Thursday, December 16, 2010


Had an enquiry this morning about screening, the practice of selecting ewes from an unregistered/unrecorded source, for addition to a nucleus or registered flock.
Coopworth Society rules permit this to be done, in fact in the early days of breed formation where no pedigreed and performance recorded sheep existed, this was order of the day.
Many flocks seeking Flock Book status were aiming to breed their own flock rams, and forming a nucleus of sheep that had established themselves in the commercial environment made sense.
Still does, particularly if small flocks on good country, comprise a large proportion of the breed register, and therefore the breed genepool.
Screening your own commercial flock expands the genepool, and allows progeny of SE standard rams retained for flock use, (but that perhaps never get the opportunity to cover in the nucleus flock), to stay in the selection mix.
In the 1960's TS Chang, (Massey) did some ground-breaking work showing that frequency of oestrus, and high growth rate and fleece weight, in ewe hoggets, was associated with subsequent superior lifetime lambing performance, a great set of criteria for screening nucleus flock prospects from unrecorded sources. In simple terms, that's a big ewe hgt with a good fleece in the characteristic range you want, that conceives early.
Under Coopworth Society rules, you can put these sheep into your recorded flock, they aren't registerable, but if mated to a single entered ram, the progeny are registered as of right, ie. provided both parents are qualifying blood mix Coopworth.
There is one pitfall to be mindful of.
Because these ewes have no known parents, half-sibs, or progeny, they will be disadvantaged by SIL comparative to existing recorded flock sheep that do. Culling ewes from the recorded flock should then be done on the old phenotypic basis of lambing string, not SIL DPP.
Similarly, their progeny will be compromised on hgt selection lists, analyses of my own sheep show a discount of around 10-15 points of DPP, so again I select these groups on phenotype. Actually this isnt as blasphemous as it sounds, as these selections are more a case of dropping off the worst, and easily accomplished using actual weights, deviations, and dam lambing string.
For ram sale purposes its not hard to identify by tag, those from screen ewes, tell their story in a separate group, about their origins from the back of beyond, and they find a market.
It is rare for rams of this origin to qualify as SE against the within flock competition, but that's all the more argument for giving them a run in the commercial flock, and giving their female progeny a chance of coming back into frame in the screening cycle.
Its important if you are screening to be using the within-flock option for BV calculation, or the disadvantage will be worse.
Restrict across-flock participation to the selection of outside sire sourcing, which its the best tool for anyway.
One final comment, you have to wonder, in the Frontier Genetics scenario, how an introduced bloodline can ever establish itself, therefore defeating the purpose. However, I noted some time ago, a special facility for compensation of this being made by SIL.
Which sort of gives some qualification to my above points.

Monday, December 13, 2010

Don Brash at Orewa

Mr Brash says reducing govt spending takes the pressure off overseas borrowing, allowing the OCR to come down, and the exchange rate to follow.

Plenty to think about here: