Resource centerProductivity4 min read
Kilos weaned per ewe exposed
The one figure that puts fertility, prolificacy, survival and milk on the same scale.
The question
A ewe lambed twins but lost one. Another lambed a single and weaned it heavy. A third was exposed and came back empty. How do you compare them fairly?
The concept
Kilos weaned per ewe exposed divides the total weaning weight of a ewe's lambs by the number of times she was put to the ram. An empty exposure counts as zero; an abortion counts as zero; a dead lamb adds nothing. One figure captures whether she got pregnant, how many she carried, how many survived and how much milk she gave.
Why it matters
It is the number closest to the income a ewe generates. Two flocks with the same prolificacy can differ by 10 kg per ewe exposed because of weaning weight or losses, and that difference is what pays the feed bill.
The data behind it
BreedIQ computes it per ewe and per flock from real records: exposures with a known outcome, weaned lambs with a weight, abortions and empties. In the demo, Estrella (DEMO-H006) shows 2.00 lambs and 52.87 kg weaned per exposure over 2 exposures, with 4 of 4 weaned lambs weighed, and by ewe-year 2.73 lambs and 72.28 kg. The profile states that this is a descriptive history, not a genetic value: it is not corrected for group, age or year, and the kilos are real weaning weights, not adjusted.
- 1Current status chips: empty, lactating, last diagnosis, bred to
- 2Nursing which lamb since when
- 3Lambings, born alive/dead, prolificacy, lambing interval
- 4Age at first lambing (upper bound if history started elsewhere) and lambs weaned
- 5Record joining (natural, AI or ET)
- 6Method and sire
How to read it in BreedIQ
At flock level, Productivity › Productive indices lets you choose evaluation groups (breeding seasons) and indicators: pregnancy rate, abortion rate, empty rate, lambing rate, prolificacy, fecundity, survival at birth, pre-weaning mortality and survival, average weaning weight, weaned per female exposed, kg weaned per female exposed and weaning weight per lambed female. Only what you ask for is calculated, and you can compare with your own average or the previous period.
Decisions it supports
Cull on this figure rather than on a single lambing; compare breeding seasons; and judge a ewe's real contribution when her lambs were sold by weight. Estrella's 1.67 prolificacy looks modest until you see 52.87 kg per exposure.
Limitations
Weanings without a weight cannot be counted in kilos; BreedIQ reports how many were weighed ("4 of 4") rather than filling the gap. A ewe bought as an adult has a history that starts on arrival, so her first lambing age and lifetime figures are bounds, not facts, and the profile says so.