Eliezer Aizinbud, Pinhas Gur
A German scientist Schutzbar (1976) tried many years ago to answer that question. He found that from 376 cows only 32% showed a significant decrease of milk yield (MY) at the day of successful insemination; 50% of them showed a MY decrease 1-2 days before or after the day of successful insemination, and 18% did not exhibit any change in MY near or during estrus.
Farmers who use computerized dairy management systems with automated milk-meters are able to day to monitor the MY of individual cow at each milking session.
The MY decrease of a normal cow, as mentioned, can not be a reliable indicator of estrus. However it can be an important supporting evidence detecting estrus, if additional automated estrus detection aids, for example the pedometers, are used.
The use of pedometers in Israel’s dairies is widespread. An extension officer of Israel’s Ministry of Agriculture, Daniel Hojman (1997, personal communication) found that in 54.9% of 1396 estruses a decrease of MY has occurred during or near the time of significant increase of cow’s walking activity.
The following three graphs were printed out by Afimilk system in kibbutz Gesher dairy farm. They illustrate at the same time the daily walking activity parallel to MY readings of individual cows.
In one case the peaks of walking activities were an exact mirror image of the MY decreases (Fig. 1).
Fig.1. The coincidence of walking activity peaks and the decreases of milk yield during estrus
In another case the walking activity peaks were not accompanied by any changes in MY (Fig.2). In this case the normal interval (20 – 24 days) between the peaks is the main supporting evidence for estrus detection by pedometry.
Fig.2. The absence of milk yield decrease during estrus
In the third case (Fig.3), a decrease of MY near the occurrence of the pedomertry peak also supports the pedometric indication of the estrus.
Fig.3. A decrease of milk yield near the time of the peak of walking activity
A letter from Professsor Eliezer Aizinbud and the manager of Kibbutz Gesher Dairy farm Pinhas Gur (Israel)
