A case study of Prototheca zopfii infection in a Hungarian Dairy Herd and its economic impacts

“Mastitis is the most prevalent infectious disease of dairy cows” (Edmondson and Bramley, 2004) resulting in major economic losses. Bacteria are the most commonly known pathogens to cause mastitis, however Prototheca zopfii has been identified as a pathogen causing mastitis which can prove problematic for many reasons. Prototheca zopfii is a unicellular colourless algae which occurs sporadically and is classified as an environmental pathogen. However, recently it has been reported to have an endemic nature in some farms. It is commonly found in wet areas and also areas with a high level of faecal contamination. Infection occurs via the mammary gland through environmental contamination, especially when the farm’s hygiene standards are not optimal. Protothecal mastitis cannot be definitively identified without culturing for it in the laboratory; however, a decrease of milk production with a watery secretion and white flakes can be seen with an increase in the SCC. Protothecal infections are hard to eradicate as resistance is common, consequently, although some sensitivity to drugs are noticed, there are still no drugs with proven clinical efficacy and no correlation between in vitro activity and clinical response. The best way to treat a Protothecal infection is to cull cows as soon as the infection has been identified. This thesis is based on a Hungarian dairy farm of Holstein Friesians which was heavily infected with Prototheca zopfii causing a great impact economically on the productivity of the farm. Pely –Tiszataj Agrar Zrt had a persistently high SCC and antimicrobial treatment was proving inefficient at treating the mastitis cases. Dr. Peter Kovacs (Animal Hygiene Department, Szent Istvan University) was contacted by Pely dairy farm in regard to the persistently high SCC. The first visit took place in May 2010 where a number of observations were made. The sheds were very dirty, with no clean areas for the cows to lie down putting the herd at risk of contracting environmental mastitis pathogens. There was a technical problem with the milking parlour, as well as poor milking technique; insufficient cleaning of the udder pre-milking, inconsistent treatment of cows with clinical mastitis, force stripping was not performed into a cup but onto the floor, the plug was not used on the cluster, once the cluster fell off the udder it was not checked to see if the cow had been milked adequately. 150 samples were taken from 86 cows with 18% of these proven to be infected with Prototheca zopffi. In 48% of the samples no pathogen was identified. This could be due to various factors, for example, Prototheca zopfii can be hard to identify as it is not possible to culture it all the time. The results could also be due to mechanical irritation with no pathogen involved. After the visit recommendations were outlined to prevent the further spread of infection and prevent uninfected cows contracting the infection. Some of these recommendations included proper maintenance of the milking equipment with improved milking technique. It was advised to identify Prototheca infected cows and separate them from the rest of the herd and to identify cows with high SCC. Some of the recommendations were implemented, for example, the farm management did separate the Prototheca infected cows. Despite the measures taken problems persisted. During the summer of 2010 there was construction on the farm to adhere to new EU legislation therefore the cows could not be turned out during this period, increasing the likelihood of infection. The SCC remained persistently high and another farm visit was requested as Prototheca zopffi was found in the bulk tank even though these animals had been separated from the infected group. The farm management thought it wise to contact the Animal Hygiene Department to investigate further into the mastitis problem. During the second farm visit the aim was to sample the non infected groups to check for new infections or infections that were not identifiable first time round. 75 samples were taken from 47 animals with 18.67% infected Prototheca zopfii and in 34.67% no pathogen was identified. After the first visit it was hoped that the situation would improve but, unfortunately, due to the construction on the farm and the lack of implementation of the recommendations the situation worsened. In the sampling from the first and second visit other pathogens were also identified. Due to the magnitude of the problem and the economic losses facing the farm, a new strategy was needed. A questionnaire was drafted to try and ascertain the best method for dealing with the problem, to acknowledge the real costs of the infection and to identify the economic implications. The options discussed with the management included culling the whole herd and buying replacements or separating the infected animals to a part of the farm which was on the other side of the road (refer to map) and buying milking separate equipment for this group. Regarding the financial evaluation it can be concluded that decreasing production losses may be one of the key factors of increasing profitability in stock-keeping farms (Kasche, 1995). Certain production losses are of little significance in themselves and thus escape attention. However, if they prevail for a longer period (e.g. lower milk production) their significance becomes greater. Some losses are directly visible e.g. deaths – other losses are less obvious e.g. the reduced income due to decreased yields. Efficient milk production requires minimum losses due to diseases at herd level. Our calculations modelling the economic effects of mastitis caused by Prototeca zopfii also attract attention to the importance of dealing with the mastitis problem. In my essay a model calculation was carried out to quantify the annual herd level losses resulting from mastitis caused by Prototeca zopfii. In the research 594 Holstein-Friesian cows of a Hungarian large-scale herd were surveyed in 2010, and the production factors of Prototeca zopfii-positive cows were compared with those of Prototeca zopfii -negative cows in the control group. The agro-economic conditions of the year 2010 were taken into consideration to quantify the losses. In the economic calculation the partial budgeting method was used. According to the results of the calculations Prototeca zopfii infected cows produced annually 567 kg less milk on average than the healthy cows and the average SCC of their milk was about 3 times more (approaching to 1.5 million SCC/ml) compared to those in the control group. The annual loss caused by the 152 Prototeca zopfii positive cows on the examined farm was almost 25 million HUF (89,828 EUR). The yearly loss per cow came up to almost 42,000 HUF (151 EUR). On average, 9.1% of all the cows were culled because of P. zopfii mastitis. For 53.9% of this loss the premature disposal was responsible, for 18,5% the loss due to discarded milk and for 17.3% the loss coming from reduced milk production could be blamed, respectively, while the easily demonstrated cost of medical treatment amounted to only 10.4% of the total damage