Effects of Standardized Ileal Digestible Valine:Lysine Ratio on the Growth Performance and Economics of Finishing Pigs from 55 to 100 lb
finishing pigs, growth, valine
The objective of these experiments was to determine the effects of SID Val:Lys ratio in low CP and low lysine diets on the growth performance and economics of finishing pigs from 55 to 100 lb. In Exp. 1, a total of 1,134 gilts (PIC 337 × 1050, initially 68.8 lb BW) were used in a 19-d growth trial with 27 pigs per pen and seven pens per treatment in a randomized complete block design with pens blocked by initial average BW. There was a total of six dietary treatments: 59.0, 62.5, 65.9, 69.6, 73.0, and 75.5% SID Val:Lys ratio. In Exp. 2, a total of 2,100 gilts (PIC 327 × 1050, initially 56.6 lb BW) were used in a 22-d growth trial with 25 pigs per pen and 12 pens per treatment in a randomized complete block design with pens blocked by initial average BW. There was a total of seven dietary treatments: 57.0, 60.6, 63.9, 67.5, 71.1, 74.4, and 78.0% SID Val:Lys ratio. In both experiments, the intermediate Val:Lys levels were obtained by blending different proportions of the low and high Val:Lys diets. Responses measured at the pen level were analyzed using general linear and non-linear mixed models. Competing statistical models were: a broken-line linear ascending (BLL) model, a broken-line quadratic ascending (BLQ) model, and a quadratic polynomial (QP). Competing models were compared using Bayesian information criteria (BIC). In Exp. 1, ADG increased linearly (P = 0.009) with increasing SID Val:Lys ratio whereas ADFI only marginally increased (linear, P = 0.098) with no evidence for differences on F/G. Feed cost per pig, feed cost per lb of gain, and total revenue per pig increased (linear, P < 0.009) with increasing SID Val:Lys ratio without evidence for differences in IOFC. In Exp. 2, ADG and ADFI increased (P < 0.002) with increasing SID Val:Lys ratio resulting in an improvement in F/G (P < 0.001). Similarly, increasing SID Val:Lys ratio increased feed cost per pig (quadratic, P < 0.001), feed cost per lb of gain (linear, P < 0.001), total revenue (quadratic, P < 0.001), and IOFC (quadratic, P < 0.001). In conclusion, the SID Val:Lys ratio to optimize performance ranged from 71.0% for minimum F/G to 74.4% for maximum ADG. However, feed cost per lb of gain was minimized at less than 57% SID Val:Lys ratio and maximum income over feed cost was estimated at 62.3% SID Val:Lys ratio with a plateau thereafter. Therefore, 99% of the optimum ADG and F/G were estimated at approximately 69% and 65% SID Val:Lys ratio, respectively.
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Goncalves, M. A.; Jacquez, J.; Tokach, M. D.; Dritz, S. S.; Touchette, K. J.; DeRouchey, J. M.; Woodworth, J. C.; and Goodband, R. D.
"Effects of Standardized Ileal Digestible Valine:Lysine Ratio on the Growth Performance and Economics of Finishing Pigs from 55 to 100 lb,"
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