The influence of a prolonged release formulation of bovine somatotropin (USAN sometribove) on milk production and the concentration of bovine somatotropin (bST) and insulin-like growth factor-I(IGF-I) in serum and milk of Malaysian Sahiwal × Friesian cows : A.R. Azizan1, R.H. Phipps2, I.A. Forsyth3, D.L. Hard4, W.E. Wan Hassan2 and J.A. Taylor2. 1Malaysian Agricultural Research and Development Institute (MARDI), PO Box 12301, Kuala Lumpur, Malaysia; 2University of Reading, Centre for Dairy Research, Reading, RG6 2AT, UK; 3Institute of Animal Physiology and Genetics Research, Cambridge, UK and 4Monsanto Europe, Brussels, Belgium