Stomach Emptying of Milk Diets in Pigs. A Mathematical Model Allowing Description and Comparison of the Emptying Pattern

Abstract

The effect of doubling the nutrient intake in pigs fed a liquid cow's milk diet was investigated. This was done, either by doubling the volume given, or by doubling the dry matter content of the milk. There were two experiments in which the cumulative outflow of fresh contents, dry matter, crude protein and total carbohydrates, relative to the intake, was studied as affected by the treatments. This was done using pigs equipped with a simple duodenal cannula and an occluding balloon. The cumulative outflow curves indicated that the emptying process was biphasic both for the fresh contents and the nutrients emptied. A rapid emptying, followed by a period during which the emptying was inhibited was seen during the first emptying phase, the so called initial emptying. Thereafter the emptying was resumed again during the second phase: the final emptying. The individual emptying patterns were described very accurately by an adapted mathematical function with four parameters: y = c (1-2-(at)b)+dt3. The parameters c, b and a describe the initial emptying which is intrinsically exponential while d is descriptive for the final emptying. The appearance of the outflowing material, changing with time from unchanged milk, whey plus clot fragments, pure whey to whey with granular clot fragments indicated that the clotting of the milk was complete after about 15 min. The clotting certainly was responsible for the biphasic appearance of the emptying pattern. The emptying pattern of fresh contents was not related to the emptying pattern of dry matter and nutrients. Due to the rather high variability, there were no significant differences between the emptying patterns of dry matter and nutrients studied, although there were clear indications that crude protein was emptied at a slower rate than the other nutrients. Doubling the nutrient intake either by doubling the volume given, or by doubling the dry matter content of the milk did not change the initial emptying pattern to a great extent, except in the first experiment, where doubling the volume increased the relative amount of dry matter and nutrients emptied. A difference of gastric capacity related to a difference in age between the pigs used in the two experiments is thought to be the reason for this discrepancy. The relative amounts of dry matter and nutrients emptied during the final emptying phase on the other hand were inversily related to the amount of nutrients given.(ABSTRACT TRUNCATED AT 400 WORDS)