Dynamic Changes in Amino Acid Digestability and Endogenous Nitrogen Losses in Pigs during Experimental Salmonella Infection

Infection is known to reduce the productive performance of animals. Pathogen-induce immune activation causes fever and reduces protein synthesis rates in skeletal muscle among other symptoms. In the gut, pathogens can cause diarrhea but its effect on nutrient digestibility is unknown. Our objective was to quantify dynamic changes in amino acid (AA) digestibility and endogenous nitrogen losses (ENL) during experimental infection with Salmonella enterica serovar Typhimurium in ileal cannulated pigs.

Eight crossbred pigs (47.0 ± 1.5 kg) were surgically fitted with a simple T cannula at the distal (Wubben et al., 2001). Corn-soybean meal or nitrogen-free diet was used to determine apparent and standardized AA digestibility and ENL (Stein et al., 2007) at -24 to -16, 4-8, 8-16, 24-32, 32-40, 48-56, 56-64, 70-78 h post-inoculation (PI). Salmonella was culture and pigs (76.0 ± 1.4 kg) were inoculated as previously described (Price et al., 2010). A Complete Randomized Design with 4 pigs per Treatment was used and data were analyzed using proc mixed (SAS® Institute, Gary, NC).

All comparisons are made against pre-inoculation values. Rectal temperature peaked 16 h PI. Dry matter content of digesta decreased (P = 0.002) to about 50% indicating the presence of diarrhea. Both AA digestibility values decreased 20 to 30 percent points while ENL more than double during the first 8-16 h PI. Threonine displayed the biggest changed in digestibility and ENL during this period. Ileal digesta dry matter content, both AA digestibility values, and ENL slowly fluctuated to baseline values 56-64 h PI and drop again during the collection period of 70-78 h PI indicating lack of complete recovery from the disease.

AA digestibility and ENL rapidly and markedly change in pigs experimentally infected with Salmonella and exhibiting an initial diarrhea response. Pig AA digestive capacity appears not to be fully restored 70-78 h PI compared to pre-infection values.

Diets containing highly digestible proteinaceous sources should be considered for pigs afflicted with enteric pathogens and infections in general.

Price K et al. 2010. J. Anim. Sci. 88:3896-3908; Stein H et al. 2007. J. Anim. Sci. 85:172-180; Wubben J et al. 2001. Contemp. Top. Lab. Anim. Sci. 40:27-31.

Keywords. Amino acid, digestibility, Salmonella.