Trophic factors in natural milk are potential mediators of the rapid growth of intestine in neonates. To determine whether nursing stimulates growth and development of small bowel mucosa, litters of piglets were divided into suckled and artificially reared groups at birth. The latter animals were raised in an automated feeding device (Autosow) with an artificial diet simulating the nutritional composition of sow milk. At 2, 8, and 15 d of age, animals were killed and 10-cm segments of jejunum, mid-bowel, and ileum were removed. Mucosal homogenates were prepared for enzyme assay and measurement of mucosal mass. Mean body weight, total length of bowel, and circumference of bowel segments did not differ between the two feeding groups at any age studied. As anticipated, mean mucosal ornithine decarboxylase activity decreased (p p 3H-thymidine incorporation in Swiss 3T3 cells in vitro. Colostrum, but not artificial diet, stimulated greater incorporation of 3H-thymidine than culture medium alone (p in vitro. Neither epidermal growth factor nor IGF-I alone in colostrum appears to be required for this mitogenic effect.
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