4. The influence of type of palm oil and cassava leaf maturity on digestibility and N balance for growing pigs
Authors: Chhay Ty, Preston T R and Ly J 2003
Livestock Research for Rural Development (15) 8 Retrieved from
Summary : This experiment was carried out in the ecological farm of the University of Tropical Agriculture Foundation (UTAF) in the outskirts of Phnom Penh City , Cambodia . Mean environmental temperature was 30 o C at midday (12:00) during the trial from 28 July to 3 September 2002. Four Mong Cai x Large White castrate male pigs with an average initial body weight of 20.7 kg were used in the trial. The treatments arranged as a 2*2 factorial within a 4*4 Latin square were: Age of cassava leaves (old versus young) and type of palm oil (refined versus crude). Each experimental period consisted of five preliminary days when the animals were adapted to the diets followed by another five days for collection of faeces, urine and recording of feed refusals. The old leaves were harvested from cassava grown for root production in farmers' fields in Kandal province. The leaves were harvested when the plants were between 4.5 and 5 months old. The young leaves were harvested from a 2 month re-growth of cassava managed as a semi-perennial forage crop in the ecological farm of UTA. Both type of cassava leaves (after removing stems and petioles) were wilted for half a day before being chopped into small pieces and ensiled with 5% of sugar palm ( Borassus flabellifer ) syrup diluted with water 1:1 (fresh basis). Leaves and syrup were carefully mixed and stored in plastic containers tightly closed to prevent entry of air for 30 and 60 days for young and old leaves, respectively. Every container contained approximately 100 kg of fresh material. The diets were formulated to contain 45% (in DM) of the two types of ensiled cassava leaves and 15% of either refined or crude oil from oil palm ( Elaseis guineensis, Jacq ), the remainder being broken rice and fishmeal. The refined oil originated from Malaysia ; the crude oil was from the oil palm plantation in Cambodia (Mong Rethy Investment of Oil Palm in Cambodia ). A premix was purchased and added to all diets in recommended amounts according to NRC (1998). The pigs were fed thrice daily with equal rations at 8:00 am, 12:00am and 3:00pm. Feed refusals and faeces were collected every day during the last 5 days of each period and were kept frozen in plastic bags until analysis. At the end of every period, feed refusals and faeces were mixed thoroughly by hand, ground in a coffee grinder in the fresh state and, thereafter, representative samples were used for chemical analyses. Urine was collected in a plastic bucket to which a 10% solution of 4N sulphuric acid was added to maintain the pH below 4.0.
Abstract: Four Mong Cai x Large White castrate male pigs of mean initial weight 20.7 kg were allocated at random into four treatments according to a 4x4 Latin square arrangement to study the influence on digestibility indices of crude or refined palm oil and the maturity of cassava leaves prior to ensiling. The silage was made from sun-dried, wilted, cassava leaves harvested after 4.5 to 5 months of growth (from farmers' fields, managed for root production) and from young cassava leaves, which were harvested after 2 months of re-growth from the UTA ecological farm. The characteristics of the silages were pH 3.93, 4.00; DM 38.5, 34.2; NDF 25.4 and 23.5; CP 24.5, 23.6 in dry basis, for young and old leaves, respectively. The cyanide content of the silage was 200 and 97.2 mg/kg DM for young and old cassava leaf silage, respectively. Feed intake was on average 44.3 and 41.7g DM/kg bodyweight for young and old cassava leaf silage, respectively and 44.7 and 41.1g DM/kg body weight for refined and crude palm oil, respectively. There was no significant interaction (P>0.05) among any factors for digestibility indices between the maturity of the cassava leaves and type of palm oil. Digestibility was higher for young versus old cassava leaves for DM (P<0.001), organic matter (P<0.001), crude fibre (P<0.05), NDF (P=0.07), ether extract ( P<0.05), NFE (P<0.05) and energy (P<0.05). N balance indices also appeared to favour silage from young cassava leaves compared to old leaves. There was no significant effect of type of palm oil on nutrient digestibility or N balance indices. It is suggested that the nutritive value for pigs of ensiled cassava leaves can be improved if young instead of old leaves are used for ensiling. Crude palm oil could be used in those places where it is available instead of refined palm oil, thus avoiding the extra cost of refining the product.