@conference {40144,
	title = {Control of the oestrous cycle in farm animals: A review},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {71-80},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The pregnancy status of over 4700 ewes, divided into 21 flocks (137 to 688 ewes) and grazed on 14 properties in the Hawkes Bay, were diagnosed using either or both real time ultrasonic body scanner (ultrasonic) and video-fluoroscopy (X-ray) systems. The diagnosis was checked with the number of lambs born, dead or alive, to each ewe. For the ultrasonic system the percent of ewes whose lambing status was correctly predicted ranged from 96.1 to 100\% for 19 flocks examined. In the case of the X-ray system the values for 13 flocks examined, except for one property, ranged from 94.3 to 99.6\%. The operators must have a special aptitude in handling the instruments and interpreting an image on a screen if good results are to be obtained. The maximal throughputs for the ultrasonic and X-ray systems were 200 and 250 ewes per hour respectively. The major differences between the two systems (ultrasonic v X-rays) were: i) The capital outlay for the ultrasonic system was about a twelfth of that of the mobile X-ray system. ii) A good backup service is needed to maintain the X-ray equipment. iii) To sustain a throughput of over 200 ewes per hour, excluding the operator, 5 labour units were required for the sheep handling associated with the ultrasonic system compared to one for the X-ray system.},
	issn = {1176-5283},
	author = {Swanson LV}
}
