SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES (SLU)

PhD studies supported by MEKARN

Sweet potato leaves for growing pigs; biomass yield, digestion and nutritive value

An, Le Van (2004) Sweet potato leaves for growing pigs. Doctoral diss. Dept. of Animal Nutrition and Management, SLU. Acta Universitatis agriculturae Suecia. Agraria vol. 470.

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Abstract

The aim of the present studies was to evaluate the potential of using sweet potato leaves (Ipomoea batatas (L.) Lam) as a protein source in diets for growing pigs. A number of sweet potato varieties were evaluated with respect to the biomass yield of the leaves, stems and tubers under different leaf harvesting intervals and defoliation techniques with the aim of selecting the best varieties for forage production. The biomass yields of leaves, stems and tubers were found to vary according to variety, season and defoliation technique. The best options in terms of leaf and stem production were a cutting interval of 20 days and a defoliation of 50% of the total branches. Defoliation reduced tuber production. Sweet potato leaves (SPL) had a crude protein (CP) content of 25.5-29.8% in dry matter, which was markedly higher than in the stems. The leaves can be preserved as feed for pigs by ensiling with either cassava root meal, sweet potato root meal or sugarcane molasses as additives. The optimum level of additive is 60 g kg-1 of the wilted sweet potato leaves. The digestibility in growing pigs of dry matter, organic matter (OM) and CP of ensiled sweet potato leaves was high, but that of crude fibre was low. Sweet potato leaves can be used for feeding pigs in fresh, dry and ensiled forms. The total tract and ileal digestibility values of CP, OM and neutral detergent fibre (NDF), and ileal digestibility of amino acids were not different among fresh, dry and ensiled sweet potato leaves. The mean ileal and total tract digestibility of the CP of sweet potato leaves was 74% and 76%, respectively. Sweet potato leaves are high in protein content compared to other protein-rich forages. Lysine is the first limiting amino acid. Growing pigs fed sweet potato leaves with addition of synthetic lysine had daily live-weight gains of 536 g day-1, which was similar to that of pigs fed a control diet with fish meal as the protein source (542 g day-1). However, without addition of lysine to the SPL diet daily live-weight gain was only 482 g day-1. It is concluded that SPL can be considered as a potentially valuable protein source for pigs. The leaves can be used fresh, dried or as silage, and can replace fish meal and groundnut cake as a protein source for growing pigs under small farm conditions in central Vietnam.

Keywords:	Biomass yield, Sweet potato leaves, Silage, Growing pigs, Ileal digestibility, Performance, Carcass characteristics
Agrovoc terms:	sweet potatoes, ipomoea batatas, leaves, silage, animal feeding, biomass, nutritive value, swine, carcass composition, viet nam
ISBN:	91-576-6750-0
Series.:	Acta Universitatis agriculturae Suecia. Agraria
ISSN:	1401-6249
Volume:	470
Papers/manuscripts:	I. An, L.V., Frankow-Lindberg, B.E. and Lindberg, J.E. 2003. Effect of harvesting interval and defoliation on yield and chemical composition of leaves, stems and tubers of sweet potato (Ipomoea batatas L. (Lam.)) plant parts. Field Crops Research 82, 49-58. II. An, L.V. and Lindberg, J.E. 2004. Ensiling of Sweet Potato Leaves (Ipomoea batatas (L.) Lam) and the Nutritive Value of Sweet Potato Leaf Silage for Growing Pigs. Asian-Australian Journal of Animal Sciences 17(4), 497-503. III. An, L.V., Hong, T.T.T. and Lindberg, J.E. 2004. Ileal and total tract digestibility in growing pigs fed cassava root meal diets with inclusion of fresh, dry and ensiled sweet potato leaves. Animal Feed Science and Technology 114, 127-139. IV. An, L.V., Hong, T.T.T., Ogle, B. and Lindberg, J.E. 2004. Utilisation of ensiled sweet potato leaves as a protein supplement in diets for growing pigs. Tropical Animal Health and Production. (In Press).
Number of pages:	47
Year of publication:	2004
Language:	eng
ID Code:	639
Deposited By:	EPSILON, Staff
Deposited On:	23 September 2004