- Maternal responses to daily maternal porcine somatotropin injections during early-mid pregnancy or early-late pregnancy in sows and gilts. Gatford, K.L., Smits, R.J., Collins, C.L., Argent, C., De Blasio, M.J., Roberts, C.T., Nottle, M.B., Kind, K.L., Owens, J.A. J. Anim. Sci. (2010)