@conference {40362,
	title = {Dairy Production in developing countries},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {52},
	year = {1992},
	month = {Jan},
	pages = {3-6},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Measurement accuracy for ultrasonic tissue depths was examined  in order to determine the relative importance of factors affecting it.  Repeatabilities for ultrasonic fat depth (UFD) and ultrasonic muscle  depth (UMD) were assessed from repeated runs (2) in three groups of  animals; Dorset Down ewes (LW=45.4kg, 7.5mo, n=50), Coopworth rams  (LW=51.5kg, 11mo, n-50) and Dorset Down rams (LW=38kg, 4.5mo, n=50).  Repeatability values were higher for UMD (0.77, 0.95 \& 0.87 for the 3  groups, respectively) than for UFD (0.63, 0.84 \& 0.82, respectively).  Lower repeatabilities were due to high within-animal variance rather  than low between-animal variance. Measurements made on videotaped  images demonstrated that image registration had a great effect on  repeatability, with image interpretation having a negligible effect. A  comparison of two operators differing in experience showed that fat  depth was measured equally accurately by both operators but that the  experienced operator measured muscle depth more accurately. It was  concluded that tissue depths can be accurately assessed from one  measurement.  },
	issn = {1176-5283},
	author = {McDowell RE}
}
