Lysine requirement of 1.5–5.5 kg pigs fed liquid diets

Abstract

An experiment was conducted to define the lysine requirement of neonatal pigs fed a liquid diet up to 5.5 kg bodyweight (BW). Neonatal pigs, 1–2 days old, with an initial bodyweight of 1.63 ± 0.04 kg, were randomly allotted to 10 isocaloric diets varying in lysine concentration from 0.76 to 1.62 g lysine/MJ gross energy (GE). Diets were formulated using whey protein concentrate and casein as protein sources and contained similar balance of indispensable amino acids. On day 1 of the experiment, pigs were fed 350 g liquid diet/kg metabolic bodyweight (BW0.75) according to the average BW of all pigs. On day 2, feeding rate was increased to 400 g/kg BW0.75. Increments were 100 g/kg BW0.75 per day for the subsequent 3 days until pigs reached 700 g/kg BW0.75 on day 5. Thereafter, feed was offered to pigs at a common feeding level of 700 g/kg BW0.75 each day until they reached 5.5 kg BW. Feed intake and BW were measured daily. Concentration of fat in the carcass decreased (P < 0.05) and the ratio of crude protein (CP) to fat in the carcass increased (P < 0.05) linearly as lysine inclusion increased. Both average daily gain and CP accretion increased (quadratic, P < 0.05), whereas fat accretion decreased (quadratic, P < 0.05) as lysine inclusion increased. Using the maximum point of the quadratic function, the estimated dietary lysine required for maximal growth (271 g/day) and CP accretion (45.2 g/day) was 1.41 and 1.32 g lysine/MJ GE, respectively. The dietary lysine required, estimating the requirement at the lower limit of the 95% confidence interval for CP accretion of 42.9 g/day, was 1.12 g lysine/MJ GE. Gross efficiency of CP deposition (CP deposition/CP intake) achieved a maximum of 0.85 at 1.01 g lysine/MJ GE.