Development and evaluation of methods to assess the machine milking process
In order to perform the dairy cows’ milking resource-saving, economic effective and as healthy as possible for the dairy cow, the milking process should be quick, complete and gentle. In case that not all three attributes can be fulfilled farmers ask for help from milking advisory services. Currently there is no official apprenticeship provided for milking advisors, therefore advisors have different levels of prior education and no gold standard for the approach of advisory service is available in machine milking. In consequence of this, the aim of the present study was to develop a helping concept for milking advisors, which simplifies the assessment of the machine milking process in milking parlours on a sound scientific basis. In the present concept the Milking System, the Dairy Cow, the Milking Operator and the Milking Parlour and Waiting Area were identified as key areas of the milking process. For each key area indicators were presented, which provide further information about the machine milking process and enable the assessment. Some indicators can be used for an initial troubleshooting and other for an analysis of causes. Influences and interdependencies of indicators were highlighted and illustrated by the present concept. In addition, a new, precisely defined hand-milking method to assess the completeness of the milking process was developed and compared to two other methods, which are already applied in practice. The first method was a visual method, which assesses the degree of the quarter filling. This method was not related to the actual rest milk in the quarter. The second method, a quantitative assessment of the number of easy strips, and the new precisely defined hand-milking method for 15 s per quarter, were suitable to predict the rest milk in the quarter. Despite to the strict definitions of the hand-milking handgrip and handgrip frequency it was not possible to avoid the influence of the evaluator on the amount of collected strip yield in 15 s. In consequence of this, the amount of strip yield among herds can only be compared under the premise that the hand-milking is performed by the same person. Previous thresholds were set at 100 ml. Reasoned by a slower milking by the precisely defined hand-milking in comparison with a stripping hand-milking method, the threshold must be lower for the new developed method. The precisely defined hand-milking method was investigated for cow and milking system related influencing factors on the outcome of the method and the rest milk in the udder. It was outlined, that the rest milk in the udder is influenced by the positioning of the milking cluster and herd specific settings of the milking technique, the milking routines and the herds’ individual characteristics. The outcome of the full-hand hand-milking of 15 s per quarter was influenced by the herd, evaluator, milking cluster positioning, teat length and palpable rings at teat base. The individual milking characteristics of the quarter varied too much to predict the amount of rest milk in the udder by only hand-milking one or two quarter. Furthermore, the intensity of the dairy cows’ hind leg activity during the course of milking was observed in ten farms and two milking times per farm and day for its relation to the vacuum level in the short milk tube and mouthpiece chamber. In addition, the machine-on-time and lengths of milking phases was investigated for its influence on the frequency of observed hind leg activity and its influence on the degree of hyperkeratosis. Finally, also the influence of hyperkeratosis on the shown intensity of hind leg activity was evaluated. The dairy cows’ hind leg activity was divided into stepping (claw raised < 15 cm) and kicking (claw raised > 15 cm). Kicking was shown at significant higher mouthpiece chamber vacuum levels than stepping. Cows, which have shown kicking, had significant higher degrees of teat-end hyperkeratosis than cows which have shown stepping. The length of machine-on time did not affect the frequency of hind leg activity, but the degree of hyperkeratosis. Longer machine-on times led to higher degrees of hyperkeratosis. The kicking was assumed to be avoidance behaviour, while stepping is influenced by various factors.
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