TABLE 1.

Characterization of the studied chicken breeds.

Breed	Code	Type of divergent selection			Origin	Description
		TCM a	EM b	PCM c
Broiler	BR	Meat	Meat	Meat	Russia	4-way BR cross Smena 8 developed in 2011 at the Breeding Genetic Center “Smena”—Branch of the Federal Scientific Center “All-Russian Poultry Research and Technological Institute” of the Russian Academy of Sciences
White Cornish	WC	Meat	Meat	Meat	Russia/England	B56, male grandparent stock, of BR cross Smena 8. The initial breed was developed from English local game chickens, Asil, White Malay, Indian Game, and Cochin
Plymouth Rock White	PRW	Dual purpose (meat-egg type)	Meat	Dual purpose (meat-egg type)	Russia/United States	B79, female grandparent stock, of BR cross Smena 8. The initial breed was developed from Java Black, Brahma, Cochin White and Buff, Dominique, and White-faced Black Spanish
Yurlov Crower	YC	Dual purpose (meat-egg type)	Meat	Dual purpose (meat-egg type)	Russia	Derived in 19th century from crossing local and game chickens, Brahma, Cochin, and Langshan. Selected for long crowing
Brahma Buff	BB	Fancy	Meat	Dual purpose (egg-meat type)	USA/India	Derived in early 20th century from crossing Cochin and Gray Chittagong (of Malay type)
Orloff Mille Fleur	OMF	Fancy/Game	Game	Dual purpose (meat-egg type)	Russia	Derived in late 18th century from crossing local chickens, Gilan, and Old English Game
Layer	LR	Egg	Egg	Egg	Netherlands	Commercial 4-way layer cross Hisex White
Uzbek Game (Kulangi)	UG	Game	Game	Game	Uzbekistan	An old cock fighting breed derived from local Uzbek game chickens

Chicken breed types according to:

^a TCM, traditional classification model (Bogolyubsky, 1991).

^b EM, evolutionary model (Moiseyeva et al., 2003).

^c PCM, phenotypic clustering model (Larkina et al., 2021).