Final report for GS19-208
Use of organic waste material by ruminant animals from food processing operations potentially reduces costs and reduces environmental issues from disposal of these residues. Therefore, 2 experiments were conducted to evaluate the storage and feeding value of residual from edamame soybean processing for ruminant animals. Two types of waste streams, waste during harvest time and waste from processing stored material, were ensiled (on a laboratory scale) using various methods and effects on post-ensiling nutritive value were examined. Material from both waste streams were ensiled either without wilting or after wilting; each moisture level was ensiled with and without an inoculant. Pre-ensiled processing waste material averaged 55 ± 4.5% NDF, 39 ± 3.3% ADF, 11 ± 2.4% CP, and 8 ± 2.6% ash (average of material from 4 trips ± SD). For harvest waste, there was an inoculant by ensiling dry matter (DM) interaction (P = 0.05) for post-ensiling pH. Recoveries of DM after ensiling of the harvest waste tended (P = 0.06) to be greater with the inoculant (92.6 ± 1.41 vs. 88.5% ± 1.41).
Additionally, wilted material ensiled with and without inoculant (average of 3 trips = 29.7% DM with inoculant and 28.5% DM without inoculant) from the waste from the processing of stored material were evaluated for post-ensiling intake, total tract digestibility (DM, NDF, ADF), and nitrogen balance using sheep offered silage produced in 167 L plastic barrels. Dorper crossbred ewes (n = 18; ages 2 to 3 years old; 55 ± 1.2 kg BW) were assigned randomly within a block to treatments within a trip, then assigned to a barrel of silage. Dry matter digestibility was not affected (P = 0.98) by inoculant and averaged 55.7 ± 0.66%. Ewe average daily gain for the 17-day trial tended to be greater (P = 0.08) for the ewes offered the silage without inoculant (0.18 ± 0.05 vs. 0.04 ± 0.05 kg/day).
Overall, the use of edamame waste as silage for feeding and ensiling as a form of storage shows potential.
Results of the project have been shared with the edamame processing facility and are published in a thesis in the University of Arkansas library.
Further research about preservation of edamame residual will aid in improving the probability of producers having a positive experience in producing a value-added product from edamame and soybeans. The objectives of this study were to:
1. Evaluate the nutritive value of fresh and wilted, but non-ensiled, samples of edamame residual from both the harvesting and processing waste streams of the processing plant.
2. Evaluate the nutritive value and preservation characteristics of edamame residual from both waste streams of the processing plant that were ensiled after wilting to 4 different moisture levels and ensiled without or with a commercial silage inoculant (on a laboratory scale, in bags for 42 or 50 days).
3. Offer ensiled material from the processing waste stream to sheep and evaluate intake, total tract digestibility, and nitrogen balance.
- (Educator and Researcher)
Edamame waste was obtained from an edamame processing plant near Mulberry, Arkansas beginning in September 2019 and replicated with 1 trip from the waste generated when beans were received following harvest and 4 more trips in November 2019 representing waste from when stored material was shelled or processed. Edamame residual was brought to Fayetteville, Arkansas (approximately 96.6 km) to study the effects of silage preservation methods. The harvest waste, which included bigger pieces of the edamame plant, like stems, was processed through a forage chopper. Stored edamame that was processed for market created processing waste which included more pods and cracked or culled beans and was not chopped before ensiling. The processing waste is available when frozen stored edamame is shelled to sell edamame beans for market.
Edamame waste was wilted to the target dry matter (DM) for ensiling. To wilt, material was spread to 0.15 m deep on a concrete pad, under roof, and turned once daily using a shovel. This was done because frequent rain events did not allow outside drying. During wilting, random samples from all treatments were monitored for moisture concentration. After edamame waste reached the targeted DM concentration, material was weighed, prepared inoculant (57 mg inoculant dissolved in 25 mL of deionized water and applied to 11.3 kg of edamame material) was mixed by hand into the waste material for the inoculant treatment group and material was immediately transferred to the laboratory (within 30 minutes of preparing the material) for packaging in vacuum-sealed plastic bags.
Harvest waste (a single trip) was ensiled either with or without wilting (fresh [28% DM], and 39% DM [wilted for 3 days]). Material at each targeted moisture level was ensiled with and without a commercial lactic acid bacterial inoculant. Material from processing (4 replicate trips) was ensiled at 20 (fresh), and targets of 35, 50, and 65% DM. Trip 1 processing waste was wilted for 2, 6, and 15 days. Trip 2 processing waste was wilted for 3, 8, and 14 days. Trip 3 processing waste was wilted for 2, 7, and 13 days. Trip 4 processing waste was wilted for 11, 13, and 14 days. Material at each targeted moisture level was ensiled with and without a commercial lactic acid bacterial inoculant (Lactobacillus buchneri). The Purina SI© Buchneri inoculant applies 500,000 cfu/gram of buchneri and 100,000 cfu/gram of LAB.
Target weight for each particular silo was 500 g (exact weight was recorded) and at least 3 silos were made per treatment for each trip. Using 0.2794 m vacuum packaging rolls, material was transferred to plastic bags, cut to size, and closed with a vacuum sealer. Sealed samples were wrapped with another bag and vacuum sealed to prevent rupture and to ensure near-anaerobic conditions throughout the experiment. Samples were incubated at room temperature (22°C) in darkness. Silos were opened after 42 days (harvest waste) and 50 days (processing waste) of ensiling. Measurements taken after opening silos included: post-ensiled sample weight, pH, and nutrient composition (DM, crude protein [CP], neutral detergent fiber [NDF], acid detergent fiber [ADF], and ash, and in vitro DM and organic matter digestibilities). If pH was ≤ 4.8 – proportions of lactic, acetic, and butyric acids (39 samples) were determined.
For the feeding portion of the research, larger quantities of processing waste were ensiled. Waste from processing frozen and stored edamame was obtained in 3 trips as previously described. The edamame waste was wilted on a concrete pad, as previously described, to 28% DM for Trip 1 (wilted for 6 days), 25% DM for Trip 2 (wilted for 8 days), and 37% DM for Trip 3 (wilted for 7 days). After edamame waste reached the targeted DM concentration, material was weighed, and the prepared (Lactobacillus buchneri: Purina SI© Buchneri) inoculant was mixed into the waste material for the inoculant treatment group. This material was ensiled in 167 L plastic barrels with 2 or 3 barrels per treatment from each trip. Waste was packed into the barrels that were lined with two heavy-duty plastic trash can liners. Air was removed from the silage by walking on it as it was being placed into the trash cans. After packing the silage, air was removed using a vacuum and each trash bag was tied shut. Barrels of silage were stored undercover in a non-heated barn at the University of Arkansas North Farm in Fayetteville, AR. Trip 1 waste was ensiled for 72 days while Trip 2 and 3 waste were ensiled for 69 days.
All experimental procedures were approved by the University of Arkansas Animal Care and Use Committee (Protocol # 18118). Dorper crossbred ewes, (n = 18; ages 2 to 3 years old; 55 ± 1.2 kg body weight) that were confirmed pregnant via blood test were used for this study. Ewes were blocked by body weight (light, medium, and heavy), assigned randomly within a block to treatments within a trip, and then assigned to a barrel of silage. The experiment consisted of a 10-day dietary adaptation period followed by 7 days of total fecal and urine collection. Ewes were housed in individual 1 x 1.5-m pens and offered water for ad libitum intake. The lighting in the barn was set for a total of 10 h of daylight each day. Ewes were removed from the individual pens and comingled in a group pen on day 10 for an exercise period and to allow for thorough pen cleaning prior to starting total collections.
One ewe was not eating or drinking enough water, so on day 3, she was removed from the study and replaced with an alternate ewe. Each barrel contained a finite amount of silage, so instead of the planned 7 days of total fecal and urine collection 1 ewe was collected for 5 days, and 3 additional ewes for 6 days. On the final day of the trial the ewes were weighed and returned to pasture.
On day 1, the pregnant ewes were all fed 450 g of edamame silage from their individual barrels. On day 2 all ewes were fed 1,000 g of edamame silage. On day 3 if all offered silage was consumed, ewes were offered 2.5% of their body weight of silage (as-is basis). Silage throughout the entire trial was offered in small portions throughout the day. Starting on day 4 and throughout the rest of the trial, feeding was based on a refused amount, to have 10% refusal. Altogether, ewes were offered silage, allowing for 10% orts, soyhulls given once daily at 0.2% of their body weight, 4 g of dicalcium phosphate, and 32 g of mineral supplement/day to meet predicted nutrient requirements for gestating ewes. Soyhulls were fed immediately after removing orts which were removed between 0600 and 0700. Silage, mineral, and dicalcium phosphate were weighed, mixed, and offered throughout the day.
Feed sampling for the digestion portion of the trial began 2 days prior to the start of the fecal collection. Silage sampling included 2 samples/barrel of silage: 1) for nutrients, placed into the drying oven and dried to a constant weight, and 2) for fermentation analysis, placed in the freezer and stored frozen (-20° C) pending further analyses. Soyhulls, dicalcium phosphate, and mineral were collected once daily into composite samples and then dried to a constant weight in a 50° C oven. Orts collection began 1 day before the fecal collection. Orts were weighed and dried to a constant weight at 50° C. Feces were removed twice daily, weighed, and dried to a constant weight at 50° C. Urine was collected twice daily from plastic containers and a 20% aliquot was stored frozen (-20° C) pending later analysis. Hydrochloric acid (~ 40 mL) was added to collection containers to prevent microbial activity and ammonia volatilization. The urine acidity was checked using a portable pH meter to verify that the pH was at or below 2.
Daily silage samples were composited by barrel, and orts and feces were composited by animal. Dry matter was measured on all samples and samples were composited for further analysis. Composites of the silage, soyhull, ort, and fecal samples were ground through a Wiley Mill using a 1 mm screen and analyzed for nutrient content. Dried samples were analyzed for NDF and ADF (ANKOM Technology Corp., Fairport, NH), N by total combustion, and ash concentrations determined by burning samples in a muffle furnace at 500° C for 6 h. Forage fermentation profiles were analyzed by a commercial laboratory using a composite of the frozen subsamples from each barrel. Urine samples were analyzed for N by a commercial laboratory.
For the small silo project, harvest waste data were analyzed using the GLM procedure and processing waste data were analyzed using the Mixed procedure of SAS. Dry matter at ensiling, inoculant treatment, and DM × inoculant treatment were the fixed effects. Trip was a random effect. Linear, quadratic, and cubic contrasts were treated orthogonally for DM effects using the Mixed procedure of SAS. Concentrations of acids that were non-detectable in the fermentation profiles were given a value at the detection limit. A logistic regression analysis was completed including all silos to find the effects of DM to meeting the pH threshold for silage to be analyzed for fermentation profiles. For the feeding project, one ewe consumed less than 0.1% of body weight (average intake 422 g/d) and DM intake and digestibility data were removed before statistical analysis; however, barrel samples were retained in the nutrient composition dataset. Data for the feeding project were analyzed using the MIXED procedures of SAS (SAS Inst., Inc., Cary, NC). Statistical analysis was conducted as a randomized complete block design with trip and ewe weight group as the blocking variables. Inoculant treatment of the silage was the fixed effect. The experimental unit was the ewe or barrel. Block was the random effect. For both projects, statistical significance was declared at P < 0.05, and tendencies were declared between 0.05 ≤ P < 0.1.
The ash concentrations (23 and 30%) in both treatment dry matter (DM) harvest waste silages were very high. The high ash content could be expected since the material picked up from the processing plant was full of soil. The total digestible nutrients (TDN) of the pre-ensiling harvest waste was not different between the two silages (average of 56%). Pre-ensiling harvest waste in vitro DM digestibility (average of 40%) and in vitro organic matter digestibility (average of 37%) were not different for the 2 different treatment DM of silage.
Post-ensiled harvest waste silage at 26% DM (unwilted) had greater (P < 0.01) NDF (51 vs. 44%) and ADF (40 vs. 33%)contents than the silage at 36% DM (wilted). The silage with 36% DM (wilted) had greater (P < 0.001) ash content than the silage at 26% DM (unwilted). There was no treatment DM effect for the crude protein (CP) of the 2 silages. The TDN of the post-ensiling harvest waste was greater (P ≤ 0.001) in the 36% DM (wilted) silage vs. the 26% DM (unwilted) silage. Edamame silage harvest waste (post-ensiling) averaged 14% CP, 37% ADF, 47% NDF, 28% ash, and 59% TDN (as calculated by the formula: 88.875 – (0.812 × % ADF)). There were greater in vitro DM (42 vs. 35%; P < 0.005) and organic matter (35 vs. 30%; P < 0.02) digestibility concentrations in the 36% DM (wilted) silage than in the unwilted harvest waste.
Harvest waste recoveries of DM after ensiling tended (P < 0.06) to be greater with the inoculant (93 vs. 88%), with no effect of treatment DM (P = 0.12) or a treatment DM by inoculant interaction (P = 0.48). For harvest waste material, none of the silos reached the pH (≤ 4.8) to be submitted for fermentation profiles. There was an inoculant by ensiling DM interaction (P = 0.05) for post-ensiling harvest waste pH. Ensiled fresh material without inoculant had the lowest pH (5.3) and fresh material ensiled with inoculant had a greater pH (5.5) but both were lower than either inoculant treatments using dryer material (6.5).
Pre-ensiling processing waste averaged 56% in vitro DM digestibility and 54% in vitro organic matter digestibility. Post-ensiled processing waste silage DM increased linearly (18 to 71% DM; P < 0.001) as the treatment DM increased. The CP decreased linearly (14.6 to 12.3%; P < 0.003) as the silage DM increased, with the lowest CP level in the driest material. The NDF of the silage increased linearly (56 to 62%; P < 0.001) as the treatment DM increased. The ADF of the silage increased both linearly and quadratically (range of 37 to 44%; P < 0.001) as the treatment DM increased. The ash content increased with increasing DM to a maximum ash concentration in silages dried to 44% DM, then decreased with the 71% DM silage (range of 6.9 to 8.7%; cubic response; P < 0.04). The TDN of the silage decreased quadratically (range of 59 to 53%; P < 0.001) as the treatment DM increased.
There were no effects of inoculant (P ≥ 0.37) or treatment DM by inoculant interactions (P ≥ 0.88) for post-ensiling processing waste in vitro DM or organic matter digestibilities. The in vitro DM and organic matter digestibilities for post-ensiling processing waste decreased quadratically (P < 0.001) as silage DM increased; the silage at 19% DM had the greatest in vitro DM (57%) and organic matter (49%) digestibilities whereas the silage at 44% DM had the lowest in vitro DM (42%) and organic matter (31%) digestibilities.
Processing waste recoveries of DM after ensiling showed a cubic effect for DM (P < 0.10) with the 26% DM silage showing the greatest DM recovery (98%) and the 19% DM silage showing the lowest DM recovery (88%). The post-ensiled processing waste DM recoveries showed no effect for inoculant (P = 0.69) or treatment DM by inoculant interaction (P = 0.97).
Total VFA (% of DM) concentrations were not different (P ≥ 0.36) by treatment DM. Lactic acid concentration (% of total VFA) was affected (P < 0.001) by treatment DM with 26% DM silage samples having the greatest concentrations (31%), 44% DM silage with the next greatest concentration (18%), and the 19% DM silage with the lowest concentration (0.8%). Lactic acid concentrations (% of DM) were affected (P < 0.001) by treatment DM with 26% DM silage samples having the greatest concentration (2.5%). These concentrations of lactic acid are less than optimal; potentially indicating that clostridial bacteria, causing clostridial fermentation, utilized the lactic acid.
Fermentation profiles were only conducted on samples of silos that had a post-ensiling pH of ≤ 4.8. There was a skewed comparison among the samples analyzed for fermentation profiles because fewer samples that were managed for the targeted 44% DM at ensiling had a pH that met the pH threshold for further analysis. Therefore, a logistic regression was conducted to compare sample DM to the odds of meeting the 4.8 pH threshold. The probabilities of silage meeting the 4.8 pH threshold are as follows: 19% DM: 0.80, 26% DM: 0.37, and 44% DM: 0.005. Based on the logistic regression, the pH threshold, and DM of silage, more observations could have been noticed based on the pH and DM had the pH threshold been at 5.5 and DM < 50%.
Post-ensiling pH of processing waste was lowest for fresh and 26% DM (4.4 and 4.6) then increasing to 5.2 and 6.7 when ensiled at 44 and 71% DM (quadratic effect of ensiling DM; P < 0.01. There was no effect of inoculant (P = 0.67) or an inoculant by ensiling DM interaction (P = 0.66) on post-ensiling pH. Acetic acid concentrations (% of DM) were different (P < 0.001) by treatment DM. Acetic acid concentrations were typical, with the greatest concentration in processing waste ensiled at 26% DM (4.9%). Propionic acid concentrations (% of DM) tended (P = 0.04) to be affected by treatment DM with the greatest concentration in the 19% DM silage. Ammonia concentration (% of DM) was not affected (P ≥ 0.27) by treatment DM. Butyric acid concentrations (% of DM) were different (P < 0.001) by treatment DM with the greatest concentrations in the 19% DM silage. The 19% DM silages were positively impacted by the high moisture content when noticing the lower pH levels whereas the 19% DM silage was negatively impacted by the high moisture content when noticing greater butyric acid concentrations. Therefore, the increase in moisture content was not necessarily advantageous for successful ensiling of the edamame processing waste.
There was no effect of inoculant treatment on the nutrient composition of silage used in the feeding project (P ≥ 0.11). The nutrient composition of the silage fed was: 29% DM, 8% ash, 62% NDF, 45% ADF, 12% CP, and 53% TDN. This edamame silage had greater moisture and fiber content and a decreased CP content compared to a typical legume silage.
Butyric acid concentration tended (P = 0.06) to be greater in silage with inoculant. There were no effects of inoculant treatment DM (P ≥ 0.54) or ammonia (% of DM) (P ≥ 0.48). The DM of the silage was 28.5% DM for silage with no inoculant and 29.7% DM for silage with inoculant. The moisture levels were 71.5% for silage with no inoculant and 70.3% for silage with inoculant. Silage pH was not affected (P ≥ 0.61) by inoculant treatment, the pH of the silage with inoculant was 5.1 and 5.0 for the silage with no inoculant. Lactic acid concentrations (% of total acids, P ≥ 0.33; and % of DM, P ≥ 0.30) were not affected by inoculant treatment. There were no effects of inoculant treatment on acetic acid concentrations (% of DM; P ≥ 0.30). There were numerically greater acetic acid concentrations (5.52% vs. 4.93%) in the silage with inoculant. Propionic acid concentrations (% of DM) were numerically different (P ≥ 0.16) in the silage with inoculant versus the silage with no inoculant (0.82% vs. 0.58%).
Ewes consumed 1,616 ± 54.4 g DM/day or 2.9 ± 0.12% of their body weight and there was no effect (P ≥ 0.85) of inoculant treatment on DM intake (g/day or % of body weight). In this study, intake was equivalent to average ewe intake, but two of the ewes on study did have intake issues. One ewe refused to consume edamame silage and was taken off the study and another ewe’s intake was minimal and therefore could not be used for data analysis. It was unknown why intake problems occurred in the two ewes mentioned above, but the moisture content and butyric acid, ammonia, and pH of the silage could have impacted intake. Dry matter intake during adaptation to the diet was not affected by inoculant treatment (P ≥ 0.60). As expected, DM intake during adaptation was numerically less compared to DM intake during collection, but ewes increased consumption of each treatment at similar rates. Fecal (P ≥ 0.85) and urine (P ≥ 0.31) output (Table 3) were not affected by inoculant.
Dry matter digestibility was not affected (P = 0.98) by inoculant and averaged 55.7 ± 0.66%. Treatment with inoculant did not affect NDF digestibility (P ≥ 0.74), ADF digestibility (P ≥ 0.78), organic matter digestibility (P ≥ 0.89), N apparent absorption (P ≥ 0.56), or N retention (P ≥ 0.42).
Ewe average daily gain for the 17-day trial tended to be greater (P = 0.08) for the ewes offered the silage without inoculant (0.18 vs. 0.04 kg/d). The tendency for an increased ADG in the group of ewes fed silage with no inoculant was for a short period of time and a long-term performance study may be advantageous for more understanding. The ewes on the study went on to have healthy lambs. Most of the ewes, 12 of the 18, had twins, with the rest having singles. Ewes having twins included 6 ewes fed silage without inoculant and 6 ewes fed silage with inoculant. One of the ewe’s lambs died and another ewe, who had twins, only raised one because the other was stillborn. All ewes lambed in March or May, with a majority lambing in May. Average lambing date for the 6 ewes lambing in March was March 14th and May 13th for the 12 ewes lambing in May. Ewes lambing in March included 3 ewes fed silage without inoculant and 3 ewes fed silage with inoculant. Ewes lambing in May included 6 ewes fed silage without inoculant and 6 ewes fed silage with inoculant. Ewes lambing in March included 2 sets of twins and 4 singles all evenly distributed among the two silages offered to the ewes. Ewes lambing in May included 10 sets of twins and 2 singles, again evenly distributed among the two silages offered to the ewes.
In summary, ensiling edamame processing waste yielded a feed that was consumed in an adequate amount to maintain body weights over 17 days when ewes were also supplemented with soyhulls. The addition of silage inoculant had minimal effects on intake, digestibility, or ewe body weight change.
Educational & Outreach Activities
Ellen Herring presented 2 abstracts at the 2020 Annual Meeting of the American Society of Animal Science. She did an oral presentation and a poster presentation on this research. The entire meeting attendance was over 700 people, we are estimating that 70 people attending the Forages and Pastures sessions where Ellen presented. Within 2021, we intend to submit a journal article for publication in a peer reviewed scientific journal. Ellen Herring has successfully defended her thesis, which includes this research, and the thesis is available at the University of Arkansas library site.
The purpose of this research was to evaluate the storage, nutritive value, intake, and total-tract digestibility of residual from edamame soybean production with and without an inoculant. Currently, the edamame processing plant, in Mulberry, AR produces a substantial amount of edamame waste with little to no value. To increase the sustainability of edamame production the edamame waste, which contains a high moisture content, could be used as stored forage by ensiling the waste. Ensiling wetter material resulted in a lower post-ensiling pH for both residual materials. Ensiling edamame processing waste yielded a feed that ewes consumed in adequate amounts to maintain their body weights over 17 days when also supplemented with soyhulls. Adding a silage inoculant had minimal effects on intake, digestibility, or ewe body weight change.
Ellen Herring earned a M.S. degree using the research generated by this project for her thesis. She learned many skills related to conducting ruminant nutrition research projects as well as the theory and practice of making silage. She is currently employed by the University of Missouri and will utilize these skills in her present position.
Drs. Beth Kegley and Shane Gadberry intend to continue working with the edamame processor to help them better utilize the waste from processing.
The two waste streams produced at the processing plant provide considerably different material. The harvest waste included considerable amounts of soil, and the potential for it's use as livestock feed may be limited. The fermentation profiles of the processing waste in this project did not show successful ensiling of the waste material, but nutrient content of this material indicated there should be additional research investigating management strategies (i.e. wilting, addition of other feedstuffs) or other inoculants that could enhance silage fermentation and produce a ensiled feedstuff from edamame soybean processing waste.
Edamame waste availability is variable and availability can occur in times of the year when the weather is not best for wilting. This will be a challenge to its use. Overall, the use of edamame processing waste for feeding ruminants shows promise. Ensiling may be a viable means of storing this material, but further research is necessary to find optimal ensiling dry matter and type of inoculant (if any) that should be used.