Abstract
The objective of this study was to estimate the SID Lys requirement for growth and feed efficiency of 120- to 170-lb finishing pigs. A total of 700 barrows and gilts (600 × 241, DNA; initial BW of 117.2 ± 1.89 lb) were used in two separate studies, each lasting 21-d. Pens of pigs were blocked by BW and randomly allotted to 1 of 6 dietary treatments with 8 to 10 pigs per pen in a randomized complete block design. A similar number of barrows and gilts were placed in each pen. Dietary treatments were corn-soybean meal-based and formulated to 0.65, 0.72, 0.79, 0.86, 0.93, and 1.00% SID Lys, with 12 replications per treatment. Increasing SID Lys increased (linear, P < 0.001) ADG, with pigs fed 1.00% SID Lys having the greatest final BW. In addition, increasing SID Lys decreased (quadratic, P = 0.004) ADFI. Feed efficiency improved, while Lys intake/d, and Lys intake/kg of gain increased (quadratic, P < 0.005), with increasing SID Lys. At both high and low ingredient and pig prices, feed cost/pig increased (quadratic, P < 0.05) as SID Lys increased, while feed cost/lb of gain decreased (quadratic, P < 0.001), with pigs fed 0.79% SID Lys having the lowest feed cost/lb of gain. At high and low feed prices, increasing SID Lys increased (linear, P < 0.002) IOFC. A linear model resulted in the best fit for ADG and predicted that the maximum ADG response was beyond 1.00% SID Lys. For F/G, the quadratic polynomial model predicted a requirement of 0.97% SID Lys. At high ingredient and pig prices, the broken-line linear model to maximize IOFC predicted that there was no further significant improvement to IOFC past 0.76% SID Lys. Meanwhile, at low ingredient and pig prices the quadratic polynomial model predicted a requirement of 0.91% SID Lys to maximize IOFC, however, a similar fitting linear model predicted maximum IOFC response at greater than 1.00% SID Lys. In summary, the optimal SID Lys level for 120- to 170-lb finishing pigs depends upon the response criteria, with growth performance optimized at or greater than 0.97% SID Lys and IOFC maximized between 0.76 to 0.91% SID Lys.
Highlights
At low ingredient and pig prices the quadratic polynomial model predicted a requirement of 0.91% SID Lys to maximize income over feed cost (IOFC), a similar fitting linear model predicted maximum IOFC response at greater than 1.00% SID Lys
Pens of pigs were blocked by BW and randomly allotted to 1 of 6 dietary treatments with 8 to 10 pigs per pen in a randomized complete block design
A similar number of barrows and gilts were placed in each pen
Summary
In order to optimize growth performance and efficiency it is vitally important to have an accurate estimation of dietary requirements for proper diet formulation. Due to modern advancements in dose-response models, it has become increasingly possible to set precise requirement estimations.. Due to modern advancements in dose-response models, it has become increasingly possible to set precise requirement estimations.2 This pair of trials is a part of a larger study with the objective of predicting the SID Lys requirement of DNA 600 sired pigs from approximately 50 to 285 lb. The objective of this study was to determine the SID Lys requirement of DNA 600 × 241 pigs from 120- to 170- lb BW to optimize growth performance and economic return
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