Results of a German field survey exploring the relationship between udder health and milking hygiene involving 5000 dairy farms.
In the light of intensified discussion on the political structure of milk pricing within the framework of the Agenda 2000, and with falling milk prices and the increasing cost of overhead and production - due, for example, to economic measures taken by the German Federal Government, or the effects of the imposed environmental tax - it is interesting to contemplate on losses suffered in production and the reasons why this is happening.
This automatically poses the question of avoidable losses, these being apparently caused by udder diseases and poor milk quality due to a high cell count. Of the 67.600 milk producers in Bavaria, 4.76%, that is 3.218 were penalized on milk sales off farm during 1998 within the framework of milk quality legislation governing increased cell counts. However, the number of dairy farms producing milk exceeding the permitted cell count each month is significantly higher. These producers may not yet have been penalized, but they are indeed suffering considerable forfeiture in yield due to milk, fat and protein losses.
In order to determine causes and effects it is important to know whether certain types of housing or milking procedures, or even the herd size, have a positive or negative influence on milk sold off farm, or whether the implementation of appropriate milk hygiene management can guaranteee udder health, high milk yield and consistency in the production of high-quality milk.
Investigations and results
A step was made towards answering these questions in the winter of 1997/1998 when a survey was made of 5.000 dairy farms which, largely due to an increased cell count, had needed to call in the Eutergesundheitsdienst (EGD), a department of the Tiergesundheitsdienst Bayern.The immense amount of data recorded was split up into the following categories:
Housing facilities and milking techniques with the associated categories „tank cell count“ and „percentage of dairy farms penalized“ (this analysis was based solely on the parameter cell count). Milking techniques and respective quality attributes of the milk sold off farm. Sizes of dairy herds being managed and the variation in milk quality for each size of herd, these being determined in degrees of ten < 10, < 20 to < 80 and > 80. Data relating to milking hygiene and the respective variation in the quality of the milk supplied off farm. The results show a varying number of farms assessed in the individual groups. This is attributable to data not being recorded, either because it was unknown or undeterminable. Due to the relatively high number of farms taking part in the survey, we were able to omit from the questionnaire those farms for which insufficient data was available without fear of a negative effect on the evaluation.
An analogy exists as far as the validity of the results is concerned. Although the information was derived mainly from farms which „stood out“ in particular because of a high cell count, it is to be considered official as negatively influencing factors are far more evident on such farms.
The rough perusal showed that full information was supplied by a total of approx. 4.900 farms. In the category dealing with a differentiated formulation of questions incomplete information was not taken into account (see above).
Statistical method and results
Owing to the varying cause and effect principle, variables such as statistical data were recorded in the structural evaluation as „independent to a certain degree“, and variables seen as „dependant to a certain degree“ calculated and classified into these structural groups.
This evaluation implemented according Sachs (1978) formula.
This method resulted from the classification of farms into 9 cell count ratings: < 100.000/ml, < 200.000/ml, < 200.000/ml to < 800.000/ml and > 800.000 cells/ml.
Table 1 shows that 4.032, that is 80.62% of those farms included in the survey were too late in reacting to an increased tank cell count. 50.89% of the farms listed in table 1 did not utilize the information relating to the tank cell count for quality premium purposes until the critical mark of 400.00 cells/ml had been exceeded.
Frequency of farms (n=5.001) within each tank cell count rating
|Cell count rating
||number of farms
||percentage of farms
They disregard or are unaware of the fact that this limit applies solely to the quality of the milk supplied off farm to the dairy for processing. It is a proven fact that a cell count exceeding this limit is detrimental to milk processing and the quality of milk products. To this day dairies have no technology at their disposal for eliminating the problem of milk supplied off farm with a high cell count.
The milk yield and the milk components are negatively correlated to the cell count, i.e. the higher the cell count, the greater the negative effect on milk production and milk components in the mammary gland. As the milk produced on the farm is an mixture of milk from all cows in a herd, cell counts higher than 200.000/ml point to serious udder health problems within this herd. Cell counts exceeding 400.000/ml lead to an increase in mastitides, a marked reduction in processing quality and considerable financial loss.
Housing facilities and milking techniques
Housing has been grouped into two main types of facility - tiestall and freestall.
Special types of stall and other housing facilities were not assessed in this survey. However, it is interesting to note that even the rough grouping shows differing results.
Information relating to tied up and Loose housing
Of the 5.001 questionnaires, 4.794 contained complete data relating to this question category, 4.319, that is 90% of the farms kept their cows in a tiestall, 475, i.e. 10% in a loose housing
For these groups the following results shown in table 2 were obtained when classifying the catagories Average density of the cell count and percentage of farms penalized.
Housing techniques and milk quality
||number of farms
||Cell count D/ml
||Percentage of losses
The parameter „percentage of farms penalized due to increased cell count“ encompasses the period of time before the EGD technician’s visit and completion of the questionnaire, thus it generally relates to the month or months prior to this. Hence this may result in incorrect estimates, as the deductions from the current tank cell count have to be added. Chart 1 shows the percentage of farms penalized due to a cell count exceeding the regulatory level.
unexpectedly high percentage of farms penalized within the cell count rating < 100.000/ml may, for example, result from the fact that the farmer was warned and penalized for repeatedly exceeding the permitted cell count and, consequently, took immediate measures before the EGD technician’s visit and completion of the questionnaire to implement appropriate milking and hygiene management and to exclude milk which contained a high cell count, thereby inducing a permanent reduction in the tank cell count.
If for this comparison we limit the period of time in which penalties were paid (to 3 months, for example) and compare housing facilities only for herd sizes from 30 cows and more kept in a tied up ll or loose housing, the following data is obtained when classifying the categories average density of the cell count and percentage of penalized (table 3).
ousing techniques and milk uality (> 30 cows)
||number of farms
||Cell count D/ml
||Percentage of losses
The facility „Loose housing with milking parlour“ offers far better possibilites of ensuring udder health and consistently high milk quality.
Depending on the utilized milking technique, the previously determined independent criteria also differ significantly on each farm.
As far as the bulk tank cell content and correlated udder health and milk quality are concerned, milking in milking parlours is by far the most superior method (table 4), although it must be said that this category contains a conglomeration of several influencing factors. In general, however, one can derive from the findings that milking in milking parlours offers more favourable conditions for udder health, milk yield and milk quality.
Milking techniques and milk quality (4.675 farms)
||number of farms
||Cell count D/ml
||Percentage of losses
Herd sizes and penalization
In the category herd size and penalization, size ratings from < 10, < 20, to < 80 and > 80 cows in a herd were fixed, after which penalized farms within these size ratings were established and classified. The result of this statistical evaluation clearly shows a higher frequency of penalization of dairy farmers with smaller herds (table 5).
Frequency of penalization according to herd size rating (4.597 farms)
||Percentage of farms penalized
||Total percentage of all farms
This does not necessarily mean that problems with udder health are generally more frequent in smaller herds. It is just that individual diseases (acute imflammation of the udder) are more likely to affect the cell count in milk gained from herds producing a smaller quantity of milk than larger herds supplying larger quantities off farm. This means that when determining the bulk tank cell count, the cell content becomes less significant as a parameter for assessing udder health with increasing herd size, and should be seen more critically in the case of larger herds (> 30 lactating cows).
Milking hygiene and milk quality
In this evaluation milk quality is also assessed according to the tank cell count/average density and penalization. The following points were selected from hygiene management procedures required in modern milk production as recommended by the Bavarian Eutergesundheitsdienst (EGD):
- Pre-milking in a pre-milking cup with lacteal secretion test
- Udder/teat wash
- Teat disinfection after milking
Moreover, following procedures were included in the assessment:
- After-milking by machine
- Implementation of milk cell count
Owing to insufficient data it was not possible to record the average density of the tank cell count, however, complete data relating to penalization is available (table 6).
Milking hygiene and penalization
||Number of farms evaluated
||per-centage of penalization
||Total number of farms
Pre-milking in pre-milking cup
- prior to milking, of which
- used one cloth per herd
- cleaned correctly*
by machine no
Teat dip yes
Milk cell count yes
|*The item „cleaned correctly“ comprises all procedures carried out with disposable items
It can been clearly seen from table 6 how essential milking hygiene and udder disease prevention are in achieving high milk quality. Farms utilizing necessary milking hygiene procedures such as correct pre-milking, adequate teat sanitation and after-milking by machine as well as teat dipping after milking have considerably fewer problems with milk quality, and consequently suffer far less penalization. However, a vast number of farms conducting a cell count are obviously not making full use of the information gained from this.The documentation available does not, however, contain information as to whether this is the case and, if so, which consequences were drawn from positive cell count results.
In a similar survey conducted in 1997 by the EGD Bayern of around 10.000 Bavarian dairy farms managing a predominant number of cattle with udder health problems (approx. 80%), it was ascertained that farms with a bulk tank cell count of < 200.000 cells/ml milk (around 13% of their livestock) were more frequently prepared to take the necessary steps to implement improved milking hygiene and mastitis prevention than farms with > 400.000 cells/ml milk supplied off farm.
Maintenance and care of milking machines
The assessment of maintenance and care of milking machines was made according to whether or not a farmer had signed a service agreement and how often teat liners were being replaced.
Teat liner replacement intervals have very little effect on the tank cell count. However, one should bear in mind that worn teat liners do indeed have negative effects on milking, milk yield and milk quality.
Just as the cell count affects penalization (chart 1), there could also here be a reversal of cause and effect in so far as teat liners are not replaced until a complaint is brought forward or the cell count increases. Replacing teat liners results in an drop in cell count, irrespective of how long they have been used. This is verified by the results in regard to penalization:
707 farms replaced liners after 6 months:
18% were penalized
3.534 farms replaced liners after 12 months:
433 farms replaced liners after > 12 months:
24.8% were penalized
The results relating to milking machine maintenance carried out in accordance with a service agreement paint a much clearer picture (table 7). Of the 4.602 farms from which complete data pertaining to this issue was made available, 3.296 had not signed a service agreement (71.6%), 1.306 (28.4%) had.
||Cell count D/ml
||Percentage of losses
Summarization of results
In analysing the results we come to the conclusion that milk producers are not sufficiently aware of the importance of the tank cell content in ensuring udder health within the herd and for the milk yield and milk quality associated with it, this having a negative effect on the profitability of milk production. This is underlined by the fact that 50.9% (table1)of the farms assessed do not take necessary steps to define and eliminate problems until after they are due to be penalized for a high cell count (> 400.000/ml) or have already been penalized. This behaviour by around one half of the dairy farmers from whom information was gathered is reason enough to begin analysing the results by pointing to the losses incurred due to cell-count-related udder disease and inadequate action taken by milk producers when replacing liners, for example.
Analysis of milk production losses
Using a calculation example we have estimated milk yield losses for dairy cattle producing milk with a high tank cell count due to subclinical udder disease (table 8).
Calculation example yield losses
Monetary losses/month attibutable to mastitis with a livestock of 30 dairy cows and 18.000 kg of milk supplied off farm with 400.000 cells/ml (x geom.)
Milk yield reduction (20%) of quarters with subclinical disease
(= 720 kg á DM 0,60)*
Treatment costs for 24 udder quarters á DM 15,00
Unsaleable milk (20 kg/day) of 6 treated cows over a period of 8 days
(= 960 kg á DM 0,60)
Loss of bonus payment of DM 0,01for 18.000 kg of milk
Minimum deduction of DM 0,02 for 18.000 kg of milk (according to milk quality regulations)
*Average milk price paid in Bavaria in autumn 1999
The monthly losses and expenditure amounting to more than 1.400,00 DM due to subclinical udder disease on medium sized dairy farms are not sufficiently recognized by milk producers, in spite of them exceeding yield losses due to penalization. This is the only explanation for the delayed reaction to increasing tank cell counts. Penalization can be expected as soon as the tank cell count for cows with healthy udders has exceeded the limit of around 100.000 cells/ml.
This loss of milk, fat and protein was calculated by the LKV Bayern in 1988 based on data relating to milk yield on farms surveyed and the respective cell counts (table 9).
Loss in milk and milk contents according to cell count
(excerpt from annual report of the LKV Bayern e.V., 1998)
from 3rd lactation
- 39 (277)*
- 2,0 (11,9)*
- 1,2 (7,9)*
- 2,5 (13,5)*
- 1,8 (9,1)*
|*Difference in loss from payments for milk with cell counts up to 50.000 and 201-300.000/ml of milk
If one compares the performance data of high yield cows with less than 50.000 cells/ml with those having a cell count varying between 200.000 and 300.000/ml, a loss of DM 310,00 per cow and lactation in Fleckvieh herds and DM 355,00 in Braunvieh herds based on an anticipated milk price of DM 0,65 and a price of DM 0,06 per unit of fat and DM 0,075 per unit of protein.
Even if we compare cows with cell counts of < 100.000/ml with those having middle value cell counts (201.000 to 300.000), the losses of DM 121,00 per cow and lactation for Fleckvieh and DM 159,00 for Braunvieh are immense.
In terms of profitability the cell count is, therefore, the most important factor in assessing udder health and milk yield, its effect on the payment of quality milk premiums being only of secondary importance. Every milk producer should be aware of this. However; evaluations also show that the significance of preventive measures to ensure hygiene are generally underestimated.
A Bavarian survey carried out by Fehlings and colleagues in 1997 underlines the significance of preventive udder health hygiene management in correcting problems of mastitis and maintaining health in dairy cattle herds. The survey establishes that it is not the therapy that is decisive in fighting mastitis, but the measures taken to prevent it.
This includes replacing the teat liners regularly. More than 80% of those milk producers surveyed the were not aware of the disadvantages of waiting too long to replace teat liners.
Losses are not only incurred due to the higher frequency of penalization resulting from not observing regular liner replacement intervals. Losses in milk yield and financial forfeiture in milk sales due to the use of teat liners beyond the recommended 750 hour operational period (including cleaning of milking machine) are much higher, but not quite as evident.
Corresponding tests carried out in Ireland by O’Callaghan in 1995 showed that worn teat liners with less elasticity do not ensure correct and efficient milking. Based on a publication by Schlaiß (1996) Wickels (1998) made the following calculation, thereby drawing attention to the benefits of a service agreement:
If one set of teat liners is used for one whole year instead of six months, a saving of approx. 45,00 DM is made. O’Callaghan’s investigations show that milking with worn teat liners results in milk losses of between 4 and 5% which go unnoticed by the milker. Based on an average of 5 cows per cluster and a daily milk yield of 20 kg, a saving of 45,00 DM would, for example, result in a loss of 720 l of milk.
5 cows (per cluster) x 0.8 l = 4.0 l x 180 days = 720 l of milk per cluster!
If we assume that this lack of hygiene exists in the above mentioned herd of 30 cows, then the additional loss of milk in terms of money amounts to approx. 2.900,00 DM, this being considerably higher than the losses incurred if the farmer were to take appropriate measures.
A saving in service costs can turn out to be very expensive!
Summarization of housing methods and preventive measures in ensuring milk quality
Considerable scientific research has been carried out in the field of dairy cow housing facilities.The information available is far too extensive to be dealt with in detail in this article. If, however, we confine the analysis to housing and udder health and quote just a few examples, we must draw attention to the comprehensive work of Ekesbo (1966) in which there is clear evidence that, in terms of health and injury, freestall housing is far superior to the tiestall.
This was confirmed by Groth and colleagues (1978) in regard to teat injury. They point out that in tied up (short parlour and grate) the risk of teat injury is 33 times higher than in loose housing facilities. Ten years later similar results were obtained by Steffen and colleagues (30 times higher risk in an analogical comparison). A most detailed analysis of housing techniques and their effect on the udder health of Bavarian dairy cows was conducted by Matzke and colleagues (1989, 1992). Their findings underline the benefits of the loose housing and the reduced risk of injury when compared with tied up. The difference between loose housing and tied up is statistically substantiated by positive Schalm mastitis tests and teat injuries. In loose housing the percentage of teat injuries was 1.89%, this figure being considerably lower than the percentage of teat injuries induced in tied up (2.82%). In 1990 Rabold commented: „In addition to the most significant advantages that have always rendered loose housing the preferred method, namely
- comfortable housing,
- less labour, no neglect,
- improved ergonomic working conditions,
- less serious accidents during working hours and
- consistently better milk quality,
it must also be said that there are
- significantly less udder diseases and teat injuries“.
There are many other publications available which come to the same conclusion, all of them verifying the superiority of loosehousing just as this survey implies. In terms of milk production and the securing of milk quality, milking in milking parlours is the main beneficiary factor in loose housing.
This becomes most evident when evaluating the survey carried out last year. As long ago as 1987 investigations by Rabold and Grimm showed that consistently high milk quality obtained in milking parlours is attributable to far better milking hygiene resulting from the simplified implementation of hygiene measures. This article already makes reference to the effect of the herd size on the tank cell count, rendering a detailed analysis unnecessary. An analogy exists regarding the importance of preventive hygiene management when milking. We wish to point just one last time how essential it is that these measures are implemented. The results shown in table 6 underline this clearly.
Why around 47% of the dairy farms surveyed take inadequate measures to ensure hygiene or do not implement them at all, can only be explained by the fact that they are unaware of the consequences of neglect or underestimate them. Above all, however, they seem to ignore the previously mentioned losses in performance and the financial disadvantages associated with them, that is as long as they are only penalized and not stopped from supplying milk. Surveys on this subject conducted at home and abroad confirm that for each Euro spent on milking hygiene, one can expect a return of 4 Euros. For this reason we recommend emphatically that housing and hygiene techniques recommended by all institutions should be strictly adhered to.
Above all the following points should be observed:
- When carrying out extension or conversion work, always check whether it is possible to change to loose housing milking parlour housing facilities.
- Record the cell count regularly so that any deviations can be determined immediately.
- Never cull simply because of an increased cell count. Always conduct a microbiological quarter milk sample prior to doing this.
- Always observe milking hygiene when milking.
- Make regular checks of teats (tips) and udders for irregularities (e.g. hyperkeratosis, slight bleeding, asymmetry).
- Replace teat liners simultaneously on all clusters after around 750 hours of operation (180 days), using only genuine liners.
- Observe regular functional check and maintenance of the milking machine.
- Enter service agreements with specialists (service technicians) only, so that servicing intervals are adhered to even if you have a high workload to cope with on your farm.
- Service agreements offer ideal possibilities for outsourcing.
Data collected by employees of the Bavarian Tiergesundheitsdienst e.V. (TGD) was recorded and assessed according to the degree of influence of housing and milking techniques, herd size and mastitis prevention on the bulk tank cell count and penalization. The results as are follows:
Many dairy farmers are not aware of the correlation between cell count, udder health and economy in milk production or are simply disregarding it. A total of approx. 80% of the farms are too late in reacting to excessive cell counts, 50% waiting until the regulatory level has been exceeded, thereby suffering a considerable financial forfeiture due to losses in milk, fat and protein. Smaller herds of less than 20 cows have more frequent problems with high cell counts owing to the fact that individual incidents of udder disease have a greater effect on the milk supplied off farm. The comparison of housing facilities shows that loose housing (milking parlour) is far superior to tied up in terms of cell count and penalization. Moreover, farms with service agreements for their milking plants have lower tank cell counts and lower losses due to penalization. It is a proven fact that milking hygiene and mastitis prevention as constantly recommended by the EGD Bayern have a significantly positive effect on udder health, cell counts and penalization resulting from them being too high.
Farms on which these measures are carried out consistently and to the full extent are penalized far less frequently than farms not implementing such measures (3.4% as compared to 25.6%). Cell count related financial losses attributable to low performance, penalization and additional expenditure are verified in a comparision of cow performance conducted internally by the LKV Bayern and using calculation examples.
We wish to extend our gratitude to the Delaval company for their assistance in conducting this survey.