IMPORTANCE OF DRY PERIOD FOR COWS & ITS MANAGEMENT TIPS
Post no-1450 Dt-11/01/2020
Compiled & shared by-DR RAJESH KUMAR SINGH, JAMSHEDPUR, 9431309542,rajeshsinghvet@gmail.com
The dry period of a dairy cow should be considered an important phase of her lactation cycle. In the first three weeks following drying off, cows are at a high risk of developing mastitis; they are undergoing physiological changes and are more exposed to bacteria from the environment because the keratin plug is not fully developed for all quarters during this time. Adequate nutrition and appropriate disease prevention of the cow at this time will ensure optimal health, milk production, and reproductive performance during the lactation following calving. Therefore, the feeding and management of dry cows is very important from an economic aspect.
The mammary gland of the dairy cow requires a non-lactating (dry) period prior to an impending parturition to optimize milk production in the subsequent lactation. This period is called the dry period, and it includes the time between halting of milk removal (milk stasis) and the subsequent calving. Generally, 50 to 60 days is recommended. If the dry period is less than 40 days, then the milk yield in the next lactation is likely to decrease.
The dry period is necessary to allow the mammary gland to go through a normal period of involution and to ensure that the mammary cell numbers continue to proliferate normally during early lactation. A short or absent dry period greatly reduces the number of secretory cells in the mammary gland.
The amount of milk produced during a cow’s lactation can be influenced by the length of her dry period. Many studies have shown that cows dry for 60 days give approximately 113 kg more milk the following lactation, compared to cows dry fewer than 40 days, which produce around 225 kg less milk the following lactation. Dry periods longer than 60 days show only a moderate decline in milk production compared to those cows dry 60 days. The reason for keeping dry periods close to 60 days short dry periods do not allow enough time for mammary gland involution while long dry period results in excess body condition.
In field conditions, the dry period of the cow represents one of the most neglected. The early dry period and the close up dry period are times of increased susceptibility to new infections.
During the dry period, the risk of new infection by contagious mastitis pathogens is greatest during the first two weeks. Teat end exposure to environmental pathogens is constant throughout the dry period. 50 – 60% of all new infections during lactation are caused by environmental pathogen exposure during the dry period. Over 50% of clinical coliform mastitis cases occur within the first 70 days of freshening as a result of dry period infection (20% within first week).
As the milk demand is increasing, it has put immense pressure on the dairy farming practices and demands on early lactation cows. The stressful period can have a negative effect on a cow’s health, feed intake, and milk production.
Dairy cows are at a vulnerable state when they’re between lactations. This is why a rest period is required in between, primarily because they will be more prone to nutritional issues at this time. The rest period is an important process in a cow’s lactations because this helps to prevent health problems that may give serious problems to the cow’s milk production and future lactations.
It is important to go through the proper drying-off procedure to prevent the emergence of diseases and infections such as mastitis and intra-mammary infections. It is generally recommended to first withdraw concentrates from the cow’s ration for one to two weeks, and then afterwards to gradually stop milking.
As drying-off goes, when the cow isn’t milked for 18 hours or more, the milk glands will stop producing droplets of milk. This will reduce the size of the udder and will start the cow’s dry period of 60 days. Be reminded that during this period the cow should be placed in clean and dry pens and is separated from the lactating cows.
During the dairy cow’s dry period, we should take care to check for diseases and infections that the cows may develop. Three important things to check would be mastitis prevention, vitamin supplementation, and the cow’s body condition. (blog dated April 21, 2010).
Management factors can help alleviate some of the stress at this time , however, it takes a strong dry period program to make a successful and profitable transition from a dry to lactating cow. Management of the fresh cow also begins during the dry period. It is important to feed dry cows a balanced ration (including vitamins and minerals) and they should not lose body condition during this time. Losing body condition during the dry period can lead to metabolic disorders, such as fatty liver and ketosis, which can reduce milk production in the next lactation.
Vitamin supplementation is probably most vital for cows in late pregnancy, as it needs large amounts of vitamins, particularly vitamins A, D, E and selenium. Vitamin A helps in preventing premature and stillborn calves and retained placenta, while vitamin E and selenium helps to enhance the body’s defenses from infectious agents. A balanced vitamin supplemented diet is needed during the cow’s dry period.
Pregnancy and lactation, reproduction and milk production, takes a considerable toll on the cows. They also have a reduced dry matter intake for the first two months of lactation. This is why the cows must have stored body fat as a source of reserve energy, especially during this period.
Lactating cows usually use about 1 kg of stored fat each day to produce 7 kg of milk. If the cow uses up more than 1 kg, especially in the first 14 days of lactation, ketosis may occur because of the fat that is accumulating in the liver. The interval to the conception will be longer than normal in this case.
The normal procedure to dry off a cow is to withdraw all grain (concentrate) and reduce the water supply two weeks prior to the start of the dry period. This drastically reduces the milk production during that time. Then milking is halted abruptly about 45 to 50 days before expected date of parturition. Intermittent milking along with a decrease in the energy concentration of the ration can be used as a method to achieve the target yield. Cows should be observed closely for the first two weeks after drying off to ensure that udders are involuting properly. Udders with swollen quarters should be examined for mastitis.
Infusion of the udder with antibiotics can help prevent infections that may occur in early involution. After milking is stopped intra-mammary pressure increases, milk products accumulate in the gland, and further milk secretion is inhibited.
Infusion Procedures:
The teats must be cleaned and sanitized carefully before any infusion. Without proper preparation, organisms present on the teat end may be forced into the udder and result in a severe infection especially if Gram-negative bacteria are introduced.
- Clean and dry teats.
- Dip teats in an effective germicidal product. Allow 30 seconds contact time before wiping teats with an individual disposable towel.
- Thoroughly clean and disinfect each teat end, paying particular care to the teat orifice, by scrubbing with a cotton swab soaked in 70% alcohol. Use a separate piece of cotton for each teat.
- Prepare teats on the far side of the udder first, followed by teats on the near side. (Teats may be cleaned and infused individually, if necessary.)
- Treat quarters in reverse order; near side first, far side last.
- Insert only the tip of the cannula into the teat end and express all of the contents. Do not allow the sterile cannula to touch anything prior to infusion.
- Do not massage the teats to disperse the product.
- Dip teats in an effective germicidal product after treatment.
- Identify treated cows and remove them from the milking herd to prevent antibiotics from entering the milk supply.
Sometimes if the udder becomes extremely congested, it may need to be re-milked. However, this practice stimulates further milk synthesis because intra-mammary pressure is reduced and pituitary hormones (oxytocin and prolactin) are released. Perhaps more importantly re-milking removes the leukocytes from the udder at a time when many are needed to prevent infection. It usually is unnecessary to re-milk if production is reduced below about 22 kg per day before milking is stopped. This is as per US standards, when the average milk per lactation is 10760 kg, which on a 305 days basis would be 35 kg/day. With that said, if the milk production drops to 60%, then milking can be stopped to dry the cow.
Hence it is important to keep in mind the production level at which the cows should be dried off at, which depending on a cow’s production, may result in a dry period longer or shorter than 60 days. The production level for drying off a cow generally is defined as the daily milk yield at which the return from milk is equal to the labor cost for milking plus the cost of additional feed above maintenance and pregnancy levels. Both the current and subsequent lactation periods must be taken into consideration when making this decision.
- Drying off:
When drying off a cow, the goal is to abruptly end milk secretion and to seal the teat canal as quickly as possible. Cows should not be milked intermittently towards the end of lactation because this prevents the teat canal from sealing and creates continued stimulus for milk production, increasing a cow’s risk for developing mastitis. After the cow’s final milking, the veterinarian-recommended dry cow therapy should be administered. Teat sealant may also be administered to prevent bacteria from entering the teat cistern and causing new infections. Finally, the entire surface of the teats should be covered using an effective teat dip.
- Dry cow therapy: The cow is very vulnerable to new infections during the first three weeks after drying off, so all quarters should be treated with a dry cow mastitis treatment. During this time, risk of infection is higher because physiological changes occur in the mammary gland, bacteria do not get flushed out of the streak canal during the milking process, there is no protection from teat-dip, and milk leakage occurs. Dry cow therapy can clear up an estimated 70 to 98% of already existing infections and helps prevent new infections, making it one of the most economically beneficial methods for mastitis prevention. The prevention of subclinical mastitis is especially important at this time because it can precede clinical cases and, depending on its causative pathogens, can infect other animals. A long-acting intra-mammary antibiotic should be administered to every quarter after the cow’s final milking.
- Nutrition of dry cows: Nutrition during the dry period is important for maintaining proper body condition score of 3.0 to 3.25. Separate diets should be made for far-off and close-up dry cows. Diets of far-off cows should contain less energy and adequate amounts of fiber. Diets of close-up cows should contain more metabolizable protein and energy than diets of far-off dry cows, but should still contain controlled amounts of both energy and fiber to ensure adequate feed intake after calving. Depletion of protein reserves during the dry period can negatively affect the cow’s health, milk production, and reproductive performance during the following lactation. Diets of close-up cows can also contain forages that are lower in potassium, such as corn silage, and grain products to help prevent milk fever after calving. If a herd is not big enough or it is not possible to manage close-up and far-off dry cows separately, dry cows can be managed as one group with a shorter dry period and a negative DCAD diet.
- Length of dry period: Dry periods typically last 60 days and involve both a far-off and a close-up period. The close-up period begins three weeks before expected calving. Research has found that if no dry period is provided for a cow, she will produce 25 to 30% less milk the next lactation. However, some producers have recently begun shifting to using shorter dry periods of 40 to 42 days. These shorter dry periods involve only one group and are paired with a negative dietary cation-anion difference (DCAD) nutrition program. Some argued benefits of using this program include having cows producing milk for 18 to 20 more days and less labor and stress involved since cows only have to be kept in one group rather than two. Research has found that there is no difference in milk yield following a 30-day dry period versus a 60-day dry period for multiparous cows. However, 30-day dry periods in primiparous (first-calf) cows have been found to result in reduced milk yield.
- Minimizing heat stress: Heat stress should also be prevented by providing proper cooling through the use of shade, fans, and sprinklers. Heat stress reduces the amount of mammary tissue that can be developed, so a cow that is heat-stressed during her dry period will have a reduced capacity for producing milk in her following lactation. Studies have shown dry cows that are cooled during summer months can produce 10 to 12 lb. more milk per day during lactation than cows that do not receive additional heat abatement.
- Minimizing social, environmental, and metabolic stress for close-up cows: Stress can affect feed intake, immune function, and overall health and productivity of cows around the time of calving. Social stress can be minimized by having as few pen moves or regroupings of cows as possible so that the social hierarchy of the cows is not disturbed. Adding multiple cows to a group at once is preferable to adding cows individually. Social and metabolic stress can be reduced by providing 36 inches of feed bunk space per cow to ensure adequate dry matter intake and reduce competition for feed. A minimum of 1 freestall or100 to 125square feetper cow should be provided to ensure adequate lying time.
Summary:
The dry cow period must be of adequate length and should not be a time when cows are left to fend for themselves.
* Maintain 50-60 days dry period for first calf heifers as there is little benefit fpr dry period after first lactation of less than 50 days.
* A 30-40 day dry period after second and later lactations is beneficial to lifetime performance and can be done without any detriment to lifetime yield, if proper measures are taken.
* Dry period of less than 35 days and more than 70 days should ne avoided
Balanced rations should be fed in both the close-up and the far-off dry cow program to help minimize metabolic disorders. Dry matter intake should be stimulated two weeks before calving and during the first month after calving to maximize milk production in these highly stressed cows.
Dry Cow Management Considerations:
* Dry treat all quarters
* Barrier dips/teat sealants
* Mastitis vaccination program
* Nutritional supplementation
* Separate from milking herd
* Clean dry environment
* Quarter SCC at dry off and freshening
Milk production and somatic cell count are inversely related; as somatic cell decreases, milk production will increase.
Drying off cows abruptly, administering veterinarian-recommended dry cow therapy, and using a teat sealant will help protect cows from pathogens during the dry period and prevent mastitis in the following lactation. Meeting nutrition requirements of cows, depending on what phase of the dry period they are in and the length of the dry period, will help prevent transition cow disorders and ensure maximum milk production in the following lactation. Providing adequate heat abatement will prevent the negative effects of heat stress and minimizing regrouping and pen moves will minimize social stress of dry cows. Following these steps will help dry cows have better health, milk production, and reproductive performance in their next lactation.
