1. Naturally protected proteins:

A few proteins are naturally protected by heat during normal processing and have good bypass characteristics. These includes corn gluten meal, distillers grains (wet and dry), extruded or roasted soybeans, extruded soybean meal, meat meal, blood meal, fish meal, and hydrolysed feather meal. Normally solvent extracted soybean meal contains 28% bypass protein; by comparison a modified expeller processed soybean meal contains 65% bypass protein.

2. Heat and pressure treatment:

Heating protein feeds, usually under pressure, creates cross-linkages of free amino groups within and between protein molecules. In addition to altering the solubility properties of the protein, these cross linkages reduces the surface of the protein that comes in contact with enzymes, thereby blocking the site of enzymic attack.

3. Treatment of protein with formaldehyde or other aldehydes, with or without heat:

This is the most widely used technique of protein protection. The aldehyde reacts with free amino groups and N-terminal groups to form Schiff bases and cross-linkages between protein chains. This process decreases the solubility of the protein and protects it from bacterial action. Once the treated protein enters into a highly acidic environment, the reaction is reversed, and the protein is degraded. Combine aldehyde and heat treatment is also being used.

4. Lipid (fat) treatment:

Fat is emulsified with protein, then the protein is treated with formaldehyde. The product can not be digested in the rumen due to the formaldehyde linkage on the protein. However, the pH of the abomasum is such that the formaldehyde linkage of the protein is broken, with the result that the protein is then digested. Also, and the most  significant, by use of the protein protected  fat system, it is possible to alter the ratio of the unsaturated  fatty acids in beef fat and in butterfat.

5. Non-enzymatic browning:

Through this process bypass content of soybean meal have increased as much as 2.5 times. The process involves mixing the meal with xylose sugar, then heating the mixture to 200-250F. A patent has been applied for on the process.

6. Adding ionophores:

Bovatec (lasalosid) and Rumensin (monensin), two ionophores, are (a) effective n decreasing rumen degradation of natural proteins and (b) in increasing rumen bypass-perhaps by as much as 25%.

7. Alcohol Treatment:

Treatment of soybean meal (SBM) with aqueous solutions of ethanol or propanol at room temp. resulted in lower solubility and reduced in vitro ammonia release. Availability of SBM protein in the small intestine was not reduced when SBM was treated with 30 or 50% aqueous ethanol, propanol or isopropanol at room temp. Similarly total and dispensable amino acids flows at the duodenum tended to be higher when alcohol-treated SBM was fed. Duodenal flow of aspartic acid, serine, proline glycine, and arginine were increased when alcohol treated SBM was fed. Treatment utilising ethanol, pressure and heat allowed more SBM protein to escape the rumen of the steers as compared to alone ethanol treatment.

8. Organic acid treatment:

Treatment of proteins with acetic acid decreased ammonia production when treated proteins were incubated in the rumen fluid. Sheep fed proteins treated with a mixture of VFA also had lower conc. of ammonia in the rumen than did control animals, suggesting a lower rate of protein degradation in the rumen.  The presence of acetyl groups also decreased ruminal digestibility of forage cell walls.

9. Ruminally protected methionine and lysine products:

Methionine (Met) and lysine have been identified as one of the most limiting amino acids for the synthesis of milk and milk protein by dairy cows. Addition of Met hydroxy analog to diets of dairy cows frequently has resulted in increased milk fat contents, Addition of encapsulated forms of Met to the diet has increased protein content of milk or has increased both protein content and production of  milk.