The identified trials provide only low quality evidence about the effects of feeding preterm infants  with protein hydrolysate versus st and ard formula .
The existing data did not support conclusions that feeding with protein hydrolysate affects the risk of feed intolerance or necrotising enterocolitis .
BACKGROUND When human milk is not available for feeding preterm infants , protein hydrolysate rather than st and ard cow 's milk formulas ( with intact proteins ) are often used because they are perceived as being tolerated better and less likely to lead to complications .
However , protein hydrolysate formulas are more expensive than st and ard formulas , and concern exists that their use in practice is not supported by high- quality evidence .
OBJECTIVES To assess the effect of feeding preterm infants with hydrolysed formula ( versus st and ard cow 's milk formulas )  on the risk of feed intolerance , necrotising enterocolitis , and  other morbidity and mortality in preterm infants .
Gastric emptying in preterm infants.
An ultrasonic technique was used to compare gastric emptying after a feed of expressed breast milk and formula milk in a blind , cross over study of preterm infants . Fourteen infants ( median gestational age 33 weeks ) were studied on 46 occasions . Each infant received a nasogastric feed of either expressed breast milk or formula milk , and the alternative at the next feed . Real time ultrasound images of the gastric antrum were obtained and measurements of antral cross sectional area ( ACSA ) were made before the feed and then sequentially after its completion until the ACSA returned to its prefeed value . The half emptying time ( 50 % delta ACSA ) was calculated as the time taken for the ACSA to decrease to half the maximum increment . On average , expressed breast milk emptied twice as fast as formula milk : mean 50 % delta ACSA expressed breast milk 36 minutes ; formula milk 72 minutes . The technique was reproducible and there was no significant difference between the emptying rates of feeds of the same type for an individual infant . These data show that breast milk has a major effect on gastric emptying , which may have important implication s for preterm infants who have a feed intolerance due to delayed gastric emptying
The identified trials provide only low quality evidence about the effects of feeding preterm infants  with protein hydrolysate versus st and ard formula .
The existing data did not support conclusions that feeding with protein hydrolysate affects the risk of feed intolerance or necrotising enterocolitis .
BACKGROUND When human milk is not available for feeding preterm infants , protein hydrolysate rather than st and ard cow 's milk formulas ( with intact proteins ) are often used because they are perceived as being tolerated better and less likely to lead to complications .
However , protein hydrolysate formulas are more expensive than st and ard formulas , and concern exists that their use in practice is not supported by high- quality evidence .
OBJECTIVES To assess the effect of feeding preterm infants with hydrolysed formula ( versus st and ard cow 's milk formulas )  on the risk of feed intolerance , necrotising enterocolitis , and  other morbidity and mortality in preterm infants .