein, fat, and chitin levels among insect species.…”