3. The effect of graded levels of palm oil on N digestibility and N balance

Authors: Chhay Ty, Preston T R  and  Ly J 2003.

Livestock Research for Rural Development (15) 7 Retrieved, from http://www.cipav.org.co/lrrd/lrrd15/7/chha157.htm

Summary: The experiment was carried out in the ecological farm of the University of Tropical Agriculture Foundation (UTAF), located in Chamcar Daung, in the outskirts of Phnom Penh , Cambodia . The ambient temperature was about 35 0 C in the middle of the day (12:00) during the trial in May 2002. Cassava leaves were harvested after 4.5 to 5 months of growth from farmer's fields in Kandal province. Stems and petioles were removed from the leaves and then the leaves was sun-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 bags, inside rigid plastic containers. The bags were tightly closed to prevent air contact and stored for 30 days before feeding. Feed formulated contain 45% ensiled cassava leaves (DM basis), broken rice and fish meal, partially substituted by refined palm ( Elaeis guineensis, Jacq ) oil originally from Malaysia and currently available in the local market. The experiment was carried according to a 4*4 Latin Square arrangement of 4 dietary treatments with 4 Mong Cai x Large White castrate male young pigs weighing on average 9.6 kg. The animals were housed in metabolism cages during the whole trial. The metabolism cages (80 x 80cm) were built to allow the quantitative collection of faeces and urine. The pigs were fed thrice daily with equal rations at 8:00 am, 12:00 am and 3:00 pm. The cassava leaf silage was mixed with the other components of the ration. Feed intake was programmed to be 50 g DM/kg bodyweight, and water was permanently supplied through drinking nipples. The animals were weighed at the beginning of the trial and every ten days. Feed refusals and faeces were collected every day and were kept frozen in plastic bags until analysis. A representative sample was obtained from every type of thawed material after a careful homogenization. At the end of each period, feed refusals and faeces were mixed thoroughly by hand and then homogenized in a coffee grinder, prior to taking representative samples that were analysed for DM, N, Crude fibre, NDF, crude fat and ash. Urine was collected in a plastic bucket to which sulphuric acid was added to maintain the pH below 4.0. At the end of each period the volume was measured and a sample analysed for N.

Abstract: Four Mong Cai x Large White castrate male pigs weighing on average 9.6 kg were allocated at random into four diets to study the effect of graded levels (0, 5, 10 and 15% in dry basis) of refined palm oil introduced in diets of broken rice and ensiled cassava leaves to study nutrient digestibility and balance of N according to a 4x4 Latin square design. The silage was made from sun-dried, wilted, chopped leaves of cassava harvested after 4.5 to 5 months of growth. The cassava leaves were ensiled with 5% of sugar palm syrup and stored during 30 days in plastic containers of 100 kg capacity. The characteristics of the silage were pH 4.10, DM 50.7 %, ash 14.1, organic matter 85.9, NDF 47.0, crude fibre 35.3, and N 3.92 % in dry basis, respectively. The cyanide content of the silage was 110 mg/kg DM. Observed feed intake was slightly lower than that programmed (50 g DM/kg body weight) and was on average 45.6 g DM/kg body weight. A non significant slight increase of feed intake from 88.4 to 92.2% from that programmed was found with increasing levels of dietary palm oil. During the entire trial the pigs were in a positive body weight balance and there were no symptoms of animal discomfort. Dry matter and organic matter digestibilities were decreased as the level of dietary refined palm oil was increased.  Energy digestibility was not significantly influenced by graded levels of palm oil in the diet. In contrast, ether extract digestibility increased significantly (P<0.001) with increased levels of refined palm oil in the diet. The digestible energy content of the diets increased from 14.03 to 17.26 MJ/kg DM with increasing levels of palm oil. Neither N digestibility nor N retention was affected by the inclusion of refined palm oil in the diet. N digestibility was relatively low (overal mean, 66.7%) but N retention as related to N digested was high (overall mean, 82.7%). It is suggested that if refined palm oil is included in the diet up to 15% of the DM, there will be no adverse effect on nutrient digestibility and N balance of pigs fed diets based on high levels of ensiled cassava leaves and broken rice.

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