Dairy farmers can minimise their use of antibiotics in drying off cows by only treating those at 'high risk'.

That was the welcome outcome of an SAC Consulting project which found that reducing antimicrobial use through Selective Dry Cow Therapy (SDCT), by only treating ‘high risk’ cows can cut unnecessary use of antibiotics while also saving money with no threat to udder health.

Dairy specialist Lorna MacPherson of SAC Consulting, who coordinated the project said: “There is mounting pressure on the livestock sector to reduce antibiotic use due to the global threat from the emergence of antibiotic-resistant strains of bacteria.

"The dairy industry has cut prophylactic antibiotic use significantly in the past few years and is well on track to meet government targets but it’s important for farmers to feel confident that by cutting out treatments they are not risking greater need for antibiotics later down the line, which was the main objective of the project.”

The project focussed on reducing the use of antibiotics at drying off and involved eight farms in Aberdeenshire and nine in Ayrshire. Dry period performance was analysed on 3342 cows, 57% of which had SDCT and 43% antibiotic DCT. All cows received an internal teat sealant at drying off.

“Initially farmers were concerned about stopping the routine treatment of cows with antibiotics at drying off. However, as the project progressed, their confidence grew and many were pleasantly surprised that the incidence of mastitis in cows on SDCT (teat sealant alone) was less than those receiving antibiotics and there was no increase in cows calving in with a high cell count.

“The results showed next to no difference in either the dry period protection rate or the dry period cure rate between the systems. In fact it proved that 74% of the cows self-cured.”

Bruce Mackie of Rora Dairy, Peterhead, was involved in the project and said taking part had given him the impetus to stop using dry cow antibiotic tubes.

“Three years ago we were tubing 75% of the dry cows with antibiotics and now it is less than 25%, with no health or yield issues and no change to the bulk somatic cell count.

“Our 260-cow herd on average produces 3.15 lactations and, despite the data showing infection rates are higher in older cows, carrying out SDCT has not altered the age profile of our herd.”

At a conference held to mark the end of the three-year project, 45 delegates heard that antimicrobial resistance is not only a threat to livestock but also to public health with an estimated 700,000 people dying globally of drug resistant infections every year. If nothing is done, this figure could rise to 10m people by 2050.

The UK action plan relates mostly to human health and medicine, but between 2016 and 2020 its aim is to reduce antibiotic use in food-producing animals by 25%. RUMA (Responsible Use of Medicines in Agriculture) figures show that from 2015 to 2018 the total use of antibiotics in the UK dairy herd is down 35%, so the industry is well on track to meet targets or exceed them.

The majority of the conference audience were practicing SDCT by identifying the cows with high cell counts to be treated and reducing the overall use of antibiotics in their herds. Dairy farmers are encouraged in this by the various farm assurance schemes they are part of, whether they be supermarket linked or Red Tractor.

Lucy Squire, milk supply technical manager with Müller said that the company already pays a 0.5ppl premium to those farmers engaged in a range of welfare and sustainability targets including the responsible use of antibiotics and she announced that this premium will be increased to 1ppl in January 2020.

She said the company is committed to reducing prophylactic antibiotic use and has developed Müller’s Farm Insight Programme, which allows farmers to benchmark a wide range of data including welfare outcomes (for example, mobility) and sustainability measures and aims to feedback practical information to farmers.

Dr James Breen from the University of Nottingham and EBVC who was involved in the project said dry cow therapy is the biggest investment in individual cow health and the most important factors were not antibiotics, but teat sealants and the environment.

“The most cost-effective way of preventing new udder infections during the dry period is to minimise the risk by using a teat sealant and pay careful attention to hygiene at drying off. The dry cow housing environment can also have a significant effect on the infection risk during the dry period. There is a place for antibiotics in cows with high cell counts but they should never be used routinely.”

Research at the University of Nottingham backed up the findings of the SAC Consulting project, with statistics showing that there is no benefit in treating low cell count cows with antibiotics at drying off, and that cows treated with a teat sealant only are at no greater risk of calving in with a high cell count or more likely to have mastitis in early lactation.

Dr Breen added: “Environment should be prioritised when adopting a selective dry cow therapy approach; straw courts should have plenty of space – ideally 1.25 square metres per 1000litres herd average production – and calving pens cleaned out daily.

"Cubicles should be scraped and bedded every day and if dry cows are at grass, ideally they should be on pasture which is rested for four weeks and grazed for two. Our trials showed that moving dry cows to fresh pasture regularly reduced the rate of infection from one in three to one in 10."