Effect of pressure and temperature on the availability of lysine in meat and bone meal as determined by slope-ratio assays with growing pigs, rats and chicks and by chemical techniques

I. The availability of lysine for pigs, rats and chicks was determined using samples of meat and bone meal (MBM) subjected to different pressure and temperature treatments during dry-rendering processing. The relation between slope-ratio estimates and three chemical tests for estimating 'available' lysine was assessed. 2. The availability of lysine (proportion of total) for pigs was 0.97 in the control. Pressure (275 kPa gauge, 141°, for 30 min) in the early stage of rendering reduced availability to 0.74 and, in the late stage, to 0.46. Maintaining the final temperature at 125" for 4 h had little effect (0.84) whereas a higher temperature of 150" for 4 h reduced availability to 0.38. 3. Availability estimates for rats were lower than those of the pig, ranging from