Authors : Strauch T. A , J. A. Carroll , E. L. Berg and B. E. Salfen
Abstract: Objectives were to determine the effects of the estrogenic compound zeranol on maternal and piglet performanceand components of the somatotrophic axis. Treated sows (R) were administered a Ralgro? implant, which contains 36 mg zeranol, subcutaneously in the ear on d 60 of gestationand control (C) sows were administered a sham implant. There was no difference (P>0.38) in serum growth hormone (GH) between C and R sows, but there was a trend for increased (P<0.12) insulin-like growth factor-I (IGF-I) in R sows. There was no difference (P<0.14) in litter size, number born alive, or piglet survival to weaning; however, there was a trend (P<0.11) for greater total litter weight at birth in C sows. There was no difference (P>0.47) in piglet body weight at birth, but there was a treatment effect (P<0.002) on average daily gain (ADG) to 7 d of age, with increased ADG in R pigsand the increased ADG continued until weaning (P<0.02). Treatment did not affect piglet serum concentrations of GH at birth (P>0.18) or weaning (P>0.64); however, it increased (P < 0.0006) serum concentrations of IGF-I in R pigs at birth, but not weaning (P>0.31). Hypothalamic mRNA expression of growth hormone-releasing hormone tended (P<0.07) to be greater in R pigs. These data indicate that zeranol administration to gestating sows increases circulating concentrations of IGF-Iand improves pre-weaning ADG of pigs exposed to zeranol in utero.
Strauch T. A , J. A. Carroll , E. L. Berg and B. E. Salfen , 2004. Zeranol Administration to Gestating Sows Alters Sow Blood Serum IGF-I Concentrations and Improves Piglet Performance . Journal of Animal and Veterinary Advances, 3: 270-277.