Dietary lipids and fatty acids are not only fundamental in determining animal performance, but also determine the eating qualities of animal products. Several methods have been used to quantify fatty acid metabolism but most involve expensive in vitro approaches that are not suitable for most laboratories. Furthermore, there is considerable variation between methods with regard to enzyme activity, which makes comparison of results between studies difficult. The recently developed whole-body fatty acid balance method (WBFABM) is a simple and reliable in vivo method for assessing fatty acid metabolism, including rates of liponeogenesis and de novo fatty acid production, β-oxidation of fatty acids and bioconversion (elongation and desaturation) of fatty acids to long-chain polyunsaturated fatty acids. Initially developed for implementation with a fish model, the WBFABM has proven to be a simple and effective method that can be used in any laboratory equipped with a gas chromatography unit. Since its development, it has been used in several farmed finfish feeding trials and in broiler chicken feeding trials. The WBFABM is currently used at research institutions worldwide and its use is increasing in popularity among animal scientists. With this method, it is possible to track the fate of individual dietary fatty acids within the body. The WBFABM could contribute significantly to information generated by animal feeding trials.
As starch is the main energy source for animals fed grain-based diets, its rate and extent of digestion affects the efficiency of feed utilisation, feed intake and rate of gain. Characterisation by electron microscopy and solid state 13C NMR spectroscopy of undigested feed recovered from the ileum of pigs shows that some milled grain fragments can survive gastric and small intestinal digestion largely intact. In contrast, feeding of isolated (uncooked) maize starch granules results in essentially complete digestion by the mid-point of the small intestine. For milled grains, particle size is the dominant determinant of digestion rate in vitro, and the rate-determining step is proposed to be diffusion of a-amylase within the cellular structure of the endosperm. As the rate of granule digestion is much faster than the rate of enzyme diffusion through grain fragments of cereals used in animal feeds, starch gelatinisation per se is not required to increase ileal digestibility, even though starch gelatinisation is desirable for increasing a-amylase digestion rate. The beneficial effects of heat-moisture processing on grain digestibility in vivo may be due to the opening-up of grain structure, thereby reducing barriers to enzyme diffusion.
Feed processing technology is essential in the concept of sustainable precision livestock farming. This concept aims to optimize productivity and efficiency in pig production by an integrated approach taking into account as many relevant factors dealing with feed, animal, microbiota, farm and their interactions, as well as customer, consumer and societal demands. In this chapter relevant aspects are presented with the aim of identifying new opportunities. The focus is on feed manufacturing rather than processing of feed ingredients, both on an industrial and farm level.Physical treatments have been studied most intensively. Particle size reduction has shown to be of importance and results in more consistent effects than particle size uniformity. Nevertheless, the best strategy remains difficult to prescribe as the results indicate an optimum between 600 and 900 mu m, depending on several other factors involved. Correct mixing is also of importance but does not seem to be a critical factor in practice for at least fattening pigs and sows. Further processing of meal into pellets has proven to increase growth rate and feed efficiency under controlled pelleting conditions on average by 6 and 6-7%, respectively. The impact of other pellet characteristics on pig performance, such as diameter and the quality in terms of hardness and durability, is often unclear although the presence of fines in the pelletized feed has been proved to be undesirable.Relatively new are studies on microbiological treatments, such as fermentation. The concept of fermented liquid feed seems to be promising and several studies have shown beneficial effects such as improved gastrointestinal health and growth performance, and reduced mortality and morbidity in both piglets and fattening pigs. Unfortunately palatability, health and nutritional value can be affected by uncontrolled fermentation and amino acid degradation.In conclusion, feed processing technology is important both for minimizing feed production costs and optimizing pig health and performance. Although it offers many opportunities, more research is necessary for optimization of existing and development of new technologies. A potential bottleneck for innovation is the fact that implementation in practice often requires relatively large investments. Therefore, it is necessary to have better estimates and more quantitative data of the effects of feed processing technology on pig performance.
