Nutrient profile and in-vitro digestibility of tubers in swine
In order to assure the sustainability of swine production in areas where traditional feed ingredients cannot be grown or fed to animals, it is important to study and develop alternative feeding systems. Tubers are grown widely in the tropics and are generally rich in starch, and thus have potential as an alternative energy source. Their use, however, is limited by limited information on nutritional value and digestibility. Five tuber samples grown in Hawaii [sweet potato-2, purple sweet potato (PSP) and Okinawan sweet potato (OSP), Dioscorea alata yam (yam), taro and cassava] were analyzed for their nutritional profile. In vitro digestibility of samples was determined using a 3-step enzymatic assay. On a DM basis, gross energy ranged from 3332 Kcal/kg (Taro) to 4272 (yam), sweet potatoes and cassava were in between (PSP-4137, OSP- 4157, and Cassava- 4196). CP content ranged from 3.4% (Cassava) to 13.6 (Taro), ether extract from 2.8% (PSP) to 14.5 (cassava), ADF from 5.7% (PSP) to 10.4 (Taro), NDF from 8.0% (PSP) to 11.5 (taro), ash from 2.0% (PSP) to 3.8 (Taro) and. In vitro DM digestibility of PSP (87.4%), OSP (87.1%) and cassava (82.3%) was significantly higher (P ˂ 0.05) than yam (30.0%), while taro was in between (66.0%). In conclusion, both sweet potato and cassava are rich in energy content with high in vitro DM digestibility and can be used as an alternative source of energy in swine diets, but protein needs to be supplemented as these tubers are low in protein.
Keywords: In vitro digestibility, tubers, swine