4. Six alternatives for scanning
ALSSg offers the following scanning services
- The presence or absence of pregnancy (Wet & Dry),
- The presence of zero, one, or more than one fetus within the uterus ewes.
- Identifying the late lambing, single-bearing ewes (late singles).
- Identifying the exact number of fetus within the uterus.
- Determine the cycle of conception (identifying the early joining, most fertile ewes).
- Determining the day of conception. This enables the determination of paternity in progeny tests and decisions as to whether a pregnancy is the result of a successful artificial insemination (AI), embryo transfer (ET) or is the pregnancy following a conception from a natural, backup joining.
- With maiden ewes where twinning rates are likely to be low and dry rates high, a "wet & dry" scan might suffice. However, given the lower lamb survival rates experienced by maiden ewes, a "late singles" scan is recommended.
- Choosing a "wet & dry" scan for a flock of mature, highly fertile and fecund ewes, might identify too few dry ewes to cover the cost of the scanning operation. In a flock like this, services 2, or 3 should be considered.
- The lower the twinning rate the greater are the numbers of single-bearing ewes and hence, later lambing, single-bearing ewes, "late singles". Identifying these ewes is probably the most profitable scan that can be conducted for the reasons discussed. The decision not to scan for twins because there are too few of them can be the wrong decision and is arrived at because of the misplaced focus on twins.
- Scanning for "late singles" will be profitable but will be more so If the ewes are in good condition coming up to scanning time.
- If the ewes are in poor condition coming up to scanning time, scanning for late singles is less important because, overall, birth weights are likely to be lower. However, scanning for twins is essential.