There are two key types of drugs used on farm that play an important role in animal health and welfare; antimicrobials (antibiotics) and pain relief (commonly non-steroidal anti-inflammatories (NSAIDs)). Both are monitored within the WelFarm programme but must be interpreted in context with further information of the farm system.


Antimicrobials have been integral to living longer and healthier lives and have revolutionised how we treat diseases in both humans and animals. But their effectiveness is being undermined by misuse. The rise of antimicrobial resistance (AMR) will be a central challenge of the 21st century and the World Health Organisation has said it is one of the greatest global health challenges we face.

The more we use antimicrobials the more we increase antimicrobial resistance.

AMR is the ability of micro-organisms (these include bacteria, viruses and some parasites) to stop an antimicrobial drug (such as antibiotics, antivirals and antimalarials) from working against it. As a result, standard medical treatments have become ineffective, infections persist, and they may spread to others. 

The most critical issue is in the resistance of highly infectious strains of bacteria to antibiotics. Health care professionals are left with limited or, in some instances, no available treatment options. This is compounded by no new antibiotics being discovered in the last 30 years.

When bacteria develop resistance, this may:
  • Reduce the ability of antibiotics to cure infections
  • Require the use of different drugs
  • Increase the risk of spreading resistant bacteria to other animals, farms or humans.

Mastitis and antimicrobials

Mastitis control, including dry cow therapy (DCT), accounts for about 85 percent of the antibiotics used on dairy farms. Lactating antibiotics and dry cow antibiotics are used for mastitis control. Preventative use of dry cow antibiotics (i.e. whole herd or blanket DCT), whereby every cow receives antibiotic therapy at the end of lactation, is no longer supported unless specifically recommended by the herd’s veterinarian as part of a herd animal health plan.

On many farms, good management practices and targeted treatment of animals with either Internal Teat Sealants (ITS) or a combination of ITS and DCT will result in great milk quality outcomes, without unnecessary antibiotic use. Talk to your veterinarian about your mastitis control plan.

Pain relief

When an animal has an illness or injury, they will have inflammation and pain. The degree of pain is not always obvious to us as animals cannot tell us, but they do show us in a variety of ways.

Pain has both physiological (increased temperature, increased heart rate, inflammation, loss of function) and psychological (painful lameness means the cow doesn’t want to walk to the feed leading to not eating; kicking the cups off because of a painful udder) effects.

Animal welfare studies have highlighted the wellbeing aspects of preventing and controlling pain in cattle. We perform many husbandry procedures on-farm to reduce aggression, carcass damage and improve identification, handler safety and meat quality. If a painful husbandry practice is justifiable, it is important to determine methods that could be used to mitigate the pain.

Improving outcomes

Treating inflammation and pain effectively can lead to improved productivity, most likely due to animals returning to normal grazing (and other) behaviour more rapidly. Optimal health, wellbeing and productivity all lead to long-term sustainability and the dairy sector’s ability to respond to consumer pressure puts New Zealand in a stronger and more sustainable position.

Common NZ dairy conditions where adding pain-relief, in the form of NSAID treatment would likely be beneficial to the cow:

  • Mastitis (especially moderate to severe cases, where there is obvious swelling and heat and / or the cow is ‘off-colour’)
  • Calving difficulty / assisted calvings (including caesarean section)
  • Down cows – often cows down due to musculoskeletal injury can be treated with appropriate nursing including NSAID use
  • Lameness and prior to use of hoof knife
  • Metritis and retained foetal membranes (especially when the cow is ‘off-colour’; i.e. in conjunction
  • with antibiotic treatment)
  • Respiratory infection in cows and calves (including viral infections)
  • Calf scours
  • Calf disbudding

Talk to your veterinarian about how you could be utilising pain relief in your animal health plan.

Measuring drug use on farm

In New Zealand, all antimicrobial and pain relief used by farmers is under veterinary stewardship. To monitor drug usage within WelFarm we utilise the sales information directly from the vet clinic. As different drugs are sold in different volumes and at different concentrations we need to standardise the measures to create an easy method for comparisons and benchmarking.

PCU: Population correction unit

PCU stands for population correction unit, it is an estimate of the total liveweight (or biomass) of the animals that could be exposed to the antimicrobial.

One method of measuring antimicrobial use is to divide the amount of active ingredient in milligrams by the total liveweight (PCU) for the herd or population. This gives us a comparative figure to assess usage between farms and seasons.

But this approach doesn’t take into account the varying doses between antibiotics so there are limitations when it comes to understanding the quantities of product and number of treatments administered.

ADD: Average daily dose

ADD stands for average daily dose, which uses the amount of drug given for a 24 hour period. It tells us how many days of treatment can be given from a container of product. 

This is a useful measure to compare between products and is used to assess the use of pain relief on farm within WelFarm.

Where to go for further information?