Table 2.

Occurrence of β-casein gene variants in Holstein-Friesian (HF) in Poland and Red in other countries (data sorted by increasing A1 allele frequency) (adapted from Kamiński et al., 2007 [5]).

Breed	Country	Allele Frequency of β-Casein		N	References
		A1	A2
HF	Denmark	0.266	0.614	415	Gustavsson et al., 2014 [15]
	The Netherlands	0.28	0.50	1929	Visker et al., 2010 [21]
	The Netherlands	0.029	0.69	1629	Heck et al., 2009 [22]
	Poland	0.32	0.68	177	Cieślińska et al., 2012 [8]
	Poland	0.35	0.65	650	Oleński et al., 2012 [14]
	Thailand	0.363	0.602	231	Molee et al., 2011 [23]
	Italy	0.371	0.546	1226	Massella et al., 2017 [24]
	Italy	0.395	0.57	100	Chessa et al., 2013 [25]
	Poland	0.40	0.60	143	Kamiński et al., 2006 [16]
	China	0.432	0.459	133	Dai et al., 2016 [26]
	Turkey	0.485	0.456	49	Dinc et al., 2013 [27]
	Iran	0.50	0.50	119	Gholami et al., 2016 [28]
Red	Sweden	0.48	0.51	392	Gustavsson et al., 2014 [15]
	Denmark	0.71	0.23	169	Bech and Kristiansen, 1990 [29]
	Poland	0.53	0.47	201	Present data

Other variants of the β-casein gene are not included.