The effect of dietary energy and protein interaction on the physiological plasticity of the small intestine of the young ostrich

Abstract

The study includes separate papers, which are all linked by their emphasis on the effect of different diets on the impact of the development of the small intestine of the young ostrich. This abstract is intended to provide readers with a broad overview of the outcomes of the study. Part 1: Yolk utilisation and the development of the small intestines Chapter 2 deals with the composition of egg yolk as it is absorbed by starved ostrich Struthio camelus L. ) chicks from one to seven days post-hatching and for ostrich (Struthio camelus L.) chicks from one to sixteen days post-hatching on a pre-starter broiler diet. Chapter 3 provides information on the intestinal enzymes of ostrich (Struthio camelus L. ) chicks from one to sixteen days post-hatching on a pre-starter broiler diet. The effect of growth on enzyme activity immediately post-hatching up to sixteen days of age was studied. Chapter 4 details a histological and morphological study of the gastrointestinal tract of ostrich (Struthio camelus L.) chicks from two to sixteen days post-hatching on a pre-starter broiler diet. The effect of growth on histological and morphological changes in the various parts of the small intestines was examined. Part 2: Influence on various pre-starter diets on growth and the development of the intestinal tract Chapter 5 discussed a growth and digestibility study of ostrich (Struthio camelus L.) chicks on eight different pre-starter diets. The performance, growth and physiological development of the chicks on high and low variations of different nutritional components were examined. Chapter 6 provides information on certain intestinal enzymes of ostrich (Struthio camelus L.) chicks on the eight different pre-starter diets. Chapter 7 dealt with the histological and morphological changes of the gastrointestinal tract of ostrich (Struthio camelus L.) chicks as a result of high and low variations of different nutritional components in prestarter diets. Implications The first part of this study revealed that although it appeared that yolk content was absorbed faster in starved ostrich chicks, intake of external feed had a positive influence on the absorption of fat from the yolk. The changes in the fatty acid composition of the yolk fat content that were observed may indicate that ostrich chicks have the ability to withdraw certain fatty acid components, especially unsaturated fatty acids. The digestive tract of ostrich chicks was compared with that of broiler chicks and differences observed in amylase and lipase activity between the birds in this trial and in poultry could be due to genetic differences between species. It could also be due to the genetic homogeneity of the poultry chicks that were used in the trials, whereas ostrich chicks have not been subjected to the same extent of advanced breeding improvement to date. Results on histological and morphological growth of the small intestines of the ostrich chick indicate increased absorption with an increase in age. The second part of this study revealed that ostrich chicks performed differently on diets formulated with different nutritional components. It appears that a high fat and low sugar content in the diet is advantageous in ostrich pre-starter diets. Although there were a few mortalities during the trials, there is no clear indication as to why the chicks died, as the causes of mortalities were not investigated. Differences in composition of the eight pre-starter diets did not seem to have an influence on the protein content or enzyme activity of the small intestines of ostrich chicks. An anti-nutritional factor within certain feedstuffs may, however, have had an influence on enzyme activity. Similar results were obtained for the histological and morphological parameters which were measured in chicks fed the different diets. There was no single diet that promoted intestine development, although it seemed as if the small intestines of the chicks fed the high protein diet were under higher digestive stress than those of the chicks fed the other diets.