Lysine Requirement for Barrows Fed Ractopamine

and ADFI at week 4 (P = 0.02). During phase 2 (week 3 to 4), greater ADG (P = 0.05) and ADFI (P = 0.004) were observed in pigs consuming a diet containing DDGS (Treatments B and D) compared to pigs that did not receive DDGS in phase 1 (Treatments A and C); however, G:F ratio was not affected by DDGS. There was a lactose effect on ADG in week 3 (P = 0.05) and a trend of lactose effect on ADG during phase 2 (P = 0.09); pigs fed lactose in phase 1 (Treatments C and D) had lower ADG compared to pigs that did not receive lactose in phase 1 (Treatments A and B). These observations reinforced the traditional lactose effects on improving pig growth performance during the early postwean-ing period. Also, these results indicate that lactose can be added to the DDGS-containing diets and maintain growth performance. For the overall experimental period (week 1 to 4), greater ADFI (P = 0.02) and ADG (P = 0.07) were observed in pigs fed DDGS (Treatments B and D) compared to pigs that did not receive DDGS in phase 1 (Treatments A and C); however, no effects of DDGS on G:F ratio. In addition, there were no lactose and lactose × DDGS effects on ADG, ADFI, and G:F overall. In summary, the following observations were made: 1) pigs receiving DDGS in phase 1 (Treatments B and D) had greater ADG and ADFI (P = 0.05 and 0.004, respectively) during phase 2 compared to non-DDGS fed pigs in phase 1 (Treatment A and C); 2) pigs receiving lactose in phase 1 (Treatments C and D) had greater ADG, G:F (P = 0.01), and ADFI (P = 0.07) during phase 1, but decreased ADG during phase 2 (P = 0.09) compared to pigs that did not receive lactose in phase 1 (Treatments A and B). Conclusions In conclusion, there was no interaction between DDGS and lactose on growth performance of nursery pigs in any phase of this experiment. How ever, the inclusion of lactose in diets containing DDGS did have positive effects on improving growth performance of nursery pigs. Additional research needs to be conducted to determine level of lactose that should be incorporated with DDGS in diets to maximize pig performance and health. Barrows fed ractopamine during the fi nishing phase require 0.76% total lysine in order to maximize growth performance. …