Today’s dairy cows are genetically superior to your father’s cows. Intensive selection for milk yield and stature has produced bigger, more productive cows. When you combine this with improved nutrition and cow management, it’s easy to see why dairy feed efficiency in North America has doubled in the past 100 years.
Today’s cows produce, on average, 22,000 pounds of milk per cow per year. Elite herds achieve 30,000-plus pounds per cow per year, and the latest individual world record-holder surpassed 78,000 pounds in one year.
The average dairy cow in the U.S. today has the genetic potential to produce far more milk than farmers are getting. And in some ways, that superior genetic potential and “drive” to milk creates the problems we have to overcome in order to keep cows healthy, productive and in the herd.
Why such difference in milk production from one herd to another? For one, nutritional or management barriers prevent cows from producing at their genetic potential. But differences in selection criteria and selection intensity over time have also led to differences in genetic potential between herds.
And research shows some cows are just more efficient; they produce more milk from the same amount of feed than other cows. But, simply stated, some cows are just more tolerant of our lapses in nutrition and management.
In order to help cows meet their genetic potential – produce lots of milk, have a calf on a regular basis, remain healthy and productive in the herd for many years – we have had to change how we feed cows. For lactating cows, many of the nutritional strategies used today were developed as research identified barriers preventing cows from achieving higher production with good health and reproduction.
Two nutrient categories that present special challenges for lactating cows today are supplying sufficient energy and protein.
Energy demands
Race cars require high-octane fuel to achieve top speeds. Much the same, today’s dairy cows require more energy-dense rations to achieve top milk production. This has led us to increase the amount of starchy grains in the diet.
As a concentrated source of energy, starch helps cows meet energy demands for milk production. In addition to the amount of starch fed in the diet, the source of starch makes a difference, too. Starch availability of corn grain from different hybrids varies, and the relationship between starch and the protective prolamin protein in corn grain can be used in hybrid selection and to test for digestibility.
However, feeding more starch can increase cow health issues. Ruminal acidosis, problems from lower forage-to-concentrate ratios and faster rates of passage through the digestive tract all have to be accounted for and negative effects minimized.
Ruminal buffers and alkalizers are commonly fed to help the rumen deal with increased starch levels. Also, feeding ionophores will moderate the production of lactic acid by ruminal bacteria, allowing the rumen to tolerate higher starch feeding levels with less challenge from ruminal acidosis.
Yeasts, yeast and fungal extracts and a host of other additives are also available to assist the rumen in dealing with increased levels of starch.
More recently, the development and commercialization of specific strains of lactic acid-utilizing bacteria and other probiotics that can be fed or administered to cows further addresses the problems created when we incorporate more starch into diets. Maintaining a desirable population of rumen microbes is an ongoing challenge as we alter diet composition to increase energy density.
Fats have also been used to meet the superior cow’s demand for energy. But there are limits on the amount of fats that can be fed without causing problems with digestion or palatability or butterfat synthesis. New research is looking into supplying specific fatty acids in the diet to better meet cows’ energy needs without negative consequences.
Protein demands
The ability of the rumen microbes to convert non-protein nitrogen and degradable protein into high-quality microbial protein and metabolizable protein is simply amazing. Back when cows averaged 10,000 to 15,000 pounds per lactation, sufficient metabolizable protein could easily be supplied without using concentrated sources of rumen-undegradable protein or commercial rumen-protected amino acid products.
But there is a limit to how much metabolizable protein can be supplied via this route. Research has demonstrated we should balance the amino acid supply in metabolizable protein instead of balancing the diet for crude protein like we used to do.
As milk production has increased, high-quality rumen-undegradable protein and rumen-protected amino acids have become valuable tools for meeting the superior cow’s high metabolizable protein requirement.
Modern nutrition models and ration-balancing programs can help optimize the dietary supply of all nutrients. Of particular interest is their ability to estimate the products derived from the complex interactions among proteins and carbohydrates within the rumen. These programs can help us create diets that remove barriers for high-genetic-merit cows to produce milk at their potential.
Transition cow challenges
Increased milk production has created new challenges and magnified existing ones for cows transitioning into lactation. For lower-producing cows, milk fever and subclinical hypocalcemia exist, but these problems are greater for cows of superior production potential. Cows that suffer any degree of hypocalcemia in early lactation will likely not milk to their genetic potential. Nutritional practices targeted specifically at reducing hypocalcemia are needed now more than ever before.
Increased milk production translates into greater early lactation protein and energy demands, which exacerbates an already difficult time in a dairy cow’s life. Research into how energy intake prepartum influences feed intake as well as the utilization of energy postpartum has helped us keep up with the energy challenge.
Mike Allen’s Hepatic Oxidation Theory and development of the “Goldilocks” concept for pre-fresh diets are all the result of ongoing research into problems that did not exist when cows were of lower genetic merit.
Other areas of focus
Improved feedstuff storage and harvesting techniques, and improved forage genetics such as BMR corn and sorghum, reduced-lignin alfalfa and corn silage hybrids with increased fiber digestibility, are just a few of the new tools that allow us to do a better job feeding today’s cows. But it takes more than just good nutrition to pave the way for cows to reach their genetic potential.
We must also address cow comfort, environmental conditions and overall management. Lying time, eating time, ruminating time and time spent away from the bunk are all interconnected. Cows will sacrifice eating time in favor of lying time if they have to. It is important we pay attention to all of the details.
One stressor may not cause a noticeable problem on its own but, when combined with another stressor and perhaps yet another stressor, it is easy to see how milk production and cow health can be impacted.
Genetic selection has also been key to our rapid progress in milk production. Genomics allows selection for feed efficiency, and new indexes allow us to select for specific health traits.
Genetic improvement in milk production will continue. And hopefully genetic improvement in traits related to health and longevity will help remove barriers that prevent cows from reaching their genetic potential for milk production. It is all tied together in the makeup of the cow, after all.
But research into all areas of nutrition must continue so we don’t lag behind. And research into newer areas such as the effects of inflammatory response during the transition period on cow health, immune function and milk production will lead to nutritional, management or therapeutic practices that can help us keep pace with the ever-increasing genetic potential of cows.
Dairy cow management and research must strive to keep pace with today’s and tomorrow’s cows. When we remove the bottlenecks and deliver consistent care and nutrition, dairy cows can produce a whole lot of milk. Make it your job to pave the way for improved cow health, longevity and productivity on your dairy. 
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Tim Brown
- Director of Technical Support
- SoyPlus & SoyChlor
- Email Tim Brown
