Association of glutamine supplementation during the early suckling period with growth, weaning, and lipopolysaccharide induced stress in low birthweight piglets

Glutamine (Gln) supplementation has been shown to improve bodyweight (BW) in suckling low birthweight (LBiW) pigs. However, it is not known if Gln has lasting effects on growth and stress resilience beyond the supplementation period in LBiW suckling pigs. Therefore, we explored if post-Gln supplementation LBiW pigs show reduced stress during weaning and a lipopolysaccharide challenge. Twenty pairs of male German Landrace littermate piglets, originating from 14 L with 12 to 22 (live and stillborn) piglets, were selected at birth (0 d of age). One littermate was LBiW (mean 1.10 ± 0.02 kg; n = 20; below the lowest BiW quartile of the FBN pig facility) and the other normal (NBiW; mean 1.48 ± 0.02 kg; n = 20; within the middle 50th BiW quartile) birthweight. At 24 h postfarrowing, litter sizes were standardized to 12 piglets, and experimental LBiW and NBiW piglets assigned to Gln (1 g/kg BW/d) or alanine (Ala: isonitrogenous control to Gln; 1.22 g/kg BW/d) supplementation groups (LBiW-Gln, LBiW-Ala, NBiW-Gln, and NBiW-Ala). Piglets were orally supplemented 3 times daily (0700, 1200, and 1700), from 1 to 12 d of age, and remained with their birth litter until weaning at 28 d of age. At 55 d of age, pigs were challenged with lipopolysaccharide (i.p. 100 µg/kg BW) and euthanized at 61 d of age. The piglets were weighed, and their abdominal circumference, crown-rump length, body mass index and ponderal index were determined. Plasma metabolites, amino acids, TNF-α, and white blood cell counts were also measured. At birth, LBiW pigs were lighter (P = 0.002), had a shorter crown-rump length (P = 0.02), a smaller abdominal circumference (P = 0.02), a lower body mass index (P < 0.001), and plasma glucose (P = 0.07) but higher inositol (P = 0.001) levels, than their NBiW littermates. From pre- (27 d) to postweaning (32 d), the lymphocyte percentage decreased, and the segmented neutrophil percentage and the neutrophil to lymphocyte ratio increased in LBiW-Ala (P < 0.001), NBiW-Ala and NBiW-Gln (P < 0.05) pigs. Postlipopolysaccharide-challenge, TNF-α was lower at 1 h in Gln than Ala-supplemented pigs (P < 0.05). In conclusion, LBiW piglets had zootechnical and metabolic markers associated with impaired development at birth, and supplementation with Gln moderately improved immune markers of stress during weaning, and reduced the TNF-α peak in LBiW and NBiW pigs during a lipopolysaccharide challenge. However, no effect on LBiW piglet bodyweight was observed.