Reduction in the consumption of intramammary products for the treatment of clinical mastitis through the use of autogenous vaccine.

Vacas leiteiras saudáveis em ambiente de produção moderna, representando o impacto positivo das vacinas autógenas no controle da mastite e na redução do uso de antibióticos.

Mastitis is defined as inflammation of the mammary gland caused by infectious agents such as bacteria, fungi, algae, and yeasts. Bacteria are known to be the predominant cause of mastitis, and therefore treatment consists of using antimicrobials. However, the indiscriminate use of antimicrobials can lead to the development of bacterial resistance, which can be seen in the low effectiveness of treatments.

Mastitis control and prevention strategies have become essential to minimize the impact of this disease on dairy farming. Implementing appropriate milking management and cow environment measures is crucial. Vaccination emerges as a complementary alternative to management measures, aiming to reduce both the severity of cases and the infection pressure in the herd, and consequently, the need for antimicrobial use. In this way, the risk of milk contamination by antimicrobial residues is also minimized, leading to safe and high-quality dairy products for the end consumer.

This text reports on the case of a commercial dairy farm located in the ABCW region of Paraná, which implemented the use of an autogenous mastitis vaccine at the end of 2021 and experienced a significant reduction in the consumption of intramammary antimicrobials for mastitis treatment. The farm's herd consists of approximately 340 lactating Holstein cows, kept in a free stall with sawdust bedding, milked twice a day with an average daily milk production of 38.6 liters per animal. To identify the microbiological profile of mastitis on the farm, milk samples were collected from cows with clinical and subclinical mastitis and subsequently sent to the laboratory. As a result, the following agents were identified from these samples: Corynebacterium bovis , Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus chromogenes, Streptococcus agalactiae, Streptococcus dysgalactiae , and Streptococcus uberis , which were used in the manufacture of the autogenous vaccine.

The pre-calving vaccination protocol was initiated on this property in October 2021, consisting of vaccinating cows at the time of drying off, at the beginning of the pre-calving period, and 30 days postpartum. The dose of the oil-based adjuvant vaccine is 2 mL and is administered subcutaneously. Thus, the results of the vaccination could be observed from the beginning of 2022, when the lactation of the first vaccinated cows began. All intramammary tube purchases were made at the agricultural supply store of the cooperative to which the producer is affiliated. The quantity of intramammary tubes acquired, both for drying off and for use during lactation, was determined using invoices issued in the name of the cooperative member from January 2018 to December 2024. The value of the intramammary tube was not considered, only the quantity, and the data were analyzed descriptively.

It was found that the herd in question grew in number of animals until 2022 (37%) and remained stable from that year onwards. Consequently, a gradual increase in the consumption of drying-off intramammary tubes was observed until 2023, with a reduction of 100 units in 2024 compared to 2023. The consumption of drying-off tubes is directly related to the reproductive efficiency of the herd. In the first year of implementation of the autogenous vaccine (2022), a 48.8% reduction in the consumption of intramammary tubes for mastitis treatment was observed compared to the previous year. In subsequent years, there was a 13.3% reduction in the consumption of intramammary tubes when comparing 2023 to 2022, and a 12.7% reduction from 2024 to 2023.

In 2018, the farm used an average of 4.9 treatment tubes per cow, while in 2024 this number dropped to 1.7 tubes per cow, representing a reduction of 3.2 tubes, or 46.7% , over the evaluated period. In addition to the direct impact on medication costs, the additional gains in productivity and the reduction in milk discarded due to antimicrobial residues should also be considered.

It is important to emphasize that this farm does not use on-farm culture tools for mastitis diagnosis, which could directly influence the consumption of intramammary samples for treatment, since there is no recommendation for the use of antibiotics in cases where bacterial growth is negative.

Figura 1. Número de bisnagas intramamárias para secagem, para tratamento de mastite durante a lactação e média anual de vacas em lactação entre os anos de 2018 e 2024.

In conclusion, it was found that in the years following the implementation of clinical mastitis treatment using autogenous vaccines, there was a significant reduction in the consumption of intramammary antimicrobials for mastitis treatment during lactation in the evaluated herd. This result demonstrates the benefit of using autogenous vaccines in increasing immunity against mastitis challenges, in addition to the indirect gains related to the conscious use of antimicrobials and the reduction in the risk of developing bacterial resistance.