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 3/17/2024

Dairy Perspective on Enogen® Feed Corn Hybrids

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Corn silage harvest operation - evening

Shared from Inside the ZONE® newsletter, Pioneer Nutritional Sciences

What Are Enogen Feed Corn Hybrids?

Enogen feed corn hybrids are transgenic corn with an enzyme technology (event 3272) marketed only by Syngenta. Enogen feed corn hybrids express a bacterial alpha-amylase, the enzyme is contained in the endosperm of the kernel and breaks down corn starch into sugar. This technology was originally designed for the ethanol industry to replace liquid fermentation enzymes used in ethanol production and promised added premium opportunities for growers. There has been limited adoption of Enogen feed corn hybrids among ethanol plants and corn growers. Recently, Syngenta began promoting Enogen feed corn hybrids as a superior feed for both grain corn and silage.

What Are Their Claims?

Syngenta claims that Enogen feed corn hybrids significantly increase starch and sugar availability in ruminant diets. In addition, claims of improved fiber digestibility have been made implying that Enogen feed corn hybrids feed similarly to brown mid-rib (BMR) hybrids.

The Facts

Enogen feed corn hybrids do not contain a BMR gene.
The Enogen alpha-amylase trait was developed to produce more ethanol from corn kernels in an industrial setting. There are no credible explanations why an amylase in the kernel would impact fiber digestibility.

Enogen feed corn hybrids present no advantage in fiber digestibility.
Pioneer silage plots from 2017 showed no significant difference in fiber digestibility (NDFD, 24-hr) between Enogen feed corn hybrids and Pioneer brand non-BMR (standard) silage products; both of which demonstrated inferior fiber digestibility compared to Pioneer brand BMR products in the same trials.

  # of
Comps		 Tons/acre
@35% DM		 Starch
%		 NDFD
24 h
Pioneer (standard) 81 25.2 39.4 53.4
Enogen 24.0 37.4 53.6
Pioneer (BMR) 34 23.4 36.4 59.5
Enogen (non-BMR) 24.4 38.5 53.9

2017-2020 strip trial comparisons of Pioneer® versus Enogen feed corn products within 5 relative maturity units of each other (OH, MI, WI, IA, MN, SD, and NE).

The alpha-amylase in Enogen feed corn hybrids does not work at rumen temperature.
The bacterial alpha-amylase is marketed as “robust” by Syngenta because remains active and stable in adverse conditions. In fact, the enzyme’s ideal working temperature range is 160 – 220 ̊F. Clearly, Enogen is an industrial product not developed to work in animals, given that rumen temperature is quite lower and stable (101–104 ̊F in healthy cows) Hu et al.10.

Enogen feed corn is not food-grade corn.
The bacterial alpha-amylase in Enogen feed corn can cause a number of corn food production issues like non-forming dough, crumbly chips, and soggy cereal1. Growing Enogen requires adherence to a stewardship protocol2, nevertheless due to the potential of Enogen contamination markets like ethanol production, grain handling and grain milling3 require continuous inbound testing for the Enogen GMO trait to manage the risk of contamination4.

Growing Enogen feed corn takes away flexibility compared to any other regular commodity corn.
In addition to 30 ft. physical or border rows, the stewardship protocol requires cleaning all equipment used in planting, harvest, transport, and storage. Upon harvest, all grain and/or silage must be segregated from non-Enogen corn. Moreover, the closed-loop system forces the grower to commit the crop for animal feed and prevents from selling into the commodity grain even if the market economics are favorable.

Animal trial data is very limited on Enogen feed corn.
Note that data collected in beef cattle has little value for dairy, because intakes, as well as fiber and starch levels fed are not comparable. In addition, responses in beef cattle were reported only when Enogen corn was fed not fermented, but as whole grain or coarsely cracked.

To date, there are only 4 peer-reviewed university trials in which Enogen corn was fed as silage to dairy cows. All trials used the corresponding isogenic counterpart (background hybrid minus the alpha-amylase transgene) as control. Across trials, silage was fed at 40% of diet DM.

  1. Cueva et al., 20215 (PSU). This study reported no differences in starch digestibility. Further, significant differences in starch content, with the Enogen hybrid having 3% units more starch confounds the results as starch content is unrelated to alpha-amylase present in corn. Silage was fermented for 220 days.
  2. Cueva et al., 20226 (PSU). Replacement of normal corn silage with Enogen, failed to have any effect on dry matter intake, milk yield, or energy corrected milk. Starch digestibility was not reported. Feed efficiency declined from 1.47 to 1.32 kg milk/kg DMI on Enogen fed cows.
  3. Krogstad et al., 20227 (MSU). Effects of Enogen on milk yield, milk components yield, and dry matter intake were all reported as non-significant. Whereas increasing starch from 25 to 30% of diet DM increased both milk yield and feed efficiency regardless of the diet containing Enogen or its non-amylase isogenic hybrid. The study failed to detect any benefit of alpha-amylase when feeding a higher starch diet. Silage was fermented for 41 days.
  4. Rebelo et al., 20238 (OSU). This study compared Enogen with its isogenic hybrid fed as silage or as ground grain. Silages were similar in DM (30%), and starch (35% of DM), however, ground grain differed in particle size (1.05 vs. 0.65 mm). Intakes were higher in cows fed Enogen (58.8 vs. 55.3 lb/d), as well as milk yield (77.8 vs. 72.9 lb/d). No differences reported on milk fat, milk protein, or energy corrected milk. The study found no differences in ruminal digestibility of dry matter, organic matter, starch or NDF. Total-tract apparent starch digestibility was highest in the isogenic control (98.3%) compared to Enogen.

Overall, published dairy research indicates no consistent effect on intakes, milk yield or starch digestibility that could justify feeding Enogen feed corn.

The summary table below, presented in May, 20239 by Dr. Luiz Ferraretto (UW-Madison Dairy Extension Specialist), included his recommendation for caution in interpreting results given the limited research data. Moreover, he also stated that the mechanism behind field-reported production responses is still uncertain. In other words, there is not enough research available to substantiate the claims or to link observed responses to the expression of alpha-amylase in Enogen corn.

Study DMI,
lb/day		 Milk Yield,
lb/day		 ECM,
lb/day		 Fat % Feed
Efficiency,
lb milk/lb DMI		 Total Tract
Starch Digestibility,
% of intake
PSU
Cueva et al., 2021		 No diff +4.4 No diff No diff +0.08 No diff
PSU
Cueva et al., 2022		 No diff No diff No diff NR -0.15 NR
MSU
Krogstad et al., 2022		 No diff No diff No diff No diff No diff NR
OSU
Rebelo et al., 2023		 +3.4 +7.6 No diff Lower No diff Lower

References

  1. Erickson, A., Comment on Docket No: APHIS-2007-0016, U.-A.a.P.H.I. Service, Editor. 2011, Corn Refiners Association.
  2. Syngenta Enogen Stewardship Guide. 2018.
  3. Holdgreve, C., Comment on Docket No: APHIS-2007-0016, U.-A.a.P.H.I. Service, Editor. 2009, National Grain and Feed Association, the North American Export Grain Association, the North American Millers Association and the Pet Food Institute.
  4. Envirologix Case Study: High-Sensitivity Testing for Enogen Corn. 2022.
  5. Cueva, S.F., H. Stefenoni, A. Melgar, S.E. Raisanen, C.F.A. Lage, D.E. Wasson, M.E. Fetter, A.M. Pelaez, G.W. Roth, and A.N. Hristov. 2021. Lactational performance, rumen fermentation, and enteric methane emission of dairy cows fed an amylase-enabled corn silage. J Dairy Sci. 104(9):9827-9841.
  6. Cueva, S., D. Wasson, S. Raisanen, L. Martins, T. Silvestre, and A. Hristov, Lactational performance and enteric gas emission in dairy cows fed an amylase-enabled corn silage, in Journal of Dairy Science. 2022. p. 57-57.
  7. Krogstad, K.C. and B.J. Bradford, The effects of early postharvest feeding of α-amylase enhanced corn silage and different starch concentrations on milk production and blood metabolites of Holstein cows. 2022: Journal of Dairy Science. p. 68.
  8. Rebelo, L.R., M.L. Eastridge, J.L. Firkins, and C. Lee. 2023. Effects of corn silage and grain expressing alpha-amylase on ruminal nutrient digestibility, microbial protein synthesis, and enteric methane emissions in lactating cows. J Dairy Sci. 106(6):3932-3946.
  9. Ferraretto, L.F. Silage-Specific Corn Hybrids for Dairy Cattle Diets. Forage Focus, 2023.
  10. Hu et al. In vitro ruminal fermentability of a modified corn cultivar expressing a thermotolerant α-amylase. Journal of Dairy Science Vol. 93 No. 10, 2010.

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