@conference {40390,
	title = {The role of computer software in the feeding of farm livestock},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {52},
	year = {1992},
	month = {Jan},
	pages = {111-114},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Romney ewes with consistently high (H, n=5) or low L, n=5)  seasonal changes in wool growth and with differences in ovulation rate  and the onset of anoestrus, were blood sampled every 30 min for 24 h at  the winter and summer solstices and at the spring and autumn equinoxes.  Plasma samples were assayed for melatonin by direct radioimmunoassay.   Mean melatonin levels were higher during the hours of darkness than  during daylight at all sampling times. However, the ratio between day-  and night-time melatonin levels tended to be smaller in spring (1.8) and  summer (1.5) than autumn (2.9) and winter (1988 - 3.8; 1989 - 4.1).  There were no significant differences between H and L ewes in mean  melatonin concentrations during daylight or darkness at any of the  seasons. There was however, considerable variation between individual  ewes in the diurnal pattern of melatonin secretion in spring and summer.  The high levels of melatonin usually associated with darkness were  sometimes found during the day. These disrupted patterns of melatonin  secretion occurred in all ewes at one or other of these two seasons.  The results suggest that during anoestrus, melatonin profiles may  differ from the normal pattern of secretion that is aligned to  photoperiod.  },
	issn = {1176-5283},
	author = {Brookes IM and Parker WJ and Gray DI}
}
