The dry period is as important to the life of a cow as any period during lactation. Proper management and nutrition while dry is crucial for obtaining maximum milk production in the following lactation. The transition from lactating to dry and dry to lactating is marked by significant physical and metabolic stresses.
Cows experiencing excessive stress prior to calving are more susceptible to:
- metabolic (ketosis, milk fever, fatty liver, etc.) and digestive problems
- decreased dry matter intake
- reduced milk production
- lower lactation peaks
- reproductive failure
- postpartum reproductive diseases
- involuntary culling
The main goal of the dry period is to provide some resting time for the cow. During this period the mammary gland tissue regenerates and mineral body reserves are replenished before the next lactation begins.
The dry period has two main phases with different nutritional requirements:
- Far-off period (from the day of dryoff until three weeks before the expected calving date)
- Close-up period (last three weeks prior to the expected calving date)
During the far-off period the main focus is mammary gland involution. Feed a low-energy diet during this period to promote less milk synthesis by the mammary gland, consequently minimizing the risk of mastitis. In addition, formulate far-off diets to provide the required amount of minerals and vitamins, limiting energy and protein to avoid overconditioned cows, which increases the odds of metabolic diseases after calving.
The goals in the close-up period consist of:
- adapting the rumen microflora and rumen papillae to the feedstuffs being fed to milking cows
- maintaining normal calcium levels
- minimizing negative energy balance and immunosupression around calving
Increased energy density during the close-up period is required to meet the needs of the rapidly growing fetus. This energy increase also helps to minimize any late-gestation weight loss that the cow may experience in response to increased fetal growth.
Anionic salts are commonly used in the close-up diets to prevent milk fever (hypocalcemia). Using anionic salts to shift the dietary cation-anion difference towards a more negative charge promotes the release of calcium from tissues.
Keep in mind that anionic salts are unpalatable and may lead to decreased dry matter intake if not managed properly. Evaluate the success of anionic salts by evaluating urine pH once or twice per week. In Holstein cows, urine pH between 5.8 and 6.8 indicates effectiveness of the diet. In Jersey cows the optimum pH is between 5.5 and 6.5.
Keep the yearly incidence rate of these undesirable diseases at low levels:
- Milk fever – less than 3 percent
- Displaced abomasums – less than 5 percent
- Retained placenta– less than 8 percent
- Ketosis – less than 3 percent
In summary, the dry period is both the end of one lactation and the beginning of the next. Careful attention to management and feeding for animals is crucial to achieving optimum animal performance with minimal health problems and increased productive and reproductive efficiency during the following lactation. PD
— Excerpts from Texas Dairy Matters newsletter, Winter 2010
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Ralph Bruno
- Dairy Extension
- Texas A&M
- Email Ralph Bruno
