Ma. Johns, ESTIMATION OF THE WEEK OF CONCEPTION IN MERINO EWES USING REAL-TIME ULTRASONIC-IMAGING, Australian journal of experimental agriculture, 33(7), 1993, pp. 839-841
Real-time ultrasonic imaging was used to estimate the week of concepti
on in a flock of 4- and 5-year-old Merino ewes. Rams were joined with
ewes for 6 weeks after the ewes were 'teased' for 2 weeks by testoster
one-treated wethers. The ewes were scanned 92 days after the introduct
ion of the rams to determine litter size, then, based mainly on the si
zes of the heads and bodies of the fetuses, the week of conception was
estimated. These results were compared with the actual week of concep
tion determined from weekly mating and daily lambing records. The week
of conception was correctly estimated for 71% of the ewes. The consec
utive 2-week period from the start of joining within which conception
occurred was correct for 91% of the ewes. The correct half of the join
ing period within which conception occurred was diagnosed for 98% of t
he ewes.