Comparison of the pharmacological properties of the gut of the young animal with those of the adult
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Date
1966Author
Bywater, R. J.
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Abstract
The transition from foetal to nee-natal existence involves
an abrupt change in intestinal function. The relatively passive
role of the foetal gut must rapidly become that of a completely
adequate absorbing membrane (Moog, 1962) able to cope with all
nutritive requirements, and even, in some species, with absorption
of intact colostral antibodies.
Nevertheless, the nee-natal intestine has properties by no
means identical with those of the adult, since post-natal development
occurs both in morphology and function (Spencer, 1964). This
seems particularly true of herbivores.
Various aspects of the digestive system of the calf have been
investigated: digestive enzymes were studied by Huber et al (1958)
by killing calves at various ages and examining the enzymes present
in the gut. This showed that pancreatic lipase, protease and
amylase increased during the first post-natal week, intestinal
lactase decreased with age, and maltase remained static. The
dimensions of the various stomach compartments were studied by
Godfrey (1961) who found that the reticulo-rumen was still developing
at seventeen weeks, while the abomasum had stopped developing
at five weeks. Small intestine transit times were examined by
Smith (1964) who found no consistent changes between one and twenty
weeks of age, while Deutsch and Smith (1957) showed that antibody
absorption had largely ceased by twenty-four hours after birth.
.
Despite the work of the above authors and others, much of the
field remains unexplored. It was decided therefore to examine
the changes in motor activity of the intestine, and its responses
to drugs, in vitro and in viva (Section I) and also to examine an
aspect of the developing mucosa, namely alkaline phosphatase
activity (Section II).