Essay On Syndactyly

Syndactyly, also known as mule foot, is the term used to describe when the functional digits of an animal are partially or completely fused together. It is a congenital defect. Dairy cattle are the most commonly effected by this disease while it is less common in beef breeds when it does occur it is more severe. It affects Holstein-Friesian, Angus, Chianina, Hereford, Simmental, German Red Pied, Indian Hariana and Japanese native cattle. It became very common in Holstein-Friesian cattle because of the overuse of a heterozygous bull for artificial insemination; however it is rare in other breeds. In America the use of an outstanding Holstein bull for artificial insemination resulted in 60,000 services before it was discovered that he was heterozygous for the syndactyly gene. This has led to syndactyly being the most common breed defect in the American dairy industry.

Syndactyly has been identified as an autosomal recessive trait. It has varying degrees of severity and genetic penetrance. This is important as sometimes

This helps in removing their genetics from the national herd however this doesn’t help with carrier animals. After the Holstein bull incident in America there was a push to test bulls for the gene. This was usually done by heterozygous Holsteins being identified through test matings to known heterozygotes, daughters, daughters of known heterozygotes and syndactylous cattle. The calves were then carried to full term. This resulted in a large time investment and expense. The current method of progeny testing is quicker and more economical because it employs superovulation of affected animals (sy/sy), embryo transfer, and fetal recovery by 60 days when fetal offspring are analysed for the syndactylous phenotype. A minimum of seven phenotypically normal fetuses must be produced before the suspect parent can be proven free of the syndactylous gene with 99.6%