Effect of parenteral administration of glutamine on autophagy of liver cell and immune responses in weaned calves.

The objectives of this study were to determine the effects of an increased jugular supply of L-Gln on post-weaning growth, immune responses, intestinal morphology and autophagy of weaned calves. At 35 days of age, 24 Holstein calves (initial 50 ± 1.5 kg; 35 ± 2 day of age) were randomly allocated to four treatments, and each treatment included five male and one female calves. Holstein calves were assigned to treatments of (i) i.v. infusion of 2 l of 0.85% NaCl, Control group [C]; (ii) i.v. infusion of 8 g/day of L-Gln mixed with 2 l of 0.85% NaCl solution [L]; (iii) i.v. infusion of 16 g/day of L-Gln mixed with 2 l of 0.85% NaCl solution [M]; and (iv) i.v. infusion of 32 g/day of L-Gln mixed with 2 l of 0.85% NaCl [H]; The infusion was 2 h/day for each of 14 consecutive days starting on day 1 after weaning. Feed and water were freely available to all calves. All calves were killed on the 14th day post-weaning for measurements of autophagy of liver cell and intestinal morphology. Gln has no effect on dry matter intake (DMI) and average daily gain (ADG). Gln infusion increased quadratically the abundance of CD4+, monocyte and the ratio of CD4+/CD8+. The urea N, Gln and Glucose in plasma increased linearly with increasing Gln loads. Gln infusion increased quadratically villus height and crypt depth of intestine. The autophagy level of liver cell was improved with the Gln infusion dose increased.