Utilization of Soy to Produce By-Pass Fat for Dairy Cattle
We often discuss the dairy industry and how we fit into helping it. For example, here are topics we have focused on in the Insta-Pro blog:
- Importance of energy in dairy diets
- How the digestive structure of dairy cattle makes the concept of rumen by-pass protein important
- Benefits (and necessity) of switching to a higher-quality by-pass protein ingredient
- Data helping to explain why extruded/pressed (ExPress®) soy meal is a highly-digestible source of by-pass protein
- Added benefits of using high-quality by-pass ingredients, including enhanced rumen function
You may notice a trend in the above posts – by-pass protein. We have a great story to tell here. Every commercial dairy herd uses an ingredient, or mixture of ingredients, to supply by-pass protein in order to maximize performance. By-pass protein (also called rumen undegradable protein or escape protein) resists digestion in the rumen and proceeds to the small intestine, where it is digested and utilized by the cow to support milk production.
Another important and related concept we get asked about is by-pass fat. With extrusion of soybeans, are we creating by-pass fat (from the residual oil in the meal) along with by-pass protein?
I took some information from a published paper, including the amount of linoleic acid (chemically known as 18:2, which is the main fatty acid in soy) that was consumed, and this was then compared to the amount of linoleic acid that made it into the milk. I compared ExPress® (high shear, dry extruded and pressed) soy meal that was extruded at lower and higher temperatures to see if increasing temperature resulted in more by-pass fat, which is exactly what happens with protein. The results follow:
The blue bars indicate that the cows consumed very similar levels of linoleic acid, the main fatty acid in ExPress® soy meal; however, when a higher extrusion temperature was used, the amount of linoleic acid in milk was increased (orange bars). While not directly proving that this came from by-pass fat, it certainly is the most likely explanation. Just like with protein, extrusion at higher temperatures seems to create more dietary fat by-pass. The fat then “escapes” the rumen bacteria for intestinal digestion. This speaks to the high-quality nature of any by-pass fat from high shear dry extrusion – if it were heat damaged, it would not be utilized by the cow.
Another way to consider this data is that, while dairy cows fed the ExPress® meal extruded at a higher temperature consumed 4% more linoleic acid from soy, this corresponded with a 19% increase in linoleic acid in milk.
Feeding your dairy cows a diet that consists of high-quality ingredients can increase production of milk. Speak with us about using a high-quality by-pass protein and fat ingredient for your dairy operation.
