Phenotypes

Reith et al. (2024): "Whole-genome sequencing (WGS) of 7 blind cattle and 9 unaffected relatives revealed a 1-bp frameshift deletion in ceroid lipofuscinosis neuronal 3 (CLN3; chr25 g.26043843del) for which the blind cattle were homozygous and their parents heterozygous. The identified variant in exon 16 of 17 is predicted to truncate the encoded protein (p. Pro369Argfs*8) ... ."

The absence of horns (polledness) is of substantial benefit in cattle, from an economic and welfare point of view: bruising due to horns is eliminated, and the stress associated with de-horning is avoided. (Information complied by Ulrika Tjälldén and Vanja Kinch, Uppsala, March 1998). In addition to naturally occurring variants for this trait, variants have been created artificially: Genetically-modifed organism; GMO.

Syndactyly has been reported in many breeds of cattle in many countries. Most of the documentation, however, concerns its occurrence in US Holsteins, where, as a result of the siring of more than 60,000 calves by a bull who was subsequently shown to be a carrier, the disorder attracted considerable attention (Anon., 1967). The possibility that artificial selection favouring heterozygotes may have contributed to the unacceptably high frequency ...