SIOUX FALLS, S.D. – Today, most farmers do not have issues with acidosis as they did 20 years ago, but may not be making the most of their cows’ rumen. A balanced diet is important for milk production, but so is understanding the proper function of a cow’s unique anatomy.
    In her presentation, “Balancing sugars, starch and fibers for a profitable rumen and higher milk components,” Mary Beth de Ondarza presented research on optimal rumen function on March 27 at the Central Plains Dairy Expo in Sioux Falls.
    “We need to take advantage of the rumen in our cows,” said de Ondarza, nutritionist with Paradox Nutrition. “She can digest fiber as well as starches and sugars, and can grow microbial protein in her gut. If we keep that gut healthy and keep the acid low, we can get a lot of value out of the rumen.”
    Even if a farm is not struggling with acidosis, there could be more done to make the most of a cow’s rumen.  
    “If there is a cow in your herd that is making 85-90 pounds of milk, there’s a chance you could reduce the hourly fluctuations in that rumen and create a situation where there’s more hours of the day or more minutes of the day where pH is higher,” de Ondarza said. “That could take you from 90 to 92 pounds per day. If we can improve rumen health even in those already high-producing cows, we can make more milk overall.”
    The first thing de Ondarza will check when she is on a farm is manure.
    “If the manure has bubbles and is shiny with mucus, there’s intestine fermentation happening,” she said. “That tells me the rumen is not doing its job adequately.”
    When feed is fermented in the hind intestine, the acids produced irritate the bowel. To combat this, the cow will produce more mucus to protect herself. The bubbles are from fermentation in the intestine, where they cannot be belched up so it shows in the manure.
    A way to improve rumen health is by ensuring the formation of a rumen mat. Physically effective neutral detergent fiber facilitates the movement of rumen contents and the absorptions of acids.
    “With a good mat, you get that washing machine-baffling effect and that’s a good thing. It pushes acids out to the sides of the rumen where they can be absorbed,” de Ondarza said.
    There are other ways to measure how much a cow, including undigestable NDF.
    “Think of this as the woody fiber that sits in a cow’s rumen for a while,” de Ondarza said. “It’s very necessary for our cows. Think of NDF as the gas we give our cows to have her make more milk. We also need the brakes, the uNDF serves here to keep the rumen healthy and avoid rumen acidosis.”
    Another component to optimizing rumen efficiency and making the most out of the rumen in our cows is starch fermentation.
    “We want the fermentation to occur at the right speed,” de Ondarza said. “It all depends on the source. Wheat and barley are faster; corn and sorghum are slower.”
    The occurrence of grain in manure can be from a variety of factors including poor processing of grain, poor rumen mat foundation or late corn silage harvest. Regardless of source, it is bad for milk production.
    “When I’m on a farm and I see corn or grain in the manure, I know we have to lessen the starch in the forage,” de Ondarza said. “You’re losing energy for milk, but you’re also losing microbial protein.”
    Maximizing rumen microbial immuno-acid synthesis is another factor in getting the most out of rumens.
    “We want to provide a blend of sugars and starches to synchronize the nutrient supply in the rumen to our cows,” de Ondarza said.
    Sugars are a natural part of a cow’s diet, and with fermented feed, bacteria eats a lot of those sugars. To combat this, de Ondarza suggests adding legumes, peas, molasses or whey.
    de Ondarza warned benchmarks are a good guide, but monitoring manure, the bulk tank and the bottom line are all important.
    “Look at your feed costs per hundredweight of energy-corrected milk, then look at microbial protein, milk fat, less acidosis, higher days in milk, better feet, overall cow health, improved reproduction – the list goes on,” she said.
    While all these tweaks may not be feasible for every farm, it is a place to start. Understanding the proper function of the rumen can be a way for farmers to get the most out of their beloved bovines.