Ziegenbock is an amber ale brewed by Anheuser-Busch. It is billed as "for Texans by Texans."
Ziegenbock is an imitation craft brew marketed under Anheuser-Busch's ICS (Import - Craft - Specialty) brand, positioned as a Texan beer to compete with Shiner Bock. Ziegenbock is brewed at Anheuser-Busch's Houston brewery and is very similar to Michelob Amber Bock, but it is sold exclusively in the Texas market. Like Shiner Bock and Amber Bock, it does not conform to the BJCP style guidelines for a Bock, either in terms of flavor profile or potency. A Traditional Bock typically has an ABV range of 6.3 - 7.2%, where Ziegenbock is 4% (Shiner Bock is 4.4%; Amber Bock slightly truer in this respect at 5.2%.) Also lacking is the complex richness of Munich and Vienna malts. Shiner Bock comes somewhat closer to the flavor profile of a Bock.
Ziegfest is an annual music festival sponsored by Ziegenbock and its parent company, Anheuser-Busch. Ziegfest typically features "red-dirt" musicians. There are typically several venues with the events scheduled around a month apart.
BJCP Style Guidelines - Category 5 - Bock http://www.bjcp.org/2008styles/style05.php