Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. The aim of the study is a complex evaluation of parameters of lactation in 5 fast- and 5-slowly milked cows with an equal value of a single milk yield. The milking was done by a serial milking machine. The recording of the milk removal process was carried out using a bucket-counter sensor. On the registered curve, as well as by calculation, the parameters of milk removal were determined. By the rate of milk removal in the first two minutes of milking, fast and slow-milked cows were allocated. Individual characteristics of cows were determined by parameters and dynamics of milk removal. In the rapidly milked cows, compared with slowly milked, a shorter (P<0.001) period of removal of the cisternal portion of milk and a higher (P<0.001) index of milk removal for the first minutes of milking. In fast milked cows, compared with slowly milked, the average milk removal rate was higher by 15% (P<0.05), and a maximum removal rate by 19% (P<0.001). The delay and low intensity of milk removal in slow milked cows resulted in longer durations periods of total milking by 20% (P<0.05), machine milking by 26% (P<0.001), reaching a maximum intensity of milk removal by 40% (P<0.001). For slowly milked cows, the delay in milk removal and its lower intensity is characteristic as compared with the rapidly milked ones. A longer period of first portion of cisternal milk removal and a lower its intensity in slowly milked cows lead to a increase in the total time of milking. Dynamics of milk removal in rapidly milked cows represents a single-peak curve with a pronounced period of machine milking in some cows. The presence of a two-peak milk removal curve, indicative of the separate removal of the cisternal and alveolar fractions of milk, is characteristic only of slow-milked cows. The reason for the appearance of a two-peak curve in slowly milked cows is the low rate of milking and the presence of a long latent period of milk removal. It is assumed that the individual intensity of milking is due to the tone of the sympathetic nervous system of the mammary gland. In slowly milked cows, the tone of a nipple isphincter is raised in comparison with quickly milked ones. The reduced tone of the mammary gland in rapidly milked cows leads to a more effective opening of the nipple channel and ensures the highest rate of milk removal during milking. The individual intensity of milk removal in rapidly and slowly milked cows may also be due to the different rate of movement of milk from the alveoli to the lower udder sections.
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