The effects of the periodical use of in-feed chlortetracycline on the reproductive performance of gilts and sows of a commercial pig farm with a history of clinical and subclinical viral and bacterial infections - Alexopoulos, C; Fthenakis, GC; Burriel, A; Bourtzi-Hatopoulou, E; Kritas, SK; Sbiraki, A; Kyriakis, SC (Reprod Dom Anim, 2003)