A third round of feeding trials conducted by a team of scientists from the U.S. Department of Agriculture's Agricultural Research Service (ARS) and Purdue University has again shown that the dietary supplement L-glutamine can naturally promote growth and wellness in pigs.

Jay S. Johnson, an animal scientist with the ARS Livestock Behavior Research Unit in West Lafayette, Ind., and his Purdue collaborators are investigating L-glutamine as a natural alternative to using dietary antibiotics, ARS said in an announcement. Swine producers were using antibiotics to help piglets cope with stressful events like being weaned from their mothers and then transported, which can lower young animals' immune function, feed intake and growth.

The team's investigation of L-glutamine, a naturally occurring amino acid found in the body and in food, is part of a broader research effort to identify suitable replacements for antibiotics that are just as effective, safe and economical to use, ARS added.

The latest study is an expansion of trials conducted in 2017 and 2018. As before, groups of piglets were weaned and then transported for 12 hours, simulating what they might experience in a commercial operation. After transport, the piglets were housed in a nursery barn. This time, the researchers supplemented the young animals' diets for 14 days with L-glutamine at one of five feed concentrations: 0.2%, 0.4%, 0.6%, 0.8% or 1.0%, ARS said. Another group of piglets also received feed with antibiotics (chlortetracycline and tiamulin) but no supplemental L-glutamine, and a final group received a non-supplemented diet.

ARS highlighted the following results, which were published in Translational Animal Science: