Morphological characteristics of the duodenum of piglets fed with various feed additives

Abstract

Early weaning of piglets from the sow and a sharp transition to granular feeding usually leads to the development of feed stress. As a consequence, changes occur in the small intestine epithelium, which are associated with desquamation of the epithelium of the villi, crypt hyperplasia and atrophy of the villi, colonization of pathogenic microflora, which leads to a decrease in digestion and absorption of nutrients. Hence the aim of this study was to evaluate the effect of various feed additives on the morphofunctional state of the duodenal mucosa of piglets in the pre-weaning period. Forty piglets of the same age were involved in the experiment, which were divided into four groups of 10 head each. The first group of piglets was a control one and received a standard diet and free access to water from the 7th day of life. Additionally to their standard diet, the piglets of group II were given a drug which included a combination of live yeast of the genus Saccharomyces and a complex of 6 enzymes (proteases, cellulases, xylanases, α-amylases, β-glucanases and phytases) in the amount of 0.5 kg/t of feed. Piglets of group III received 0.2 kg/t of a feed additive consisting of a mixture of essential oils from plant extracts. Piglets of group IV were given a supplement with dry yeast and egg powder enriched with immunoglobulins. Piglets had constant access to feed and water. On the 14th and 28th day of the experiment, three piglets from each group were euthanized in compliance with ethical standards for animals used in experiments. According to the results of histological studies, it was established that the duodenum mucous membrane in piglets of all experimental groups was characterized by insignificant variability. Mostly, the villi had a leaf-like or finger-like shape. The crypts were mostly closely adjacent to each other. The muscle layer was well developed, represented by smooth muscles that diverged in the places where the excretory ducts of Brunner's glands pass. The lamina of the mucous membrane was represented by a loose connective tissue made of collagen fibers and, to a lesser extent, elastic fibers and small capillaries between which lymphoid cellular elements were located. The enterocytes of the apical surface of the villi had a well-defined brush border and elongated nuclei that occupied a third of the cytoplasm. Morphometric studies showed that, compared to the control group of piglets, the addition of feed additives with a mixture of essential oils increased the taste and smell of the feed, contributing to its better consumption, thus having a positive effect on the condition of the mucous membrane. On the 14th and 28th day, a significant increase in the height and width of the villi was noted. In piglets that received feed supplements with a combination of live yeast, positive dynamics were also observed in terms of increasing the ratio of villi height to crypt depth. Summarizing the experiment results, we can note that various feed additives had a positive effect on the condition of the duodenum mucous membrane, but the feed additive containing a mixture of essential oils from plant extracts was more effective.