LYSINE REQUIREMENTS OF PIGS FROM 2 TO 7 KG LIVE WEIGHT

Thirty-two male pigs were used to investigate the effects of nine leve ls of dietary lysine ranging from 0.41 to 1.30 g lysine per MJ gross e nergy (GE) on the performance of pigs weaned at 1 to 2 days of age and growing between 2 and 7 kg live weight. The nine dietary lysine treat ments, which contained similar levels of GE and balance of essential a mino acids, were offered to the pigs at a common feeding level of 2.0 MJ GE per kg metabolic live weight (M-0.75) per day. Growth performanc e and protein deposition rates increased linearly with increasing diet ary lysine content up to about 0.97 g lysine per MJ GE and remained re latively constant thereafter. The response of protein deposition (PD, g/day) in the whole body of pigs to dietary lysine (L, g lysine per MJ GE) was described by three models. The respective regression equation for the quadratic function was PD = -14.23 + 87.66 L - 36.00 L-2 and maximum protein deposition occurred at 1.22 g lysine per MJ GE. The re ctilineal model, which had an ascending linear phase (PD = 1.49 + 40.1 0 L, R-2 = 0.98, P < 0.001) and a horizontal component representing a mean protein deposition rate of 39.7 g/day revealed that maximum prote in deposition occurred at 0.95 g lysine per MJ GE. Finally, applicatio n of the asymptotic model also revealed a highly significant equation: PD = 43.40 - 79.99 x 0.0711(L), R-2 = 0.94, P < 0.001; which indicate s a dietary requirement of 1.07 g lysine per MJ GE assuming that the d ietary requirement was estimated at 0.90 of the asymptote maximal valu e. The results indicate that the dietary lysine requirement for pigs d uring the first 3 weeks of life appears to have changed little over th e past 20 years despite substantial changes in genotype.