Changing The Dry Cow Mindset

This paper, from Jantijn Swinkels and Rinse Jan Boersma of Intervet/Schering-Plough Animal Health, reviews the principle issues and attitudes concerning the dry cow period and the role of 60-day antimicrobial dry cow therapy. Summarised by Charlotte Johnston, TheCattleSite junior editor.
calendar icon 30 August 2010
clock icon 7 minute read

Speaking at the Large Herd Conference, in Devon, Mr Swinkels said that the dry period should be managed with just as much attention and dedication as any stage of lactation.

Over the last 80 years, the worldwide dairy industry standard duration for the dry period has been 8 weeks, or 60 days. It constitutes a period of rest and recuperation for dairy cows, to prepare them for a healthy and productive lactation.

Mr Swinkels is a believer in the "Recharge" concept, so that come calving, the udder and the cow are in the best physical condition for a healthy and productive lactation.

"The dry period should be managed with just as much attention and dedication as any stage of lactation," he says. He says that a full 60-day recharging period results in optimal milk production and performance in four essential ways:

  1. Recharging milk secretion capacity: in 60 days the population of milk producing epithelial cells in the udder is renewed;
  2. Recharging udder health: a broad spectrum dry treatment with up to 60 days activity cures existing infections and prevents new infections;
  3. Recharging the hooves and legs: during the 60 day dry period a complete new sole grows;
  4. Recharging the rumen: the microbial population and the ruminal epithelium are fully recovered from possible incidents of ruminal acidosis during the previous lactation.
Maximising the recharge period through antimicrobial dry cow therapy

The application of antimicrobial dry cow therapy makes an important contribution to recharging udder health during the dry period. An appropriate dry cow treatment cures existing intramammary infections at drying off with an estimated effi cacy of 70 to 98 per cent, and prevents new intramammary infections during the full length of the dry period. Blanket antibiotic dry cow treatment reduces new infections during the dry period by nearly 40 per cent. This not only prevents clinical mastitis cases during the dry cow period itself, but also clinical mastitis in the next lactation. Around 50 per cent of the clinical mastitis cases caused by coliforms during the first 100 days of lactation originate from infections in the dry period.

Recharging the hooves

The dry period is ideal for preparing the hooves for a healthy, productive lactation. Hoof trimming at drying off , together with curative and preventive treatment if indicated, are needed, together with comfortable dry housing. Hoof horn grows with a speed of 4 to 5 mm a month and the sole is approximately 7 to12 mm thick6. Therefore, 60 days or 2 months is the time required for a completely new sole to form.

Recharging the rumen

A substantial proportion of dairy cows experience a subclinical ruminal acidosis during lactation. Figures in studies vary from 19 to 50 per cent of cows. Ruminal acidosis damages the rumen. Recharging rumen health during the dry period comes from feeding a ration that is high in fi bre and low in rapidly degradable carbohydrates. This creates the environment for the ruminal papillae and epithelium to heal and recover.

Not the "forgotten group"

Every lactation starts with calving. Whilst calving itself comes with risks of trauma and other birth problems, the main issues around calving consist of drastic changes in physiology and metabolism, i.e. abrupt increases in calcium and energy excretion, along with the impairment of the immune system.

The dry period and especially the six-week period around calving, called the transition period, are generally recognised as crucial to successful lactation. When cows make it through the fi rst three weeks of lactation without problems, they have an excellent chance to complete the lactation at maximum productivity and with minimal health problems.

Too often it appears that farmers are drying off their cows routinely without taking into account the targets they want to reach through deliberate dry cow management. Dry cows often are kept in poor housing, with poor environment and feeding routines. This observation has led some people to qualify dry cows as “the forgotten group”.

Impact on daily operations

Over the last decades, substantial investments have been made and continue to be made in research, extension eff orts, consultancy and building design towards the management of dry, calving and fresh cows. The vast majority of these eff orts have focused on dry cow metabolism and nutrition. Udder health has had a proper share of attention too.

The daily operations of feeding, husbandry and housing have become more and more decisive in meeting the goals of the dry period. Over the last 5 years, a growing amount of attention has been focused on managing both human factors and cow factors:

  • human factors: how farmers and their staff are really managing the dry cows on a day to day basis;
  • cow factors: is there minimal cow stress, a well mixed diet and good access for every individual cow to feed, water and to rest?

Research has highlighted the importance of dry cow nutrition to ensure a healthy and productive next lactation. Therefore, practically all nutritionists in practice are able to formulate a functional dry cow ration. However, a ration on paper is only a starting point. It is the farmer who has to ensure and check that cows are really eating the calculated ration. The farmer can do this by monitoring the dry cows regularly, checking their body condition score, rumen fi ll, manure consistency and feed digestability, etc.

Short vs. long dry cow period

Studies indicate that a shorter dry period may lead to fewer metabolic problems after calving based on negative energy balance. This has created some interest in shortening the dry period5 from 60 days to 30 days. Despite that, only a limited amount of farmers actually plan for a short dry period. One of the explanations for this eff ect is because milk production is lower in cows with shorter dry periods.

So, the downside of shortening the dry period is a lower milk production in the subsequent lactation, which is very pronounced in primiparous cows (going through their fi rst dry period) and less in multiparous animals. The general opinion is therefore that primiparous cows should have a 60 day dry period as a shorter dry period leads to too much production loss in the next lactation.

In practice, on certain farms, a rational approach could be to give the primiparous cows a 60 day dry period and multiparous cows a shorter dry period to avoid metabolic problems.

This way of working can be economically attractive but is not convenient because it makes operating procedures more complex, as it entails an individual decision made for every cow rather than treating all cows in the same way. From the perspective of the “keep it simple” strategies that are often followed in farm management, choosing to work with only one dry period length for all cows makes sense.

Cows with a planned short dry period should be treated at dry off with a diff erent dry cow product than cows with a planned long dry period. Every cow in the herd should be treated with the right dry cow product, as giving the wrong treatment to a cow either brings a higher risk for intramammary infections at the end of the dry period or entails a signifi cant risk that antibiotic residues will end up in the bulk milk tank.

What’s more, to really gain the benefi ts of the full dry period, the expected calving date should accurately be known for every cow. Indeed, a cow with a planned 6-week dry period that calves 3 weeks earlier than expected will result in substantial losses in milk production or worse, culling.

Factoring in variation in calving dates

The average gestation length of a Holstein Fresian dairy cow is approximately 280 days. If farmers aim for a dry period of, for example, 60 days, cows should be dried off at 220 days (280-60) after the last insemination date, if pregnancy is confi rmed. Despite careful planning, the dry period length remains diffi cult to predict.

The dry period can be shortened unexpectedly due to natural variation, disease or mistakes. Firstly, in real life the exact point of calving has a margin of accuracy of +/- 3 days in adult cows1, so calving 3 days earlier than expected is normal. Secondly, three to five per cent of pregnant cows carry twins and they tend to calve 7-13 days earlier than their single calf-carrying herd mates1. What’s more, cows can abort and as a result calve a month earlier than planned. Even in well managed herds it happens that the cow is not pregnant from the last insemination but from an earlier insemination. In this case the cow can calve 21 days earlier than expected.

For the reasons indicated previously it is advisable to plan a dry period length that is long enough, with a necessary safety margin. Then, if a cow calves earlier than planned, she still has a chance for a reasonable dry period length, allowing enough epithelial cells to replicate to ensure milk production after calving.

Therefore, planning for a short dry period of 30-40 days is risky. For the reasons indicated above, some cows will unexepectedly have a very short or no dry period depriving the epithelial cells the time needed to replicate; this results in a very low or no milk production after calving. This frequently leads to culling of the animal. For these reasons planning for a short dry period is risky and can be a disappointing and costly exercise.

September 2010
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