|Summary||As only little detailed microbiological data about only few farms with automatic milking systems were available at the time of the study, a complete compilation of farms using AMV (Automatische Melkverfahren, Automatic milking procedures), the assessment of the working surroundings and the implementation of microbiological and chemical-physical investigations were planned and carried out.
In the course of the 18-months-project it was confirmed that an AMV is always very demanding on the farmer concerning his farm’s management. The big advantage of these systems is the flexibility of the working hours. The results of the milk study and the swabs samples reveal strong differences in part between farms with a system of the same manufacturer indicating the importance of the factor management among other factors. But only if the total concept of milking technique and -hygiene, the animal‘s house construction and -hygiene, animal’s health and feeding are harmonized, the striven saving of working hours can be reached.
The microbiological results of the examination often show a worse status of hygiene concerning AMV than concerning conventional systems. The scope of the study comprised 108 samples from 99 farms with a total of 110 milking systems. The investigation comprised 15 parameters. Only in two cases (pseudomonads and yeasts) the values of the automatic systems are lower than those of conventional systems (including one exception: sulphitereducing anaerobes). For all other microbiological criteria in the milk of automatic systems higher values can be found. Examinated parameters are total viable count, lactic acid bacteria, lactobacilli, coagulase positive staphylococci, enterococci, enterobacteriaceae, coliforms, E. coli and molds. Salmonella spp. and Listeria monocytogenes could be detected each once. In both cases, an automated system was affected.
When viewing the physical-chemical examination results (cell count, fat, protein, lactose, freezing point, dry matter) the benefits are related to conventional milking systems.Thus, these systems show higher fat, protein and lactose - values and lower cell numbers than the automatic systems. Both a detectable freezing point depression and the lower dry matter content of milk from automated systems compared to conventional processing leads to the conclusion that the water content in the milk from farms applying automatic milking systems is higher.
Overall, the automated systems are able to meet the relevant requirements of milk regulation at present time and would also meet the values defined in Reg. (EG) 853/2004. In addition, a large range of data arises when comparing different brands of milking systems. However, even at the time of the investigation it was possible to get milk of the best quality with all brands of the tested automatic milking systems. Meanwhile the AMVs have been established in daily farm work and are on a high technical level.
The evaluation of the 381 swab samples, in which the same spectrum of germs was investigated as in the milk tank samples, exhibits different trends. Regarding the study of the liner heads a trended very homogeneous picture is received. Except for the parameter yeast and Bacillus cereus, all values of automatic systems were lower than the ones of conventional milking systems.
Shafts of the teatcup liner show, based on the total bacterial count, a similar trend. The same applies for staphylococci and Bacillus cereus. With respect to the other criteria, the majority of the results of the automatic milking exceed those of the conventional systems (lactic acid bacteria, pseudomonads, enterococci, coliforms, E. coli, molds and sulphite-reducing anaerobes).
In the conventional systems, the strongest bacterial load was detected on the rinsing heads. Regarding the environment-associated coliforms indicating dirt (especially the faecal germ E. coli), the trend is reversed. In this aspect, significantly higher values could be detected in the automated systems.
The results of the investigations of the special udder/teat cleaning systems indicate a lack of clean condition.
The requirement for a successful management of these systems is hygiene and cleanliness on the farm, because an automatic milking system is not able to bring the cleaning intensity into line with the individual grade of the udder’s dirtiness and it is not able to control the success of cleaning. That’s why a low output bacterial count is desirable. Stable and animal hygiene are important starting points to reduce the bacterial load on the slabs and teats. A drying of teats after cleaning would have a positive impact on hygiene.
Importance should be attached to cleaning and disinfection of the milk carrying components as hygienic vulnerabilities exist in both the automatic and conventional systems.
The weak point of all systems - the timely identification and following separation of nonmarketable milk before it reaches the bulk tank - will be continued to work on. On the basis of their computer programmes, automatic milking procedures are capable of comparing current milking with relevant previous ones, so information about differences can be obtained. However, these systems lack precision so often incorrect positive or negative results are created. The first lead to economical losses, the last are decreasing milk quality.
The automatic milking procedures must be able to recognize mastitis perfectly and eliminate non-marketable milk before reaching the bulk tank. The usage and development of biosensor technology promises improvements.
The problem with the depressed freezing point requires future measures to reduce the residual water content in the milk-carrying equipment.