Luteal Characteristics and Progesterone Production on Day 5 of the Bovine Oestrous Cycle |
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| Authors: | MP Green GE Mann MG Hunter |
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| Institution: | Division of Animal Physiology, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK. |
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| Abstract: | In this study we have examined luteal function in non-lactating and late lactation dairy cows on day 5 of the cycle, during the period of the post-ovulatory progesterone rise. Comparison of luteal progesterone content and in vitro synthetic capacity with circulating plasma progesterone demonstrated that circulating progesterone concentration is a function of total luteal activity rather than the activity of individual units of tissue. Incubation of luteal tissue in vitro demonstrated stimulatory activity of LH and IGF-I, and to a greater degree IGF-II, on luteal progesterone synthesis. Finally the study showed no effect of double ovulation on luteal function. Occurrence of double ovulation in 35% of animals was not associated with any difference in luteal function or plasma progesterone concentrations. |
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