Here's a link to my town's ordinances. I think it is fairly thoughtfully written, with clear definitions and distinctions. Livestock are not allowed on less than 1 acre, but fowl are. They even define what constitutes a "unit" of livestock.
http://www.roundrocktexas.gov/docs/ordinances_ch_02.pdf
Hope it helps. I'm technically in violation of the law because I let my chickens free range in the yard.
http://www.roundrocktexas.gov/docs/ordinances_ch_02.pdf
Hope it helps. I'm technically in violation of the law because I let my chickens free range in the yard.