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There are many reasons to scan. Check out Pregnancy Scanning: Management Tips by Anita O'Brien for some of these. However, the fundamental reason to scan would be the opportunity to add dollars to the bottom line.

New Liskeard Agricultural Research Station (NLARS) scanned 96 ewes last year. Did it pay? As we examine the records we see some interesting facts.

Scanning costs: average $2 per ewe x 96 ewes = $192.00

Total Lambs born = 227
Average Lamb Drop = 2.36

From scanning we found out that four ewes were open. By selling these ewes immediately after scanning we could save the feed costs.

Using the formula suggested by A. O'Brien we realize the following feed savings:

Number of open ewes X number of days to lambing X pounds hay/ewe/day

Number of open ewes X number days on grain X pounds grain/ewe/day

Hay: 4 ewes X 60 days X 5 lbs. per day = 1200 lbs. (0.54 tonnes@ $80 per tonne = $43.20

Grain: 4 ewes X 45 days X 1.5 lbs. Per day = 270 lbs. (0.122 tonnes@ $160 per tonne = $19.52

Feed Savings = $62.72

Lamb Mortality

Lamb mortality from those 96 ewes = 12.33% death loss = 28 lambs. The figures show the typical increase in mortality associated with lower birth weights of multiple births.

Through separation of ewes and management this could be reduced to 10% resulting in an extra 5 lambs.

Using a market price of $115 per lamb, this would give an extra gross revenue of $575.

Cost-Benefit Analysis

At NLARS there was no sorting for management based on scanning. However, if there had been, the following cost benefit may have been seen.

The other benefit would be getting the money for the cull ewes immediately, not waiting until the ewe did not lamb before selling.

However, when you look at average birthweight you see a straight line decrease from singles to quints. When you compare 50 and 100-day weights we see the same trend. However, the weight decrease does begin to flatten out. But we could hypothesize that by increasing birthweight of the high multiple-birth lambs through management, reducing death loss (and sickness) the average weight on these lambs would be increased by 50 and 100 days. The ewe lambs in this group would have a higher breeding percentage, as they would have higher breeding weights. They should grow out to be more productive ewes.

Average Weights Based on Birth Category

Reference

O'Brien, A. 2002. Pregnancy Scanning: Management Tips. Ontario Ministry of Agriculture and Food Factsheet. Order Number 02-061.