antibiotics | OZOLEA

When dairy cows will not benefit from the use of antibiotics

Marketing 7 April 2021 News

Mastitis can occur in dairy cows at different severity levels. In the past weeks (read “What milk changes tell us when we forestrip”), we made an overview about the visible signs at milk level according to the severity of the clinical or subclinical mastitis. All these aspects will help us act promptly with the proper decisions and solutions.

Not all mastitis cases need an antibiotic treatment

From his field activity, Mike Zurakowski, DVM (Cornell Quality Milk Production Services) was able to verify that around 85% of mastitis cases are mild or moderate. These are cases that do not require a systemic and immediate treatment: thus, waiting 24-36 hours for the treatment will not change the results. In this range of time, we evaluate for an autonomous regression of the disorder.

The remaining 15% of cases should be treated immediately and systematically.

Defining and developing a mastitis management plan is critical for the prevention and/or control of mastitis. This means that we must work methodically and find out any critical point that deserves higher attention on our dairy farms.

Moreover, milk cultures are crucial to determine what type of pathogens have caused the infection at udder level. Culturing the milk helps us to discriminate between contagious or environmental pathogens. It also gives clues about whether an antibiotic treatment is needed or not and, thus, what antibiotic has to be applied, if needed.

This approach follows a pathogen-based treatment decision pattern for mastitis. It is extremely useful: it can contribute to the prudent use of antibiotics; it allows the farmer to save money on health care and labor expenses; it helps decrease antibiotic residues in the milk tank and minimize milk losses; it mitigates the risk of antimicrobial resistance since the treatment will be targeted and clearly established on the basis of analyses.

Some dairy cows will not benefit from antibiotic usage

When dealing with mastitis, there are some situations in which treating affected animals with antibiotics will not be beneficial.

Long history of chronically high SCC

Each dairy cow has her own personal lactation history. We published in Hoard’s Dayriman Guest Blog an article discussing this issue. High SCC values in milk can be related both to bacterial factors (intra-mammary infections) and other factors (environmental changes, stressful conditions, micro-traumas, etc.). When the milk culture tells us that there is no infection in the udder, the udder tissue may be stressed because of other reasons. As we saw in HD Guest Blog, supporting and protecting the udder tissue are a helping hand in reducing chronically high SCC values. This can be one of the several applications of OZOLEA-MAST in lactating cows.

Repeated previous treatment failures

Last week, when we discussed how biofilms are involved in recurrence of clinical mastitis, we also said that there is a link with increased resistance to antimicrobial substances leading also to repeated failures in treating the cow with antibiotics. The effectiveness of the specific antibiotic relies also on the synergies between the active substance and the udder tissue: when the latter is stressed and damaged, these synergies are reduced. Protecting the damaged udder tissue would be beneficial for the antibiotic activity, as well. Another potential application for OZOLEA-MAST.

Chronic Staphylococcus aureus

S. aureus is a hostile enemy for dairy farmers. Subclinical infections caused by this bacterium remain the largest mastitis issue in dairy cattle: despite in vitro effectiveness of active substances, in vivo cure rates with antibiotics are very low during lactations and the infection tends to become chronic. The reason behind low cure rates lies in the ability of S. aureus to form micro-abscesses that prevent active substances from reaching the microorganism. Unfortunately, chronicization of the infection makes culling the only frequent option. S. aureus causes contagious mastitis; therefore, it is generally spread from cow to cow via milking equipment, the milker’s hands, and improper hygiene and milking sequence. We can control it through prevention of new infections and the culling of affected animals.

In case of S. aureus that gives milk flakes and up-and-down SCC values, OZOLEA-MAST can help mitigate these signs for better herd management while taking time to sort the problem out through the vaccination of the herd or the replacement of animals.

Mycoplasma bovis

Mycoplasma bovis is a respiratory pathogen and can cause polyarthritis in beef cattle. Moreover, it is also recognized as a primary pathogen of mastitis in dairy cows. The infection it causes can become persistent, characterized by progressive chronicization. In this case, affected dairy cows will not benefit from therapy since there are no effective antibiotics or vaccines for the treatment or prevention of the mammary infections generated by this pathogen. Again, in case of M. bovis infections culling is the option recommended for controlling.

Multiple infected quarters

When more than one quarter is affected by mastitis, the dairy farmers should better consider a clinical picture of the situation as their priority. Thus, veterinary advice becomes essential in this situation. Also in this case, supporting the udder tissue and protecting it will help us to take time to find the proper solution.

Damaged teats

Teats can be damaged in many different ways. Dairy cows can smash teats themselves, or injury can occur during milking. Damaged teats are more susceptible to infections: in this case, what should be treated first is the specific physical injury.

Other serious metabolic disease

There is a connection between mastitis and metabolic diseases in dairy cows. Metabolic diseases generally depend on nutrient deficiency or excess. A balanced diet is essential for the proper functioning of all the physiological mechanisms and defensive system in the dairy cow. As we had the opportunity to discuss, there is particular attention to nutritional aspects around calving. A weakened defensive system means major susceptibility to infections also at udder level.

No-growth milk cultures

Negative results when culturing milk mean that, if sampling, transport of samples and analysis have been conducted properly, the dairy cow has autonomously solved the infection thanks to the immune system. Thus, even if there are signs of mastitis, using antibiotics would be not necessary. We can instead support the functionality of the udder tissue with proper protection.

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Recurrent mastitis in dairy cows: the role of bacterial biofilms

Marketing 31 March 2021 News

Recently (see “What changes in milk tell us when we forestrip“), we focused on the worst-case scenario referred to udder issues in lactating cows to understand the mechanism behind tissue damage and the importance of a proper foremilk stripping.

Being able to identify and understand the meaning of milk flakes and other visible signs in foremilk helps early detect clinical cases of mastitis. A correct approach in such a delicate moment is strategic in preventing and controlling mastitis in dairy cows. And it has also an impact in minimizing the recurrence of clinical cases in our herd.

Recurrence of clinical mastitis is discouraging. It can cause huge economic losses on dairy farms.

The reasons why mastitis can be recurrent are explained as a persistent infection of the mammary gland by a mastitis pathogen or reinfection of the udder (or quarter) after an antibiotic treatment.

As other issues, there is a series of risk predisposing factors of recurrent mastitis: parity (the risk is greater in older cows), a higher milk production, what pathogens have been involved in preceding cases, and whether the antibiotic therapy has been strictly followed previously.

Recurrent clinical cases represent an economic loss due to the following effects on dairy cows, herd and farm: reduction of milk yield, increased risk of culling and mortality. Moreover, we should also consider animal health costs met for treating affected cows.

Undoubtedly, bacteria have many selective advantages if compared with other living beings. They have survived the worst environmental conditions, which have somehow guided their evolution. They are simple and they replicate at high speed rates. And, among other things, they can form biofilms.

The ability of forming biofilms becomes a real selective advantage for pathogens causing mastitis since it facilitates bacterial persistence in the udder. Unfortunately, this is not the only consequence: it has been shown that biofilms have a role in increased resistance to antimicrobials and to the host defensive system.

Bacterial biofilms are more difficult to treat and eradicate, thus knowing how microorganisms interact within these structures and how these structures spread throughout the udder could let us think over different prevention and control strategies.

The formation of the biofilm structure begins with the adhesion to a surface and subsequent agglomeration of cells. Adhesive forces are required by the biofilm to colonize surfaces and allow cell communication. Biofilms also have the potential to create fluid-filled channels thanks to disruptive forces. Channels are needed for the delivery of nutrients, oxygen and metabolites throughout the structure.

These disruptive forces are also essential for the detachment of cells, which limit the expansion of the biofilm structure but allows the infection to disseminate and colonize other niches in the cow’s udder through a dynamic process. This aspect can render the dissemination of the infection systemic.

Significant genetic and physiological changes occur in those bacteria forming the biofilm. The resulting effect is a loss of sensitivity to antibiotics.

The presence of biofilms in mammary glands can be linked to a reduction of the effectiveness of antibiotic therapies. According to scientific literature (Gomes et al., 2016) biofilm formation can be triggered by sub-inhibitory concentrations of several antimicrobial agents.

Moreover, the effect of the environment on biofilm formation has been studied (Atulya et al., 2014), in particular the influence of milk components, finding a certain effect exerted by pH. A decrease in pH facilitates biofilm formation thus causing serious issues when using acidic antibiotics to treat mastitis.

Recurrence of intra-mammary infections and the fact that biofilms are less susceptible to antibiotic treatments can exacerbate the ongoing challenge of antimicrobial resistance.

In this context, prevention, control, responsible use of antibiotics and a mutual dialogue between dairy farmers and veterinarians are key measures to tackle recurrent mastitis.

Moreover, there is an aspect that we should consider: the effectiveness of a specific antibiotic relies also on synergies it creates with the targeted tissue at the cow’s body level. The udder tissue, if damaged, would not be able to properly play its role in this powerful synergy.

Thus, protection of the udder tissue is essential, as we have already seen previously.

Those right tools that protect the udder tissue, in combination with all the abovementioned practices, can really help reverse the pattern.

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The One Health approach against antimicrobial resistance

Marketing 18 March 2021 News

The fight against antimicrobial resistance deserves an urgent and coordinated approach, and many are the reasons why.

Humans coexist with animals in the same environment. The relationship is complex and interdependent. We deal with animals for food production and when they are wild and companion animals. This means that human health and animal health are strictly interconnected.

The environment where they live in also has a role in their relationship. All these connections can be a source for diseases which would impact public health, society and the economy. These diseases, commonly referred as zoonoses are transmissible from animals to humans and vice-versa through direct contact or with food, water, and environment.

This process involves resistant bacteria as well.

The principle that recognizes these interconnections between human and animal health is globally known by the term One Health, and the EU embraced this principle as a tool against antimicrobial resistance.

In June 2017, the European Commission adopted the EU One Health Action Plan against AMR. The aim was to call for effective action against this threat, which must be tackled in human and animal health and the environment. The prudent use of antimicrobials is vital to limit its spread. The action plan is built on 3 main pillars, which address its key objectives:

making the EU a best practice region;
boosting research, development and innovation;
shaping the global agenda.

From the implementation of this Action Plan forward, important updates aiming at strengthening EU’s response to AMR have been made. Among the key updates, it is worth citing the adoption of the Farm to Fork Strategy in May 2020, as we discussed previously (click here). This strategy is supported by the implementation of two new regulations [Reg. (EU) n. 2019/6 on Veterinary Medicinal Products (VMP Regulation) and Reg. (EU) n. 2019/4 on Medicated Feed (MF)], providing for a wide range of measures to tackle AMR and stimulate a more prudent use of antimicrobial products in animals.

At EU level, the AMR One-Health Network is chaired by the European Commission and involves government experts in human health and animal health, Commission experts, and the EU scientific agencies – namely ECDC, EMA, and EFSA. These agencies will provide scientific expertise on infection prevention, biosecurity measures and control practices in human healthcare and in animal husbandry for the reduction of infections and therefore the use of antimicrobials.

A One-Health approach is required to get better evidence, coordination, surveillance and control measures with a continuous and open dialogue between the European Commission, supported by all the experts above, and Member states.

The VMP Regulation is one of the tangible expressions of the efforts currently made by the EU against AMR. Its preamble n. 41 clearly defines the need of a One-Health approach to AMR: it is recognized as a complex issue, it has a cross-border dimension and implies a high economic burden for the society. Moreover, “its impact goes beyond its severe consequences for human and animal health and has become a global public health concern that affects the whole of society and requires urgent and coordinated intersectoral action in accordance with the ‘One Health’ approach.”

With the VMP Regulation, all the actors from the livestock sector are called to be part of this approach by proactively improving best practices throughout the production chain and building reciprocal and synchronized relationships. Let’s start getting ready for its application, there is lot of work to be done!

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A more valuable manure for better crop productivity

Marketing 12 March 2021 News

This brief post is meant to be the second one of a discussion series about sustainability without mentioning this word. Our main goal is to be highly efficient and good managers on our dairy farms, before making major investments.

Last time, we had a story to tell about good manure quality. We saw how feeding calves with milk rejected from the tank due to withdrawal periods is not a good option both for calves’ health and chemical and microbiological characteristics of soils when spreading.

What about crop productivity? A proper waste management and a good quality manure can help us give the right boost to our crops.

As dairy farmers, we rely on homegrown crop production. This is a great opportunity to dispose of the waste produced by our dairy cows using it as a fertilizer to meet nutritional demand of crops. Also, it is a good opportunity for the economic optimization of our own entire dairy system.

A recent meta-analysis¹ assessed more than fifty scientific studies to compare the use of dairy manure with synthetic fertilizer.

This meta-analysis showed that, when applied at rates providing equivalent levels of plant-available nitrogen content, the effects of dairy manure on crop production, quality, and digestibility were positively equal to those achieved with synthetic fertilizer.

In particular, manure application increased soil organic matter, with a suggested overall positive impact on long term-fertility. The meta-analysis reported a high variability across the studies for soil nitrate leaching and nitrous emissions, concluding that no clear trends were evident.

An increase in soil phosphorous with a potential threat to water quality may be a risk related to dairy manure application.

The good thing is that, if applied with care to limit above impacts, dairy manure is a suitable fertilizer. It is worth noting that these impacts can vary with site-specific factors (climate, soil type, and application procedures).

Now, let’s go back to the antibiotic issue. A proper management of antibiotics in dairy cows is important for our crops, as well. Dairy manure can introduce chemicals (antibiotics) and pathogens (yes, including resistant strains from calves). How do antibiotics impact the soil, in short?

Depending on a number of different factors (physical and chemical properties of the substance, climatic factors, characteristics of the soil) persistence of antibiotic residues in the soil is determined mainly by sorption to organic particles and degradation/transformation.

The effects on soil microorganisms are the change in their enzyme activity and ability to metabolize different carbon sources and an alteration of the microbial biomass and heterogeneity of microbial communities.

Soil biodiversity plays an important role in ecological processes, and this is true especially for microorganisms, most importantly for their positive role in the maintenance of soil and water quality.

Thus, we owe our crops and our fields a good waste management and rational antibiotic use – it is beneficial for us first! Now, let’s go over good manure spreading:

never forget about local and national relevant rules on manure application to soil;
know the nature and characteristic of the soil – it helps avoid water pollution;
be sure to maintain non-spread zone near vulnerable areas – water sources, settlements, etc.;
highly fertile soils do not need high quantity of fertilizer;
consider proper weather and soil conditions for the application;
pay attention to timing and level of application on heavy or impermeable soils, areas subject to flooding and sloped grounds.

¹ Peter L. O’Brien and Jerry L. Hatfield. Dairy Manure and Synthetic Fertilizer: A Meta-Analysis of Crop Production and Environmental Quality. Agrosyst. Geosci. Environ. 2:190027 (2019) doi: 10.2134/age2019.04.0027