^b Public research investment (ha^-1 yr^-1): $5.39 (1993–1994 work plan), $5.63 (1994–1995 work plan), $7.46 (1995–1996 work plan). Private research investment (ha^-1 yr^-1) assumed to be $1,792 from 1993 to 1997.

^c "a" represents the marginal impact on current output of research completed t years ago.

^d (B1_t - B1_s) > (<) 0 indicates input-saving (-using) bias due to technical change in the PL stocking input, measured in number of PL ha^-1, from year t to year s (Cox et al., 1997). Similarly, (B2_t - B2_s) gives the bias effect due to technical change for the feeding input measured in kg ha^-1.