“…The results obtained for the yield and concentration of milk fat, protein and lactose following treatment with bGH (30 u.g/kg daily) were similar to those obtained by others in that changes in the concentration of milk constituents were small in comparison to changes in their yields, which closely followed the increase in the quantity of milk (Donker and Petersen, 1952;Brumby and Hancock, 1955;Hutton, 1957;Bullis et al, 1965;Bines et al, 1980). Several groups have reported a tendency for the concentration of milk fat to increase and protein to decrease after injecting larger doses of bGH (Shaw, 1955;Bullis et al, 1965;Bines et al, 1980) and Peel et al (1983) have suggested that GHstimulated changes in milk composition may vary with the cow's energy status such that milk fat concentration is increased and protein concentration decreased when cows are in negative energy and nitrogen balance, but remain relatively unchanged when they are in positive energy balance.…”