Grading system for replacements & culling


True BYH Addict
Jan 4, 2011
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I was watching some webinars and came across trait performance ratio.
Indv performance
-------------------------------------------- x100
Avg performance of group

----------- x100 = 108%

So that lamb did 8% over the average. And you can do it for any measurable trait.

Then later they talked about the EBVs and all the different systems used to determine how good a sheep is against the group average.

So that got me thinking about writing down a sort of score card for picking replacements and culling decisions. I'd like to know what you think and what kind of systems you use for these decisions.

*Litter size 20
*Weaning weight 20
*ADG (birth to wean & wean to market time) 20
*rams- scrotal size. ewes- teat placement and extra teats. 20
*Fleece weight 10
*staple length 5
*wool cover of face/legs 5

My reasoning...
*Litter size isn't that high of heritability but selecting for it won't hurt. 2018 my lambing was 140%. Not terrible but not fantastic.
*Weaning weight is a good representative of the mom's milkability and mothering. Milk yeild is 30% heritable. As well as selecting quick growing lambs.
*Avg daily gain will show who is better at turning food into gain. Weaning to market time represents on the indv lambs genetics for growth.
*Rams with higher scrotal size have higher fertility and produce ewes with higher fertility. Extra teats.
Teat size is 20% heritable, teat placement is 25% heritable. Extra teats can be problematic for newborn lambs. Several of my sheep have extra teats and I'd like to nip that trait right off.
*Grease fleece weight is 35% heritable. Fleece yeild is 40% heritable. CV of fiber is 50% heritable.
*Staple length is 55% heritable. If having yarn milled it's important to have fiber that is within an inch staple length to prevent issues.
*Wool cover of face is 56% heritable.