A word about sex-links

by the creater of
Henderson's Handy Dandy Chicken Chart

'If I hadn't started painting, I would have raised chickens.' -- Anna Mary Moses

Henderson's chicken breed chart does not include information about sex-linked chickens even though they are among the most popular birds for commercial, small farm, and backyard flocks. The main reason they are not included on the chart is because they are not actually chicken breeds. In addition, there are too many sex-link strains and varieties to make their inclusion practical, and for many of those strains the only information about them are claims about how very productive they are. We are not purists and have Hubbard Golden Comets (one is pictured above) in our flock, but those are the only sex-links we have personal experience with. I can testify that they start laying earlier than most other pullets, at least among the brown-egg layers. They are indeed exceptional layers for at least their first couple years. They have been among the best winter layers. They are sweet birds with docile, non-aggressive personalities. None of ours have gone broody. Their eggs are large and usually a rich brown. Some pullets, when first starting to lay, have produced quite dark eggs. The rich color diminishes over time, but that is true of other hens. A couple of our Comet hens, in their later years, have layed wrinkled eggs, but none have been any more disease-prone or infirm than our purebred chickens have been. In skin color, comb, and plumage, the hens look very similar to New Hampshires, except where New Hampshires have some black in their tail feathers, Golden Comets have white. Some of them have had patches of white more widespread across their backs and hackles.

Sex-linked cross-bred chickens have been developed for two main reasons: 1) they can be sexed at hatching, and 2) they lay lots of eggs.
1) Sexing chicks is easy because females will be a different color (or feather pattern) than the males.

2) Sex-linked hens lay so many eggs is because of something called hybrid vigor or heterosis. It was discovered early in the selective breeding of domestic animals that hybrid offspring can be more physiologically robust. In chickens this vigor translates in part to being extremely productive as egg-layers coupled with high feed efficiency. It works best, of course, if you start with very productive breeds. With crossing different breeds, as well, you eliminate the problems associated with inbreeding. That said, there could be some severe inbreeding in the parent stock developed by the commerical hatcheries.



The Way Things Used to Be

Once upon a time, when chickens were mostly raised on small farms and in back yards, folks didn't try to specialize in types of chickens. They accepted that hens would lay enough eggs for home consumption and enough extra, perhaps, to supply neighbors. Cocks would be raised for meat and, except for those saved for breeding purposes, would meet their end when they got large enough. Chicks were hatched out in the spring, and by early fall cockerels would be of a large enough size and still have tender meat. Those that were caponized might not be butchered until Thanksgiving or Christmas. Chicken was such a rare delicacy that a President of the United States would sound preposterously optimistic about prosperity when he promised a chicken in every pot.

When commercial interests demanded high production from layers, and rapid development from meat birds, the old dual purpose birds lost their place in the scheme of things. The discovery of a means to distinguish between the sexes revolutionized the industry. The male chicks could be disposed of quickly, since there were no longer of use (commercially) as meat birds, since they would take twice as much time or longer as Cornish-Rock crosses to develop full size and they never would develop as much white meat.

Types

The basic principle of sex-linking is to cross-breed a female with one sex-linked trait to a male with a different trait. Color is the most common trait used, but not just any colors can be used, and the dimorphism could be a slight difference in feather pattern. There are several sex-linked hybrid types, but these two are the most common.

Red Sex-Links

What is known as the "silver trait" is found in hens of many, but not all, white-feathered varieties or breeds and some with silver lacing. When crossed with a male without that trait, the male chicks will be white and the female chicks will be the color of the rooster. Although the non-silver color is almost always red, that is simply because Rhode Island Reds and New Hampshires, being very productive breeds, are most often used.

Although the males are consistently Rhode Island Reds or New Hampshires, for the silver-factor in the mother, several different breeds and varieties have been experimented with. Among those used commerically have been Rhode Island Whites, White Plymouth Rocks, Delawares, and Silver-Laced Wyandottes.  I have read from several independent reliable sources that Hubbard Golden Comets are produced by crossing a White Plymouth Rock hen with a New Hampshire cock.

In addition to Hubbard Golden Comets, among the red sex-linked chickens that are most widely available from hatcheries are Red Stars, Cherry Eggers, Cinnamon Queens, Golden Buffs, Sil Go Links, and, rather unoriginally "[Name of company] Browns" such as ISA Browns, Dekalb Browns, Hisex Browns, Shaver Browns, and Babcock Browns. Amber is also used, but the difference between a Dekalb Brown and a Dekalb Amber is beyond me. A few unfortunate ones are only given numbers.

Black Sex-Links

Black Sex-Links are bred by crossing females that carry a sex-linked barring trait with males do not carry the sex-linked barring trait. Unlike the Red Sex-Links, there is a more subtle difference between the sexes at hatching. Both are mostly black, but males will have a white spot on the head. Rhode Island Reds and New Hampshires are commonly selected for cocks, since they are productive breeds that possess the non-barring trait. Barred Plymouth Rocks are by far the most commonly used hens, but any variety with barred or cuckoo feather patterns could also be used. Commercial strains of black sex-links include Black Sex-Links, Black Stars, Rock Reds, Dekalb Blacks, and Shaver Blacks.


What's Wrong with Sex-Links?

For all the positive things about sex-links, there are some negatives.

  1. As cross-breeds, they are mongrels and cannot be entered in sanctioned poultry shows.
  2. As cross-breeds, they won't breed true. The sexual dimorphism lasts for one generation only.
  3. The high productivity and large size of eggs may also be a one-generation phenomenon.
  4. Some argue that the high egg production is short-lived, lasting for one laying season only -- which is the life span of commercial layers. Defenders of Rhode Island Reds and New Hampshires say that over the course of a few years, productive purebreds will outlay sex-links. If someone has documented this, I haven't seen the study. We have noticed a drop off in egg production among our Comets, but we haven't tested it against our New Hampshires, and the only Rhode Island Reds we've owned have been Production Reds.
  5. What works for the industrial giants, may not work if you try to do your own cross breeding -- or at least not as well as you might hope. The commercial strains have been developed using decades of selective breeding for highly productive hens, and the breeding occurs under highly controlled conditions, so your attempts may not come close to producing similar results.
Moral issues and the way things used to be.
Perhaps the biggest objection to sex-links is based on moral grounds. The industrialization of chicken raising has led to a problem of too many roosters. Although experiments with sex-linked inheritance in chickens have been conducted for more than 200 years, the development of commercial sex-linked hybrid strains started largely after World War II. Until then, it was just accepted that the ratio between male and female chicks would be half and half. Once hatched, the females would be kept for egg production and the males would be raised until large enough to be butchered. When the commercial sector turned chicken raising into a large-scale industry, chickens were specialized into either egg producers or meat​ birds. The dual purpose model was thrown out.

Under the new model, it was not cost effective to raise males of layer breeds. Sex-links provided an easy way to identify males, and the industry gained a reputation for destroying male chicks immediately, often through cruel and inhumane practices. It should be said, that commercial enterprises have turned Leghorns into laying machines, and production Rhode Island Reds are quite commonly used in "egg factories," so even non-sex-linked male chicks can suffer the same horrendous fates.

A related objection involving the use of sex-links as industrial chickens is that these specialized strains have limited the genetic diversity of chickens and endangered heritage purebred chicken breeds. Even the diversity of sex-links has decreased in recent years. Where once there were a dozen or more independent enterprises specializing in the development of sex-links, now only two multi-national conglomerates, Groupe Grimaud and Hendrix Genetics, are responsible for almost all the commercially available sex-links.

Misinformation

The web can be a dangerous place to go looking for information, and researching the web for information about sex-links is no exception. Forums can be very handy sources of information about raising chickens, but they can also be particularly frustrating when they provide confusing and conflicting information. This seems especially true about sex-links. Some of these "experts" can sound so convincing, too. I've read, for example, of at least three different parentage paths for Red Stars, including one claim that they are identical to Hubbard Golden Comets. I've read that all red and black sex-links are gentle birds, but I've also read that some strains can be quite aggressive and bossy. I've read that the California White and the Tetra Tint are sex-links, but I have also read and been more convinced by better documented sites that they are non-sex-linked hybrids.

I won't try to explain the genetics of sex-linked cross-breeding -- I don't understand it well, and I don't wish to be guilty of spreading misinformation.


This page authored and maintained by John R. Henderson (jhenderson @ icyousee . org)
Sage Hen Farm, Lodi, NY.

Last modified: Old Washington's Birthday, 2015
URL: http://www.sagehenfarmlodi.com/chooks/comets.html