Received: 1 November, 2011. Accepted: 1 November, 2012. Invited Mini-Review Fruit, Vegetable and Cereal Science and Biotechnology ©2012 Global Science Books Sweet Potato as Animal Feed and Fodder Sankaran Murugan 1* • Suresh Kumar Paramasivam 2 • Maniyam Nedunchezhiyan 3 1 Central Agricultural Research Institute, Port Blair-744 101, India 2 Central Tuber Crops Research Institute, Thiruvananthapuram – 695 017, India 3 Regional Centre of Central Tuber Crops Research Institute, Bhubaneshwar – 751 019, India Corresponding author: * kmsankaran@gmail.com ABSTRACT Alternative sources of livestock feed to spur livestock production and to free cereal supplies for human consumption are receiving closer attention. Sweet potato has higher biological efficiency as food and shows highest productivity (35-45 t ha -1 ). It has relatively short vegetative cycle (4-5 months). Hence, fits nicely into tight cropping systems. It also competes better with weeds than other root and tuber crops. The DM content of sweet potato varieties ranges from 21.70 to 34.78% which is more than cassava. Its tubers can be given to all ruminants as fresh, chopped tubers, dried chips and silage for energy supplements along with locally available grasses during the dry season. Sweet potato vine and foliage is a common feed for pigs, and other livestock, in many countries, including China, India, Indonesia, Korea, Philippines, Papua New Guinea, Taiwan, Uganda and Vietnam as protein supplement. The skin and leaf tips contain comparatively higher protein, 50-90% and 18-21%, respectively. Tubers also contain essential amino acids, with the exception of the sulfur-containing amino acids, especially cystine/cysteine. Digestibility of tubers appears to be a problem for some varieties that are grown under certain types of conditions. The digestibility of sweet potato carbohydrate fraction is reported to be above 90%. Selections of varieties with low trypsin inhibitor activities helps in expand the plant's potential for wider use as an animal feed. Sweet potato roots are the good source energy (3500 kcal kg -1 ) for poultry. Main reasons for adoption of dual-purpose sweet potato are economical viability, net returns and crude protein (CP) content of the fodder. _____________________________________________________________________________________________________________ Keywords: concentrate, dual purpose variety, root crops, silage, nutrition Abbreviations: CF, crude fiber; CP, crude protein; DM, dry matter; EE, ether extract; ME, metabolic energy; NFE, nitrogen free extract; PER, protein efficiency ratio CONTENTS INTRODUCTION...................................................................................................................................................................................... 106 CURRENT SCENARIO ON USE OF SWEET POTATO FOR FEED PRODUCTION IN DIFFERENT CONTINENTS ..................... 107 Asia........................................................................................................................................................................................................ 107 Africa..................................................................................................................................................................................................... 108 Latin America ........................................................................................................................................................................................ 108 POTENTIAL FOR SWEET POTATOES AS ANIMAL FEED.................................................................................................................. 108 Influence of socio-economic factors on spread of sweet potato............................................................................................................. 109 Sweet potato: a fitting tuber for feed and fodder purpose ...................................................................................................................... 109 Dual purpose sweet potato varieties as food and fodder ........................................................................................................................ 109 Sweet potato vine fermentation ............................................................................................................................................................. 110 Sweet potato in pig ration ...................................................................................................................................................................... 110 Sweet potato in poultry ration................................................................................................................................................................ 111 Sweet potato in ruminant ration............................................................................................................................................................. 112 CONCLUSION .......................................................................................................................................................................................... 112 REFERENCES........................................................................................................................................................................................... 112 _____________________________________________________________________________________________________________ INTRODUCTION Many developing countries are under increasing pressure to make more effective use of available resources in the agri- cultural sector both to satisfy the growing demand for live- stock products and to raise rural incomes by generating additional value addition through processing (Scott et al. 1993). The cost of balancing domestic demand for livestock products with feed or livestock imports has become prohib- itively expensive. The prospects for increasing in the output of cereals of the magnitude required to meet livestock and human requirements remain problematic. Consequently, alternative sources of livestock feed both to spur domestic livestock production and to free cereal supplies for human consumption are receiving closer attention. Sweet potato (Ipomoea batatas (L.) Lam.) is among the five most important food crops in developing countries in terms of total production (Phuc et al. 2001). Although the sweet potato is of New World origin, over 90% is produced in Asia; 85% in China alone. While sweet potato production and area planted in Africa practically doubled over the last three decades, they remain less than 5% and 15% respec- tively of developing country totals (FAO 2011). Latin Ame- rica accounts for about 2% of output and 3% of area planted. Sweet potato is cultivated for food in more than 100 countries. The area under cultivation was 8.5 million ha in 2009 and the worldwide tuber yield was 12648 kg/ha (FAO 2010). Sweet potato tuber is one of only seven world food crops with an annual production of more than 100 million metric tons. Average tubers yields are 5 t/ha in Africa, 10 t/ha in South America and 16 t/ha in Asia. Sweet potato tuber is considered a major staple food only in a few coun- ®