Disease management on a dairy farm: Testing, Vaccinating, Culling, and Keeping a Closed Herd

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Managing and preventing disease on a dairy farm is a continuous effort. A UK farmer shares his key strategies for optimizing his herd’s health in this video Optimising herd health – Managing disease  

The first key measure is to run a closed herd – no cattle are brought onto the farm, not even bulls. This is even more important in this part of England due to endemic Bovine Tuberculosis (TB). Using farm software, the farmer can mark out cows that have had an Inconclusive Result (IR) for TB and ensure they are not bred from and do not stay on the farm long, potentially spreading disease.  

Leptospirosis – a zoonotic disease that can infect humans – has also been an issue in the past so all adult cows and heifers are vaccinated for this every February before turnout. Another infectious disease that affects many dairy farms in Europe is Bovine Viral Diarrhoea virus (BVD). After 2 years of BVD testing calves through the Tag and Test system and blood testing heifers, this farm is now on the national BVD eradication scheme and registered as free from BVD but continuously monitoring via bulk milk tank tests.  They do not vaccinate against BVD currently, but care is taken to keep a barrier between their cattle and neighboring cattle due to BVD outbreaks on neighboring farms. The final disease that this farmer is acting upon is Johnes. After a recent clinical case (tip of the iceberg!), this farm has been more vigilant to Johnes and test the whole herd twice yearly. Affected cows are culled out but are often the poor performing animals anyway showing more lameness, high cell counts or poor fertility. 

Antibiotic use monitoring and benchmarking

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Measuring and monitoring antibiotic use has proven very helpful for one dairy farmer in the UK as seen in this video Mastitis – Monitoring prudent use of Antibiotics  

As part of a major retailer producer pool, this farmer’s milk buyer collected and benchmarked farm antibiotic usage against other dairy farmers in order to drive progress and help farmers see where improvements could be made. This was against a backdrop of national antibiotic reduction targets set by the Responsible Use of Medicines in Agriculture Alliance targets task force. This farm’s antibiotic use has been consistently below the national average and they completely eliminated the use of Critically Important Antibiotics as part of a farmer-led research project with the University of Bristol.  

The research project led by Dr Lisa Morgans encouraged farmers to learn from one another at regular farm workshops about practical ways they could improve animal health to reduce the need for antibiotics.  Medicine data was shared and each participant hosted their group twice on their farm for a farm walk and facilitated discussion. This helped farmers share knowledge and create practical solutions to improve animal health and welfare bespoke to their farms.  

Mastitis reduction in an indoor-housed herd (use of sand beds)

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Mastitis is one of the leading causes of antibiotic use on UK dairy farms. A high yielding herd housed all-year-round has reduced their mastitis rate to 13% through a series of measures, as seen in this video.

These include installing an Automatic Dipping and Flushing (ADF) system for the teat clusters, swapping from straw bedding in cubicles to sand and changing their pre-dipping routine to using an iodine-based dip and paper towels. 

This has resulted in a drop in environmental mastitis caused by E. coli and Strep. uberis. These types of bugs thrive in dirty bedding, which is now less of a problem for this farm since they made the change to sand. Bugs in the environment can cause mastitis when pre-dipping routines are poor, so attention to effective cleaning of teats before milking is key. The ADF system ensures the spread of bugs through the milking equipment is also minimized.  

Not only has a lower mastitis rate meant reduced antibiotic treatments, which has also saved the farm money, but the farmers have also eliminated the use of Critically Important Antibiotics (CIA). The CIA were often used for mastitis cases and now the farmers find there is less need for them. The farmers also found taking part in a farmer-led research project with the University of Bristol and being benchmarked against other farms in their producer pool very helpful in learning which products were CIA and focusing on specific changes to help prevent disease.  

Preventing and treating respiratory disease in calves

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Respiratory disease is a common problem in calves and is usually associated with housing and the calves’ ability to fight disease. Basic preventive principles are that calves should be kept clean, dry, warm and receive plenty of good quality colostrum straight away. 

Calf housing must have appropriate drainage – 1 in 20 slope to drain urine away from beds. It should be protocol to remove wet, soiled bedding and replace with fresh, dry bedding. Reducing stocking density can also reduce dirt build up and disease pressure. 

Air quality and adequate ventilation is key to prevent respiratory disease. Calf accommodation should have a low level of air movement (0.2 m/s) so calves do not get cold but enough to replace stale, contaminated air within the shed with fresh air from outside. Adding spaced cladding to walls to provide greater airflow is one solution, or mechanical ventilation is another option, as seen in this video Designing buildings to improve calf health  

This farmer was very pleased with the positive-pressure ventilation tube installed in her purpose-built calf shed, which removed stale air, helped reduce levels of pneumonia, subsequent treatments and mortality. 

Newborn calves will feel cold below 10°C. It is important to provide calves with enough bedding to be able to nest in and it is worth considering calf jackets as seen here Optimising calf health – Managing respiratory disease . 

If calves receive enough colostrum at birth, many are able to fight off mild viral infections themselves. Some might develop a fever and go off their feed; in these cases, it is recommended treating with anti-inflammatories so calves continue feeding. If cases worsen or do not respond within 24-48hrs, a discussion with your vet about antibiotic treatment may be necessary. 

Preventing and treating diarrhoea (caused by rotavirus/coronavirus/cryptosporidium) in pre-weaned calves

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‘Prevention is better than cure’ for diarrhoea. This involves ensuring optimal hygiene at calving and in calf accommodation, regularly removing soiled bedding and steam cleaning, disinfecting and leaving calf pens empty, dry and in sunlight to rest between individuals/batches of calves. It is also important to clean feeding equipment with hot water and detergent between each feed. Depending on the bugs present on a farm, it is worth considering vaccination in adult cows to prevent the transmission of diseases like rotavirus to calves. 

When calves have diarrhoea, it is crucial to keep them hydrated and fed, as demonstrated in this video Optimising calf health – Managing Cryptosporidosis  

 

This farmer continues to feed milk as this provides the calf with energy, which supports their immune system in fighting disease. They also emphasize the importance of providing oral rehydration solutions to prevent dehydration, which can be purchased or a homemade solution can be used. This farmer combines glucose, salt, bicarbonate of soda, and a small amount of potassium chloride in a solution to provide calves with the necessary electrolytes when dehydrated. The imbalance in electrolytes caused by fluid loss from diarrhoea also causes acidosis, so the farmer provides a couple of tablespoons of bicarbonate of soda in the milk feeds to help combat this. 

Use of Non-Steroidal Anti-Inflammatory Drugs (NSAID) helps to reduce fever and symptoms caused by inflammation so that calves feel better and continue to drink. Taking faecal samples to test for what is causing the diarrhoea so that the most effective treatment can be selected is key. These principles have led to this farmer reducing their calf mortality from 8% to zero and only using antimicrobials occasionally. 

Improving calf housing with polycarbonate calf pen sections

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It is standard practice to thoroughly clean calf housing and pens between batches. This can be time consuming and the material that the pens are made of has an impact on how effective the cleaning and disinfection process will be. It is also important to have similar sized calves in each batch to reduce competition for food and the spread of infection from older to younger calves.  

This dairy farmer from the UK has designed and installed a novel calf pen consisting of a metal framework with a Jourdain locking yoke front and tailor-made side slots, which allow the insertion of polycarbonate side partitions. The polycarbonate side partitions can be removed and inserted quickly and easily, allowing flexibility in pen size and therefore number of calves per pen. The farmer groups 2-4 calves per pen, noting that this helps to encourage the calves to feed, reduces stress and avoids the negative effects of dominant bigger calves. Managing groups of calves of similar sizes/ages would otherwise be problematic in an all–year–round calving herd. Additionally, the polycarbonate partition is very easy for the farmer to stream clean, saving time and improving the effectivity of the cleaning and disinfection process.  

The calf shed includes a ventilation tube to improve airflow as well as sloping floors to aid drainage, keeping the calf beds dry. Improving ventilation and reducing moisture from damp beds helps lower the incidence of lung disease. This updated calf accommodation has made management much easier for staff and reduced calf mortality rates significantly (from 8% to 0%), with a corresponding reduction in antimicrobial treatments. This has led to reduced costs through better use of staff time and fewer calves needing treatment. 

Health management and welfare of young dairy animals – impact on antibiotic use

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Good husbandry practices are an important contributor to animal health on the farm. Young dairy animals that are cared for appropriately are in a better state to combat their ailments, thus reducing need for antibiotics. At the heart of all these challenges is the overall benefit of keeping calves feeling well.  The International Dairy Federation has developed a set of health recommendations regarding the welfare of young dairy animals to minimise the use of antimicrobials. Calving areas should have high standards of hygiene, be sheltered, and have appropriate bedding. An appropriate birthing plan should consider issues such as choice of sire; safe birthing facilities; and regular checking of animals to ensure prompt, experienced help is available if needed. Newborn dairy animals must receive adequate colostrum, both quantity and quality. The frequency of inspection of stock will depend on the circumstances and management systems. More than one daily inspection is particularly important in the case of animals close to giving birth, newborn, and newly weaned calves. If disbudding is performed, should be done before 2 months of age and follow appropriate birthing and weaning practices. Calves should not be offered for sale until they are sufficiently hardy to be transported. Adequate body weight and dry navel are good indicators. Appropriate transport conditions stipulated in national welfare regulations or codes of practice should be followed. 

Guidelines for antimicrobial resistance from the dairy sector

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Dairy farmers can set up biosecurity measures to prevent introduction of diseases and bacteria onto the farm; implement an effective herd health management programme, as well as for chronically infected cows; set up cleaning and disinfection strategies to prevent spread of diseases. Farmers need to ensure that the use of antimicrobials is based on adequate diagnostic and only used as directed, as well as avoid their preventive use. Withdrawal times must be respected and supported with a strategic residue testing of milk. Milking routines should not injure the animals or introduce contaminants into milk. Farmers should avoid feeding milk-containing residues to calves or other animals on the farm. Animal feed and water must be of suitable quantity and quality.  

Veterinary professionals ensure reliable diagnosis, prevention of diseases and consider alternatives to antimicrobial treatment. They should avoid treatment of incurable animals as well as self-curing diseases with antimicrobials, give clear advice on the appropriate use of an antimicrobial product, including the dose, rates and length of treatment, withholding periods, and recording. Veterinarians should declare and register to your national authorities all drugs prescribed on farm.  

The use of antimicrobials is only part of an animal health management programme that aims to limit disease in animals and improve animal welfare. Early detection of disease allows early intervention, and this minimises the need to use antimicrobials. Improved infection prevention and control measures limit disease spread and progressively reduce the usage of antimicrobial agents. 

The care of young dairy animals

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Good husbandry practices are an important contributor to animal health on the farm. Young dairy animals that are cared for appropriately are in a better state to combat their ailments, thus reducing need for antibiotics. At the heart of all these challenges is the overall benefit of keeping calves feeling well. Newborn dairy animals must receive adequate colostrum, both quantity and quality. If colostrum is not available, an appropriate commercial colostrum substitute should be provided. First colostrum feeding is preferably as soon as possible or latest within six hours of birth. In situations when pre-weaned calves cannot suckle, they should receive liquid feed in a way that fulfils their need to suckle. Pre-weaned calves should not be weaned off liquid feeds until the rumen has developed sufficiently to allow it to accept solid foods. Weaned heifers should have access to balanced solid feed of good quality from an early age to promote good rumen development. Cud feeding may be a good alternative for the development of rumen physiology in weaned replacement heifers. All feeding equipment used for young animals should be thoroughly cleaned after use. Feeds and grassland/pasture use should be monitored to deliver appropriate quality and amount of feed to growing weaned replacement heifers. Water must always be accessible for pre-weaned calves. 

Best practice recommendations regarding biosecurity and boars

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On many breeding farms, a search boar is used for good oestrus stimulation in the sows. However, this activity also carries risks. 

Direct contact between animals is the most effective way to transmit disease. With the oestrus stimulation the boar walks in front of and/or behind the sows and direct contact is possible. It is therefore important that the boar does not transmit disease to the sows and gilts. In general, it is advisable to buy animals from a farm that has at least the same health status, but preferably higher. These farms are free of a number of diseases and this reduces the chance of disease introduction. When an animal is purchased, it must be placed in quarantine upon arrival. The incubation period of a disease (the time between infection and the appearance of the first symptoms) determines the quarantine period. In general, a minimum quarantine period of four weeks is advised, but it is safer to apply a longer period, e.g. six to eight weeks. In addition to the prevention of disease introduction, the newly purchased animals can also adapt to the farm during the quarantine period and receive the necessary vaccinations (adaptation period). It is advised to administer the same vaccinations to boars and sows.  

In order to keep the boar sufficiently active, mating can be allowed occasionally. However, sperm can also be a risk for disease introduction. This also applies when new genetics are introduced to the farm by artificial insemination.  

Conclusions: 

  1. Buy animals from a farm with the same or higher health status. 
  1. When purchasing animals, maintain a quarantine period of at least four weeks 
  1. Vaccinate the boar together with the sows