Evaluation of Black Soldier Fly Larvae (Hermetia illucens) as a Protein Supplement for Beef Steers Consuming Low Quality King Ranch Bluestem Hay




Kathcart, Emma Paige

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Black Soldier Fly Larvae (BSFL; Hermetia illucens) have been identified as a potential feedstuff for livestock. Previous data indicate the land mass to produce one ton of soy protein, a conventional feedstuff, could produce 150 tons of insect protein. Further, production of BSFL is associated with 1.3-12 times the environmental benefit versus conventional feedstuffs. Accordingly, our objective was to conduct the first in vivo evaluation of BSFL in beef cattle. Six steers (603.3 ± 20.4 kg of BW, n = 3 and 404.3 ±17.5 kg of BW, n = 3) consuming King Ranch bluestem hay were used in two simultaneous 3 × 3 Latin squares. One of three treatments was provided each period: 1) a control with no supplement (CON), 2) a supplement comprised of conventional feed ingredients with whole cottonseed as the main protein source (CONV), and 3) a supplement with BSFL as the main protein source (BSFL). Three 14-d periods were conducted with 8-d to adapt to treatments, 5-d to measure intake and digestion, and 1-d to complete a ruminal fermentation profile. Dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent insoluble ash were determined in forage, supplement, and fecal samples. Metabolic body weight (MBW) was body weight0.75. Total tract digestibility was [1-(output of nutrient/intake of nutrient)] × 100. Treatment affected total digestible OM intake (TDOMI; P≤0.01); TDOMI for CON steers was 47.5 g /kg MBW/d which was significantly less (P≤0.01) than that of CONV or BSFL steers. However, CONV steers consumed significantly more TDOMI than BSFL steers (P=0.05; 62.2 vs. 60.1 g/kg MBW/d, respectively). Treatment did not significantly affect digestibility of DM (P=0.74), OM (P=0.15), or NDF (P=0.53). BSFL stimulated TDOMI relative to CON but not to the same extent as CONV. The lack of treatment effect on digestibility was expected as we observed increased intake, indicating faster passage rate. Overall, this initial data indicates BSFL may be an effective protein supplement for beef cattle consuming low-quality forage.



beef cattle, Black soldier fly larvae, insect protein, protein supplementation, Honors College


Kathcart, E. P. (2020). Evaluation of black soldier fly larvae (Hermetia illucens) as a protein supplement for beef steers consuming low quality King Ranch Bluestem hay (Unpublished thesis). Texas State University, San Marcos, Texas.


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