Isn’t it amazing how many things in our lives require some sort of balancing? My first memory of the need for and importance of balance in life was when I learned how to ride a bicycle as a youngster. Long before that – which I have no memory of – I’d learned how to walk, which required lots of balance – and still does. Then, later in life I learned how to water ski and snow ski and fly an airplane – all of which required the need for some sort of balance. Then there are the non-physical things in life like balancing time in relationships and between work and play. And, we can’t ignore the importance of balancing the checkbook!
My primary duty as a ruminant nutritionist over the years has been to balance dairy cow diets. The necessity for balance here is to ensure that cows get adequate nutrients for health and milk production to respond to the need to control expenses, since feeding cows is the most expensive task you perform on your dairy.
Understanding modern dairy nutrition
Today’s modern dairy cows have been bred to produce a lot of milk – which requires high feed consumption and a well-balanced ration. To remain productive, cows also must stay healthy – which, again, requires a well-balanced diet. Though cows are said to have evolved as herbivores – creatures that consume mostly fibrous plant material, they do have the capacity to digest low-fiber feedstuffs such as the starch that comes from grains or corn as well as sugars that come from molasses or sugar beets. However, too much of these non-fiber carbohydrates can play havoc with the rumen, resulting in a sick and non-productive cow. Because the cow is a herbivore, forage must always be the foundation of the diet.
The diets fed to our milking herds today consist of a combination of ingredients – fibrous feedstuffs such as hay crops and silage along with sugars and starches in varying levels depending on production expectations and the cost of ingredients. Added to the basic fiber and carbohydrates are the necessary vitamins and minerals. All of these must be properly balanced to get maximum performance from the cow. Dairy farmers must also realize that high quality forages always outperform poor quality forages and consistent balancing and delivery of a ration are crucial to maximizing rumen microbial efficiencies.
When we’re feeding our cows we should be thinking about how it will impact the function of the rumen. The rumen is essentially a big fermentation vat which, in cows, is 40 to 60 gallons in size, and the home to microbes such as bacteria, protozoa and fungi. All these micro-organisms work to ferment the cellulose from plants and other less complex carbohydrates, reducing them down to organic compounds that become the cow’s energy supply. So what we’re really doing when we’re balancing diets for cows is supporting a population of literally trillions of microbes who themselves have a life cycle and nutrient requirements to do their jobs. If the rumen microbes are happy, then the cow will be happy, too.
Why add carbs?
The primary reason for adding non-fiber carbohydrates such as cereal grains into dairy cow diets is to concentrate mega calories of energy per pound of feed – in other words, nutritional efficiency. But the rumen microbes that favor forage particles don’t like starches and sugars. And when larger amounts of starch and sugar are fermented in the rumen, an acid by-product called lactic acid is produced that makes the environment for the forage fermenting microbes inhospitable. Herein lies the challenge of balancing high-concentrate diets for dairy cows. We have to track how much of the sugars and starches are being fed because, by over-feeding them, fermentation and energy production will rapidly diminish in the rumen.
Another important aspect of this balancing act is keeping the rumen environment as consistent as possible – avoiding significant swings in acidity levels. Cows that stand around for many hours of the day with nothing to eat or cows that are slug-fed with concentrates and no forages have rumens that are unstable and often on the verge of acidosis. Maintaining stability and consistency in the rumen involves both proper formulation and balancing of the diet being fed to cows and the management of how and when cows are able to eat it. Total mixed rations (TMRs) have been widely accepted as the preferred means of getting cows a consistent ration. The TMRs also ensure that every bite they take has nearly the same physical and nutritional makeup throughout the day.
It’s all about balance
Optimizing microbial efficiencies and populations in the rumen require that both energy sources and nitrogen sources be as closely matched and balanced as possible so that microbes always have enough of each and don’t run out of one while there’s too much of the other still available. The importance of increasing microbial protein mass and efficiencies in the rumen will both improve fiber fermentation as well as supply a greater level of high quality protein to the small intestine where the cow absorbs that protein needed for her metabolism.
The improvement of microbial protein flow to the small intestine automatically improves amino acid balances as well as allows for the reduction in the total levels of crude protein in rations. In recent years there’s more focus on supplying and balancing the metabolizable amino acids in the diet. A side benefit of improving amino acid nutrition allows the ration to increase energy density, which is always a limiting nutrient in high-producing dairy diets. It also enables us to decrease the amount of excess nitrogen being released into the environment.
As our dairy industry moves into another year with unpredictable feed supplies and milk prices that make it difficult to pay the bills, it becomes imperative that we balance milk cow diets for optimal feed efficiencies and milk production. Understanding the value of a well-balanced diet for your milk cows at all stages of lactation will result in a more profitable dairy business.
Cover photo: bodym & stefann11/istock