TABLE 2

Gastrointestinal pH, emptying, transit time, and length in human term neonate compared with juvenile rat and pig

Data are representative of original study reports. Because of variability in study populations, measurement techniques, and reporting, ranges of observed values or ranges of means are provided. Healthy Term Neonate data replicated from Table 1.

	Human Term Neonate (GW 37+)	Juvenile Rat (Preweaning)	Juvenile Pig (Preweaning)
pH
Stomach
Fasted	2.0–6.1 (Mason, 1962; Fredrikzon and Hernell, 1977)	PND <15: 6.5^a	Göttingen minipig
		PND 15–21: decline to 4 (Ikezaki and Johnson, 1983)^a	PND 1–7: 4.3–5.3 (Van Peer et al., 2016)^a
			White X Landrace
			PND 26: 1.46–1.58 (Moughan et al., 1991)
Fed	5.2–7.5 (Mason, 1962; Fredrikzon and Hernell, 1977)	PND 9–18: 5.1 (Rodewald, 1976)^a	White X Landrace
			PND 26: 5.04–5.31 (Moughan et al., 1991)
Small intestine	5.8–7.0 (duodenum, fed) (Barbero et al., 1952)	PND 9–18: 6.2^a (duodenum), 6.3^a (jejunum), 6.9 (ileum) (Rodewald, 1976)	Göttingen minipig
			PND 1–7: 5.8–6.5^a (duodenum), 6.0–6.5^a (jejunum), 6.0–7.3^a (ileum) (Van Peer et al., 2016)
Large intestine	7–8.2 (cecum, fed) (Barbero et al., 1952)	PND 9–18: 7.4 (Rodewald, 1976)^a	Göttingen minipig
			PND 1–7: 6.0–7.5 (Van Peer et al., 2016)^a
Gastric emptying (t_1/2)
Water or aqueous	6.9 min (Lange et al., 1997)^{^b}	PND 1–2: ∼50 min (Heller, 1963)^{^c}	NA
Maternal milk or colostrum^{^d}	48 ± 15 min (Cavell, 1981)^{^e}	PND 10: 55 min (Tooley et al., 2009)^{^c}	Danish Landrace X Danish Yorkshire X Duroc
			PND 0: 20 min (Amdi et al., 2016)^{^c}
Milk formula	78 ± 14 min (Cavell, 1981)^{^e}	PND 10: 75 min (Tooley et al., 2009)^{^c}^,^{^f}	White X Landrace
			PND 26: 90–101 min (Moughan et al., 1991)^{^g}
Intestinal transit time
SITT	4 h^{^h}	ND	ND
OCT	1.2–2.0 h (Vreugdenhil et al., 1986)	ND	ND
Intestinal length
Small intestine	143–157 cm (Struijs et al., 2009)	PND 14–15: 39^a	Landrace
		PND 21–22: 55^a (Ghishan et al., 1980)	PND 0: 334^a
			PND 3: 481 (Wang and Xu, 1996)^a
			Göttingen minipig
			PND 1–7: 219–318 (Van Peer et al., 2016)^a
			White X Landrace
			PND 0: 359 cm^a
			PND 1–7: 426–575 cm (Buddington et al., 2001)^a
Large intestine (cecum plus colon, unless where indicated)	33–40 cm (Struijs et al., 2009)^ⁱ	PND 14–15: 4.9 ± 0.2 cm	Landrace
		PND 21–22: 7.5 ± 0.2 cm (Ghishan et al., 1980)	PND 0: 72.6^a
			PND 3: 87.5 (Wang and Xu, 1996)^a
			Göttingen minipig
			PND 1–7: 43.4–71.3 cm (Van Peer et al., 2016)^a

ND, No data.
^a Reported means.
↵^b Median.
↵^c Estimated from graphical representation of means; range not reported.
↵^d Species specific.
↵^e Reported mean and error (Cavell, 1981).
↵^f Rat milk replacer formula (Wombaroo Food Products, Glen Osmond, South Australia, Australia).
↵^g Simulated human infant formulae (cow’s milk, hydrolyzed cow’s milk, and soy based).
↵^h Reference value reported in ICRP (2002).
↵ⁱ Colon length only.