Date Full Report Received


Date Abstract Report Received



Primary Investigator:

When pigs become health challenged with a virus like Porcine Reproductive and Respiratory Syndrome (PRRS), production efficiency and pig wellbeing is reduced that can have a larger economic burden on the U.S. swine industry. How to best feed and manage these health challenged pig flows is poorly understood. Interestingly, the optimum dietary requirements for energy and protein as well as amino acids have not been determined for such health challenged pigs. Therefore, two experiments were conducted to evaluate the effect of increasing SID Lys:ME (g SID Lys per Mcal ME) on growth performance during a PRRSV challenge. In Exp. 1, 379 barrows (51.3 ± 0.3 kg BW) were allotted to one of six diets (1.87 to 3.41 Lys:ME) for a 35-d growth study. In Exp. 2, 389 barrows (29.2 ± 0.23 kg BW) were allotted to one of six diets (2.39 to 3.91 Lys:ME) for a 49-d growth study. These isocaloric diets represented 80 to 130% of NRC SID Lys requirement. After the 35 to 49-d growth study, all pigs were fed a common diet until they reached a target market weight of ~127 kg. Our results from this project showed:

• There were no difference in PRRS serology due to altered Lys:ME diets.
• Breakpoint analysis showed that the optimal Lys:ME for ADG and G:F was increased up to 136% and 130%, respectively, in PRRSV infected 50 kg BW pigs (Exp. 1) compared to healthy controls depending on the breakpoint model used (one slope verses quadratic).
• In 25 kg BW pigs (Exp. 2) the optimal Lys:ME for ADG increased up to 107% as determined by breakpoint analysis; however, optimal Lys:ME for G:F was decreased up to 25% in PRRSV infected pigs.
• In the 50 kg pigs, the predicted requirement for ADG and G:F in PRRSV pigs using a quadratic model were above the highest Lys:ME diet. This was similar for G:F in control pigs in the 25 kg BW pigs. Therefore, further studies should be conducted to more accurately determine the Lys:ME requirement.
• No difference in carcass characteristics were reported.
• Overall, increasing Lys:ME 110-130% above the NRC (2012) requirement increased growth performance and feed efficiency in PRRSV infected pigs, and the response was similar between natural and experimental PRRSV infection.