112 In situ evaluation of multiple edible insects as feed for cattle

Abstract

Abstract Livestock production is growing and intensifying in response to a growing population and associated food demands. Commercially reared insects have been positioned as a potential protein source for livestock due to their nutritional value and decreased environmental footprint as compared with conventional protein feeds. The American Association of Feed Officials (AAFCO) has issued a definition for black soldier fly larvae (BSFL) as feed for certain livestock but has not yet authorized feeding BSFL to ruminants. Further, AAFCO has not provided a feed definition for other edible insects [e.g., mealworm larvae (MWL)], likely due to a lack of research evaluating the value of insects as feed. The objective of this study was to evaluate edible insect species as feed for cattle by determining in situ characteristics of multiple commercially reared species. This research was approved by Texas State University IACUC (#8693). Samples (n = 14) included five insect species [i.e., black soldier fly larvae (BSFL)], mealworm larvae (MWL), house cricket, grasshopper, and banded cricket] that were commercially reared on different feed inputs and with various processing parameters and BSFL frass, which is insect excreta. There were 6 samples of BSFL, two of MWL, and three of house crickets. Three ruminally cannulated steers were used and provided ad libitum hay and water. A 6-d trial period was performed including a 3-d adaptation and 3-d experimental incubation period. Samples incubated in the rumen at 7 timepoints in reverse order (0, 4, 6, 12, 14, 48, and 72 h). After incubation, residues were analyzed for partial dry matter (PDM), dry matter (DM), and organic matter (OM). Dry matter and OM were separated into immediately soluble (IS), potentially soluble (PS), and not soluble (NS) fractions. For DM, the average NS fraction was 6.2% with a range from 3.0 to 10.4%. The sample with the greatest NS fraction was grasshopper. Across samples, the average PS fraction was 74.5% with a range from 69.3 to 79.1%. The sample with the smallest PS fraction was BSFL frass whereas the sample with the greatest was BSFL. Multiple samples had a DM degradability >85%. However, MWL and BSFL had fluctuating DM degradability across samples, likely due to variability among processing parameters. For OM fractionation, the average NS fraction was 5.7% with a range of 2.8 to 10.4%. Grasshopper had the greatest NS fraction. The average PS fraction was 74.9%; BSFL had the greatest PS fraction while frass had the least. Many samples had an OM degradability >85% and frass had the greatest degradability (90.0%). There was great variability in OM degradability across house cricket samples, likely related to rearing diet. These findings indicate that BSFL and MWL have potential value as feed for cattle but there would be challenges associated with feeding crickets.