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HUE UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY PHANTHAVONG VONGSAMPHANH CASSAVA BY-PRODUCT AS POTENTIAL FEED SOURCE FOR YELLOW CATTLE IN LAO PDR DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES HUE, 2019 HUE UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY PHANTHAVONG VONGSAMPHANH CASSAVA BY-PRODUCT AS POTENTIAL FEED SOURCE FOR YELLOW CATTLE IN LAO PDR SPECIALIZATION: ANIMAL SCIENCES CODE: 9620105 DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES SUPERVISOR 1: ASSOCIATE PROFESSOR DR NGUYEN XUAN BA SUPERVISOR 2: DR DINH VAN DUNG HUE, 2019 INTRODUCTION PROBLEM STATEMENT According to the MAF (2017), there are 1.98 million cattle in Lao PDR mostly dominated by indigenous "Yellow" cattle (Bos indicus) 95% of the total cattle population is owned by smallholders 297,000 of farm households or 38% of the total farm household have cattle The majority of the cattle production is based on low input integrated with various types of crop production systems at the household level Many rural households with cattle are currently best considered to be “livestock keepers” rather than “livestock producers" It is estimated that the five cassava starch factories have a yearly production of 55,000 tons of pulp and more than 200.000 tone of cassava pulp is stored in open pits (resulting in local pollution problems) Cassava foliage by-product from cassava plantation which annually is left in the field after root harvesting (around 1,250 tons from 63,260 of harvested area) (MAF 2017), in addition the availability of rice straw is million tons per year and brewers’ grains the residue of beer processing are around 150,000 tons per year from four brewery factories over the whole country All these all resources would be sufficient to fatten some 200,000 beef cattle per year with an added value to the Lao economy of USD $36 million In view of the decrease of natural resources and limitations in access to conventional feeds is timely to introduce cassava byproduct which is cheap and less competitive - cattle can convert it to a higher production yield and end product quality It has shown that cassava pulp composes 15.8-23.4% dry matter (DM) with 1.2-2.8% crude protein (CP), 55.0-74.4% nitrogen-free extract, 0.1-2.4% fat, 17.9-24.0% crude fiber and 1.7-2.8% ash, on DM basis (Yimmongkol, 2009; Pilajun and Wanapat, 2018), and according to Sriroth et al (2000) cassava pulp is rich in starch with 69% in DM, Keaokliang O et al (2018) reported the total digestible nutrients, digestible energy and ME contents of cassava pulp were 74.4%, 12.9 MJ/kg DM and 11.3 MJ/kg DM respectively, it suitable as the energy component of an intensive feeding system for fattening cattle it would need to be supplemented only with urea, a source of roughage and bypass protein and minerals, as has been demonstrated for other low-protein, carbohydrate-rich tropical feeds such as molasses(Preston 1971) and sugar cane (Preston et al., 1976; Ffoulkes and Preston 1978) Cassava foliage can be harvested from months old without any effect on average total biomass and storage root yields, with non-significant effects on both height and stem diameter (Munyahali et al 2017) For every tonne of roots that are harvested there are an additional 600 kg of stems and leaves which also have a high potential feeding value for cattle (Ffoulkes and Preston 1978; Wanapat et al., 1997), and goats (Ho Quang Do et al., 2002) The protein content in cassava leaves is around 22-25% in dry matter (DM), Cassava foliage also contains antinutritional factors (ANF’s) such as cyanogenic glucosides and tannins Cyanogenic glucosides can give rise to toxic hydroxyanic (HCN) by the action of either enzymatic activity in damaged plant tissue or within the digestive tract of the animal (Van Soest, 1994) The varieties used for industrial starch production are known as “bitter” varieties due to the high content of cyanogenic glucosides that are converted into the highly toxic hydrocyanic acid (HCN >50mg/kg as fresh), The cassava varieties that are planted for human consumption are known as “sweet” varieties as they have a lower content of (HCN < 50mg/kg as as fresh) Much research on evaluating the use of cassava for livestock feeding has thus concentrated on methods to reduce the HCN content, such as sun-drying and ensiling (Phuc et al 1995) Development of cassava by-product to cattle feed sources has been negligible and not been studied previously under Lao conditions especially cassava pulp storage in open pit THE OBJECTIVES OF THE STUDY To evaluate the potential of feeding value of the storage cassava pulp in an open pit To measure the response of cattle performance on bitter cassava foliage or/and brewers’ grains as a source of bypass protein and fiber supplements to cassava pulp-urea basal diet for feeding local yellow cattle To evaluate the effect of different varieties of cassava leaves and supplementation with brewers' grains (0 or 4%) on methane production in an in vitro production of cassava pulp – urea as the main substrate To find out the most efficient/economic methodology for incorporating bitter cassava foliage as the protein-fiber source in the cassava pulp for a cattle fattening system SIGNIFICANCE / INNOVATION OF THE DISSERTATION - Cassava pulp about 100.000 tones in open pit at cassava starch factory can be high potential feed in term of nutrition value and production for fattening cattle in Lao condition and could be used as basal diet The bypass protein and fiber source can be provided in the form of either: (i) brewers’ grains or: (ii) bitter cassava foliage combines with brewers’ grains (50:50) will give good performance In vitro rumen incubations of a substrate of cassava pulp showed that: methane production was decreased by: supplementation with cassava leaves of bitter rather than sweet varieties; and by the addition of low levels of brewers’ grains (4%) Cassava pulp through various methodologies such as separate, fermented and ensilage feed was shown to have potential for developing intensive fattening of cattle in feedlot and also in small holders in Lao PDR CHAPTER 1: LITERATURE REVIEW In this chapter, there are main points following (i) cattle production system in Lao PDR; (ii) cattle feed management; (iii) Challenge and opportunities for cattle production in Lao PDR; (iv) rumen microbial ecosystem; (v) manipulated feeding practices and (vi) cassava by-product for cattle feeding The literature review shows a potential to use cassava by-product as local feed resources for cattle production in Lao PDR for the purposes of increasing animal performance CHAPTER 2: CASSAVA PULP IN OPEN PIT AS POTENTIAL FEED FOR FATTENING CATTLE IN LAO PDR INTRODUCTION The Lao-Indochina Cassava Factory at Vientiane Capital, processes up to 100.000 tons per year of cassava roots into starch for export During the 6-7 month harvest season from October to March-April this amounts to 480 tons of roots daily The byproduct remaining after starch extraction, known as cassava pulp, represents from 10 to 15% of the original weight of fresh roots (Sriroth et al 2000) Over the past years, very little of the cassava pulp was bought by farmers and almost all of it had been stored in a pit adjacent to the factory, which had not been covered or protected in any way The cassava pulp is composed almost completely of non-structural carbohydrate, 65% of which is starch according to Sriroth et al (2000), and is very low in crude protein (less than 3% in the dry matter) and in minerals To take advantage of the high carbohydrate content of cassava pulp it should be supplemented with:  Fermentable nitrogen that will produce the ammonia needed to optimize the growth of the microbes in the rumen  Protein that will by-pass the rumen to complement that produced by the rumen microbes  A source of fiber that will act as the support structure for the formation of biofilms (Leng, 2014) which is where rumen microbes and their required nutrients come together to optimize the digestive process in the rumen The cheapest source of ammonia for rumen microbes is urea, which is produced and used as fertilizer One of the best sources of "bypass" protein is brewers’ grains (Promkot and Wanapat 2003), a by-product from the beer factory An excellent source of fiber is rice straw, most of which is presently burned, adding carbon dioxide to the atmosphere and thus contributing to global warming Minerals are required only in small quantities (1-2% of the feed), and are available locally or can be imported Sulfur is important as a component of the process of detoxification of HCN to thiocyanate MATERIALS AND METHODS Testing the pH, dry matter and nutritive value content The cassava pulp sampling was collected at the cassava factory from Lao-Indochina Group Public Company at Nashaw village, Vientiane Capital, taken over the pit was at a depth of 0.5 to 7.0 m Further tests were done on 16th of July 2014 taking consecutive samples as far as to the bottom of the pit using a 10cm diameter PVC tube 8m long, collected in points of open pit Figure.1 cassava pulp sampling points were taken points, for the corner and for middle In vitro gas and methane production A sample of the cassava pulp was taken at 2.5m depth to determine in vitro gas production according to the method developed The sample had a pH of 3.5 In the in vitro test it was compared with fresh whole cassava root Urea and cassava leaf meal were added to both substrates (Table 1) There were two replicates of each of the treatments (cassava root and cassava pulp) Fresh cassava root was chopped into small pieces 1-2 cm of length, then ground (1mm sieve) by machine The cassava leaf was collected in the farm of Souphanouvong University; Luang Prabang and chopped into small pieces around 1-2 cm, then dried in an oven at 60°C for 24h and ground (1mm sieve) by machine Table Proportions of the substrates in the in vitro incubation Cassava root Cassava pulp Fresh cassava root 67.0 Cassava pulp 67 Urea 3.01 3.01 Cassava leaf meal 30.0 30.0 Total 100 100 Davis, Durwood 1959 Representative samples of the substrates (12 g DM) were put in each incubation bottle, after which were added 960 ml of buffer solution (Table 2) and 240 ml of rumen fluid (obtained from a recently slaughtered buffalo in the local abattoir), prior to filling each bottle with carbon dioxide The bottles were incubated at 38ºC in a water bath for 24h Table Ingredients of the buffer solution Ingredients CaCl2 NaHPO4.12H2O NaCl (g/liter) 0.04 Tilly and Terry (1963) 9.30 0.47 KCl 0.57 MgSO4.7H2O NaHCO3 0.12 9.80 Cysteine 0.25 The gas volume was recorded over intervals of 0-6hours, 6-12hours and12-24hours after incubation The methane concentration in the gas collected over each interval was measured with a Crowcon infra-red analyser (Crowcon Instruments Ltd, UK) At the end of the incubation, the remaining substrate was filtered through cloth and the solid residue dried at 100C to determine the DM digested Feeding trail Eight local "Yellow" cattle (range 78 to 108 kg) were allocated according to live weight to two groups each of four animals They were fed a basal diet of ad libitum cassava pulp enriched with urea at the rate of 3% (DM basis) The experiment was done in the dry season (February -June 2015), 121 days Fresh Brewer’s grains were used as an alternative source of "bypass" protein (Promkot and Wanapat 2003) Rice straw was given as a source of “roughage” to stimulate rumen function A sulphur-rich mineral mixture (50% common salt, 25% dicalium phosphate,20% clacium carbonate, 5% sulphur) was provided ad libitum The urea was dissolved in water and sprayed on the cassava pulp Brewers’ grains and rice straw were offered separately Table Composition of the diet fed to the Yellow cattle Ingredient Fresh Ratio in kg/day 100 kg fresh 66.09 Cassava pulp 10 0.46 Urea 0.07 26.24 Fresh brewers’ grains 6.61 Rice straw 0.40 Minerals# 0.06 Ratio in 100 kg DM 54.2 1.7 21.7 21.0 1.4 These quantities were provided on the basis of 100 kg live weight They were increased proportionately as the animals increased in weight #50% common salt, 25% dicalium phosphate, 20% clacium carbonate, 5% sulphur Animal test The cattle were weighed before morning feeding at the beginning of the trial and every 14 days Feeds offered and refused were recorded daily Feed was sampled daily during the collection period and was composition prior to analyses Feed samples were collected weekly and divided into two parts, the first part be analyzed for DM, while the second part was kept and pooled at the end of each period for chemical analysis Samples were dried 60°C and ground (1mm screen) and then analyzed for DM, ash, EE and CP content (AOAC, 2002), NDF, ADF (Van Soest et al., 1991) Statistical analysis Data for gas production was analyzed by the GLM option in the ANOVA program of the Minitab (2010) software Sources of variation were treatments, replicates and error Regression equations were derived using Microsoft Excel software The feeding data were analyzed by the general linear model option of the ANOVA program in the Minitab (2000) software (version 16.0).Live weight gain was determined by the linear regression of live weight (Y) on days in the experiment (X) RESULTS AND DISCUSSION pH and chemical composition of cassava pulp All samples taken from the pit had a consistent pH below 3.5 and appeared to be perfectly stable as silage (Figures and 2) Due to compression of the pulp inside the tube, as this was forced to the bottom of the pit, the recovered samples most probably represented material over the whole range of depth of 0.5 to 7.0m The chemical compositions of cassava pulp, DM content is between 20.00 and 31.41 %, CP 2.28%, NDF 35% and ADF 28.4% Figure Changes in dry matter content of the pulp at increasing depth in the pit Figure Changes in pH of the pulp at increasing depth in the pit The chemical composition Table The chemical composition of cassava pulp in difference collected point Chemical Point Point Point Point Point SEM p-value composition DM 23.53 23.44 22.54 22.91 22.22 0.42 0.82 …………………………%DM…………………………… Crude protein 1.75 1.92 2.08 1.95 2.02 0.03 0.10 NDF 27.61 28.73 28.30 29.27 26.97 0.50 0.64 ADF 23.53 23.44 22.54 22.91 22.22 0.42 0.82 The chemical composition shown in table shows that DM, CP, NDF and ADF are no significant differences at any of the sample points In vitro gas and methane production There were no differed for total gas production, methane in the gas and DM mineralized among the treatments, but there was higher for cassava root as basal substrate supplemented with urea and cassava leaf meal compared with cassava pulp (Table 5) Table Mean values for gas production, methane in the gas and DM mineralized in the in vitro incubation of cassava pulp and cassava root supplemented with urea and cassava leaf meal Gas production, ml Cassava pulp Cassava root SEM p-value 0-6h 6-12h 12-24h Total CH4, % DM mineralized,% 365 775 835 1975 23.5 66.5 385 840 960 2185 25.5 67.3 14.1 10.6 17.7 42.3 2.12 0.53 0.5 0.14 0.12 0.18 0.63 0.38 Figure Gas production from cassava pulp and cassava root supplemented with urea and cassava leaf meal Total gas production over 24 h tended (p