Black Soldier Fly Larvae (BSFL) and Frass as Protein Supplements for Beef Steers Consuming Low-Quality Forage

Maggitt, Shakara
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Increased global meat consumption has led to an increase in livestock production. While the demand for output increases, so has the need for alternative protein sources in feed to minimize the environmental impact of livestock production. Insect protein is a potential alternative to conventional sources of protein (e.g., soybean meal or cottonseed meal) for cattle consuming low-quality forage (LQF). The use of insects as livestock feed has been documented in the literature, and interest is growing; however, the Association of American Feed Control Officials (AAFCO) has only approved the use of dried black soldier fly larvae (BSFL) for salmonid, poultry, swine, and adult dogs. The objective of this experiment was to evaluate the use of Black Soldier Fly Larvae meal (BSFLM) and BSFL frass and larval sheddings (FRS) as novel supplemental proteins for beef steers consuming low-quality forage. Eight ruminally fistulated steers (240.2 ± 22.5 kg of BW) were used in replicated 4 × 4 Latin squares. One of four treatments were provided to each steer per period: a control (CON) with no supplement, cottonseed meal (CSM), partially defatted BSFL meal (BSFLM), or BSFL frass and larval sheddings (FRS). Four 16-day periods were conducted with an 8-d adaptation to treatments, 7-d measurement of intake and digestion, and 1-d collection of ruminal fermentation and microbial samples. Dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) were determined for forage, supplement, ort, and fecal samples. Microbiome analysis of microbial communities’ composition was conducted using 16S rRNA sequencing for liquid and solid rumen fractions. Protein supplementation of CSM, BSFLM, and FRS increased forage organic matter (OM) intake (P < 0.01) relative to CON with no significant differences between CSM and FRS (P=0.84) or BSFLM and FRS (P=0.13) and with a trend for a difference between CSM and BSFLM (P=0.08). Provision of BSFLM and FRS increased total digestible OM intake (TDOMI) relative to CON (P < 0.01), from 2.33 kg/d for CON to 3.07 kg/d for BSFLM and 3.05 kg/d for FRS. The dominant microbial phyla in the liquid fraction were Firmicutes (44.3%) and Bacteroidetes (40.7%) and, in the solid fraction, were Firmicutes (70.4%) and Bacteroidetes (20%) with no significant differences for phyla across treatment within either fraction. There were treatment effects within the liquid and solid fractions for certain genera. Overall, our results indicate that BSFLM and FRS can be incorporated as a protein source for beef steers consuming low-quality forage.
Maggitt, S. (2023). Black Soldier Fly Larvae (BSFL) and frass as protein supplements for beef steers consuming low-quality forage [Unpublished thesis]. Texas State University, San Marcos, Texas.