Role of the Dry Period on Future Milk Production

							                  Role of the Dry Period on Future Milk Production

                             Sara Monroe and Donna Amaral-Phillips
                                    University of Kentucky

        Managing dry cows can be compared to depositing money into a savings account. The
more money you deposit into your account, the greater the interest earned and greater the total
balance at withdrawal time. When managing dry cows, the inputs of good nutrition and health
care during the optimum time period will be returned by a more productive cow during her next
lactation. The opposite is also true! Poorly managed dry cows adjust slowly to the milking herd
diet and routine, are more susceptible to metabolic disorders, and are ultimately less productive
over the entire lactation.

        The dry period benefits the dairy cow in several ways. The change in diet to lower grain
and higher forage content allows liver lesions and rumen ulcers to heal and increases rumen
muscle tone. Also during this time, the secretory cells in the mammary gland involute, regress,
and then multiply again. A short or absent dry period greatly reduces the numbers of secretory
cells which are a major factor affecting milk yield.

       As a result, the length of the cow’s dry period influences the amount of milk produced
during her next lactation. Cows dry for 60 days give approximately 250 pounds more milk over
the next lactation. Comparatively, cows dry fewer than 40 days produce 500 pounds less milk the
following lactation. Dry periods longer than 60 days actually show a moderate decrease in milk
production compared to cows dry 60 days. Very short dry periods do not allow enough time for
mammary gland regeneration, while long periods result in excess body condition. A 60-day dry
period promotes optimum milk yield for cows.

         Approximately two months before calving, the cow should be prepared for her dry period.
If possible, one week before going dry, her feed intake should be reduced and combined with a
low quality forage to lower milk production. Abruptly stop milking the cow, dry treat, dip her
teats, and separate her from the milking herd. Cows are most susceptible to environmental
mastitis infections during the dry period. To reduce the risk of new infections and cure existing
cases, treat all quarters of all cows with an approved long-lasting antibiotic product at drying-off.
Housing dry cows in a clean, well-bedded environment will also greatly reduce the risk of new
infections.

        Nutrition during the dry period should promote a smooth transition into the milking herd,
optimum milk production in early lactation, and reduce the incidence of metabolic disorders.
Ideally, cows should be fed and managed in two separate groups: far-off (first 5-6 weeks) and
close-up cows (last 2-3 weeks before calving). Basically, the dry cow ration should contain
higher proportions of medium quality forage and small amounts of grain. Dry cows need a
relatively low energy level diet with adequate protein, vitamins and minerals. They should be fed
to maintain a body condition score of approximately 3.5. Dry cows should never be put on a diet!
        After the cow freshens, she will need to rely on her energy reserves for the next 6-8 weeks
to achieve maximum milk production. Without these reserves, the cow will experience a severe
negative energy balance, which will limit peak milk production, and cause excessive weight loss.
Conversely, if the cow gains weight during the dry period and enters lactation with too much
body condition, she will be more predisposed to calving difficulty, displaced abomasum, and
ketosis and will not eat as well after calving.

       Careful attention should be given to ration formulation for dry cows to prevent metabolic
disorders and prepare the cow for her next lactation. Grass forages combined with corn silage
with the appropriate amount of grain per head per day can provide a balanced overall ration for
dry cows. During the last two weeks of the dry period, increase the grain to no more than 10 lbs
(for Holsteins) and include forages more similar to those fed to the milking herd. This method of
feeding allows time for rumen microbes to adapt to diet changes, so the cow will be able to
maintain a high level of feed intake at calving. If cows go off-feed in early lactation, they are
more likely to experience disorders such as ruminal acidosis, displaced abomasum, and ketosis.
Formulating the diet to include anionic salts, lower levels of calcium and potassium, and not
adding buffers may reduce the risk of milk fever. Low levels of salt and potassium, along with
exercise also help prevent udder edema. Studies have shown added niacin in close-up cow diets
may decrease the risk of ketosis. In addition, disease resistance may be boosted by including
recommended levels of selenium, vitamin A, and vitamin E.

        Good nutrition and health care administered during the dry period will help the cow adjust
quickly to the milking herd, maintain a high dry matter intake, and avoid costly metabolic
disorders. Managing cows to maximize these benefits of the dry period will enable them to start
the next lactation in the best possible condition. Over the entire lactation, these cows will return
the investment with greater production and profitability for the producer.