Optimal dietary standardized ileal digestible lysine and crude protein concentration for growth and carcass performance in finishing pigs weighing greater than 100 kg1,2

Abstract

Three experiments were conducted to determine the optimal dietary standardized ileal digestible (SID) lysine and CP concentrations for finishing pigs over 100 kg BW. In Exp. 1, 253 pigs (DNA 600 × 241, initially 102.0 kg) were used in a 23-d trial with 7 to 8 pigs per pen and 8 pens per treatment. Dietary treatments contained 4 SID lysine concentrations (0.45, 0.55, 0.65, or 0.75%). To formulate the experimental diets, a corn-soybean meal diet with 0.45% SID lysine was formulated without L-lysine HCl. Then, a corn-soybean meal diet containing 0.75% SID lysine was formulated including 0.23% L-lysine HCl. The 0.45 and 0.75% SID lysine diets were blended to provide the 0.55 and 0.65% SID lysine diets. Increasing SID lysine increased (quadratic, P < 0.05) ADG and ADFI with pigs fed 0.55% SID lysine having the greatest final BW. Marginal improvements in gain:feed (G:F; quadratic, P = 0.058) and carcass yield (linear, P = 0.051) and reduction in backfat (quadratic, P = 0.074) were also observed with increasing SID lysine. The quadratic polynomial models predicted maximum ADG and G:F at 0.62 and 0.63% SID lysine, respectively. The broken-line linear model predicted no further improvement in G:F over 0.55% SID lysine. In Exp. 2, 224 pigs (PIC 327 × 1050, initially 109.4 kg) were used in a 20-d trial with 7 pigs per pen and 7 to 8 pens per treatment. Dietary treatments included 4 concentrations of CP (10, 11, 12, or 13%) that were formed by reducing the amount of L-lysine HCl in a corn-soybean meal diet. Increasing CP increased (linear, P < 0.05) ADG and ADFI with the greatest responses observed in pigs fed the diet with 12% CP. Increasing dietary CP also improved (linear, P < 0.05) G:F, final BW, and hot carcass weight (HCW). In Exp. 3, 238 pigs (DNA 600 × 241, initially 111.8 kg) were used in a 26-d trial with 7 to 8 pigs and 6 pens per treatment. Dietary treatments included 5 concentrations of CP (9, 10, 11, 12, or 13%). Increasing CP improved (quadratic, P < 0.05) ADG and G:F with the greatest response observed in pigs fed 13% CP. Increasing CP marginally increased (quadratic, P < 0.074) HCW, with the greatest response observed in pigs fed 12% CP. In conclusion, the SID lysine requirement for pigs from 100 to 122 kg was 0.55 to 0.63% depending on the response criteria with performance maximized with diets containing 12 to 13% CP.

Evaluation of nutritional strategies to slow growth rate then induce compensatory growth in 90-kg finishing pigs

“…On average, control pigs consumed approximately 18–20 g/d SID Lys where pigs fed 0.18% SID Lys diets consumed approximately 10–12 g/d. Similarly, Soto et al (2019) reported a decrease in ADG and G:F as SID Lys intake per day decreased in 100- to 135-kg pigs, but the magnitude of reduction was less than what we observed in our experiments with severely deficient Lys diets. Goncalves et al (2017) reported that the optimal performance for ADG and G:F of 100- to 135-kg pigs was associated with a SID Lys intake per day of 19.5 and 19.7 g/d, respectively.…”

“…The NRC (2012) SID Lys requirement estimate is 0.73% for 75- to 100-kg pigs and 0.61% for 100- to 135-kg pigs. Soto et al (2019) reported that the predicted maximum ADG and G:F for pigs beyond 100-kg BW was achieved at 0.62% and 0.63% SID Lys, respectively. Distinct from regular Lys titration studies, we used diets (0.50%-Lys and 0.18%-Lys diet) that were severely deficient in Lys and other AAs for this weight range to evaluate the effects on growth performance.…”

“…Therefore, producers were forced to utilize a variety of strategies to reduce the growth rate of pigs and minimize economic hardship. Because lysine ( Lys ) is the first limiting amino acid ( AA ) for corn–soybean meal-based diets, reducing dietary SID Lys in the late-finishing period has been shown to reduce the ADG and ADFI of pigs beyond 100-kg body weight ( Soto et al, 2019 ). Therefore, feeding finishing pigs SID Lys (as well as other AA) concentrations below their estimated requirements can reduce the growth rate, but the magnitude of the reduction is not fully researched.…”

Effects of standardized ileal digestible lysine on growth performance and economic return in duroc-sired finishing pigs

“…The level of feed consumption and associated growth rate may be an important source of variation in estimated SID Lys requirements among experiments. Research conducted with 112–136 kg pigs in a university setting, reported an average feed intake of 3.1 kg ( Soto et al, 2019 ). Conversely, research conducted in a commercial environment reported an average feed intake of 2.6 kg for 102–120 kg pigs ( Main et al, 2008 ).…”

Estimating Amino Acid Requirements in Real-Time for Precision-Fed Pigs: The Challenge of Variability among Individuals

“…Still, the variation in the response in PD to Lys and Thr observed was large, with Lys and Thr intake explaining only 11% (R 2 = 0.11) of the variation observed in PD. This large variation in growth performance is often observed in titration trials [11,18,19]. Due to the large data variation and presence of outliers, a more robust adjustment based on the LOESS procedure was adopted.…”