Feeding of spinach or sweet-potato leaves and growth performance of growing pigs kept on smallholder farms in Central Vietnam.

We investigated whether the addition of either spinach or sweet-potato leaves to the diet of growing pigs, kept in small holdings in Central Vietnam, would improve growth performance. A control diet was formulated and mixed with each of the vegetables to a final concentration of 15% of the total dietary dry matter. The diets were fed to the pigs from 70 to 100 days of age on six different smallholder farms in Central Vietnam. There were three animals per treatment group per farm and biopsies of adipose tissue were analysed for their contents of alpha-linolenic, eicosapentaenoic and docosahexaenoic acids. The diets without and with vegetables contained on average 0.14 and 0.32 g alpha-linolenic acid per MJ metabolizable energy. The relative percentage of alpha-linolenic acid in adipose tissue was raised by the intake of the vegetables. Eicosapentaenoic acid was not detectable in adipose tissue and the level of docosahexaenoic acid was unchanged. There was a significant stimulatory impact of the intake of either spinach or sweet-potato leaves on growth performance of the growing pigs. It is suggested that an adipose tissue content of alpha-linolenic acid less than 1% of total fatty acids does not allow maximum growth in growing pigs.