SoyPlus Bypass Protein Research

SoyPlus® positively benefits dairy farmers around the globe by offering a positive return on investment for milk production as a high quality protein source. As a dairy bypass feed ingredient, SoyPlus delivers a research-proven 60% bypass protein with an excellent profile of available amino acids, including lysine and methionine, key in milk production. Used in more than 180 published university trials, SoyPlus is the established industry constant.

Bypass protein, or ruminally undegradable protein (RUP), is defined as that portion of dietary protein that escapes degradation by ruminal microorganisms.

Bypass protein from feed, along with microbial protein synthesized in the rumen, is passed into the small intestine for digestion and absorption. Bypass protein helps support production that exceeds levels that can be supported by microbial protein alone.

The purpose of feeding bypass protein is to supply amino acids that may be absent or lowered in a cow's current diet. The addition of these amino acids can lead to increased milk production. Soybean-based bypass proteins are considered very high quality protein because of their amino acid profile.


See the research that stands behind our product with these comprehensive bibliographies for SoyPlus®.

SoyPlus® Bibliography

Quality For the Benefit of Science

SoyPlus offers proven protein nutrition: from its percentage of RUP to its amino acid profile and its natural extraction method to its unwavering consistency.

SoyPlus has been used in more than 180 academic trials designed to test concepts. All of the concepts (RUP/RDP ratios, limiting amino acids, microbial protein synthesis, etc.), when put together, constitute the industry's current understanding of protein nutrition and the importance of bypass protein of a certain amount and quality.

SoyPlus has been proud to participate in these tests as a consistent, quality feed ingredient. Recommended trials in which SoyPlus was used:

Abstracts from Important SoyPlus® Articles

Expeller Soybean Meal and Corn By-Products Versus Solvent Soybean Meal for Lactating Dairy Cows Fed Alfalfa Silage as Sole Forage

Production responses obtained with supplemental protein from expeller soybean meal or corn by-products, relative to solvent soybean meal, were determined in three replicated 4 × 4 Latin square trials. Dietary forage (54 to 58% of DM) was solely alfalfa silage containing 30 to 55% DM and 21% CP (DM basis). Main concentrate ingredient was either ground shelled or high moisture corn; diets were fed as total mixed rations. In Trials 1 and 2, supplements were: control (0 CP), .6× (60% of the supplemental CP of the 1× treatment) solvent soybean meal, .6× expeller soybean meal, and 1× solvent soybean meal. In Trial 1 (DM intake = 24.4 kg/d), supplement had no effect on production but increased weight gain; expeller soybean meal increased production of milk and lactose relative to either amount of solvent meal. In Trial 2 (DM intake = 20.0 kg/d), supplement increased production of milk and milk components; milk production on .6× expeller soybean meal was greater than .6× solvent soybean meal. In Trial 3 (DM intake = 22.4 kg/d), distillers dried grains plus corn gluten meal replaced .6× solvent soybean meal; supplement increased production of milk, 3.5% FCM, protein, and fat with no difference among the three proteins. Across all three trials, response to supplemental protein appeared to decrease with increased DM intake. Results indicate that resistant protein from expeller soybean meal and corn by-products can replace greater amounts from solvent soybean meal, and suggest that, despite high dietary CP, absorbed protein supply may be inadequate when alfalfa silage is the sole forage.

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Relative Value of Solvent and Expeller Soybean Meal for Lactating Dairy Cows

Nitrogen solubility and enzymatic and rumen in vitro degradabilities indicated protein from expeller soybean meal was more resistant to ruminal degradation than that from solvent soybean meal. This was confirmed in Trial 1 by reduced rumen ammonia and branched-chain volatile fatty acids, and by 64% more supplemental protein escaping the rumen when cows were fed expeller soybean meal. In Trial 2, rations supplemented with either solvent or expeller soybean meal, averaging 16.4% protein, were fed to 12 cows in a crossover study. Production averaged 35.3 kg/d but was not influenced by diet. A small but significant improvement in milk to feed ratio occurred with expeller soybean meal. In Trial 3, four sources of protein were fed to 20 cows in a 4 X 4 Latin square: 6.3% solvent, 4.1% expeller (plus .3% urea), 10.0% solvent, or 6.6% expeller soybean meal. Production of milk and milk components was similar on the diets containing 6.3 and 6.6% soybean meal, intermediate on 10.0% solvent, and least on the expeller-urea diet. Milk to feed was equal and greatest on diets containing 6.6% expeller and 10.0% solvent soybean meal, indicating comparable utilization of the expeller diet containing only 60% as much supplemental protein.

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Ruminal degradation and intestinal digestibility of protein and amino acids in high-protein feedstuffs commonly used in dairy diets

A study was conducted to determine the rumen degradation and intestinal digestibility of crude protein (CP) and AA, and AA composition of the rumen-undegradable protein (RUP) from 3 sources of blood meal (BM1, BM2, BM3) and canola meal (CM), low-fat distillers dried grains with solubles (LFDG), soybean meal (SBM) and expeller soybean meal (ESBM). Two Holstein cows fitted with ruminal and proximal duodenal cannulas were used for in situ incubation of 16 h and for the mobile bag technique. To correct for the bacterial contamination of the RUP, 2 methods were used: purines and DNA as bacterial markers. Ruminal degradations of CP were 85.3, 29.8, 40.7, 75.7, 76.9, 68.8, and 37.0 ± 3.93% for BM1, BM2, BM3, CM, LFDG, SBM and ESBM respectively. Ruminal degradation of both total essential AA and nonessential AA followed a similar pattern to that of CP across feedstuffs. Based on the ratio of AA concentration in the RUP to AA concentration in the original feedstuff, ruminal incubation decreased (ratio <1) the concentrations of His, Lys, and Trp, and increased (ratio >1) the concentrations of Ile and Met across feedstuffs. Compared with purines, the use of DNA as bacterial marker resulted in a higher estimate of bacterial CP contamination for CM and lower estimates for LFDG and ESBM. Intestinal digestibility of RUP could not be estimated for BM1, BM3, and SBM due to insufficient recovery of residue. For the remaining feedstuffs, intestinal digestibility of RUP was highest for ESBM, followed by BM2 and LFDG, and lowest for CM: 98.9, 87.9, 89.7, and 72.4 ± 1.40%, higher for BM2 compared with CM and LFDG, at 61.7, 17.9, and 20.7 ± 2.73% CP, respectively. As prices fluctuate, intestinal absorbable protein or AA may be used as a tool to aid in the selection among feedstuffs with different protein quality.

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