Recipient Organization
TEXAS STATE UNIVERSITY
601 UNIVERSITY DRIVE
SAN MARCOS,TX 78666
Performing Department
(N/A)
Non Technical Summary
Global predictions indicate an increase to nine billion people by 2050, translating to a 58% increase in the demand for meat versus 2010. To meet these food demands, livestock production will increase, placing pressure on natural resources, such as land and water. The production of conventional livestock feeds, such as soy, is associated with significant natural resource inputs. Further, soy competes in the human food and animal feed sectors. As a result of this competition, the demand for (and, thus, price of) soy is expected to increase the price of meat by at least 30% from 2000 to 2050. Ultimately, the environmental and economical impacts of conventional livestock feeds justify identification and evaluation of alternative and potentially more sustainable feeds for beef cattle.We have identified insects, specifically Black Soldier Fly Larvae (BSFL), as a potential replacement for conventional livestock feeds. BSFL have high feed efficiency and can be grown on food and feed byproducts that would otherwise have an economic and environmental cost for disposal. Previous data indicate that production of BSFL is associated with less natural resource inputs than that of conventional feeds. Finally, BSFL are also an attractive livestock feed as consumers in the Western world are not likely to accept insects into their diets, indicating there will not be competition between the feed and food sectors.BSFL have previously been evaluated as feed for fish and chickens. However, they have not yet been evaluated in beef cattle. Accordingly, we will feed different amounts of BSFL to cattle, along with the same amount of a conventional feed, such as soy, to serve as a comparison. We will evaluate how the different supplements impact feed intake and digestibility. We will also conduct a preference study, documenting if cattle express a desire to consume BSFL when presented with BSFL and other conventional feeds as options. Finally, we will use specialized equipment that mimics conditions of cattle's digestive system to evaluate other nutritional characteristics of BSFL in the laboratory. Cumulatively, these research trials will give us insights into how BSFL affects digestion in beef cattle, informing our decision to recommend it as a livestock feed or not.Our long-term goal is to increase the sustainability of beef cattle production. By assessing a novel feed that does not directly compete with existing crop production, is associated with low natural resource inputs, and will not be accepted as a human food, we hope to advance our progress towards achieving this long-term goal.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Our long-term goal is to increase the sustainability of beef cattle production in the U.S.Objective 1.Assess forage utilization in steers supplemented with graded levels of a novel protein source, defatted Black Soldier Fly Larvae (BSFL)Objective 2.Evaluate if defatted BSFL stimulates forage utilization by steers to a similar extent as an isonitrogenous level of a conventional protein supplementObjective 3.Assess steer acceptance of and preference for defatted BSFL as compared to a conventional protein supplementObjective 4. Determine the site of protein degradability of BSFL usingin vitromodels
Project Methods
Trial 1 is designed as described by Drewery et al. (2014). Five steers fitted with ruminal cannulas will be used in a 5 × 5 Latin square design to determine intake, digestion, and energy availability in response to BSFL supplementation to a low-quality forage diet. A positive control (conventional protein supplement) will be included to facilitate a comparison. Treatments will include four levels of supplemental BSFL: 0, 50, 100, or 150 mg N/kg BW (CON, 50B, 100B, and 150B, respectively) and one level of SBM at 100 mg N/kg BW (100S). Level of supplementation is based on previous experiments in which this range of protein maximized forage utilization of ruminants [Köster et al., 1996; Wickersham et al., 2008; Drewery et al., 2014].Steers will be individually housed in a partially enclosed barn. Low-quality forage will be offered daily at 130% of the previous 5-d average consumption. Prior to feeding, treatments will be dosed ruminally. The five experimental periods will be broken down as follows: 8-d for adaptation to treatment, 5-d for measurement of intake and digestibility, and 1-d for determination of ruminal fermentation parameters and characterization of circulating hormones and metabolitesCalculations of intake and digestion will be made from observations on d 9 through 13. Diet samples will be collected d 9 to 12, feed refusals will be collected d 10 to 13, and fecal grab samples will be collected d 10 to 13. A rumen fermentation profile will be conducted on d 14; immediately before feeding. Rumen fluid will be collected prior to feeding (0 h) and at 4-h intervals for a 24-h period after feeding. A pH meter will be used to measure the pH of each sample at the time of sampling. Subsamples of ruminal fluid will be prepared and frozen at -20°C for determination of volatile fatty acid (VFA) andammonia N. Prior to freezing, 8 mL of rumen fluid will be combined with 2 mL of 25% m-phosphoric acid for VFA and ammonia-N determination..Blood will also be drawn on d 14; plasma will be retained and stored for later determination of urea N.Hay, supplement, feed refusal, and fecal samples will be dried at 55°C in a forced-air oven for 96 h, allowed to air-equilibrate, and weighed to determine partial dry matter. Dried samples will be ground to pass a 1-mm screen then dried at 105°C for dry matter determination. Organic matter will be determined as the loss in dry weight upon combustion for 8 h at 450°C. Nitrogen will be measured by Dumas combustion and crude protein will be calculated as N × 6.25. Analysis for neutral and acid detergent fiber will be performed using an Ankom Fiber analyzer with Na sulfite and amylase omitted and without correction for residual ash. Acid detergent insoluble ash (ADIA) will be determined by sample combustion for 8 h at 450°C. After thawing, rumen fluid samples will be centrifuged at 20,000 × g for 20 minutes. VFA concentrations will be measured with a gas chromatograph. Ammonia N and plasma urea N will be measured with colorimetric procedures using a UV-vis.Trial 2 is designed as described by Van Emon et al. (2015). Steers will be used to determine if ruminants readily consume BSFL as a protein supplement. The study will be a 3 × 6 Latin Square using 3 steers for 6 × 5-d periods. Four dietary treatments will be offered as 6 possible paired combinations. Period breakdown is as follows: a 3-d acclimation period where steers will be supplemented only SBM (CON) and a 2-d experimental period where paired combinations will be offered. Steers will consume a basal diet of forage offered at 130% of the previous 5-d consumption. Dietary treatments will be: 100% SBM (CON); 33% BSFL and 67% SBM (B33); 66% BSFL and 33% SBM (B66), and 100% BSFL (B100). The 6 possible paired combinations will be: CON vs B33, CON vs B66, CON vs B100, B33 vs B66, B33 vs B100, and B66 vs B100.Steers will be housed individually in a partially enclosed barn. Within each pen, there will be a feed bunk divided in half by a barrier. Dietary treatments will be provided in separate removable tubs within each feed bunk to facilitate recording of individual treatment weights. During the acclimation period, steers will be provided CON in equal parts on either side of the divider within the feed bunk. During the experimental period, treatments within each paired combination will be offered on separate sides of the divider. To ensure preference for side of feed bunk is not a confounding factor, the treatments will be offered on opposite sides of the divider on d-4 and -5. Initially, each treatment will be offered at 25% of the prior 3-d consumption rate.To determine preference, bunks will be monitored in 30-min increments and treatment disappearance will be recorded by weighing the removable tubs through 4-h. Treatments will be added as needed during 30-min checks to ensure availability does not limit intake. After the 4-h monitoring period each day, steers will be provided additional SBM (CON) for the remainder of the day. Forage and treatments will be analyzed for nutrients as described for Trial 1.Trial 3In vitrotrue digestibilitywill be quantifiedwith a Daisy® in vitro incubator(Ankom Technology Corp., Macedon, NY) and three ruminally cannulated steers consuming forage and a conventional protein supplement. Rumen fluid will be sampledfrom the cannula 2 h after feeding, filtered through cheesecloth, and mixed with McDougall's buffer at a 1:4 ratio. The Daisy® in vitro incubator will be preset at 39.5°C with an approximate rolling speed of 49 seconds per round. The incubator and sample jars will be purged with 30 seconds of CO2 prior to sample insertion. Approximately 0.5 kg of feedstuff (BSFL, SBM) will be placed into sealed nylon bags and immersed in the incubation solution in sample jars. Four jars with 24 nylon bags each will be placed into the incubator for 0, 6, 12, 24, and 30 h. After incubation, sample bags will be rinsed with water and dried in a forced-air oven at 60°C for 48 h. Analyses for nutrients will be executed as described for Trial 1.