Although a negative dietary cation-anion difference (DCAD) diet has long been used to help control milk fever in transition dairy cows, more recent research is evaluating whether it is also effective in reducing the risk of subclinical hypocalcemia, or slightly below normal blood calcium concentrations, according to Tom Overton, Ph.D., professor of dairy management at Cornell University.
“Subclinical hypocalcemia affects 50 to 60 percent of cows post-calving, and can result in lower milk production, poor reproductive performance and decreased responsiveness of the immune system, which makes the cow more susceptible to infection,” said Dr. Overton.
Dr. Overton spoke at a series of presentations sponsored by Prince Agri Products during the 2014 World Dairy Expo. He said transition period goals should include high milk production; a low incidence of metabolic disorders; a minimum loss of immunological capacity; controlling and/or decreasing days to first ovulation; maintaining and/or enhancing fertility; a low stillborn rate; and healthy calves, all of which support dairy profitability.
He suggested that a dry cow diet should deliver 15 to 18 Mcal/d of NEL (net energy for lactation) during both the far-off and close-up dry periods and sufficient metabolizable protein (minimum 1,100 to 1,200 grams per day) for Holsteins during the close-up period. His DCAD and mineral recommendations for close-up dry cows included:
- Feed low potassium forages along with full use of an anionic supplement in a close-up ration or one-group dry cow ration.
- Supplement magnesium during close-up period (0.40 to 0.45 percent).
- Supplement calcium (0.9 to 1.0 percent for low potassium only diets, and 1.4 to 1.5 percent if feeding a full anionic diet).
Dr. Overton said that in addition to dietary strategies to reduce subclinical hypocalcemia, non-nutritional factors also are important for a healthy transition. These include: proper stocking density, avoiding excessive pen moves, segregating cows and heifers during the transition period and heat abatement. He also recommended more emphasis on blood sampling at the herd or cow level to monitor for low blood calcium levels.
“Transition cow success is attainable, but there is still more to learn and more consistency of adoption is needed in the field,” Dr. Overton concluded.
Animate® is a nutritional specialty product that has proven effective in helping to reduce the risk of subclinical hypocalcemia when fed a minimum of 21 days before calving as part of a negative DCAD diet. It also has been shown to help maintain dry matter intake because of its palatability.