#18-119

Complete

Date Full Report Received

04/30/2020

Date Abstract Report Received

04/30/2020

Investigation

Institution:
Primary Investigator:

Funded By

When pigs encounter a health challenge with a virus such as Porcine Reproductive and Respiratory Syndrome (PRRS) or bacteria such as Mycoplasma Hyopneumoniae, production efficiency is often reduced along with increased mortality, leaving an economic burden on the producer and the industry. Nutrient requirements, specifically amino acids (AA) and energy, of health challenged pigs are poorly defined compared to healthy pigs due to uncertainties in the use of AA and energy during an active disease state. We have previously reported (16-062) that increasing Standardized Ileal Digestable (SID) Lysine (Lys) to Metabolizable Energy (ME) ratios 110-130% above the requirement increased growth performance and feed efficiency in PRRSV infected pigs, and the response was similar between natural and experimental PRRSV infection. Thus, three experiments were conducted to further evaluate the effect of increasing SID Lys:ME on growth performance during a health challenge. In particular, this project aimed to address the importance of how this ratio is achieved and does this diet philosophy also work under non-viral challenge conditions. In Exp. 1, 400 mixed sex pigs (25.6 ± 4.31 kg BW) in which half of the pigs received a MLV PRRS vaccine, were then allotted to one of three diets (2.67, 3.23 and 3.22 g SID Lys:ME) for a 42-d PRRSV challenge growth study. In Exp. 2, 472 mixed sex pigs (24.05 ± 4.33 kg BW) in which half of the pigs received a killed autogenous PRRS vaccine, were then allotted to one of three diets (2.98, 3.57 and 3.57 g SID Lys:ME) for a 42-d PRRSV challenge growth study. These diets represented 100, 120 and 120% of SID Lys requirement, with the third diet in both Exp. 1 and 2 being achieved by a dilution of ME. In Exp. 1 fine grade washed sand was used to achieve a 20% dilution of energy and in Exp. 2, 8% soybean hulls were used to dilute ME 10%. In Exp. 1 after the 42-d growth study pigs were fed a common diet until they reached a targeted market weight of ~127 kg. However, after the 42-d growth study in Exp. 2, pigs were utilized for Exp. 3. In Exp. 3, 464 mixed sex pigs (79.6 ± 3.02 kg BW) in which all pigs had been previously vaccinated for Mycoplasma Hyopneumoniae (MHP) were allotted to one of two diets (1.95 and 2.34 g SID Lys:ME) representing 100 and 120% of NRC requirement. Thereafter, half of the pigs were exposed to a MHP challenge and all pigs fed the experimental diets until they reached targeted market weight of ~127 kg. Results from these projects can be summarized as follows:

Exp. 1:
• There were no differences in PRRS serology due to altered Lys:Me diets.
• Overall, increasing Lys:ME by 120% of requirement by either increased SID Lys or decreasing ME resulted in similar increased growth performance in PRRSV infected pigs in both vaccinated and non-vaccinated pigs compared to the control fed pigs.
• PRRS MLV vaccinated grower pigs had increased end BW after undergoing a 42 d PRRS challenge. Thus, it pays to vaccinate.
• PRRS challenged pigs ate to their energy needs when energy was diluted with an inert feedstuff (sand).
• Formulating diets with increased SID Lys:ME enhanced overall growth performance.

Exp 2:
• There were no differences in PRRS serology due to altered Lys:Me diets.
• Overall, increasing Lys:ME by 120% of requirement did not improve growth in pigs with a mild PRRS challenge (Exp. 2). These pigs were only intranasally inoculated and viremia was not as severe as reported in Exp. 1.
• Diluting the dietary ME with soyhulls did not increase feed intake during PRRS.
• Pigs that were given a killed autogenous PRRS vaccine, did not have increased performance over the PRRS challenge period.

Exp. 3:
• Although MHP reduced pig performance in late finishing, Increasing the dietary Lys:ME ratio in late finishing did not have an effect on MHP vaccinated finisher pig performance.
• Formulating diets with increased Lys:ME for bacterial challenged pigs was not beneficial in late finishing. However, this work needs exploring in younger pigs.