I’ll add my two cents on this topic as well. WARNING – Long.
I have been unable to find quotable material in any of the articles read thus far as to Punnett’s production purpose for the Legbar. If someone does have a citable statement from Punnett, please post it. These are the verifiable facts: Punnett developed the Legbar as an experiment in auto-sexing chickens just after WWI (1920s) (Journal of Genetics – The Legbar - .
http://www.ias.ac.in/jarch/jgenet/41/1.pdf )
What is the value in auto-sexing chicks? To determine male / female at hatch, eliminating a need for (training and payment of) vent sexing staff and to best utilize expensive or limited resources (feed & housing) for one sex over the other. So which sex is more important? In a dual purpose breed, numbers of both male and female are desirable, one for eggs and one/both for meat. If both are utilized, there is no need to select at hatch; therefore, the logical conclusion is that auto-sexing allows one to select for more females and fewer males at hatch, indicating a market preference for eggs over meat.
Now we know the
–bar part of the equation, the Barred Plymouth Rock, is a dual purpose breed but Punnett chose it for the barring gene according to the article. The
Leg- part of the equation, the Brown Leghorn, was used for its sexual dimorphism between the male and female plumage, again a component of auto-sexing, not functional purpose. In 1930 he began experiments with the blue egg laying Chilean hens. Again the focus on eggs. The Cream Project arose from those experiments and focused on crossing with various colours in the Leghorn. (Journal of Genetics – The Blue Egg
http://www.ias.ac.in/jarch/jgenet/27/465.pdf ) At some point the Cream birds were crossed with a Legbar, resulting in the Crested Cream Legbar which was standardized and the SOP accepted by the UK poultry authority. Subsequently the Crested Cream Legbar diminished in popularity and were brought back by various breeders in the 1980s, presumably to the same SOP.
The (Crested) Cream Legbar at the time we began acquiring them from Greenfire in 2011/2 were known as an egg laying breed in their country of origin and their size there was set at 2.70-3.40kg (6-7lb) for cocks and 2-2.70kg (4-6lb). Since the APA requires one ideal weight instead of a range, 7 lbs was selected for our cocks and 6 lbs for hens – both the high side of the British weight range. Note that these weights are already larger than that of the Leghorn which is 6 lbs for cocks and 4.5 lbs for hens, yet smaller than the Plymouth Rock at 9.5 lbs for cocks and 7.5 lbs for hens.
Other interesting notes from the APA Standard of the Plymouth Rock, a dual purpose breed, “Overlarge specimens are not to be desired, they become clumsy and poor producers. They are not the active useful fowl desired for this dual purpose breed.” From the Leghorn SOP, “[Leghorns] comprise a group characterized by great activity, hardiness and prolific egg-laying abilities. Aside from their [beauty and variety] as exhibition specimens, their excellent productive qualities are valuable assets of the breed. Breeders, exhibitors and judges should pay due regard to the Standard weight of the Leghorns.” In reading these comments it appears that deviations in size [form] over the standards reduces function.
Since the Cream Legbar was based on the Legbar/Leghorn, and is distinguished from the other Cambridge breeds by its blue egg production, it makes sense for our draft standard to remain as is with respect to its economic qualities of “Especially noted for the auto-sexing feature in offspring, and production of eggs. […] blue or green.” The current draft standard weights are already midway between the Legbar’s parent breeds. What is the benefit to increasing its standard size by two pounds or more, possibly diminishing its egg production characteristics? Seven pound cocks and six pound hens are decent sizes for standard chickens and would certainly dress out to a reasonable table size of an earlier time (pre-Cornish X). Dominques, Andalusians, Barnvelders and Welsummers are four other breeds with an ideal weight of 7 lbs. for the cock.
And last, but certainly not least, the (Crested) Cream Legbar
is what it is --- and still considered critical. Its standard was set 60 years ago, give or take, with direct input from its creator. If we don't like that standard, then we don't breed to it or outcross and don't call it the Crested Cream Legbar. If one truly wants a meaty auto-sexing Cambridge breed there are several already in need of dedicated breeders: the Brussbar (8-10# cocks), Buffbars (Orpington 8-10# cocks) and Wybars (Wyandotte 8-9# cocks)
Quote DCChicken:
I take this to be an acknowledgement that aiming for a dual purpose CCL would sacrifice something the breed already HAS i.e. egg production characteristics, to gain what it DOESN'T i.e. meat production, in order to make it dual purpose. Why is egg production such an anathema to you? There aren't quite so many non-hybrid egg laying breeds out there and so many fantastic dual purpose breeds already, several also in need of preservation. And as noted above there are plenty of large Cambridge auto-sexing breeds in need of breeders too. Why must the CCL be changed from what it is to a bigger dual purpose breed?
If you (and your customers) really want something
like the CCL: an auto-sexing, cream barred, blue egg gene carrying crested chicken in a larger size that lays fewer eggs, then by all means select for those characteristics in your flock, you don't need the standard to do so; but please stop trying to alter the breed and impose your ideals upon others who are trying to preserve the Crested Cream Legbar described in the Standard as drafted by Punnett and modified here only insofar as it needs to fit APA format. Aiming for 7 lb cocks and 6 lb hens is necessary to achieve that. 9 or 10 lb cocks is not.
