Replacing Dietary Antibiotics with 0.20% L-Glutamine in Swine Nursery Diets: Impact on Health and Productivity of Pigs Following Weaning and Transport during the Summer

Recently, our lab determined that supplementing nursery diets with 0.20% L-glutamine improved health and productivity of weaned and transported piglets in a controlled environment. Therefore, study objectives were to determine the impact of replacing dietary antibiotics with 0.20% L-glutamine on growth performance and health status of piglets following weaning and transport in a production environment during the hot summer months. In July 2016, 246 mixed sex piglets [5.64 ± 0.37 kg BW; Duroc x (Landrace x Yorkshire)] were weaned (19 d of age), loaded onto a trailer, and transported for 12 h. During transport, ambient temperature (28.5 ± 0.3⁰C) and relative humidity (61.6 ± 1.1%) in the trailer were monitored in 5 min intervals, feed and water were withheld, and intra-abdominal temperature of 6 sentinel piglets was monitored every 10 min (39.7 ± 0.1⁰C). Following transport, 240 piglets were unloaded, blocked by BW, and randomly allotted to 1 of 3 dietary treatments [n=10 pens/treatment (8 piglets/pen)]. Treatments were dietary antibiotics [A; chlortetracycline (441 mg/kg) + tiamulin (38.6 mg/kg)], no dietary antibiotics (NA), or 0.20% L-glutamine (GLU) fed for 14 d (Period 1). Following Period 1, all pigs were provided a common antibiotic free diet until d 34 (Period 2). Data were analyzed using PROC MIXED in SAS 9.4. In Period 1, ADG tended to be greater (P=0.06) in A (234 ± 11 g/d) compared to NA (194 ± 11 g/d), with GLU (213.0 ± 11 g/d) being intermediate and not different from A and NA pigs. During Period 2, ADG increased (P=0.03) in A (455 ± 9 g/d) versus NA (420 ± 9 g/d) pigs; however, no differences were observed in GLU (443 ± 9 g/d) compared to A and NA pigs. Overall, A and GLU increased ADG (P<0.01; 359 ± 8 g/d) compared to NA (329 ± 8 g/d), but no differences were detected between A and GLU pigs. Feed efficiency was improved overall (P=0.03) for A (681 ± 13) compared to NA piglets (633 ± 13); however no G:F difference was detected for GLU (647 ± 13) versus A and NA pigs. No ADFI differences (P>0.11; 538 ± 13.1 g/d) were detected. Treatments for enteric challenges were greater overall (P=0.02) in NA (4.9 ± 1.5%) compared to GLU (1.5 ± 1.5%) and A (1.5 ± 1.5%) piglets. In conclusion, 0.20% L-glutamine supplementation improved piglet health and productivity similarly to dietary antibiotics following weaning and transport during the summer.