Multiple pregnancy tester

Waimarino Bulletin, Volume 2, Issue 12, 21 August 1984, Page 14

Multiple pregnancy tester

A mobile laboratory unit developed for multiple pregnancy testing of sheep and the only one of its kinds in the world was put through its paces in the Waimarino last week. The testing technique — based on x-ray fluoroscopy — gives up to 98% accuracy in ascertaining single, double or multiple lamb-carrying ewes. The testing rig in its present form has taken a total of five years to develop and is a joint venture between the DSIR's Applied Biology Division of Animal „ Nutrition in Palmerston North and the Auckland Industrial Development Division (AIDD) branch of the DSIR. For the first two years the equipment was used piecemeal in existirig woolsheds and other buildings where it had to be set up and adapted to different conditions each time. Three years ago a mobile laboratory, housing all the equipment and designed to allow the sheep to be scanned. as they passed through, was constructed on the back of a truck. This selfcontained rig — worth about $250,000 in development costs alone to date — can now be driven into any yard,backed against a loading race, attached to an off-ramp (extreme left of picture) and testing commenced. Between 120 and 200 sheep per hour, or roughly 1 ,000 a day — depending on breed, weather conditions etc — can be scanned and recorded. Three operators are required. On George Drayton's 300 acre Dreadnought Road property last week, two MAF advisors, Roy Fraser and Will Wilson from Taihape and a DSIR Scientist, Adrian King, from Palmerston North provided the team work to process 1,100 breeding ewes. Mr Adrian King of the Animal Nutrition branch of the DSIR's Applied Biology division who has been with the project since its inception five years ago and developed it with Mr David Beach of AIDD, operated the x-ray equipment. The two farm advisory officers were responsible for ensuring a steady flow of ewes through the rig... one from the yard, the other from the rig after using a different coloured dye on the head of the animal to identify the multiple, twin and single bearing ewes as well as the 'empties'. On Mr Drayton's farm only orie percent of the ewes were found to be empty and, at the end of the day, a lamb-to-ewe ration of 150% was recorded. The dye will last until lambing and so will give the farmer an accurate guide as to how to allocate feed and optimise nutritional intake for each group of ewes by

varying the stocking rates on each paddock. Adrian King explained how the scanning procedure worked. "The animal — only sheep and goats at this stage — is held momentarily in a crush bale while the x-ray scanner is moved backwards and forwards, up and down, until the uterus is located." "At that stage the columnated x-ray beam picks up the bone structure — usually the head, spine and legs — of the foetus or foetuses and projects the image onto a screen." "A skilled operator only needs three seconds to diagnose the number of foetuses on the screen but it takes a little longer to get the animal to co-operate," said Mr King. "It depends on the flow through: Romneys are the most co-operative, Perendales are the worst." "Because the testing depends on the identification of bone structures in the foetus it can only be done after the bones have occified which is about 80-85 days into the pregnancy," he said. Asked. about the possible dangers of radiation from the x-ray equipment to both operators and animals Mr King explained that this has been very carefully monitored by the NZ Radiation Laboratory over the years.

At first all sorts of precautions were taken and operators had to wear radiation-sensitive discs. But this is no longer the case as it was found that no significant 'scatter' occurred due to the narrow columnated beam which is

projected through the uterus onto an intensifier which reflects the beam back onto the screen. Asked about alternative methods of diagnosing multiple pregnancies Mr King said that up until this DSIR rig was developed an