Replacing soybean meal with house cricket (Acheta domesticus) meal in ruminant diet: effects on ruminal fermentation, degradation, and biohydrogenation

Abstract

Abstract Insect meals could be a sustainable protein source in ruminant diets to overcome the environmental, market, and feed-food-fuel issues associated with the widespread use of soybean meal (SBM). However, research on this topic is still very scarce. This study was conducted to examine the possibility of replacing SBM with house cricket (Acheta domesticus) meal (HCM) in ruminant feeding. Four cannulated sheep were fed a total mixed ration containing either 10% SBM (Control diet) or 10% of non-defatted HCM (Insect diet) over two consecutive periods. Effects on ruminal fermentation, degradation, and biohydrogenation were evaluated. Despite some differences in rumen dry matter and N degradation kinetics, replacing dietary SBM with HCM did not affect the ruminal disappearance of dry matter, N and, neutral detergent fibre of in situ incubated feedstuffs. Nor were there differences between the meals in the in vitro intestinal digestibility of rumen non-degraded nitrogen. The replacement had no negative effects on rumen pH or ammonia concentrations, but resulted in lower total and individual (i.e. acetate, propionate, butyrate, and minor) volatile fatty acid concentrations. This adverse effect was probably due, at least in part, to the unexpectedly high content of fat in HCM and its relatively high degree of unsaturation. Inclusion of HCM in the diet facilitated modulation of the fatty acid profile of the rumen digesta without negative effects on biohydrogenation pathways (e.g. it increased trans-11 18:1 and cis-9 trans-11 CLA concentrations, with only a small variation in the trans-10:trans-11 18:1 ratio). Replacing SBM with HCM in ruminant diets could be a promising alternative to address the challenges related to SBM and to improve the lipid composition of ruminant-derived products. However, further research is still needed to investigate, for example, the most appropriate level of inclusion of HCM in the diet or the use of defatted meal.