COLUMNISTS

Providing a good meal to dairy cows is more than diet formulation

Luiz Ferraretto
Maximizing consumption of dry matter increases the cow’s ability to produce more milk and milk components.

Maximizing consumption of dry matter increases the cow’s ability to produce more milk and milk components. Optimizing intake goes beyond diet formulation and includes more efforts directed towards providing a good feeding environment. Studies designed to learn about how the cow’s feeding environment affects how the diet is utilized are more frequent.

Fiber quality

Greater fiber digestibility often triggers a chain reaction beginning with greater rumen passage rate and ending with greater milk production. The rumen of a dairy cow requires feed particles to sink and reach a specific size threshold to cross the rumen exit door.

In another words, it requires particle reduction which will be achieved by mastication and digestion. It is well-established that physically effective fiber maximizes rumen function and milk fat synthesis. But diets containing too many coarse particles or formulated with high fiber concentration entraps particles in the rumen for too long. Besides, it induces more rumination activity to reduce particle size for passage out of the rumen.  

Overall, forages with greater fiber digestibility are more fragile and undergoes greater particle size reduction. This greater flow of particles leaving the rumen allows for enhanced intake of dry matter, and energy and thereby an increase in milk production. Greater energy intake is not the sole responsible for greater milk production.

Changes in chewing behavior also play a major role. Several studies indicate that cows fed silage with less digestible fiber spend more time eating to consume similar or lower amounts of diet. This extra time eating is often at the expense of resting time and may impair production.

Some years ago, our team reviewed the relationship between eating time and milk production. Eating time is defined as the time a cow spend in the feed bunk and likely includes the time eating, masticating, and sorting. Cows spending more time eating were associated with lower yields of milk and milk components.

Feeding environment

Cows are very curious, and part of the time they spent at the feed bunk is not consuming feed. Cows are predisposed to sorting and selecting feedstuffs which will often push feed away from the bunk and change the diet consumed by the next cow reaching for feed in that spot.

The goal is to provide an environment for maximum consumption (and not eating time), followed by resting and rumination. It begins with fresh, consistent, well-mixed feed being always available for cows along the entire feed bunk. Consistency on time and quality of mixing and delivery are important to decrease sorting, promote rumen health and support targeted levels of production.

Feeding twice rather than once a day incentivizes cows to return to the feed bunk and consume more feed. It also limits the amount of time the diet can be sorted. Another way to improve consumption is with frequent feed push-ups, particularly during the first two hours after feed delivery. Most feed bunk displacements occur during this period. Push-ups makes feed accessible to cows. The combination of feeding twice a day and push-ups permit smaller, more-frequent meals which benefits rumen fermentation, and lying behavior.

Last, having sufficient feed bunk space (more than 18 inches per cow) increases consumption and minimize competition for feed. Slug feeding is very common in environments that promote competition. Slug feeding, consumption of sorted diets, or less-frequent, larger meals can put cows at risk of developing ruminal acidosis and milk fat depression. Under these scenarios having a diet with coarse particles or high fiber concentration is beneficial to reduce events of subacute ruminal acidosis.

Luiz Ferraretto

Luiz Ferraretto is Assistant Professor and Ruminant Nutrition Extension Specialist in the Department of Animal and Dairy Sciences at the University of Wisconsin - Madison

UW Extension