Fatty acid supply of growing pigs in Central Vietnam

Abstract

This thesis concerns the influence of essential dietary fatty acids on the fatty acid composition of adipose tissue and growth performance of growing pigs kept on samll holdings in Central Vietnam. Essential fatty acids cannot be synthesized by the body and have to be ingested with the feed. There are two families of essential polyunsaturated fatty acids (PUFAs) that cannot be metabolically interconverted. Linoleic acid (LA; C18:2 n-6) is the parent compound of the n-6 PUFAs and aleph-linolenic acid (ALA; C18:3 n-3) that of the n-3 PUFAs. In the body, LA can be converted into the n-6 PUFA arachidonic acid (AA; C20:4 n-6) and ALA can be elongated and desaturated to eicosapentaenoic acid (EPA; C20:5 n-3) and docosahexaenoic acid (DHA; C22:6 n-3). The n-6 and n-3 PUFAs are essential structural components of the cell membranes and are precursors of eicosanoids, compounds affecting functions such as immunity, platelet aggregation and vasoconstriction. It is well-known that the quantitative intakes of n-6 and n-3 PUFAs are reflected in the adipose tissue of non-ruminants. This implies not only that the fatty acid composition of adipose tissue can be modulated by diet, but also that the adipose tissue composition can be used as an index of the qualitative PUFA intake. The LA requirement of growing pigs has been set at 0.08 g/MJ metabolizable energy (ME), but the requirement of ALA is not known. The present research shows that the intakes of LA, ALA, EPA or DHA are directly correlated with their concentrations in adipose tissue of growing pigs, and the correlations can be expressed in the form of equations with high degree of predictability. The current recommended intake of LA for growing pigs, i.e. 0.08 g/MJ of metabolizable energy, may be too low to support maximum growth in growing pigs in Central Vietnam, their LA intake required for maximum growth being about 2 g/MJ. ALA intakes up to an intake level of 0.3 g/MJ may increase average daily gain (ADG) in pigs kept on the Vietnamese farms. Based on a literature survey, it is concluded that the stimulatory effect of extra ALA intake on ADG pigs may not relate to improved disease resistance