As I first started in my veterinary practice in the early 1980s, dry cow management was essentially “management by neglect,” as we did not see the non-lactating cow as a significant cog in the wheel of farm income. Emphasis was always on how to manipulate the lactating cow diet to make more milk efficiently and economically.
Since that time, much research addressing dry cow feeding and management has opened our eyes to the critical importance of the once perceived “resting” period just prior to calving and ensuing lactation.
Hall of Fame basketball coach and player John Wooden, also known for his witty statements, proclaimed: “Failing to prepare is preparing to fail.” This concept most certainly fits our current vision of the dry cow relative to the dairy cow’s production cycle. Ignoring the details of dry cow feeding and management will result in a failed lactation no matter how much you manipulate and add special supplements to the lactating diet.
Why is the dry cow diet so important? Although nutritional requirements are not high compared to lactation during the dry period, here defined as the last 40-60 days of pregnancy, the ability of the pregnant cow to consume sufficient nutrients to make the metabolic transition into lactation is critical. Studies show cows experiencing a marked decline in dry matter intake in the 2-3 weeks prior to calving are at greater risk for a range of disease conditions postpartum, such as ketosis, displaced abomasum, metritis and retained fetal membranes. Poor quality forage, limited feed availability, or management issues account for possible factors imposing the decline in feed intake. Management issues such as overcrowding dry cow pens, not addressing heat stress, and grouping strategies resulting in frequent pen moves or comingling heifers and mature cows are more of an issue in affecting dry matter intake than feed quality.
The story of Goldilocks and the three bears is a well-known children’s fable. The current approach to helping the dry cow meet her energy needs takes its name from this fable, the Goldilocks Diet. Research has shown dry cows consuming too much energy, especially early in the dry period, or too little energy are at greater risk for a failed lactation compared to cows that consume the “just right” amount. Cows consuming too much energy in the early dry period are more prone to metabolic failures of ketosis and fatty liver. Too little energy intake results in lower milk production, body condition loss, and reproductive failure.
Protein content of the dry cow diet has been somewhat controversial as the defined requirement suggests 12% would be more than adequate; however, heifers perform better consuming a higher (14-15%) crude protein diet. Research investigating higher dietary protein to mature dry cows has been mixed in outcomes, though milk yield was the primary objective compared to health and reproductive performance. Cows do not have reserve body protein and will mobilize muscle and blood proteins to scavenge needed amino acids to support fetal development or milk production should the dietary intake be inadequate. Excessive protein mobilization in late pregnancy or early lactation results in low milk protein, greater disease risks and poor reproduction. Since extra dietary protein cannot be stored in the body for later use, the dry cow should be properly formulated to deliver the critical amount of protein to the greatest number of cows in the group, thus one must formulate protein intake based on observed variation in dry matter intake within the group.
The single most crucial issue of the dry cow diet is preparing to ensure stable calcium homeostasis following calving. Hypocalcemia, better known as milk fever, is considered a significant “gateway” disease of the postpartum period predisposing the cow to many other disease events. Clinical (down milk fever cow) and subclinical (droopy fresh cow) hypocalcemia are metabolic concerns immediately following calving. The presence of hypocalcemia is greater in older cows and directly associated with dry cow diet mineral content. The single most important mineral issue in the dry cow diet is the potassium content of the forages. You want to select a forage as low as possible (preferably less than 1.2%) to use as the primary forage of the dry cow diet. Next supplement magnesium to a minimum of 0.35% up to 0.4% dry matter. Be sure the magnesium source is one that is available. Most recent research has not suggested calcium concentrations are a big player here, although that is what most of us had been taught. I worry more about higher phosphorus intakes (greater than 0.4% dry matter). If your veterinarian is concerned about calcium issues, consider the use of an anionic program. This involves adding a supplement high in chloride to “acidify” the cow helping her to better maintain calcium homeostasis. Ask your nutritionist about the options.
Finally, the little items need to be considered, trace minerals and vitamins. These essential nutrients are all important in supporting the immune response and protecting the cow and its developing calf from metabolic oxidative damage by promoting a better antioxidant status. Vitamins A and E have been shown to minimize retained fetal membranes and mastitis. You want to ensure the dry cow is consuming sufficient trace minerals that are available to the cow and vitamins to support her immune response. Adding organic mineral sources at 20-50% of the formulated requirement based on inorganic sources may further augment the cow’s immune response.
As can be seen from this description of the dry cow diet’s role on cow health and performance, one can truly appreciate that properly balancing the dry cow diet is preparing your cow for SUCCESS in her lactation rather than failure. In today’s challenging dairy environment, we need more of our cows to successfully transition from pregnancy to lactation.
Dr. Robert Van Saun is a Penn State Extension veterinarian.
Dr. Robert Van Saun is a Penn State Extension veterinarian.