Experimental Animal Nutrition
Refining early feeding strategies for premature infants is essential for mitigating adverse outcomes of prematurity. In neonatal term piglets, continuous feeding blunts growth compared to intermittent bolus feeding. Our objective was to determine the impact of feeding modality on lean growth in preterm pigs. We hypothesized that intermittent bolus feeding can mitigate low lean growth rates in preterm neonates compared to continuous feeding.
Pigs obtained by C-section (105 d gestation; 952 ± 205 g body weight) were fitted with an umbilical artery catheter (later replaced with jugular vein catheter) and an orogastric tube for parenteral and enteral nutrition, respectively. Pigs were assigned to continuous (CONT; 7.5 mL/[kg·h]) or intermittent bolus (INT; 30 mL/kg every 4 h over 15 min) feeding for 21 d. Pigs initially received parenteral nutrition and were advanced to full oral feeds over 6 d (220 kcal/kg and 16 g/kg protein per day). Body composition (by DXA), plasma insulin, and skeletal muscle anabolic signaling and fractional protein synthesis rates (PS; L-[ring-2H5]phenylalanine) were determined in INT pigs in the postabsorptive (before a meal, INT-PA; n = 13) and postprandial (after a meal, INT-PP; n = 16) states and in CONT pigs (n = 14).
Results : Body weight gain, lean mass, and fat mass did not differ between INT and CONT pigs. Insulin was lower before feeding for INT pigs than CONT pigs (P < 0.05). Insulin increased with feeding for INT pigs and exceeded that of CONT pigs at 30 and 60 min (P < 0.01) before returning to baseline levels at 240 min. In the longissimus dorsi (LD), gastrocnemius, and soleus muscles, the abundance of the eIF4E·eIF4G complex, which is required for translation initiation, was greater in INT-PP and CONT pigs than INT-PA pigs (P < 0.01), but did not differ between INT-PP and CONT pigs. PS in the LD muscle was greater in INT-PP pigs than INT-PA pigs (P < 0.01), but did not differ between INT-PP and CONT pigs.
Continuous feeding does not blunt translation initiation and protein synthesis in skeletal muscle compared to intermittent bolus feeding in preterm piglets. The resulting absence of enhanced lean growth with intermittent bolus compared to continuous feeding contrasts with term piglets and may be a consequence of prematurity.
Funding Sources :
USDA CRIS 6250-51000-055, NIH HD072891, and USDA NIFA 2013-67015-20438.