The lightest body weight goat is

The lightest body weight goat is Togganburg.
The Toggenburger or Toggenburg is a Swiss breed of dairy goat. Its name derives from that of the Toggenburg region of the Canton of St. Gallen, where it is thought to have originated.
It is medium size. Coat colour ranges from light brown to mouse grey, with white Swiss markings on the face, lower legs and tail area.
It is a highly productive dairy breed. The breed standard calls for minimum milk yield of 740 kg per lactation, with a minimum fat content of 3.56% and minimum protein content of 2.90%.