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Simultaneous recording of oxytocin release, milk ejection and milk flow during milking of dairy cows with and without prestimulation

  • Rupert M. Bruckmaier (a1) and Jürg W. Blum (a1)
Abstract
Summary

The effects of manual teat stimulation compared with stimulation by the liner of a conventional milking machine and the influence of milk ejection on the course of milk flow during the entire milking were investigated. Twelve cows were milked with or without prestimulation on three quarters and milk flow was recorded while intramammary pressure (IMP) was recorded in the left front quarter and blood samples for the determination of oxytocin (OT) were taken at 1 min intervals. OT concentrations increased very similarly in response to manual teat stimulation or liner stimulation and remained elevated during the entire milking procedure. Milk flow curves were generally bimodal without stimulation and not bimodal during milking after prestimulation. Milk yield was not significantly lower in milkings without than with stimulation, whereas machine-on time was prolonged and peak milk flow rate was reduced during milking without stimulation. Time to reach milk flow plateau, time to reach peak flow rate and IMP profiles were similar in both treatments if time was calculated from the start of stimulation. IMP increased similarly in response to manual or liner teat stimulation. In milkings with and without prestimulation IMP did not reach its maximum until the start of milking. In bimodal milk flow curves the second increase of milk flow occurred concomitantly with the start of IMP increase; ejection IMP generally occurred concomitantly with the milk flow plateau. In some cases during milking without prestimulation only small and transient OT release was observed. In response, IMP did not increase to its maximum and increased further in response to a stripping-related OT release. During the course of milking IMP decreased slightly because of the emptying of the three milked quarters. After the end of milking, and with OT concentrations decreasing to the premilking values, IMP again decreased slightly to another plateau, probably owing to myoepithelial relaxation. Thus the course of milk ejection, i.e. the IMP profile, influenced milk removal markedly during early milking.

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R. C. Gorewit & K. B. Gassman 1985 Effects of duration of udder stimulation on milking dynamics and oxytocin release. Journal of Dairy Science 68 18131818

H. Mayer , D. Schams , H. Worstorff & A. Prokopp 1984 Secretion of oxytocin and milk removal as affected by milking cows with and without manual stimulation. Journal of Endocrinology 103 355361

R. Sagi , R. C. Gorewit , W. G. Merrill & D. B. Wilson 1980 Premilking stimulation effects on milking performance and oxytocin and prolactin release in cows. Journal of Dairy Science 63 800806

D. Schams , H. Mayer , A. Prokopp & H. Worstorff 1984 Oxytocin secretion during milking in dairy cows with regard to the variation and importance of a threshold level for milk removal. Journal of Endocrinology 102 337343

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Journal of Dairy Research
  • ISSN: 0022-0299
  • EISSN: 1469-7629
  • URL: /core/journals/journal-of-dairy-research
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